EPA-460/3-74-021
DECEMBER 1974
A REVIEW
OF CONTROL STRATEGIES
FOR IN-USE VEHICLES
I'.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and W.8!e Management
Mobile Source Air Pollution Control
Emiaaion Control Technology Division
Ann Arbor, Michigan 48105
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EPA-460/3-74-021
A REVIEW
OF CONTROL STRATEGIES
FOR IN-USE VEHICLES
by
"The Environmental Programs Group
The Aerospace Corporation
and
The Emission Control Technology Division
U.S, Environmental Protection Agency
Contract No. 68-01-0417
EPA Project Officer: F. Peter Hutchins
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Mobile Source Air Pollution Control
Emission Control Technology Division
Ann Arbor, Michigan 48105
December 1974
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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the
Air Pollution Technical Information Center, Environmental Protection
Agency, Research Triangle Park, North Carolina 27711; or, for a fee,
from the National Technical Information Service, 5285 Port Royal Road,
Springfield, Virginia 22161.
This report was furnished to the Environmental Protection Agency by
The Aerospace Corporation, in fulfillment of Contract No. 68-01-0417.
The contents of this report are reproduced herein as received from The
Aerospace Corporation. Mention of company or product names is not
to be considered as an endorsement by the Environmental Protection
Agency.
Publication No. EPA-460/3-74-021
11
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FOREWORD
This report, prepared by The Aerospace Corporation for the
Environmental Protection Agency (EPA), Division of Emission Control
Technology, presents the results of a review of studies and evaluations made
by the EPA and various state agencies of the technical feasibility, emission
reduction effectiveness, and costs associated with implementing various
approaches for reducing the emission of air pollutants from automobiles
currently in use. These approaches include: inspection/maintenance pro-
grams, retrofit programs, and the conversion of in-use vehicles to permit
the use of gaseous fuels.
All of these control strategy topics were previously addressed by
EPA in a 1972 report entitled Control Strategies for In-Use Vehicles. * EPA
also provided further guidance to the States in 1973 by publishing estimates of
emission reductions that are likely to be achievable through application of
inspection, maintenance, and retrofit measures for in-use light duty motor
vehicles.**
Since the preparation and publication of the above-cited EPA
reports, there have been continuing EPA and State agency-sponsored programs
that have added to the state of knowledge concerning the in-use control
strategies for light duty vehicles. Therefore, the present report has been
prepared to supplement the above-cited EPA reports by summarizing the
more recently acquired data and by presenting cost and cost-effectiveness
values for the various in-use control strategy options.
U.S. Environmental Protection Agency, Office of Air and Water Programs,
Mobile Source Pollution Control Programs, Washington, D. C. 20460
(November 1972).
"Appendix N - Emissions Reductions Achievable Through Inspection,
Maintenance, and Retrofit of Light Duty Vehicles," Federal Register,
Vol. 38, No. 110 (Friday, June 8, 1973).
111
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A brief introductory statement and a summary of the major
findings are presented in Section 1 of the report. In Section 2, the major
aspects of the several approaches available for inspection/maintenance pro-
grams, including a detailed discussion of program implementation considera-
tions, are presented. The retrofit of both light and heavy duty vehicles with
emission control systems or devices are discussed in Section 3, and the
applicability and characteristics of the conversion of in-use vehicles for
gaseous fuel operation are examined in Section 4.
IV
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ACKNOWLEDGMENT
Appreciation is acknowledged for the guidance and assistance
provided by Mr, F. P. Hutchins of the Environmental Protection Agency,
Division of Emission Control Technology, who served as EPA Contract
Project Officer for this study. Appreciation is also acknowledged for the
various DECT members who reviewed the study progress and provided
technical guidance, including Harold Davis and Andrew Kaupert.
The following technical personnel of The Aerospace Corporation
made valuable contributions to the review and analyses performed under this
contract.
M. G. Hinton
A. Burke
F. Augustine
L. Forrest
W. M. Smalley
T. lura
Approved by:
eltzer, Group Director
vironmental Programs Group
Directorate
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CONTENTS
FOREWORD iii
ACKNOWLEDGMENTS v
1. OVERVIEW 1-1
1. 1 Introduction 1-1
1. 2 Summary of Major Findings 1-4
REFERENCES 1-23
2. EMISSION INSPECTION AND MAINTENANCE
APPROACHES 2-1
2. 1 Introduction 2-i
I
2. 1. 1 Types of I/M Approaches 2-1
2. 1.2 Criteria for Evaluation of I/M
Approaches 2-2
2.2 Emission Inspection Procedures 2-6
2.2. 1 Alternative Short Emission Test
Procedures 2-6
2.2.2 Relatability and Discrimination Charac-
teristics of Short Emission Test
Procedures 2-8
2.3 Alternative Maintenance Procedures 2-16
2. 3. 1 Engine and Emission Control System
Diagnostic and Parameter Tests and
the Sensitivity of Emissions to
Particular Malfunctions 2-18
2.3.2 Maintenance Phase Tune-up/Repair
Procedures 2-29
2.4 Emission Reductions and Repair Costs of
Alternative I/M Approaches 2-37
2.4.1 Emission Reductions Obtained Using
Alternative I/M Approaches 2-37
2.4.2 Repair Costs for Serviced Vehicles 2-43
VI1
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CONTENTS (Continued)
2. 5 Deterioration of Emissions With and Without
Periodic I/M .................. .......... 2'46
2. 5. 1 Deterioration of Emissions with Voluntary
Maintenance ...................... 2-47
2.5.2 Effective Emission Reductions Resulting
from I/M Programs ................. 2-47
2.6 Cost Effectiveness of Alternative I/M Approaches . . . 2-54
2.6.1 Cost Effectiveness Criteria ............ 2-54
2.6.2 I/M Program Costs ................. 2-55
2.6. 3 Comparison of the Cost Effectiveness of
Various I/M Approaches .............. 2-58
2.7 I/M Program Implementation Considerations ...... 2-64
2.7. 1 Initial Planning and Tradeoff Studies ...... 2-64
2.7.2 Development and Passage of Enabling
Legislation ....................... 2"9°
2.7.3 Engineering and Administrative Studies .... 2-93
2.7.4 Pilot Program Construction and
Procurement ..... . ...... • • ........ 2-94
2.7.5 Pilot Program Operation ...... . ....... 2-94
2.7.6 Planning for Full-Scale Program ........ 2-95
2.7.7 Full-Scale Program Construction and
Procurement ...................... 2-96
2.7.8 Full-Scale Program Operation . . . . ...... 2-96
2.7.9 Ongoing Licensing and Quality Control
Program ....... .... ............. 2-96
2.8 I/M of Heavy Duty Vehicles . . . . .............. 2-97
REFERENCES. ................................... 2'112
3. RETROFIT OF EMISSION CONTROL SYSTEMS/DEVICES
FOR IN-USE VEHICLES ....... .................. 3-l
3. 1 Introduction
Vlll
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CONTENTS (Continued)
3. 1. 1 Control of Exhaust Emissions 3-1
3.1.2 Control of Crankcase Emissions 3-1
3.1.3 Control of Evaporative Emissions 3-3
3. 1.4 Criteria for Evaluation of Retrofit Emis-
sion Control Systems /Devices 3-3
3.2 Evaluation of Retrofit Emission Control Systems .... 3-5
3. 2. 1 Exhaust Emission Control 3-5
3.2.2 Crankcase Emissions 3-34
3.2.3 Evaporative Emissions 3-35
3. 3 Implementation of Retrofit Strategies for Light
Duty Vehicles 3-39
3.3.1 Introduction 3-39
3.3.2 Selection and Certification 3-39
3.3.3 Cost and Financing 3-40
3.3.4 Implementation Scheduling 3-40
3.4 Retrofit Emission Control for Trucks 3-42
3.4. 1 General Considerations 3-42
3.4.2 Retrofit of Gasoline-Fueled Trucks 3-45
3.4.3 Retrofit of Diesel Powered Trucks 3-57
3.4.4 Implementation of Retrofit Programs for
Trucks 3-59
REFERENCES 3-62
4. CONVERSION OF IN-USE VEHICLES FOR GASEOUS
• FUEL OPERATION ' 4-1
4. 1 Introduction 4-1
4.2 Description of Gaseous Fuel Systems 4-2
4. 3 Emission Reductions Attainable through Gaseous
Fuel Conversion 4-6
4. 4 Initial and Operating Costs 4-9
IX
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CONTENTS (Continued)
4. 5 Cost Effectiveness of Emission Reduction through
Conversion to Gaseous Fuels 4-12
4.6 Other Aspects of Gaseous Fuel Conversion 4-14
4. 7 Usefulness of Gaseous Fuel Conversion as an
In-Use Vehicle Emission Control Strategy 4-15
REFERENCES
4-19
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FIGURES
2-1. Speed and Time Characteristics of Short Urban Cycles 2-11
2-2. Typical Key Mode Report Card 2-35
2-3. Hydrocarbon Levels vs Population Percentage 2-40
2-4. Carbon Monoxide Levels vs Population Percentage 2-41
2-5. Emission Reduction Effectiveness as a Function of
Rejection Rate 2-42
2-6. Average Vehicle Repair Cost 2-44
2-7. Effect of Maintenance on Emission Deterioration with
Vehicle Age 2-48
2-8. Key Mode Double-Lane Configuration and Mobile
Test Facility 2-73
2-9. Estimated Time Required for Implementation of State -
Owned Inspection Lanes Using Idle or Loaded Mode Tests . . . 2-91
2-10. Variation of Emission Levels with Inertia Test Weight 2-101
2-11. Vehicles in Fleets of 10 or More 2-108
3-1. Typical Spark Ignition Engine Exhaust Emission vs
Air/Fuel Ratio (Gasoline) 3-25
3-2. Location of Evaporative Control System Components 3-37
4-1. Schematic Diagram for Dual Fuel Operation with
LPG and Gasoline 4-3
XI
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TABLES
1-1. Summary of In-Use Vehicle Emission Control Strategies
Proposed in State Implementation Plans (January 1974) .... 1-3
1-2. Summary of Typical Emission Reductions and Repair
Costs for Various Rejection Rates and I/M Strategies ..... 1-8
1-3. Comparison of the Cost Effectiveness of Various I/M
Approaches .................................. j_g
1-4. Major Steps Involved in Implementation
of I/M Program ................ ..... ..... 1-11
1-5. Maximum Emission Reductions and Fuel Penalty for
Various Retrofit Strategies on Vehicles of Differing
GVW .............................. 7 ....... 1-13
1-6. The Cost Effectiveness of Various Retrofit Strategies
on Vehicles of Differing GVW ...................... i-14
1-7. Emission Levels and Reductions Obtainable Through
Single-Fuel Gaseous Conversion .................. . 1-17
1-8. Summary of Cost Effectiveness Information for Gaseous
Fuel Conversion .............................. 1-19
1-9. Comparison of the Emission Reduction Potential and Cost
Effectiveness of In-Use Vehicle Control Strategies
(Light Duty Vehicles) ........ . .................. 1-21
2-1. Summary of Major Features of I/M Studies Conducted
to Date ..................................... 2-4
2-2. Characteristics of Short Test Procedures for Emission
Inspection .................................... 2-9
2-3. Load and Speed Conditions for the Key Mode Test ........ 2-10
2-4. Advantages and Disadvantages of the Unloaded Idle Test
Procedure .................................. 2-10
2-5. Advantages and Disadvantages of Key Mode Test
Procedure ........... ..... . .............. 't 2-12
Xlll
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TABLES (Continued)
2-6. Advantages and Disadvantages of Various Loaded
Short Urban Test Cycles 2-13
2-7. Maintenance Approaches in Various I/M Strategies 2-17
2-8. Summary of Engine and Emission Control System
Diagnostic Tests and Associated Equipment/
Instruments 2-21
2-9. Effect on Emissions of Various Engine/Emission Control
System Component Malfunctions/Maladjustments 2-23
2-10. The Quantitative Effect of Minor Engine/Emission
Control System Malfunctions /Maladjustments on
Emissions 2-25
2-11. The Effect of Major Engine Malfunctions on Emissions 2-27
2-12. The Effect of Major Emission Control System Failures
on Emissions 2-28
2-13. Emission and Engine Parameter Distributions for Two
Vehicle Fleets . . . 2-30
2-14. Parts Replaced During Minimum Pollution Capability
Tune-Ups 2-31
2-15. EPA Estimated Emission Reductions for I/M Programs .... 2-53
2-16. Emission Inspection Lane Costs 2-56
2-17. Inspection Lane Utilization Data 2-57
2-18. Fuel Economy Changes of Repaired Vehicles 2-59
2-19. Summary of I/M Emission Reduction and Cost Effective-
ness for Idle Emission Test/Repair and Mandatory
Maintenance 2-61
2-20, Summary of the I/M Emission Reduction and Cost
Effectiveness for Key Mode Emission Test/Repair
Procedures 2-62
XIV
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TABLES (Continued)
2-21. Major Steps Involved in Implementation of I/M
Program ...............
.................... 2-65
2-22. New Jersey-Approved Manufacturers of Low Cost
Infrared Analyzers Suitable for Use in Repair
Garages ......
* ........................ ........... 2-72
2-23. Percent (National Averages) of In-Use Trucks in
Various Weight Classes ..........
2-24. Federal Emission Standards for Heavy Duty Engines ...... 2-99
2-25. Surveillance Study of Heavy Duty Engine Emissions
Over 12 Months . .
............................ 2-104
2-26. Maintenance of Trucks and Other Heavy Duty Vehicles ..... 2-106
3-1. Light Duty Vehicle Emission Control Requirements ....... 3_2
3-2. Estimated Emission Reductions for Retrofit of Light
Duty Vehicles ....... °
............................ 3-6
3-3. Emission Reduction from As -Received Baseline ......... 3.8
3-4. Emission Reduction from Tuned Baseline •> o
' ' ......... ... j -a
ReSultS' 1972 CVS C°ld Start Californ
a
3-18
3-6. Rebaselined Emissions, California Fleet (June 1974) ...... 3_19
3-7. Oxidation Catalyst and EGR Systems .............. 3_23
3-8. Emission Changes at Altitude (Denver, Colorado) ........ 3. 26
3-9. Retrofit Emission Control at High Altitude . . .• ..... ..... 3.28
3-10. Cost Effectiveness Summary, Light Duty Vehicles HC
Emission Reductions ............ *
***'•*••••••«.» J "* J 1
3-11. Cost Effectiveness Summary, Light Duty Vehicles CO
Emission Reductions .................... 3 --
xv
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TABLES (Continued)
3-12. Cost Effectiveness Summary, Light Duty Vehicles NO
Emission Reductions 3-33
3-13. Emission Values for Medium Duty Vehicles by Model
Year 3-44
3-14. Group Representative Vehicle-Engine Combinations
(Emission Control Devices - 1973 Models) 3-46
3-15. Experimental 23-Mode Emissions Test Schedule
(Heavy Duty Gasoline Engines) 3-49
3-16. Summary of Emission Reductions at Various Steady-
State Operating Conditions Using Retrofitted Catalyst
and EGR Systems 3-50
3-17. Summary of SWRI Heavy Duty Engine Retrofit Data 3-51
3-18. Estimated Emission Reductions for Retrofit of the 6000
to 10,000 GVW Class 3-52
3-19. Estimated Emission Reduction and Fuel Penalty Char-
acteristics of Retrofit Emission Control Systems for
Trucks 3-54
3-20. Estimated Cost Effectiveness of Various Retrofit
Strategies for Gasoline-Fueled Trucks 3-56
3-21. Comparison of the Estimated Cost Effectiveness of
Various Retrofit Strategies on Vehicles of Differing
GVW 3-58
3-22. Summary of Diesel Engine Emission Reductions Using
Various Retrofit Approaches 3-60
4-1. Properties of Gasoline and Gaseous Fuel Alternatives 4.4
4-2, Tankage and Range Comparisons 4-5
4-3. Emission Levels and Reductions Obtainable Through
Single-Fuel Gaseous Conversion 4-8
xvi
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TABLES (Continued)
4-4. Initial Costs for Conversion to Gaseous Fuels 4-10
4-5. Fuel Cost and Fuel Economy Data for Gaseous Fuel
Operation 4-10
4-6. Summary of Cost Effectiveness Information for Gaseous
Fuel Conversion 4-13
xvi i
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1. OVERVIEW
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1. OVERVIEW
1. 1 INTRODUCTION
1.1.1 Background
The Clean Air Act (Ref. 1-1) provides two basic strategies
for controlling air pollutant emissions from motor vehicles. The United
States Environmental Protection Agency is empowered to promulgate and
enforce emission standards applicable to new motor vehicles; this has been
done on an increasingly stringent basis since the 1968 model year. The
States are responsible for the establishment and enforcement of emission
control strategies that apply to vehicles in use, to the extent that limitations
on vehicular emissions beyond those resulting from the Federal new vehicle
standards are necessary for each State to achieve and maintain the National
Ambient Air Quality Standards.
In preparing their implementation plans for the achievement
of the air quality standards, a substantial number of States have determined
that the application of control strategies to in-use vehicles will be necessary
if the objectives of the Clean Air Act are to be achieved. A number of
alternatives are potentially available to the States to control emissions from.
in-use vehicles. These include programs of (1) periodic inspection and main-
tenance of vehicles to minimize excessive emissions that result from inadequate
or improper vehicle maintenance; (2) the retrofitting of emission control
systems to vehicles not originally so equipped, or the installation of more
effective emission control systems on vehicles already controlled; (3) the
conversion of motor vehicles to permit, their operation using gaseous fuels;
(4) the control of gasoline marketing hydrocarbon emissions; (5) restrictions
on the use and parking of vehicles and modification of traffic flow patterns;
(6) improvements and expansion of public transportation systems together
with incentives or restrictions to ensure the more extensive use of those
systems in place of private vehicles; (7) modification of social patterns that
1-1
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influence transportation patterns, such as work schedules; and (8) restriction
on land use to influence transportation needs and patterns.
The first four approaches either depend on the application of
emission control to the operation of individual vehicles without necessarily
altering the mode or frequency of use of those vehicles or on the control of
emissions from the gasoline marketing operations that service these vehicle!
these may be referred to as "hardware" approaches. In contrast, the other
approaches seek to modify vehicle usage patterns without altering the emis-
sions characteristics of the individual vehicles and can be seen to be comple*-
mentary to the hardware approaches. A summary of the hardware type in-u*
vehicle emission control strategies that have been included in the State impl«L
mentation plans (as of January 1974) for various cities and Air Quality
Control Regions (AQCRs) is given in Table 1-1.
1.1.2 Scope
This report deals with three hardware approaches to in-use
vehicle emission control, namely, inspection/maintenance programs,
retrofit programs, and the conversion of vehicles to permit the use of gaseo
fuels. The non-hardware approaches are discussed in other reports
(Refs. 1-2 through 1-5). This report presents the major results of recent
studies and evaluations made by EPA and various State agencies of the feasi
bility, emission reduction effectiveness, and costs of these hardware
approaches to in-use vehicle emission control. Thus, it supercedes previo
EPA publications covering these same topical areas (Refs. 1-6 and i-7).
In general, the emphasis of this report is on providing
emission reduction and cost data that may be useful to the States in evalua-
ting the alternative approaches to in-use vehicle emission control, as those
approaches may be applied to their particular air quality requirements. No
attempt has been made to identify a "best" in-use vehicle emission control
approach or an optimum combination of approaches. Such evaluations must
be performed on a region-by-region basis, taking account of the time perio1
1-2
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Table 1-1. Summary of In-Use Vehicle Emission Control Strategies
Proposed in State Implementation Plans (January 1974) a
City/AQCR
Boston
Springfield
NJ, NY, Conn.
Philadelphia
Baltimore
Pittsburgh
Nat. Capital Area
Chicago
Indianapolis
Cincinnati
Houston
Dallas, Ft. Worth
San Antonio
Denver
Salt Lake City
Phoenix, Tucson
San Francisco
Los Angeles
San Diego
Sacramento
San Joaquin
Portland
Fairbanks
Seattle
Spokane
Inspection/
Maintenance
LDVb
Le
Lg
Ig
I
L
I
L
I
I
I
I
I
I
I
X
L
L
L
L
L
I
I
I
I
HDVC
L
L
I
L
I
L
X
I
I
-
Retrofit Emission Control
Air
Bleed
Xf
X
X
X
X
X
X
X
X
X
X
X
NOX
Control
X
X
X
X
X
X
X
X
X
Oxid.
Catalyst
X
X
X
X
X
X
(taxis)
X
X
X
X
X
X
X
X
X
HDV
Included
X
X
X
X
Gasoline Vapor
Recovery d
X
X
X
X'
X
X
X
X
X
X
X
X
X
X
X
aThis table is extracted from EPA document No. EPA-450/2-74-004, dated April 1974. This document
is continually updated and should be referred to for changes to those strategies shown here
bLight duty vehicles (GVW < 6000 Ib)
GHeavy duty vehicles (GVW > 6000 Ib). In most cases, only medium duty vehicles (MDV < 10,000 Ib)
are included.
A 90-percent vapor recovery required
e
Loaded emissions test = L
Applicable = X
-Idle emissions test = I
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over which emission reductions must be achieved and the magnitudes of the
needed reductions, and using vehicle population data representative of the
area under consideration,
1.1.3 Organization of the Report
This report is organized into four major sections. In Sec-
tions 2 through 4, the subjects covered deal, respectively, with
inspection/maintenance programs, retrofit emission control programs,
and gaseous fuel conversion. The sections on inspection/maintenance
and retrofit programs include consideration of both light and heavy duty
vehicles. High altitude effects on retrofit device/system performance are
also included. Each of the major sections provides a detailed review of
available information relating to a particular emission control strategy
for in-use vehicles. Cost effectiveness, planning, and implementation
considerations are included in the discussion on each control strategy.
The major findings in each topical area are highlighted in the following
section, together with a comparison of the emission reduction potential and
cost effectiveness of the various hardware-type control strategies for
in-use vehicles.
1.2 SUMMARY OF MAJOR FINDINGS
In all cases, quoted emissions redactions or changes are
either on the basis of the 1972 or the 1975 Federal Test Procedure (FTP)
and are not to be confused with results that would be obtained by other test
procedures.
1.2.1 Inspection/Maintenance
Inspection/maintenance (I/M) programs reduce emissions
from in-use vehicles through ensuring that the emission levels of those
vehicles are not permitted to deteriorate, through inadequate or improper
maintenance, substantially beyond the levels of which the vehicles were
capable when new. The I/M programs can accomplish emission reductions
1-4
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only to the extent that voluntary maintenance is inadequate in maintaining the
engines and emission control systems in good operating condition. However,
voluntary maintenance is often not done on a regular basis, is not normally
directed toward emission control, and does not result in minimizing exhaust
emissions.
Studies conducted using representative fleets of privately owned
in-use automobiles (light duty vehicles) have demonstrated that significant
reductions in the aggregate emissions of those groups of vehicles can be
obtained through more frequent engine maintenance than is presently practiced.
It has been found that over half of the vehicles in a typical fleet had malfunc-
tions or maladjustments that, when corrected, resulted in a decrease in
emissions. When maintenance was performed on those vehicles, the average
initial reductions in emissions for the entire fleet {including the vehicles not
maintained) ranged up to 40 percent for exhaust hydrocarbons (HC) and up
to 35 percent for carbon monoxide (CO). Of course, with continued in-service
use, both the repaired and nonrepaired vehicles experienced an increase in
emissions after the initial I/M period. The vehicles included in the I/M
studies did not have nitrogen oxides (NO ) emission control and, conse-
quently, the reductions in the HC and CO emissions were accompanied by a
small increase (less than 10 percent) in NO emissions. In general, the I/M
X
study results lead to the conclusion that current voluntary maintenance prac-
tices are inadequate to keep the emissions of the in-use vehicle population at
the minimum levels of which they are capable and, therefore, that implemen-
tation of a mandatory I/M strategy could result in significant reductions in
HC and CO emissions.
The average emission reductions that can be achieved in a
given year from an I/M program depend on the emission reductions of the
repaired vehicle immediately after servicing and the rate and extent of de-
terioration in emissions of both the passed and repaired vehicles prior to
the next emissions inspection and/or service period. Considerable informa-
tion on the emission reductions that can be achieved by repair/maintenance is
1-5
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available, but data on the deterioration of both passed and repaired vehicles
are quite limited. Because of this lack of deterioration data, EPA currently
utilizes a linear deterioration method, in which it is assumed that the
emissions of all serviced vehicles (voluntary and mandatory) deteriorate in
a linear manner back to the same level they had before servicing. The
effective emission reduction (averaged over a one-year period between
inspections and/or servicing) is then one-half of the average fleet emission
reduction achieved immediately after repair of the rejected or serviced
vehicles. The actual value of emission reduction achieved also depends, of
course, on the failure criteria used (pass/fail emission levels) and the
resultantjrejection rates (percentage of inspected vehicles that fail the
emission inspection) that are incorporated into the I/M program.* As the
number of vehicles rejected increases (i.e. , require maintenance), the
potential for emission reduction also increases. However, the rate of re-
duction with increasing failure rate is not linear, with the trend being one
of smaller and smaller emissions reductions with each incremental increase
in rejection rate. Rejection rates of 100 percent often result in higher emis-
sions levels for the total vehicle population than occur at much lower rejec-
tion rates due to the ineffective maintenance being performed on many vehicles
It is advantageous if the emission test procedure utilized can minimize the
number of vehicles rejected having relatively low emissions (as measured
by the FTP) and the number of vehicles passed having relatively high emis-
sions (as measured by the FTP). Both types of errors tend to .reduce the
emission reduction that can be achieved by the I/M program.
X
As used in this discussion, the term "reject rate" refers to the fraction
of inspected vehicles that fail the initial inspection cycle. Repeated
reductions in the failure criteria for the purpose of maintaining constant
reject rates during subsequent inspection cycles is not only unnecessary
but undersirable in most cases.
1-6
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The emission reduction effectiveness of several alternative
approaches to I/M have been evaluated. These included (1) emission
inspection (testing) at idle only, followed by repair procedures developed
to use idle test results; (2) emission inspection (testing) using a loaded test
cycle (Key Mode), followed by repair procedures developed to use Key Mode
test results; (3) engine parameter diagnostic inspection and repair; and (4)
mandatory maintenance of specified emission-related engine and emission
control system components, which is done regularly without prior testing.
A summary of the emission reductions and associated repair costs for the
inspection repair and mandatory maintenance strategies are given in
Table 1-2. The results shown are typical of those that can be achieved by
mechanics familiar with emission-reduction-oriented repair procedures.
The emission reduction and cost effectiveness of the idle, Key Mode, and
mandatory maintenance approaches are given in Table 1-3. In general, the
HC and CO emission reductions achieved both increase as the fraction of
vehicles receiving mandatory maintenance increases. The cost effectiveness
of I/M programs for reducing HC emissions varies in the range $0.25 to
$3.67/lb, while the range for CO emissions is $0.04 to $0.32/lb.*
The results given in Table 1-3 indicate that the loaded (Key
Mode) test approach yields a greater emission reduction at a correspondingly
better cost effectiveness than the idle test approach for both HC and CO
emissions. As would be expected, the cost effectiveness of all the I/M
approaches is better for uncontrolled than for controlled vehicles. This is
primarily due to the fact that uncontrolled vehicles have higher emission
levels than controlled vehicles and the percent emission reductions achieved
by maintenance are at least as high for the uncontrolled vehicles as for the
controlled vehicles. The cost of maintenance does not seem to vary
significantly between the two vehicle groups.
*
These values include the effects of an improvement of approximately one
percent in the population-averaged fuel consumption. This improvement is
the result of increased maintenance on the repaired fraction of the vehicle
population.
1-7
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Table 1-2. Summary of Typical Emission Reductions and Repair
Costs for Various Rejection Rates and I/M Strategies
Rejection
Rate
(%)
Emission Reduction (%
HC
Fleet
Average
Serviced
Vehicles
Only
CO
Fleet
Average
Serviced
Vehicles
Only
Average
Repair Cost/
Serviced
Vehicles
($)
Inspection/Repair Strategy
Controlled
vehicles"
10
25
50
too
Uncontrolled
vehicles0
10
25
50
100
13
18
20
19
23
31
37
38
58
41
31
19
77
58
50
38
12
20
28
29
9
17
26
32
56
49
41
29
49
44
40
32
35.40
34.80
32.50
21.50
44.00
40.00
34.40
23.70
Annual Mandatory Maintenance Strategy
Controlled
vehicles"
Uncontrolled
vehicles0
14
10
7
7
50 to 70
50 to 70
All emission reductions (1975 CVS-CH FTP) correspond to immediately
after servicing.
bLight duty controlled vehicles (1968-1971).
Light duty uncontrolled vehicles (pre-1968).
All vehicles are required to undergo prescribed annual maintenance. These
emission reductions are based on limited data from an early program. Latef
results indicate that HC and CO reduction of almost twice these values are.
achievable with improved servicing.
1-8
-------
Table 1-3. Comparison of the Cost Effectiveness of Various I/M Approaches'
I/M Strategy
Idle test
RRd = 20%
RR = 40%
Key Mode test
RR = 20%
RR = 40%
Mandatory
Maintenance
Controlled Vehicles
HC
% Reduced
8
11
11
14
7
$/lbc
0.71
0.91
0.54
0.72
6.82
CO
% Reduced
6
9
7
11
5
$/lbC
0.075
0.088
0.067
0.072
0.77
Uncontrolled Vehicles
HC
% Reduced
8
11
11
14
4
$/lbc
0.35
0.47
0.25
0.35
5.75
CO
% Reduced
6.
9
7
11
4
S/lbc
0.047
0.056
0.039
0.044
0.57
Summary of representative data for light duty vehicles.
All emission reductions determined using linear deterioration method.
"Cost includes credit for fuel savings.
RR = rejection rate
-------
Various aspects of emission inspection have been investigated
as part of recent I/M studies. These studies indicate that several of the
short test procedures are adequate for an I/M program in that the procedures
on the average, identify vehicles with relatively high emissions that can be
significantly reduced by repair. Available data indicate that the loaded cycle
(Key Mode) test procedure is better in this sense than the idle test procedure
and it is expected that the difference in the discrimination capability of the
two will be greater as the vehicles to be inspected become more highly
emission controlled. However, other factors, such as cost of equipment and
facilities, actual emission reductions desired, potential for integration with
an on-going safety inspection program, etc. , should be considered when
selecting the emission inspection approach to be used. Because of the
limited available emission surveillance data for heavy duty engines, it is
not possible at this time to accurately assess the effect of an I/M program
on truck emissions. If subsequent data indicate that the emissions from
engines in heavy duty use deteriorate in a manner comparable to those in
light duty use, then an I/M program for heavy duty vehicles would be advan-
tageous in those urban areas such as New York and Los Angeles, which have
large truck populations.
In selecting which of the I/M approaches is most advantageous
for a given State or AQCR and in planning for the timely and effective imple-
mentation of the selected I/M strategy, a wide variety of technical, social,
and economic factors must be considered and appropriate administrative and
legislative decisions made. For example, in Table 1-4, the major steps that
would be involved in the eventual implementation of a full-scale I/M program
are presented. This delineation of major steps represents the case where a
State (or AQCR) has not yet begun or completed initial planning and tradeoff
studies, and includes a pilot (or demonstration) program phase prior to
implementation of a full-scale I/M program. Each of the major steps of
Table 1-4 is discussed in detail in Section 2.7 of this report.
1-10
-------
Table 1-4. Major Steps Involved in Implementation of
I/M Program
1.2.2
Initial Planning and Tradeoff Studies
/ Selection of Basic I/M Approach
/ Relationship to Other Existing or Planned Programs
/ Training, Licensing, and Quality Control Aspects
/ Enforcement and Vehicle Owner Requirements
/ Coordination Between Involved Agencies
/ Program Planning and Cost Estimation
Development and Passage of Enabling Legislation
Engineering and Administrative Studies
Pilot Program Construction and Procurement
Pilot Program Operation
Planning for Full-Scale Program
Full-Scale Program Construction and Procurement
/ Recruitment and Training
/ Manpower Development
Full-Scale Program Operation
Ongoing Licensing and Quality Control Program
/ Public Information Program
Retrofit Emission Control Systems
Retrofit approaches go beyond the attempt made by I/M
approaches to keep in-use vehicles at minimum emission levels consistent
with their original designs. In a retrofit approach, the goal is to reduce an
in-use vehicle's emissions below its "well-maintained" levels through adding
new emission control devices or through modifying the original design to
1-11
-------
achieve lower emissions. The retrofit approach should also be considered
a companion program to the I/M approaches. It is necessary to assure that
retrofit devices are properly installed, functioning, properly maintained,
and retained. An I/M program would make an ideal mechanism to assure
the full potential of the retrofit approach is realized. Evaluations of the per-
formance of various retrofit devices or systems on both precontrolled and
controlled vehicles have been conducted by EPA and the retrofit hardware
manufacturers. Measurements of the effect of the retrofit systems on HC,
CO, NO emissions and fuel economy have been made for passenger cars and
Jt
trucks. The evaluation tests in most cases had scatter in the data, which
presented difficulty in its interpretation. At present, EPA is in the process
of establishing well-defined certification procedures to rectify this situation.
The available retrofit data are presented in Section 3, includ-
ing best estimates of average emission reductions (percent), associated fuel
economy changes, and the cost effectiveness ($/lb) of emission reductions of
the various retrofit systems. For each system, the quality and quantity of
the data and its statistical characteristics are also discussed. The results
of the analysis of the retrofit data are given in Tables 1-5 and 1-6 for those
retrofit approaches that appear most likely to be implemented. Results are
given for precontrolled and controlled vehicles. Cost effectiveness values
are given both including and excluding the effect of fuel economy changes.
For precontrolled light duty vehicles, the CO emissions can
be reduced up to 60 percent at zero mileage by the use of an air bleed. This
strategy also results in a fuel economy improvement of about 4 percent and
a net cost savings over 50,000 miles. HC emissions on precontrolled light
duty vehicles can be also reduced by about ZQ percent by the use of an air
bleed or lean carburetion.
The use of air bleeds or carburetor enleanment are not possib
with most post-1970 vehicles as the carburetors are already set as lean as
possible without causing misfire and the associated increase in hydrocarbon
emissions. For controlled light duty vehicles, the oxidation catalyst with an
air pump is an effective means of reducing both CO and HC. By the use of
this approach, exhaust emissions of both pollutants can be reduced initially
1-12
-------
Table 1-5. Maximum Emission Reductions and Fuel Penalty for
Various Retrofit Strategies on Vehicles of Differing
GVW
Retrofit Strategies
Precontrolled vehicles
Air bleed
LDVC
Trucksd
Lean carburetion + EGR
LDV
Trucks
Controlled vehicles
f §
Oxid. catalyst w/air '
LDV
Trucks
Oxid. catalyst w/air + EGR
LDV
Trucks
Emission Reduction (%)
HC
20
15
25
10
70
80
70
80
CO
60
40
40
30
65
80
65
80
NOX
0
-5
50
30
10
-5
50
40,
Fuel
Penaltyb
-4
-4
1
0
0
0
3
6
Negative sign means increase in emissions
Negative sign means decrease in fuel consumption
°Light duty vehicles (GVW s 6000 Ib)
dTrucks (GVW = 6000 to 10,000 Ib)
Exhaust gas recirculation
f
Air injection for use with catalyst
or
6No catalyst deterioration assumed
1-13
-------
Table 1-6. The Cost Effectiveness of Various Retrofit
Strategies on Vehicles of Differing GVW
Precontrolled
Lean carburetion
Excluding fuel savings
Including fuel savings
Lean carburetion + EGR
Excluding fuel penalty
Including fuel penalty
Controlled
Oxid. catalyst with air
Excluding fuel penalty
Including fuel penalty
Oxid. catalystd w/air + EGR
Excluding fuel penalty
Including fuel penalty
Cost Effectiveness ($ /lb)
HC
LDVa
0.23
0.24
0.32
0.62
0.62
0.72
0.88
Trucks
0.28
0.84
0.84
0.45
0.45
0.57
0.87
CO
LDV
0.007
0.010
0.015
0.05
0.05
0.06
0.07
Trucks
0.009
0.024
0.024
0.039
0.039
0.049
0.075
NOX
LDV
-
0. 53
0.70
3.6
3.6
0.95
1.2
Trucks
—
0.34
0.34
-
0.81
1.24
Light duty vehicles (GVW 5 6000 lb)
'Trucks (GVW = 6000 to 10,000 lb)
*
"Plus indicates net cost savings; minus indicates retrofit device increased emissions.
No catalyst deterioration included
-------
(before any catalyst; deterioration) 65 to 70 percent. Fuel economy is
essentially unaffected by the use of the catalyst, but unleaded gasoline is
required. The durability of catalysts as retrofit devices is still somewhat in
question, but recent advances in catalyst technology make it more likely that
satisfactory durability can be achieved in retrofit applications. NOx emissions
can be reduced up to 40 percent on both precontrolled and controlled vehicles,
but there is an associated fuel economy penalty of about 5 percent. Combining
exhaust gas recirculation (EGR) with air bleed can reduce the fuel penalty to
an estimated 1 to 2 percent on uncontrolled cars.
The special case of retrofit emission control at high altitude
(e.g., Denver, Colorado) was also reviewed. Substantial differences in
emission levels occur at altitude as the result of fuel metering enrichment
due to reduced atmospheric pressure at altitude. A number of retrofit emis-
sion control systems have been tested in Denver to determine their effective-
ness in reducing emissions at altitude. However, only the catalyst systems
reduced the emissions at altitude to levels equal to or less than those experi-
enced at sea level. The air bleed devices designed for use at sea level do not
permit the addition of sufficient air at altitude to even overcome the effects
of reduced ambient density. The limited testing of retrofit devices at altitude
indicates that much additional work is needed before such devices will be
available to handle this special retrofit situation.
The problem of retrofitting gasoline-fueled vehicles of over
6000 lb gross vehicle weight (GVW) is also considered in Section 3. As
indicated by the results given in Tables 1-5 and 1-6, the emission reduction
potential (percent) and cost effectiveness of the various retrofit approaches
are approximately the same for trucks with GVW ranges between 6000 and
10,000 lb as for light duty vehicles. For heavier vehicles (GVW >10,000~lb),
however, the situation varies with the retrofit approach being considered.
For example, lean carburetion is much less effective for heavy vehicles than
for lighter vehicles, because the former operate at high engine loads a
greater part of the time. In contrast, oxidation catalyst systems appear
equally effective regardless of engine operating load. The fuel penalty
1-15
-------
associated with spark retard and EGR increases with vehicle weight so that
the cost effectiveness of NO control on heavy vehicles (GVW > 10, 000 Ib)
x
is lower than for light vehicles. However, data for retrofit of trucks also is
limited, and the above conclusion should be considered preliminary.
1.2.3 Conversion for Gaseous Fuel Operation
The modification of in-use vehicles to permit their operation
using gaseous fuels falls within the general definition of retrofit approaches.
However, the feasibility and/or attractiveness of gaseous fuel conversion as
an emission control strategy for in-use vehicles depends not only on the
availability, emission reduction effectiveness, and cost of the required hard
ware but also on a number of other factors, such as the feasibility of
providing the necessary supply and fuel distribution system, the cost of the
gaseous fuels, and the impact of the diversion of gaseous fuels from other
combustion uses. Present and projected supply problems associated with
gaseous fuels (propane and natural gas) indicate that this is not a highly
viable approach for the reduction of emissions from in-use vehicles. In
most previous studies, gaseous fuel conversion was analyzed only in terms
of fleet operation (trucks, taxis, etc.), and its attractiveness was based to
a large extent on a lower unit cost for the gaseous fuels that would not persis
if they were in widespread use for transportation. For that reason, higher
unit gaseous fuel costs are used in the present analysis than in most previous
studies.
Three basic types of gaseous fuel conversions are of interest:
(1) liquefied petroleum gas (LPG - propane), (2) compressed natural gas
(CNG-me thane), and (3) liquefied natural gas (LNG). Differences among
the types manifest themselves principally in such areas as the type of hard-
ware required, conversion and fuel costs, and operating convenience (e.g. ,
tank weight and size, and vehicle range). For example, a typical passenger
car fueled with one tankful of gasoline has a range of approximately 300
miles. When limited to the same volume for fuel storage, passenger cars
with gaseous fuels would have reduced range capability because of the lower
1-16
-------
Table 1-7. Emission Levels and Reductions Obtainable
Through Single-Fuel Gaseous Conversion
Applicable Model
Years
1968-1971
1972-1974
Fuel
Gasoline. (Baseline)
LPG
LNG/CNG
Gasoline (Baseline)
LPGa
LNG/CNGa
Emission Levels
(1975 FTP) (gm/mi)
HC
4.8
2. 1
1.7
2.8
1.5
1.0
CO
60.0
14.2
5. 1
30.0
2.7
2.0
NOX
4.8
2.9
1.4
3.0
1.1
.7
Percent Reduction
From Gasoline Baseline
HC
-
55
65
^
45
60
CO
-
75
90
90
95
NOX
-
40
70
60
70
aBest attainable, not the average, for 1972-1974 vehicles. In general, emission reductions achievable with
dual-fuel systems will be less than those shown.
-------
fuel density. On a comparable basis, LPG would provide a range of 230
miles, CNG 60 miles, and LNG 200 miles.
A significant reduction of all three exhaust pollutants can be
attained through conversion from gasoline to gaseous fuel operation
(Table 1-7). It should be noted, however, that while the CO emissions are
consistently very low (often less than 5 gm/mi), the HC and NO emissions
-?t
vary over a wide range. This variation occurs because the HC and NO
Jt
emissions are very sensitive to ignition timing and air-fuel ratio, with both
HC and NO decreasing as the engine timing is retarded and the air-fuel ratio
j£
is made leaner. Unfortunately, these engine adjustments result in higher
fuel consumption and a significant loss in engine horsepower. Hence, de-
pending on the emission standards to be met, different tradeoffs are optimum
between emissions, fuel economy, and vehicle performance. For this
reason, the emission reductions and levels given in Table 1-7 as being
achievable by gaseous fuel conversion should be considered as approximately
the best attainable, not the average.
The cost effectiveness of attaining lower emissions through
gaseous fuel conversion is summarized in Table 1-8. Comparison of the
values ($/lb) shown in the table with those for gasoline retrofit systems
indicates that the cost effectiveness, based on direct costs (initial cost minus
maintenance savings) of gaseous fuel conversion systems, is comparable to
that of the oxidation catalyst retrofit system. The total cost effectiveness of
the gaseous fuel system becomes more favorable only when the unit cost of
the gaseous fuel is much below that of gasoline. At the present time, this
seems to be the case only for CNG, and that system has the disadvantage of
a significantly reduced range (one-third that for gasoline). The high initial
costs of the gaseous fuel conversion hardware would make implementation
of that control strategy difficult, even if the gaseous fuel cost and supply
situation were favorable.
1-18
-------
Table 1-8. Summary of Cost Effectiveness Information for
Gaseous Fuel Conversion (Best Obtainable Values)
Fuel
Initial
Cost ($)
Maintenance
Savings ($)a
Unit Fuel
Price ($)b
Fuel
Savings
(*)c
Emissions
gm/mi- 1975 FTP
HC
CO
N0x
Cost Effectiveness ($/lb)
Initial Costs and
Maintenance Savings
HC
CO
NO
X
Initial Costs and Mainte-
nance and Fuel Savings
HC
CO
NO
*i
Controlted Vehicles (1968-1971)
(Baseline emissions: HC = 4.8, CO = 60, NOx = 4.8 gm/mi)
LPG
CNG
LNG
LPG
CNG
LNG
650
870
1020
650
870
10ZO
125
125
125
0.28/gal
0.20/100 scf
0.28/gal
-150
250
-300
2. 1
1.7
1.7
14.2
5.1
5. 1
2.9
1.4
1.4
1.81
2.16
2.6
0.11
0.12'
0.15
2.52
1.99
2.39
Controlled Vehicles (1972-1974)
(Baseline emissions: HC = 2.8, CO = 30, NOx = 3 gm/mi)
125
125
125
0. 28/gal
0.20/100 scf
0.28/gal
-150
250
-300
1.5
1.0
1.0
2.7
2.0
2.0
1.1
0.7
0.7
3. 18
3.77
4.5
0. 18
0.24
0.29
2.52
2.95
3.53
3.33
2.05
3.95
4.08
2.50
6.83
0. 14
0.08
0.22
0.23
0.16
0.44
3.24
1.3Z
2.61
3.24
1.95
5.34
aMaintenance saving of 0.0025 $/mi for 50,000 miles.
TMo Federal or State tax is included in the fuel costs.
°Fuel savings in 50,000 miles compared with operation with gasoline,; negative sign means an increase in fuel costs.
Lifetime of gaseous fuel conversion system is taken to be 50,000 miles.
-------
1.2.4 Comparison of the Emission Reduction Potential
and Cost Effectiveness of Various Hardware Type
Emission Control Strategies for In-Use Vehicles
The emission reduction potential and cost effectiveness of the
various control strategies for in-use vehicles have been discussed in the
previous sections. For purposes of a direct comparison of these strategies
the results for light duty vehicles are summarized in Table 1-9. The
emission reduction potential is expressed in terms of gm/mi per vehicle
while the cost effectiveness is given as $/lb of pollutant eliminated. These
cost effectiveness values (as well as all cost effectiveness values presented
throughout this report) were determined by dividing the total per vehicle
cost for a given emission control strategy by the corresponding values of
per vehicle emission reduction for each emission specie (HC, CO, NO ).
j£,
Thus, they do not represent any attempt to prorate or apportion control costs
among the three vehicle emissions considered. Results are given for HC
and CO emissions and for controlled (1968-1971) and uncontrolled (pre-1968)
vehicles. Data are not available to assess the impact of the various control
strategies on vehicles of later model years. NO emissions are not included
in the summary table because their control was not an objective of the con-
trol strategies being compared. In general, the inclusion of an NO control
(EGR and/or vacuum delay) in a retrofit program will reduce its cost
effectiveness (increase the $/lb value) for HC and CO reduction because of
the associated fuel penalty. It is important to note that, for some strategies
the inclusion of the effect of incremental fuel costs significantly changes the
cost effectiveness and in some cases could result in a net savings (NS) to the
vehicle owner.
1-20
-------
Table 1-9. Comparison of the Emission Reduction Potential and Cost Effectiveness
of In-Use Vehicle Control Strategies (Light Duty Vehicles)
Control Strategy
I/M Approaches e
Loaded test (KR = 30%)
Excluding fuel savings
Including fuel savings*
Idle test
-------
The emission reduction comparisons in Table 1-9 should be
considered as representative class examples only, as there can be a wide
variation of values within each control strategy class shown. For example,
the I/M approach values shown are typical for a rejection rate of 30 percent
only; higher or lower program rejection rates would result in different emis«
sion reduction values. Similarly,the cost effectiveness values in the table
are necessarily restricted to the assumptions made with regard to control
effectiveness, initial hardware costs, etc. However, they do provide an
overview as to the relative comparative levels of cost effectiveness that the
various in-use control strategies provide.
1-22
-------
REFERENCES
1-1 Clean Air Act. 42U.S.C. 1857 et seg. , as amended by P. L. 91-604
(December 31,. 1970).
1-2 Evaluating Transportation Controls to Reduce Motor Vehicle Emissions
In Major Metropolitan Areas; An Interim Report, Institute of Public
Administration, Washington, D. C. (March 1972).
1-3 Prediction of the Effects of Transportation Controls on Air Quality in
Major Metropolitan Areas (Six Citites Transportation Study), TRW
Systems'Group, McLean, Virginia (July 1972).
1-4 Transportation Controls for Reducing Air Pollution (Draft), Environ-
mental Protection Agency, Strategies and Air Standards Division,
Research Triangle Park (January 1974).
1-5 An Analysis of the Economic Impact of Motor Vehicle Use Restrictions
in Relation to Federal Ambient Air Quality Standards, Alan M. Voorhees
npa
"Al
and Association, Inc. (September 1973).
1-6 Control Strategies for In-Use Vehicles, U.S. Environmental Protection
Agency, Office of Air and Water Programs, Mobile Source Pollution
Control Program (November 1972).
1-7 "Appendix N - Emissions Reductions Achievable Through Inspection,
Maintenance, and Retrofit of Light Duty Vehicles," Federal Register,
Vol. 38, No. 110 (Friday, June 8, 1973).
1-23
-------
2. EMISSION INSPECTION AND MAINTENANCE APPROACHES
-------
2. EMISSION INSPECTION AND MAINTENANCE APPROACHES
2. i INTRODUCTION
The increase of automotive emissions resulting from
improper, inadequate, or insufficiently frequent maintenance affords the
possibility of achieving significant reductions of motor vehicle emissions
through the periodic inspection and/or enforced maintenance of in-use vehi-
cles. This section summarizes currently available information concerning
the alternative test procedures examined to date for the periodic inspection
of extensive vehicle populations, the potential effectiveness of emission-
related maintenance procedures for reducing automotive emission levels, and
the costs and cost effectiveness values attributable to alternative inspection/
maintenance (I/M) strategies.
2.1.1 Types of I/M Approaches
The general term "inspection/maintenance approaches" in-
cludes all procedures and strategies intended to improve the maintenance
of in-use vehicles for the purpose of reducing their emissions. Some of the
I/M approaches considered in detail in this section have separate inspection
and maintenance phases, while others have only a maintenance phase. The
various alternative I/M approaches can be divided into the following general
categories:
a. Emission Inspection/Repair Approaches. Vehicles included
in the program are subjected to an emission test and the re-
sults are compared with a set of predetermined failure cri-
teria. Vehicles with emissions in excess of the inspection
standards'are rejected (failed) and are required to have main-
tenance performed to reduce the emission to acceptable levels.
An emissions retest may be required after the maintenance to
ensure that the failed vehicles have been brought into compli-
ance with the emission inspection standards. The emission
testing phase of this approach could be done in a system of
inspection lanes provided by an appropriate State or munici-
pal agency or in private garages that are certified, licensed,
2-1
-------
and supervised by an appropriate governmental agency. A
third possibility is that random inspections could be per-
formed by specially trained officers at mobile sites on high-
ways and streets.
b. EngineJParameter Inspection/Repair Approaches. Each vehi-
cle inclvided in the program is subjected to a sequence of diag-
nostic tests to evaluate the operating condition of various
emission-related systems and to determine if malfunctions
or maladjustments are present. Vehicles showing measure-
ments outside of accepted tolerance ranges are considered to
have failed and are required to have corrective maintenance
performed. This approach bypasses the measurement of
each vehicle's emission levels, although in some cases emis-
sion measurements may be made to evaluate the state of cer-
tain vehicle systems (e.g. , measurement of the idle CO con-
centration to evaluate the idle air/fuel ratio). The same pos-
sibilities of State lanes, private garages, and mobile sites
exist for the inspection phase in this category as in the previ-
ous one,
c. Mandatory Maintenance Approaches. Each vehicle, indepen-
dent of its emission levels or mechanical condition, is required
to have specific maintenance performed at stated intervals.
Thus, the inspection phase is eliminated and appropriate main-
tenance is specified for each type of vehicle. This mainte-
nance program is identical for all vehicles of that type rather
than being whatever maintenance is necessary to achieve com-
pliance with an emission standard or to ensure that specific
vehicle systems pass parameter checks.
In all cases, it is anticipated that private service garages and dealerships
comprising the automotive repair industry would provide the requisite
maintenance.
2.1.2 Criteria for the Evaluation of I/M Approaches
The following factors and criteria are important in assessing
the feasibility, emission reduction potential, and cost effectiveness of the
various I/M strategies.
a. The extent to which inadequate or improper maintenance by
the general public causes in-use vehicles to differ from the
original manufacturer's specifications.
2-2
-------
b. The magnitude of the emission increases, which is the result
of sxrch deviations from manufacturer's specifications.
c. The effectiveness with which the inspection testing procedure
can identify from among the entire vehicle population those
vehicles with excessive emissions resulting from malfunc-
tions ajid maladjustments of the engine and emission control
system.
d. The diagnostic value of the inspection test results in identify-
ing the specific maintenance actions required to restore the
vehicle to a condition that is in compliance with the inspection
standards.
e. The effectiveness of the repair industry in applying proper
repair/maintenance procedures to reduce emissions from
those vehicles identified as having malfunctions or
maladjustments.
f. The average emission reductions that can be achieved for the
serviced vehicles and the total vehicle population.
g. The fraction of the vehicles that must be tested and failed to
achieve a desired emission reduction.
h. The rate and extent of the deterioration of vehicle emissions
following maintenance/repair.
i. The relationship between the inspection test procedure used
and the Federal Certification Test Procedure as it relates to
the impact of vehicular emissions upon ambient air quality.
j. The initial capital investment required and the annual oper-
ating costs of the inspection facilities and program
administration.
k. The maintenance (or repair) costs and indirect 'savings, such
as improvements in fuel economy and vehicle driveability and
reliability, due to the substitution of required maintenance
for existing voluntary maintenance practices.
1. The ease with which the program can be implemented.
m. The citizen acceptance of the program.
n. The extent to which the I/M approach is applicable to vehicles
with advanced control systems and/or alternative engines.
Some of the foregoing factors have been evaluated quantita-
tively for various alternative I/M approaches in the recent studies summa-
rized in Table 2-1. As a result of these studies, a considerable body of
( / ' '
lnformation and data is available concerning various I/M approaches;
2-3
-------
Table 2-1. Summary of Major Features of I/M Studies Conducted to Date
I/M Strategy
Emission inspection/
repair
Mandatory periodic
maintenance
Emission inspection/
repair and manda-
tory periodic
maintenance
Emission inspection/
repair and manda-
tory periodic
maintenance
Emission inspection/
repair
Emission mea-
surements only
Emission inspection/
repair
Emissions
Inspection Test
Idle
Key Mode
None
Idle
Key Mode
Engine parameter
Engine parameters
including
emissions
Idle
Key Mode
Key Mode
Idle /random
highway
Maintenance
Approach
Repair of failed
vehicles
Specified main-
tenance proce-
dures for all
vehicles
Repair of failed
vehicles and
specified main-
tenance
procedure
Specified
maintenance
procedures
Repair of failed
vehicles
None
Repair of failed
vehicles
Types of
Vehicles in
Fleet
Precontrolled
Controlled
NOX controlled
(Calif. 1971)
Same as above
Same as above
Same as above
Precontrolled
Controlled
Same as above
Controlled
(1966-1972,
Calif.)
Contractor/
Sponsor
Olson/EPA
Clean Air Research
Company /California
Air Resources
Board
Northrop'/California
Air Resources
Board
TRW/EPA/CRC
State of New Jersey
with Clayton
Manufacturing Co.
Washington, D.C.
Scott Lab./
California Air
Resources Board
Year of
Study
1971-72
1972
1970
1968-73
1968-70
1971-72
1973
Ref.
2-1
•
2-3
2-2
2-4
2-5,2-6
2-7
2-8
-------
however, it is limited and incomplete with respect to its usefulness in pro-
jecting the costs and benefits of I/M in the years ahead. In all the I/M stud-
ies cited, the comparisons of the various approaches examined were made
on the basis of statistically equivalent fleets of precontrolled and controlled
vehicles. In all cases, the vehicles used were 1971 or earlier models that
had experienced no previous mandatory I/M program. Hence, the detailed
comparisons found in Ref. 2-1 through 2-5 can only offer guidance as to what
would result when the same approaches are applied to later model vehicles
(1973, 1974, 1975, and beyond) with more advanced emission control sys-
tems. Thus, considerable engineering judgment is required to make quan-
titative estimates of the effectiveness of I/M on these later model vehicles.
In addition, the I/M process itself may significantly alter the emis-
sions characteristics (i.e., the fraction of vehicles with emissions less than
a given value) and state-of-repair of the current vehicle populations and, as
a result, may change the relationships between failure criteria, failure rate
(fraction failed), and the mean emission reduction achieved for a given fail-
u*e rate and I/M approach. Hence, additional data similar to that reported
ia Ref. 2-1 through 2-5 will be required on a continuing basis to effectively
Plan I/M programs and to assess the evaluation criteria listed previously.
Such continuing information and data will be required until I/M programs
have been established for several years and the present rapid changes in
^ew vehicle emission levels (standards) and emission control Systems have
stabilized.
2-5
-------
2.2 EMISSION INSPECTION PROCEDURES
The inspection phase of an I/M program is a screening
procedure applied to the population of in-use vehicles subject to I/M. Its
function is to identify, for required maintenance, only those vehicles likely
to exhibit significant emission reductions if given additional maintenance.
The inspection procedure could also provide a check on the quality of the
maintenance performed on the failed vehicles if they were required to be
retested after maintenance. The inspection can be done either in an inspec-
tion lane or by a private garage.
Consideration of alternative test procedures that satisfy the
requirements of the inspection process leads to the identification of two gen-
eral categories: direct emission measurement tests and engine parameter
tests. Detailed descriptions of several short emission test procedures (or
cycles) that have been found useful for inspection purposes are given in the
next section. The second category of inspection procedures, engine param-
eter tests, is discussed in Section 2. 3.
2.2.1 Alternative Short Emission Test Procedures
The feasibility and effectiveness of the emission inspection/
repair approach depends to an important extent upon the availability of emis~
sion test procedures that can rapidly and reliably identify vehicles whose
emissions can be reduced through maintenance. Such emission test proce-
dures are termed short emission test procedures (or cycles) to contrast then1
with the longer Federal Test Procedures (FTP) (1972 CVS-C or 1975 CVS
that are used to obtain vehicle emissions for "new vehicle" certification pur-
poses. Since the Federal Light Duty Vehicle Emissions Standards (gin/mi
HC, CO, NO ) are expressed relative to the Federal Test Procedure and
vehicle contributions to emissions inventory and ai.r quality calculations
are based on the same driving cycle, the relationships between concentration
and mass emissions obtained using the short emission test procedures and
longer FTP are of considerable importance. This subject and its effect on
acceptability of a given short test procedure for inspection purposes are dis*
cussed in Section 2. 2. 2.
2-6
-------
The minimum requirements for an emissions test procedure
to be acceptable for use on an emissions inspection lane are that it be quick
(2 or 3 minutes at the most), applicable to vehicles in the condition in
which they arrive at the inspection station (warmed-up), and capable of iden-
tifying a large percentage of the vehicles that would show high emissions if
they were tested using the FTP. Additional characteristics, which are de-
sirable but not absolutely necessary, are that the test procedure can be dup-
j.
Heated in most private garages to check the effectiveness of repairs, yield
meaningful diagnostic information to the mechanics for repair, and be well
correlated to FTP emissions for the vehicle. Unfortunately, no short test
procedure has yet been developed that completely meets all of these require-
ments. However, there are several that appear to be useful for emissions
inspection even though they are not completely satisfactory in all respects.
These short test procedures can be divided into three categories: [1] engine
Unloaded (idle), [2] engine loaded, steady state (simulated highway cruise),
and [3] engine loaded, transient (simulated urban driving). The most highly
Developed tests in each category are the following:
Unloaded
Idle Test (idle rpm and 2500 rpm)
Loaded, Steady State
Key Mode (high cruise, low cruise, idle)
Loaded-Transient
New Jersey ACID** Cycle
New York City (NYC) Quick Cycle
EPA Short Test Cycle
Single cycle of seven-mode hot start test
In this case, the test procedure could be also used in the private garage
to conduct the emission inspection.
fc r
AClD-accelerate, cruise, idle, and decelerate.
2-7
-------
Each of these test procedures is described in Table 2-2, together with
related information concerning personnel, special test equipment, and instru-
mentation requirements and applications of the test procedure to date. In
Table 2-3, the load and speed test conditions of the Key Mode cycle are fur-
ther described. Speed and time characteristics of the various short test
cycles are shown in Figure 2-1. Considerable data on the use of these test
procedures are available from recent I/M studies in which they have been
used.
Each of the short emissions tests has advantages and disad-
vantages relative to its use in an inspection lane test program. These ad-
vantages and disadvantages are listed in Tables 2-4 through 2-6.
2.2.2 Relatability and Discrimination Characteristics of
Short Emission Test Procedures
Vehicle emissions (gm/mi) corresponding to the FTP (1972
CVS-C and 1975 CVS-CH) are used for evaluating the effect of the emissions
of a particular vehicle or fleet of vehicles on air quality. Therefore, it is
necessary to relate emissions taken using other test procedures to those
emissions corresponding to the FTP. For purposes of evaluating I/M strat-
egies, there are two different aspects of the relatability problem that are
important. First, how the emissions of particular vehicles or fleets of vehi-
cles using a test procedure other than the FTP correlate with those that woul^
have been measured using the FTP. This is termed the "direct relatability of
the two procedures." Second, how vehicles having high FTP emissions can bc
identified using a test procedure other than the FTP. This problem of setting
pass-fail criteria for the short test procedures is termed the "discrimination
problem." The discrimination process (identification of failed vehicles)
be applied on a vehicle-by-vehicle basis, while direct relatability can be
applied either to single vehicles or a fleet of vehicles. These two aspects
of the relatability problem (direct relatability and discrimination) are dis-
cussed briefly in the following sections.
2-8
-------
Table 2-2.
Characteristics of Short Test Procedures for Emission Inspection
Short Test
Idle
Key Mode
Shorter urban test
cycles (New Jer-
sey ACID cycle.
NYC Quick Cycle)
Longer urban test
cycles (e.g. , EPA
short teat cycle
and single cycle
of the seven-mode
hot start)
Cycle
Description
Idle in drive and/or
freewheeling at
2500 rpm
Steady-state at high
cruise, low cruise,
idle in drive (see
Table 2-3 for load
conditions).
Consist of acceler-
ations, cruise, de-
celerations, and
idle in drive (see
Figure 2- 1 )
Seven to nine modes
including combina-
tions of accelera-
tion, cruise, de-
celeration, and idle
(see Figure 2-1 for
mode diagrams)
Cycle Test
Timea
Not
applicable
60 sec
60 to 80
sec
(see Fig-
ure 2-1)
124 to 137
sec
(see Fig-
ure 2-1)
Number of
Technicians
Required
1 or 2
2
2
2
Special Test
Equipment
Required
None
Chassis dynamom-
eter (single power
absorption curve)
Chassis dynamom-
eter (variable in-
ertia and power
absorption with
automatic test
settings)
Same as above
Ins trumentat ion
Required
HC and CO ex-
haust gas
analyzers
HC, CO, and NO
exhaust gas X
analyzers
CVS sampling
systemb - HC,
CO, and NO gas
analyzers with
computerized
data reduction
Same as above
Applications
to Date
N. J. test lane;
Calif. -roadside:
Calif. -end of
assembly line
Washington D. C,
test lane: various
I/M studies (EPA,
N. J. . NYC, Calif.
ARE)
Under development
End -of -assembly
line testing by EPA
and Calif. ARB;
I/M studies by
EPA contractors
IS)
I
aThis time includes only that required to operate the vehicle through the cycle and does not include set-up time.
Tntegration of concentration values over the cycle is possible, but CVS sampling is preferable.
-------
Table 2-3. Load and Speed Conditions for the Key Mode Test (Ref. 2-5)
•tr_1»J_1_ lir^^fvl^l f~*\ -i f> n /1"K\
Vehicle Weignt L>lass (ib;
Less than 2800
2800-3800
Greater than 3800
Low Cruise
Mode
Speed
(mph)
23
30
33
Load
(hp)
5
9
11
High Cruise
Mode
Speed
(mph)
37
45
49
Load
(hp)
14
23
29
Table 2-4. Advantages and Disadvantages of the
Unloaded Idle Test Procedure
Unloaded
Idle Test
Idle rpm and
2500 rpm
Advantages
1. No dynamometer is
required.
2. Can be duplicated
at repair garages.
3. Owner can remain
in vehicle during
test.
4. Can be added to
existing safety in-
spection lanes.
5. Can be duplicated
for roadside ran-
dom inspection.
Disadvantages
1. Emissions under loaded
conditions are not
measured.
2. Provides minimum direct
diagnostic information to
repair garages.
3. Poor correlation be-
tween idle and FTP CVS
emissions.
4. Not applicable for NOX
emission inspection.
,
2-10
-------
a
50
40
30
NYC QUICK CYCLE
a
£20
a.
«/>
10
EPA SHORT CYCLE
20 40 60 80
TIME (SECONDS)
40 60 80 100
TIME (SECONDS)
120 140
50
40
SEVEN-MODE CYCLE
Q
LU
10
NEW JERSEY ACID CYCLE
I l\ .1 I
20 40 60 80 100 120 140 0 20 40 60 80
TIME (SECONDS) TIME (SECONDS)
Figure 2-1. Speed and Time Characteristics of Short Urban Cycles
2-11
-------
Table 2-S. . Advantages and Disadvantages of Key Mode
Test Procedure
Loaded Key
Mode Test
High cruise,
low cruise,
idle
Advantages
1. Engine loaded during
test so emissions at
load and high airflow
conditions are
measured.
2. Provides good diag-
nostic information to
repair garages over
the complete range
of engine operating
conditions.
3. Test cycle easily re-
peatable; no transi-
ents to follow.
4. Applicable for NOX
inspection.
5, May be applicable
to catalyst equipped
cars.
Disadvantages
1. Power absorption dyna-
mometer (single absorp-
tion curve) required.
2. Test cannot be dupli-
cated in most repair
garages due to the need
for a dynamometer.
3. Owner probably cannot
drive car during the
test.
4. Uncertain relationship
between Key Mode and
FTP CVS emissions for
individual vehicles; how-
ever, the relationships of
average fleet emissions
are more likely to be
acceptable for program
evaluation, emission in-
ventory, and air quality
calculations.
2-12
-------
Table 2-6.
Advantages and Disadvantages of Various
Loaded Short Urban Test Cycles
Short Urban
Test Cycles
Advantages
Disadvantages
New Jersey
ACID Cycle
New York
City Quick
Cycle
EPA Short
Test Cycle
Single cycle
of seven-
mode hot
start test
1. Emission measured
from both loaded
cruise and transient
engine modes.
2. Expected to provide
closest correlation
with FTP CVS
emissions.
3. Most direct evalua-
tion of I/M program
as related to emis-
sions inventory.
4. Provides some diag-
nostic information to
repair garages; pos-
sible to use on-line
computer data
reduction.
5. May be applicable to
NOx control and
catalyst equipped
vehicles.
1. Computer needed for
rapid on-line data reduc-
tion, especially if modal
diagnostic information is
desired. High initial
cost.
2. Variable inertial and
power absorption dyna-
mometer needed.
3. Owner cannot drive the
vehicle during test.
4. Driving cycle difficult to
follow accurately even by
experienced technician;
no possibility of averag-
ing repeated cycles in
short test.
5. Test cannot be duplicated
in most repair garages.
2-13
-------
2.2.2.1 Direct Relatability Between Short Test Procedures
and the FTP
The emissions (gm/mi or exhaust gas concentrations) obtained
from a particular vehicle using only the short test procedures are different
than those obtained using the FTP because the preconditioning of the vehicle
(hot start compared with cold start) and the test cycles (time history of
engine loadings) are different. Despite this difference in emissions for par-
ticular vehicles, it is still possible that there is a useful relationship be-
tween the emissions from a short test procedure and the FTP when the mean
(average) emissions of fleets of vehicles are considered. In this case, the
criteria of acceptability of the correlation between the test procedures is the
uncertainty in the inferred means of the FTP emissions of the fleet as pre-
dicted by the short test procedure. This approach seems to be useful for
reasonable size fleets. The relatability of means is useful in evaluating I/M
programs because (1) it makes it possible to relate surveillance data (taken
using test procedures other than the FTP) to equivalent FTP emissions and
to compare them with pertinent Federal Emission Standards, and (2) it per-
mits the use of emission reduction/repair data taken using other test proce-
dures such as the seven-mode hot start. In both cases, however, caution
must be exercised in interpreting the results of such extrapolations. Since
most short test results exhibit a wide degree of scatter and the relationships
between these results and those from FTP tests are quite uncertain, this typc
of analysis can easily lead to false or distorted conclusions.
2.2.2.2 Die crimination Capability of Short Test
The primary objective of the inspection phase of an I/M pro-
gram is to identify the vehicles that have high emissions that can be signifi'
cantly reduced by proper maintenance. Ideally, pass-fail criteria would be
determined for the short test procedure that would identify perfectly
2-14
-------
(without either errors of commission or omission) those vehicles with
^missions of one or more of the pollutants (HC, CO, NO ) above standards
j£
set relative to the FTP. The pass-fail standards for a given model year
vehicle would be related to the Federal Emission Standards for that model
year.
Various approaches to discrimination (i.e., the identification
°f high emitters) using the short test procedures include (1) direct relatabil-
1ty, (2) optimization of discrimination errors, and (3) the engine diagnostic
Method. The objective of each approach is to select, for a fixed rejection
rate, the greatest possible number of high emitters. In the I/M studies con-
ducted to date, a combination of the direct relatability and engine diagnostic
aPproaches have been found to be the most practical and effective. The emis-
sions data needed to set pass-fail criteria by any other method is usually not
Available prior to the start of an I/M program or study.
The fraction of the emission reduction potential that is actu-
ally achieved in an I/M program depends to a large extent on the ability of
the auto repair industry to properly isolate and repair the causes of the high
ei^issions in the rejected vehicles. This interaction between the inspection
and maintenance phases of the program has made it difficult to evaluate quan-
titatively the relative discrimination capabilities of the idle and loaded short
test procedures based on the results of the I/M studies reported in. Refs. 2-1
2-2.
error of commission is an error in which the conclusion drawn from the
8«ort cycle test is that the vehicle is a high emitter and requires repair but
^here in fact it does not require repair as it would have passed the appro-
priate certification test. An error of omission is an error in which the
is judged to be a low emitter by use of the short cycle test, when
fact it would have been shown to be a high emitter (above the standards)
it been tested by the appropriate certification test.
2-15
-------
2.3 ALTERNATIVE MAINTENANCE PROCEDURES
The repair and/or adjustment of the engine or the emission
control systems are the only operations that directly reduce emissions from
in-use vehicles. Even if the inspection phase properly identifies the vehicles
having high emissions, the mechanics must be able to locate and repair the
malfunctions or maladjustments of the engine and/or control system that
have led to the high emissions. Otherwise the primary objective of any I/M
program — that of reducing emissions from in-use vehicles — cannot be
achieved. Tests that can be used by mechanics to locate malfunctions/or
maladjustments and/or to assess their impact on emissions are termed
"engine-control system diagnostics tests. " The auto repair industry must be
knowledgeable of and efficient in the use of diagnostic tests and associated
repair procedures for an I/M strategy to be cost effective. The differences
between the various alternative I/M strategies as they concern the mainte-
nance phase of the program are (1) at what stage in the I/M sequence, and
(2) to what extent diagnostic tests are performed. These differences are
noted in Table 2-7 where the major I/M strategies — emission inspection/
repair, engine parameter inspection/repair, and mandatory periodic mainte"
nance — are outlined, with emphasis on a description of the maintenance
phase. The effectiveness (emission reduction and cost) of each of these I/M
strategies is discussed in Sections 2.4 and 2. 6. First, it is advantageous to
consider the diagnostic tests and maintenance/repair procedures and how the'
relate to emission reductions. This is discussed in Section 2. 3. 1. In additi"
emission test results obtained in the inspection phase using short test proce*
dures can be used to select which of the diagnostics tests are the most
appropriate as further aids in making cost-effective repairs. This topic is
discussed in Section 2. 3. 2.
2-16
-------
Table 2-7. Maintenance Approaches in Various I/M Strategies
I/M Strategy
Emission Inspection/
Repair
Engine Parameter
Inspection/Repair
Mandatory Periodic
Maintenance
Maintenance
Approach
Repair of failed
vehicles to pass
an emissions
retest
Repair of failed
vehicles to pass
an engine para-
meter retest
Specified
periodic main-
tenance0
Emission
Inspection
All vehicles using
a short test
procedure
None
None
Engine Parameter
Inspection
None
All vehicles using
a specified
procedure
None
Vehicles
Serviced
Vehicles that
fail emissions
inspection
Vehicles that
fail engine
parameter
inspection
All vehicles
Extent of Diagnostic
Tests and Service
Only tests needed to
make repairs so that
the vehicle passes the
emissions retest
Tests required to
correct difficiencies
found by the diagnostic-
type inspection
Tests and service
required to perform
specified maintenance
to
I
h*
-o
Inspection performed in State-operated or franchised lanes', or in private garages.
Service performed in private garages.
CMaintenance specified in detail by the State.
-------
2. 3. 1 Engine and Emission Control System Diagnostic and
Parameter Tests and the Sensitivity of Emissions to
Particular Malfunctions
The EPA Certification Procedures for vehicles of each model
year are intended to insure that if the engine is kept reasonably well-tuned
and the emissions control systems are maintained according to manufacturer *
instructions most in-use vehicles will have exhaust emissions less than the
appropriate Federal Standards for that model year for up to 50,000 miles.
If, however, malfunctions or maladjustments are present in either the engine
or emission control systems of the vehicle, the emissions can be above the
standards for the vehicle within the first few thousand miles of use. There
have been several in-depth studies (Refs. 2-3 and 2-4) of the effect of engine
and control system malfunctions on emissions for vehicles currently on the
road and a projection of such effects for 1975-77 vehicles having more
advanced emission control systems (Ref. 2-9). In this section of the report*
the information and data reported in Refs. 2-1 through 2-4, 2-9, and 2-10
are reviewed and consolidated with emphasis on the following aspects of the
emissions/maintenance problem:
a. Diagnostic and parameter test procedures and required
e quipme nt / in s t rument s
b. Sensitivity of emissions to particular malfunctions or
maladjustments
c. Frequency of occurrence of common malfunctions in current
and future vehicle populations
2.3.1.1 Diagnostic and Parameter Test Procedures and
Required Equipment
There are many components and systems that must be check^
to determine the state-of-operation or the need-for-repair of the engine and
emission control systems on a vehicle. These components and systems can
be categorized as follows:
2-18
-------
Engine
1. Idle System (rpm, air/fuel ratio)
2. Major Engine Components
Intake and exhaust values
Cylinder rings (compression)
3. Induction/Fuel System
Carburetor (idle and main systems)
Fuel pump
Air filter
Fuel system filter
4. Warm-Up System
Choke
Heat riser valve
Carburetor air preheater
5. Ignition System
Basic timing
Primary ignition circuit
Secondary ignition circuit
Vacuum spark advance
Emission Control Systems
1. Positive Crankcase Ventilation System
PCV valve
2. NO Control System
Spark advance control
Exhaust gas recirculation (EGR) valve
3. Air Injection System
Air pump
Check and anti-backfire valves
4. Oxidation Catalyst System
Catalyst activity
Container integrity
2-19
-------
Diagnostic and parameter tests and the equipment and
instruments needed to perform them are available for checking all the com-
ponents and systems listed above. These tests involve the functional check
of components, measurement of engine parameters at idle and under load,
and measurement of vehicle emissions in various steady-state operating
modes. A summary of the diagnostic tests and the equipment needed are
given in Table 2-8. Also indicated in the table are an estimate of the time
required and the cost of the equipment and instruments for each test. It is
clear from Table 2-8 that the accumulated time (labor) that would be required
to perform all the tests is sufficiently long that it is unlikely such a complete
diagnostic/parameter test procedure would be practical for all vehicles at
an engine parameter inspection or during every periodic maintenance. Hence,
it is of importance to know how sensitive the emissions are to particular
malfunctions and maladjustments in various systems and what the frequency
of occurrence of the various malfunctions can be expected to be in vehicle
populations having only voluntary maintenance.
2.3.1.2 Sensitivity of Emissions to Particular Malfunctions
/
Qualitative estimates of the effect of particular engine and
control system malfunctions and maladjustments in HC, CO, NO emissions
3£
are given in Table 2-9. Information is included for vehicles with advanced
control systems such as EGR and catalytic converters. The sensitivity
rankings noted in Table 2-9 are given in terms of H (high), M (medium),
and Li (low).
Many of the components that can have a large effect on emis-
sions have a manufacturer suggested service interval of 6 months to one year
(12,000 miles) even though the mean time to failure is much longer. Service
and/or replacement of the many components and systems of the increasingly
complex engine and emission control systems can be expensive if done at the
manufacturer's suggested intervals. Hence, many vehicle owners do not have
the service done as often as needed to maintain low emissions from the
2-20
-------
TabIe*2-S. Summary of Engine and Emission Control System Diagnostic
Tests and Associated Equipment /Instruments
Engine Systems
ro
to
Component/System Tested
t
Idle System
RPM
Air/fuel ratio
Major Engine Components
Exhaust valves
Cylinder compression (rings)
Induction/Fuel System
Carburetor
Idle
Main system
Air filter element
Fuel filter
Warm- Up System
Choke
Heat riser valve
Ignition System
Basic timing
Primary ignition system
Secondary ignition system
Vacuum spark advance
Engine Operating Mode
Idle
Idle
Idle /loaded
Idle/loaded
Idle
Loadedb
Off /loaded
Off
Off
Off
Idle
Idle /loaded
Idle /loaded
Loaded
Type of Test
Engine parameter measurement
Engine parameter measurement
Emission measurement
Engine parameter measurement
Emission measurement
, Emission measurement
Visual/engine parameter measurement
Visual/mileage
Visual/functional
Visual /functional
Engine parameter measurement
Engine parameter measurement
Engine parameter measurement
Engine parameter measurement
Time
Required* Equipment
(minutes) Required
!, Engine analyzer
Engine analyzer
| 3Q 45 HC/CO analyzer
{ ~ compression
te ste r / cy linde r
leakage tester
1 HC/CO analyzer
j 2-5 HC/CO analyzer
1-2 Air filter tester
1-2 None
2-3 None
2-3 None
1-2 Engine analyzer
j Engine analyzer
j 2-5 and ignition scope
1
Distributor advance
1-2 tester
Cost of
Equipment ($)
100 . tOO
100 - 200
1000 - 1500
50 - 150
1000 . 1500
1000 . 1SOO
25 - 50
100 . 200
1500 . 2500
200
*After engine is warmed up and required equipment is available and calibrated.
b
'Tests at loaded engine modes require a simple (single-power absorption curve) dynamometer {cost: approximately $3500).
Advanced engine analyzers (costing $4000-36000) are bei,ng marketed that offer complete engine diagnostics capability and exhaust gas analysis in one unit, but
less expensive engine analyzers/ignition scope units are suitable for testing ignition systems.
-------
Table 2-8. Summary of Engine and Emission Control System Diagnostic
Tests and Associated Equipment/Instruments (continued)
Emission Control Systems
to
I
to
to
Component/System. Tested
Positive Crankcase Ventilation
PCV
NO Control System
X
Spark advance control
Exhaust gas recirculation
EGR valve
Air Injection System
Air pump
Check and anti-backfire valves
Oxrdication Catalyst System
Catalyst activity
Container integrity
Engine Operating Mode
Idle /loaded
Loaded
Off /loaded
Idle/2500 rpm
Idle /2 500 rmp
Idle /loaded
Off/idle
Type of Test
Engine parameter measurement
Functional /engine parameter
measurement
Functional/emissions measurement
Engine parameter
Functional
Emission measurement
Visual
Time
Required
(minutes)
1-2
1-2
1-2
1 2-5
1
! as
1 "
Equipment
Required
Crankcase pressure
gauge and PCV flow
meter
•
Advanced engine
analyzer or dis-
tributor advance
tester
NO analyzer
Pressure gauge
None
HC/CO analyzer
None
Cost of
Equipment ($)
50
t
4000 - 6000
200
1500 - 3000
10
1000 - 1500
dThe advanced engine analyzer units can be used to check spark advance control system with the vehicle on a dynamometer. There are also functional check
procedures available.
eThis NO analyzer is the NDIR type. Present price is about $30QO/unit, but with increased market, price should be comparable to HC/CO analyzers.
-------
Table 2-9. Effect on Emissions of Various Engine/Emission
Control System Component Malfunctions /
Maladjustments (Ref. 2-9)
Component
Eneine Component*
Idle System
Idle mixture
Idle rpm
Exhaust Valve Leak
Compression (low)
Induction /Fuel System ,
Carburetor
Metering rods
Internal vent*
Float
Piwer jet
Accelerating pump
Air filter element
Fuel pump
Fuel filter
Intake manifold leak
Warm- Up System
Choke
Heat riser valve
Air cleaner thermostat
Ignition System
Basic timing
Spark plugs
Plug wires
Coll
Distributor, condenser
Point!
Electronic ignition
Transmission controlled spark
Vacuum delay valve
Centrifugal advance
Emission Control System Components
PCV System
PCV valve
NO Control System
X
Spark advance control
EGR valve
Reduction catalyst
Air Injection System
Air pump
Air pump belt (slip)
Check valve
Anti. backfire valve
Oxidation Catalyst
Catalyst activity
Container integrity
HC
M
M
H
M
M
M
L
M
M
L
L.
L
L.
M
H
M
M
L
H
H
H
M
H
H
M
M
M
M
H
M
H
M
H
H
CO
H
M
M
H
H
H
M
M
U
L
M
L
L
L
H
M
M
M
L
H
H
M
H
M
H
H
N0x
L
L
L
L
L
L
L
L.
M
M
M
M
M
M
M
H
H
H
2-23
-------
vehicles. Repairs are made in most cases when the owner notices a
••
degradation in vehicle reliability, driveability, performance, or fuel economy.
Unfortunately, the same changes that cause a deterioration of emissions with
mileage may also lead to improvements in some of these areas of importance
to the vehicle owner. Hence, many conditions leading to moderate or even
large increases in emissions are not likely to lead the owner to voluntarily
have the vehicle serviced. The extent of the engine and control system mal-
functions or maladjustments that are tolerable from an emissions point of
view is considerably smaller than that tolerable to many vehicle owners from
the viewpoint of reliability, performance, etc. This becomes particularly
true in the case of older vehicles that tend to be driven with the minimum of
maintenance as long as they are reasonably reliable. Fortunately, the average
emissions from the population of older vehicles tend to stabilize as unavoid-
able repairs (e.g., ignition wiring, rebuilt carburetors, valve and ring re-
placement, etc. ) are made, which results in large reductions in emissions
from the repaired vehicles. Surveillance data indicates, however, that the
stabilized emission levels are well above the emission potential for those
model years.
The qualitative effects of various engine and emission control
system malfunctions on emissions (HC, CO, NO ) have been given in Table
2-9. In a number of cases, it is also possible to estimate quantitatively
these same effects. The primary sources of this type of data are Refs. 2-4
and 2-9. The quantitative effects can be expressed in terms of the incremental
changes in the emission of a particular pollutant (e.g., A gm/mi CO) for a
specified failure or maladjustment (e. g. , an inoperative spark advance on-off
switch or delay valve; degrees advance from specification in basic timing).
In summarizing the emission changes due to malfunctions, it is convenient to
consider three categories: (1) minor engine or control system maladjustments
or failures, (2) major engine problems, (3) major emission control system
malfunctions.
The effects of various minor engine maladjustments on emissions
are summarized in Table 2-10 for precontrolled (pre- 1968), controlled
2-24
-------
Table 2-10.
The Quantitative Effect of Minor Engine/Emission Control
System Malfunctions/Maladjustments on Emissions (Ref. 2-4)
Item
Basic Timing
Vehicle Type
Precontrolleda
Controlled
NO Control0
X
Idle RPM
Vehicle Type
Precontrolled
Controlled
NO Control
X
PCV Valve
Vehicle Type
Precontrolled
Controlled
NO Control
Air Cleaner
Vehicle Type
Precontrolled
Controlled
NO Control
Idle CO
Vehicle Type
Precontrolled
Controlled
NO Control
Change in Emissions
Agm/mi per degree advance
HC CO NO
0.06 -0.95 0. 14
0.05 -0.34 0.095
0.085 -1.03, 0.15
Agm/ml per 100 rprn increase
HC CO NO
-0.29 2.8 0.02
.0.55 2.1 0.03
.0.06 2.2 0.05
Agm/mi per cfm restriction
HC CO NO
.0.06 5.5 -0.12
0.20 6.0 -0.20
0.28 15.9 -0.38
Agm/mi per 12-1/2% area blockage
HC CO NOX
0.025 5.0 -0. 14
0,040 3.4 -0.09
0.040 2.3 -0.12
Agm/mi per 1% increase In idle CO
HC CO NOX
0,36 4.2 0.21
0.03 7.2 0.03
0.08 7.5 -0.07
aPre-1968
b!968-1970
cCalifornia 1971
dAll emissions measured using 1972 CVS-C; positive values indicate
an increase In emissions, negative values indicate a decrease in
emissions.
cCubic feet per minute flow rate
2-25
-------
(1968-1970), and NO controlled (Calif. 1971) vehicles. The magnitude of
Ji
the unit reference deviation was selected so that deviations measured in
current in-use vehicle populations are a reasonable multiple of the reference
unit. For the most part, taken singly, the effect of the minor engine mal-
adjustments are reasonably small (1 to 2 gm/mi on HC and 5 to 10 gm/mi
on CO), but the accumulated effect of several maladjustments occurring
simultaneously can result in a vehicle having emissions far above an accept-
able level for that model year. This category of malfunctions affects a
significant fraction of the vehicles in the population, but the emission increa*'
of many of the affected vehicles is relatively small.
As indicated in Table 2-11, the situation relative to emission
increases due to major engine problems, such as ignition misfire and
carburetor and exhaust valve problems, is much different. In this case, the
magnitude of the emission increase due to a single problem is very large;
however, the fraction of vehicles having these problems is relatively small.
Proper identification in the inspection phase of these vehicles, especially
those having main system carburetor problems, is particularly desirable.
The third category of emission-related malfunctions is con-
cerned with the emission control system itself. In the case of NO control*
i "" X
if the emission control system is integral with the engine system, its mal-
function may in some instances cause a deterimental effect on engine operati
or vehicle driveability or reliability. In the case of catalytic control of HC
and CO emissions, a malfunction or deterioration of the oxidation catalyst o*
air pump has no effect on engine operation, since the exhaust gases are
treated after they leave the engine. As indicated in Table 2-12, the magnit'J'1
of emission increases due to major malfunctions in the emission control
systems are large (both in absolute and percentage terms). In the case of t*1
catalyst, even a deterioration of 20 to 30 percent in catalytic activity result*
in significant increases in emissions. In many instances, minor engine mal"
adjustments would be masked if catalytic activity is high; however, major
engine problems can lead to rapid catalyst deterioration and a subsequent
2-26
-------
Table 2-11. The Effect of Major Engine Malfunctions
on Emissions (Ref. 2-4)
Malfunction4
Ignition Misfire {% of time)
2
6
IE
Main System Carburetor Calibration
Leaking Exhaust Valves or Low
Compression
Change in Emissions (gm/mi)
HC
4
12
25
5-10
CO
50-150
NOX
All of these major engine problems result in reduced NO emissions.
JL
Increase in emissions measured using the 1975 CVS-CH test procedure.
2-27
-------
Table 2-12. The Effect of Major Emission Control System
-Failures on Emissions (Ref. 2-9)
System Failure
NO Control System
x '
•L
Spark advance (off -on) switch failure
Spark advance delay valve failure
EGR valve failure
Oxidation Catalyst System
Air pump failure
Catalyst failure
Total failure
30% decrease in catalytic activity
60% decrease in catalytic activity
a
Change in Vehicle Emissions
(gm/mi) _
HC
1
2-3
0.5-1
1.5-2
CO
10
20-30
5-10
15-20
NOX
1-1.5
0.5-1.0
1.5-2.5
Increase in emissions measured using the 1975 CVS-CH test procedure.
^Component inoperative.
•»
"Assuming normal engine operation; effect would be greater if other mal-
functions are present.
2-28
-------
very large increase in emissions. Hence, it is necessary to properly
identify vehicles having major engine problems even when an oxidation
catalyst is used for emission control.
2.3.1.3 Frequency of Occurrence of Various Malfunctions
It is also of interest to know how often the various malfunctions
occur in typical vehicle populations and how large the deviations from manu-
facturer's specifications are for those components and systems that normally
need adjustment. Such information, as shown in Tables 2-13 and 2-14, has
been collected in various I/M programs by direct measurement of engine
parameters and emissions (Ref. 2-4) or by extracting data from mechanics
records (Refs. 2-3 and 2-10) of the kinds of repairs undertaken and the
replacement parts used. As shown in the tables, a wide range in the state
of repair of vehicles exists in current vehicle populations and careful diag-
nostic work by mechanics is required to locate the malfunctions present in a
particular vehicle at a reasonable cost. In general, in order of frequency
of occurrence, the various malfunctions rank as follows: idle adjustments,
ignition problems (plugs, points, wiring), main system carburetor problems,
and exhaust valves. Information on the occurrence of malfunctions of
emission control components, such as NO control (spark advance), air pump,
j£
etc. , on newer model vehicles is quite sparse. Further, essentially no
maintenance information is available on malfunctions of EGR valves and only
limited durability test fleet data is available for oxidation catalysts.
2.3.2 Maintenance Phase Tune -Up/Repair Procedures
It was found in early I/M studies that unless the diagnostic and
repair procedures were systematized and the mechanics were carefully in-
structed on their application and the relationships between emissions and
various engine malfunctions and adjustments, resultant emission reductions
from the program would be quite small and the cost of the tune-up and repair
work would be quite high. Hence, in most of the I/M studies previously
referenced (Refs. 2-1 through 2-4) the development of diagnostic, tune-up
2-29
-------
3.
Table 2-13. Emission and Engine Parameter Distributions for Two Vehicle Fleets (Ref. 2-4)
Location
Model Year
Parameters
High cruise
HC, ppm
CO, volume %
NO, ppm
Idle
HC, ppm
CO, volume %
NO, ppm
Timing, deg (deviation)
Idle speed, rpm (deviation)
Air cleaner restriction, deg
High cruise, PCV flow, ft3/min
Choke kick, in. (deviation)
Heat riser, % failed
Vacuum diaphragm, % failed
High cruise, misfire, %
Low cruise, misfire, %
Idle misfire, %
Air pump, % failed
NO control, % failed
X
Mileage, miles
Precontrolled Vehicles
Califoj
1960-1
*d
383
3.43
1666
865
6.08
1Z6.8
0.35
77.9
60.0
2.87
0.009
53.1
25.0
12.3
14.4
17.5
-
.
83358
rniab
965
o-e
450
2.6
864
989
3.0
122
5.7
137
53
1.3
0.049
-
-
11.3
9.6
12.0
-
-
26047
Michij
1960-1
X
332
1.64
-
603
4.50
-
0.62
108.5
61.7
2.86
-0.051
68.0
32.6
14.5
15.1
13.9
-
-
58280
;anc
967
(T
374
1.5
-
582
3.1
-
6.0
146
45
1.3
0.065
-
-
1.8
1.7
3.8
-
-
19377
Controlled Vehicles
California
1966-1970
X
222
1.22
2613
376
4.09
124.2
0.50
-18.2
45.6
2.62
-0.004
44.0
21.7
2.6
4.6
li.5
8.1
-
43786
tr
306
1.3
976
546
2.6
82
4.6
108
53
0.97
0.046
-
-
0.4
3.6
9.7
-•
-
20567
Michigan
1968-1971
*
198
0.69
-
300
3.15
-
1.07
2.5
47
2.85
-0.037
42. 5
21.3
4.7
4.8
4.2
-
-
27863
0"
107
0.81
-
230
2. 5
-
3.7
90
44
1.2
0.064
-
-
0.4
2.4
0.9
-
-
17340
NOX- Controlled
Vehicles
Califor
197
X
135
0.87
2537
240
3.34
168
0. 17
-5.68
28.8
2.58
-0.010
3.4
0.0
•"
-
-
-
4.9
8059
nia
-------
Table 2-14. Parts Replaced During Minimum Pollution
Capability Tune-Upsa (Ref. 2-3)
Part
% of Vehicles 1
Receiving Parts
Spark plugs
Air filters
Distributor points
Ignition wires
Complete set
Individual wires
PCV valves
Carburetor jets
Carburetor rebuilt kit
Replacement carburetor
Distributor cap
Distributor rotor
Carburetor choke parts
56
47
4
5
7
10
4
5
3 ,
3
3
2
Vehicles were tuned up to the extent necessary to minimize their
exhaust emissions.
All cars in fleet received a tune-up.
2-31
-------
and repair procedures was an important part of the effort whether the study
included a separate inspection phase (Refs. 2-1 and 2-2) to identify high
emitters and only failed vehicles were serviced, or the entire fleet was
subjected to a specified maintenance program (Refs. 2-3 and 2-4). Diagnostic
and/or maintenance procedures have been developed from the following
three points of view:
a. Maintenance after an idle inspection test
b. Maintenance after a loaded (Key Mode) inspection test
c. Mandatory maintenance and/or engine parameter inspection
of all vehicles
The objective in each case is to achieve large average emission
reduction at low average repair cost. A common approach, termed the
"truth chart approach, " has evolved in all three maintenance cases. It appar-
ently was started by the Clayton Manufacturing Company in 1968 in connection
with the Key Mode inspection test and has been adopted more recently for use
with the idle test and even as the framework on which to plan a mandatory
maintenance procedure. The application of the truth chart approach to each
of the three maintenance approaches above is discussed in the following
subsections.
2.3.2.1 Maintenance After^an Idle Emissions Test
The basic assumption of the idle test is that high idle CO and
HC emissions are a reliable indication of high emissions of these same
pollutants on a FTP-CVS test. Therefore, in making repairs on vehicles
that have failed the idle test, it is essential that it be possible to reliably
diagnose malfunctions that result in high emissions in loaded modes, which
are important in the FTP. Much of the effort in developing diagnostic and
repair procedures and truth charts for use after the idle test has been direct^
toward this problem. In Ref. 2-10, this aspect of idle test maintenance is
considered in detail. Since it is not possible to load the engine during
maintenance without a dynamometer, the off-idle malfunctions must be
2-32
-------
from engine parameter and emissions data taken with the engine in a free-
wheeling condition. It was found (Ref. 2-10) that comparison of emissions
a-t idle rpm with those at 2500 rpm (free wheeling) can in some cases yield
information useful in diagnosing off-idle malfunctions. The most difficult
engine malfunctions to recognize using idle test maintenance procedures are
incipient ignition misfire and main system carburetor problems. Both of
these malfunctions result in very large increases in emissions.
Typical idle test maintenance procedures and truth charts
are extensive in detail and are not presented here in the interest of brevity.
Effective application of these procedures requires instruction of mechanics
m their use. At the present time, most mechanics are not accustomed to
Performing emission reduction-oriented tune-ups and repairs using emission
Measuring instrumentation (HC/CO gas analyzers) as a tool. There is
considerable evidence that at least initially many errors are made by me-
chanics in making the needed repairs. The situation should improve as
Mechanics become more experienced in making emission-oriented repairs.
•3.2.2 Maintenance After a Loaded (Key Mode^ Inspection Test
Diagnostic procedures and truth charts for use with loaded
rn°de (Key Mode) emission inspection results have been developed by the
Clayton Manufacturing Company. Classroom instructions on the use of the
rutti charts and dynamometer/vehicle demonstrations of the effect of various
engine malfunctions on emissions have been given to mechanics by Clayton
Personnel as part of several I/M studies (Refs. 2-1, 2-2, and 2-5). Since
Missions data are available to the mechanic from loaded as well as the idle
ngine operating modes, some engine malfunctions are indicated to the
rilechanic more pointedly and with less ambiguity than when only unloaded
Udle and 2500 rpm) emissions data are available. This should result in
e\ver errors by mechanics in identifying the malfunctions causing high
6rnissions, Almost all the field experience with the Key Mode system has
6en with HC and CO emissions on pre-1971 model vehicles, but NO emission
2-33
-------
data from loaded (cruise) modes should permit its use for NO inspection
and repair also.
A typical Key Mode emission report card is shown in Fig-
ure 2-2. Note that maximum values for HC and CO are shown for each mode.
These values, which would be different for vehicles with differing emission
control potential, are well below the failure criteria for the vehicle of interest.
They indicate emission levels for a normally functioning engine in that mode.
A complete set of diagnostic truth charts has been developed for use by
mechanics (Ref. 2-11). It is assumed that if a mechanic correctly diagnoses
the reason for the high emissions from a vehicle, he will have a better
chance of repairing it properly.
2.3.2.3 Mandatory Maintenance and/or Engine Parameter Inspection
of all Vehicles
A reasonable fraction of the vehicles in use are maintained
reasonably well voluntarily by owners and it is commonly assumed that it is
primarily the poorly maintained or neglected vehicles that are the high emit-
ters. However, if each in-use vehicle was subjected to prescribed mandatory
annual maintenance or engine parameter inspection/repair, the average
emissions from in-use vehicles would be significantly reduced. This approach
would be even more attractive if a functional check on components, such as
the EGR valve, air pump, and oxidation catalyst, * in the more advanced
emission control systems would be an effective way of insuring low emissions
from late (and future) model vehicles.
There have been several I/M studies (especially in California)
in which the mandatory maintenance approach has been evaluated. In this
approach, the State would specify portions of the vehicle manufacturer's
suggested maintenance procedure to be followed by private garages Two
such procedures are outlined in Refs. 2-2 and 2-3. These procedures would
have to be extended to include functional checks of NO control s
j{
A catalyst activity check, in which idle HC emissions with -
shorted spark plug are measured, has been suggested *
2-34
-------
NOH- EXHAUST EMISSION CONTROLLED
-CO-
CARBON
MONOXIDE
-HC-
UNBURNED
HYDROCARBON
HIGH
CRUISE
MAX 3%
7,6
V
MAX
450 PPM
4t>5
LOW
CRUISE
MAX 3.5%
5.4
MAX
450 PPM
3£P
IDLE
MAX 5.5%
2.S~
MAX
700 PPM
492
= REJECT
EXHAUST EMISSION CONTROLLED
-CO-
CARBON
MONOXIDE
-HC-
UNBURNED
HYDROCARBON
HIGH
CRUISE
MAX 2%
, ^
MAX
220 PPM
/2$~2.
^
LOW
CRUISE
MAX 2.5%
,£
MAX
240 PPM
/35"0
//
IDLE
MAX 3%
3,f
MAX
290 PPM
/***
\s
= REJECT
Figure 2-2. Typical Key Mode Report Card
(Ref. 2-11)
2-35
-------
(spark advance on-off switch and/or EGR valve) and the activity of the
oxidation catalyst if the procedures were to be applied to late (and future)
model vehicles.
The prescribed annual maintenance procedures are a combin-
ation of engine parameter checks and adjustments, idle emission measure-
ments, and visual (or functional) inspections and/or replacement of various
engine and control system components. As in the case of idle test mainte-
nance previously discussed, it is difficult without a dynamometer to correctly
identify engine malfunctions that occur most pointedly at loaded-engine
conditions. Reliable diagnosis of such malfunctions requires careful atten-
tion by mechanics and the use of test equipment that is not currently available
at many garages. In developing such maintenance procedures, available
malfunction-emission sensitivity and frequency of occurrence data, such as
that given in Ref. 2-4, have been used to determine those component checks,
emission measurements, and component replacements needed to correct
malfunctions and maladjustments that occur with highest frequency and/or
contribute the most to increased emissions. Refinement of specified main-
tenance procedures would continue in the future as more data become available
on late model vehicles.
Because mandatory maintenance programs require the appli-
cation of uniform maintenance procedures to all vehicles, some unnecessary
repairs and parts replacements may result and in some cases may even
cause an increase in emissions. A compromise program based upon inspec-
tion of specific engine and emission control system parts and adjustments
reduces the tendency to over-repair while eliminating the need for purchas-
ing emission measuring equipment. The elimination of direct emission
measuring equipment is accomplished at the cost of a more extensive engine
parameter inspection procedure.
2-36
-------
2.4 EMISSION REDUCTIONS AND REPAIR COSTS OF
ALTERNATIVE I/M APPROACHES
In this section, results obtained in various I/M field or
experimental studies using alternative I/M approaches and fleets of in-use
vehicles are reviewed, compared, and correlated. Of particular interest are
the emission reductions achieved and the cost of repairing and/or servicing
vehicles subjected to maintenance. The results discussed in this section are
for a single inspection/repair cycle and do not include the effects of deteriora-
tion between inspections or the accumulative effect on average fleet emissions
of repeated inspection/repair cycles.
2.4.1 Emission Reductions Obtained Using Alternative
I/M Approaches
As indicated previously in Table 2-1, various I/M studies have
been conducted using one or more alternative I/M approaches. The effective-
ness in terms of emission reduction achieved of a particular I/M strategy
depends on a number of factors including:
a. Emission inspection test used and its discrimination
capability
b. Emission characteristics of the test fleet
c. Failure criteria and resultant failure rate
d. Repair/maintenance procedures
e. Thoroughness of instructions to mechanics
f. Limits on the extent of repairs permitted to
failed vehicles
r«ere often are significant variations in one or more of these factors, even
etween studies designed to compare the same two I/M approaches. This
s«ould be kept in mind in the subsequent comparison of both the emission
Deduction achieved and the cost of repair incurred for different I/M strategies.
t is important also to note that emission reductions (even percent reductions)
using different emission test procedures (seven-mode hot start, idle,
y«5 CVS-CH) should not be compared directly. In some studies, results of
2-37
-------
tests using one procedure have been compared with those using another by
first applying a regression relationship determined by comparing the results
of tests using both procedures on the same vehicles. This type of analysis
can lead to false conclusions because in most instances the scatter in the data
is quite large and the results of the two procedures do not correlate well even
on a fleet average basis.
In comparing the effectiveness of various I/M approaches it
is convenient to do so at selected failure or rejection rates. Since there is
only a single failure rate associated with each 1/M study, the emission reduc-
tion effectiveness at other rejection rates (necessarily lower ones) is deter-
mined by analyzing a subset of the entire group of repaired vehicles from that
program. It is assumed that the emission characteristics (before and after
repair) of that subset are equivalent to those that would have resulted from
lowering the rejection rate by changing the failure criteria. The accuracy of
this assumption is difficult, if not impossible, to assess.
A final, but important, limitation on the quantitative results to
be given in the following paragraphs is that they apply in a strict sense only
to precontrolled (pre-1968) and controlled (1968-1971) vehicles that have not
been previously subjected to an I/M program. As noted previously, vehicles
with more advanced control systems and vehicles that have been inspected
and maintained for several years may respond differently to a given I/M pro-
gram than the vehicles included in the I/M studies whose results are being
analyzed. Nevertheless, much has been learned from past I/M studies and
the results are important in evaluating alternative I/M strategies for future
application.
The feasibility of an enforced mandatory tune-up requires the
identification of specific engine components and adjustment parameters that
have a significant effect upon vehicle emissions and whose malfunctioning can
be predicted with a reasonable degree of certainty. The cost effectiveness of
mandatory maintenance is highly sensitive to the identification of the optimal
tune-up specifications for each engine component and the reliability of pre-
dicting the frequency of malfunction.
2-38
-------
The test fleet used to evaluate this strategy was composed of
pre-1966 vehicles representative of the domestic vehicle population in
California. The repair action included the replacement of the major compo-
nents in the secondary ignition system (spark plugs, spark plug wires, breaker
points, condenser, and distributor rotor), the air cleaner filter, and the posi-
tive crankcase ventilation (PCV) valve, and adjustment of the idle parameters
(air/fuel ratio, rpm, and timing). The estimated cost for the required parts
and labor was $55 per vehicle. A 15-percent average reduction of exhaust
HC emissions and an 11-percent average reduction of CO emissions were
observed following the tune-up of the entire sample fleet.* There was no sig-
nificant change in the fleet mean NO emissions.
X
Every vehicle in the test fleet received identical maintenance
regardless of the as-received exhaust emissions. The total fleet average
emissions after tune-up as a function of the percentage of vehicles receiving
maintenance are shown in Figures 2-3 and 2-4. For this analysis, the vehi-
cles were ranked according to the as-received (before tune-up) exhaust emis-
sions; progressively larger fractions of the population were assumed to have
been identified for maintenance using an emission test. Each percentile
represents the highest emitters comprising that fraction of the test fleet.
As indicated in Figure 2-3, the maximum leverage for reduction
°f fleet HC emissions is obtained from the highest emitters composing 20 to
30 percent of the population. Carbon monoxide reductions improve linearly by
increasing the maintenance fraction through 50 percent of the population. The
Maximum reduction of CO emissions would have resulted from repairing 80 per-
cent of the vehicles.
Data obtained in the emission inspection study reported in
Ref, 2- 1 have been reviewed and compared in detail. Summaries of the data
being compared are shown in Figure 2-5. Curves are given for the Idle Test
Key Mode inspection repair procedures discussed in Sections 2.2 and 2.3.
These emission reductions are based on limited data from an early test
Program. Later test results indicate that higher HC and CO emission re-
are achievable immediately after servicing.
2-39
-------
Fig. 2-3. Hydrocarbon Levels vs Population Percentage (Ref. 2-12)
2-40
-------
1 »
u
Si
a
i
i
8
8 »
II -
,
-
KPULtTIGN IplrUMI
Figure 2-4. Carbon Monoxide Levels vs Population Percentage
(Ref. 2-12)
2-41
-------
UJ
CONTROLLED
VEHICLES (1968-1971)
4.0
UJ
=! o
2 I
o
VI
O
u
Ul
cc
o
in
O
o
g
UJ
OC
O
in
ui
i
UJ
3.0
2.0
1.0
O
O
30
20
10
40
U 30
10
0
40
30
IDLE
Loaded steady state
—o
I I
10 20 30 40 BO
REJECTION RATE (%)
60
UNCONTROLLED
VEHICLES (pre-1968)
i i
10 20 30 40 GO
REJECTION RATE <%>
60
Figure 2-5. Emission Reduction Effectiveness as a Function of
Rejection Rate (Phase II results of Ref. 2-1)
2-42
-------
The data reported in Refs. 2-2 and 2-3 were obtained using
the seven-mode, hot-start test procedure. The results for both controlled
and uncontrolled veTiicles are consistent with those shown in Figure 2-5 and
indicate clear trends relative to the effect of failure rate and the effectiveness
of the various alternative I/M strategies in reducing emissions after a single
inspection/repair cycle. The major conclusions drawn from these analyses
are the following:
a. The additional fleet emission reductions achieved by
failing more than 50 percent of the fleet are small.
b. The Key Mode test/repair procedures have a clear
superiority over the idle test/repair procedures in
reducing fleet emissions at all failure rates.
2.4.2 Repair Costs for Serviced Vehicles
Repair cost data for vehicles serviced in the I/M study reported
in Ref. 2-1 are summarized in Figure 2-6. The repair costs depend pri-
marily on the scope of the engine adjustments and/or tune-up specified in the
maintenance instructions to the mechanics taking part in the program and the
average state-of-maintenance of the vehicles being repaired. There are,
however, considerable variations in costs from program to program even for
the same I/M approach and rejection rate due to differences in the ability of
the mechanics to identify correctly the causes of the high emissions of the
failed vehicles and to make only those repairs needed to reduce the emissions.
The detailed maintenance procedures and truth charts discussed in Section 2.3
were developed to aid the mechanics in making more cost-effective, emission-
oriented repairs. Detailed examination of the emissions data for individual
vehicles taken before and after repair in all the I/M studies reported to, date
shows that in a significant number of instances the potential for large emission
reduction was not realized even though the vehicle repair cost was quite high.
As the repair industry becomes more accustomed to emission reduction as an
important reason for vehicle repair and servicing, their performance in this
regard should improve.
While there have been variations in costs between I/M studies,
°n the average simple idle adjustments on failed vehicles can be made for $5
2-43
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HI
70
60
50
z
111
a 40
UJ
o
£ 30
cc
S 20
w
8
10
CONTROLLED
VEHICLES (1968-1971)
1
•— — — IDLE
-"•"—~ Loaded
steady-state
I
1
10 20 30 40 50
REJECTION RATE (%)
60
S2
3
in
o
ui
8
70
60
o 50
I
UJ
«
30
20
10
UNCONTROLLED
VEHICLES (pre-1968)
J L
0 10 20 30 40 SO
REJECTION RATE (%)
60
70
60
K! SO
o
$ 40
cc 30
UJ
a.
8 20
10
—O
10
20
30
40
GO 60
REJECTION RATE (%)
70
60
JS 60
in
3
E «
30
20
10
0
J L
10
20
30
J L
40
50
60
REJECTION RATE <%)
Figure 2-6. Average Vehicle Repair Cost (Phase II Results of Ref. 2-1)
2-44
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or less, while a thorough minor tune-up costs between $25 and $35. When
major repairs are needed or more extensive engine diagnostic measurements
are specified, the repair costs are significantly higher. The average cost per
vehicle repaired increases as the rejection rate is decreased. This is as
expected, since the most out-of-repair vehicles are the ones that are -rejected
first and require more extensive work. In the other extreme of subjecting
all vehicles to a specified tune-up regardless of their emissions levels, the
average cost per vehicle is about $55 (Ref. 2-4).
2-45
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2.5 DETERIORATION OF EMISSIONS WITH AND
WITHOUT PERIODIC I/M
There are several aspects of the deterioration of emissions
from in-use vehicles that should be considered in evaluating the net emission
reductions to be expected from I/M strategies. First, what increase of emis-
sions would occur for the various vehicle model years in the absence of a
mandatory I/M program? Second, after a rejected vehicle with high emissions
is repaired and its emissions reduced, what increase in emissions will occur
prior to the next emissions inspection? Third, what emissions increase will
occur in the vehicles that passed the inspection before they are subject to
inspection again? It is the offsetting effects of the emission reductions due
to the repair of rejected vehicles and the increase in emissions of both
repaired and passed vehicles between emission inspections that determine the
net emission reductions achieved by I/M strategies.
Emission deterioration can be expressed in terms of the frac-
tional change per unit time (or mileage) or directly as the absolute change
(gm/mi) per unit time (or mileage). The fractional change or deterioration
factor approach has proved to be more convenient in studies of I/M because
the absolute level of emissions for various classes (model year and control
system) of vehicles in the population differ markedly (reflecting the changing
Federal Emission Standards for new vehicles). In determining the deteriora-
tion factors for a given class of vehicles, one can either (1) average the
deterioration factors of the individual vehicles of that class, or (2) average
the emissions from a fleet of such vehicles taken at specified times or mile-
ages and calculate the deterioration factors for the fleet from the change in
the average emissions. The statistical character of emissions testing, vehi-
cle repair, and the occurrence of malfunctions and maladjustments in engine
and emission control systems results in the second approach being the most
advantageous. Most of the deterioration-related information in the literature
is presented in terms of deterioration factors obtained using averaged emis-
sions data.
2-46
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2.5.1 Deterioration of Emissions with
Voluntary Maintenance
The exhaust emissions from vehicles tend to increase with time
(or age), even when the manufacturer's recommended maintenance program
is followed. Many vehicle owners have only that maintenance performed
that they feel is needed to maintain good operating reliability and driveability
of the vehicle. As indicated in Figure 2-7, the emission characteristics
(gm/mi vs vehicle age) resulting from these limiting types of maintenance
Practices are significantly different. The objective of the I/M strategies is
to reduce the deterioration of emissions with vehicle age so that the emission
characteristics of in-use vehicles approach those that would result from fol-
lowing the manufacturer's recommended maintenance schedules.
2.5.2 Effective Emission Reductions Resulting
from I/M Programs
The effective reduction in emissions that results from an I/M
Program is the difference between the average (annual) vehicle emissions
after the program has been implemented and those emissions that would have
occurred in the same vehicle population in the absence of the I/M program
^•e. , with only normal voluntary maintenance). The effective emission reduc-
tions thus can depend on a large number of factors, including:
a. The average levels of emissions of the vehicle population
prior to implementation of the I/M program.
b. The emission reductions achieved in the vehicle popu-
lation subject to mandatory repair/maintenance.
c. The increase in the emissions of the maintained vehicles
after repair and prior to the next inspection or mandatory
maintenance period.
d. The increase in the emissions of vehicles not subject to
mandatory maintenance or repair during an I/M period.
e. The potential for a general upgrading of the state of main-
tenance of the vehicle population due to repeated I/M
cycles, and any accumulated emission reductions due to
such upgrading.
2-47
-------
-STANDARD
I
u
I
2
ui
AVERAGE EMISSIONS WITH VOLUNTARY MAINTENANCE
EMISSION REDUCTION POTENTIAL WITH
I/M PROGRAM
END-OF-ASSEMBLY
LINE VALUE
AVERAGE EMISSIONS FOLLOWING MANUFACTURER'S
RECOMMENDED MAINTENANCE SCHEDULES
I
I
I
456
VEHICLE AGE (years)
8
10
Figure 2-7,
Effect of Maintenance on Emission Deterioration with
Vehicle Age (Illustrative example only)
2-48
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f. The effect of the existence of the I/M program on the
maintenance practices of vehicle owners who are not
required to have mandatory maintenance done during a
given period.
g. The effectiveness of the I/M program and any associated
training'and licensing programs in bringing about a
general improvement in the ability of the auto service
industry to perform emission-oriented repairs/
maintenance.
h. The effectiveness of the enforcement provisions of the
I/M program with regard to compliance and prohibition
of tampering between inspections.
The interactions between these various technical and socioeconomic factors
are complex and difficult to evaluate quantitatively. Most of the relevant
analytical work to date has attempted to include only factors a through e listed
above. Factors f through h are of such nature that they are extremely diffi-
cult to include in an analytical model. In addition, it will take a number of
years after the initiation of an I/M program before the actual net effect of all
of these possible interactions is realized in a particular State or Air Quality
Control Region (AQCR). Therefore, it is necessary to make initial estimates
°f the emission reduction effectiveness of the various I/M approaches when
Planning for I/M program implementation. Actual data taken during the I/M
Program proper can then be used to verify initial estimates or to adjust failure
criteria to obtain the desired emission reduction levels.
A comprehensive and detailed quantitative evaluation of various
approaches has been made by TRW and reported in Ref. 2-4. In that
, the statistical character of the various engine and emission control
8ystem maladjustments and malfunctions present in the vehicle population is
e*amined, as well as the effect on emissions of applying various inspection
and re pair/maintenance procedures. A computer program was developed to
calculate the effects of the maintenance procedures on the various maladjust-
^ent/malfunction distributions of the serviced (rejected) vehicles over a period
°£ years. One difficulty encountered in modeling the I/M processes was the
n°nlinear character of the response of the various engine maladjustments to
2-49
-------
the maintenance procedures and deterioration between inspection periods.
The computer program developed by TRW is potentially a very useful tool
for evaluating various I/M approaches; however, a systematic evaluation of
the computer program itself has not been made to date.
A simpler approach to the problem of estimating emission
reduction effectiveness than the computer model previously discussed would
be to use estimating parameters for which data have been already obtained
for at least a significant fraction of the vehicle population. For example,
the change in the average emissions of a fleet of vehicles subjected to the
I/M cycle (inspection, repair of rejected vehicles, and deterioration of both
passed and failed vehicles prior to the next scheduled inspection) can be
written as
AE = E - E° =PE?(DP - 1) + (1 - P)E°[(1 - RF)(DF ) -1] (1)
J_i O fl O
where
AE = net change in emissions over period between inspections
E = average emissions at time of initial inspection
E = average emissions at time of subsequent inspection
P = fraction of vehicles passed
(1 - P) = fraction of vehicles failed
E, = average emissions of passed vehicles
E-, = average emissions of rejected vehicles
RF = fractional reductions in emissions of serviced vehicles
DP = deterioration factor of the passed vehicles for the period
between inspections (emission level after the deterioration
period divided by the initial emission level)
DF = deterioration factor for serviced vehicles for the period
between inspections (emission level after deterioration
period divided by the post-tuning emission level)
2-50
-------
This equation applies,individually to each of the exhaust pollutants (HC, CO,
and NO ) and in principle describes adequately the effect of repeated I/M
-------
E (1-RF)
! I-YEAR!
INSPECTION
1 PERIOD ' -
I I
EMISSION LEVEL
BEFORE SERVICE
- -TIME-AVERAGED
EMISSION LEVEL
AFTER SERVICE
TIME
It is possible that the emission reductions predicted using the
above linear deterioration approach may be found to be conservative when
more I/M program data become available, because it does not account for any
general upgrading of the state of maintenance of the vehicle population after
repeated I/M cycles. Calculations made by TRW (Ref. 2-4) indicate that such
a general upgrading may occur, particularly if the proficiency of the repair
industry improves with time after the I/M program is implemented.
As noted previously, there have been various estimates of the
effective emission reductions for HC and CO that can be expected using the
various I/M approaches. All of the estimates are based in one way or the
other on the limited available I/M study and emissions surveillance data.
The reduction values that are estimated by EPA for I/M programs utilizing
both idle and loaded test/repair procedures have been published in the Federal
*
Register (Appendix N). The EPA-estimated values for rejection rates
between 10 and 50 percent are shown in Table 2-15.
''Appendix N - Emission Reductions Achievable Through Inspection, Main-
tenance, and Retrofit of Light Duty Vehicles" Federal Register, Vol. 38,
No. 110 (Friday, June 8, 1973).
2-52
-------
Table 2-15. EPA Estimated Emission Reductions for
I/M Programs3-
Rejection Rate (%)
% Reduction
HC
CO
Idle Emission Test
10
20
30
40
50
6
8
10
11
11
3
6
8
9
10
Loaded Emission. Test
10
20
30
40
50
8
11
13
14
15
4
7
9
11
12
aAppendix N of 40 CFR 51 (Federal Register. Vol. 38,
No. 110 (Friday, June 8, 1973)
It would appear that these values are reasonable estimates of
average I/M program performance, particularly in the early years of a pro-
8ram when the auto service, industry level of proficiency in making emission-
°**iented repairs is uncertain and the general state of maintenance of the vehi-
cle population has not been upgraded to any extent. Data obtained during the
of pilot and/or full-scale I/M programs might indicate that the present
estimates of emission reduction are conservative and that greater reduc-
tions are achievable. On the other hand, less than full compliance, inade-
enforcement techniques, and poor repair proficiency during an I/M pro-
could result in lower emission reductions than those projected by the
estimated values.
2-53
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2.6 COST EFFECTIVENESS OF ALTERNATIVE
I/M APPROACHES
2. 6. 1 Cost Effectiveness Criteria
The cost effectiveness of an emission control strategy can be
described in terms of the pounds or tons of pollution controlled and the net
cost paid by or in behalf of the public to administer and comply with the regu-
>!<
lations and/or standards set by the program. The term net cost means the
actual cost of the labor and materials required by the program (including
overhead and profit) and excludes any funds that are not expended for goods
and services required by the program itself. In this report, all cost effec-
tiveness values are given as dollar cost (labor and materials) per pound pol-
lutant eliminated ($/lb).
Both the costs and the pounds of pollution eliminated should be
calculated or averaged over the same base or reference period of time.
Since the average fleet emission reductions in gm/mi may vary significantly
from year to year as the I/M cycle is repeated, and since it is the cumulative
effect of the program that determines its ultimate benefits, a 5-year period
of repeated I/M cycles has been used as the reference or base period rather
than the period (usually one year) between emission inspections.**
The total cost incurred is the sum of the cost of inspection and
the subsequent repair of rejected vehicles, minus any fuel savings cost
resulting from the improved state-of-maintenance of the vehicle population.
The cost effectiveness is this cost divided by the total emission reduction
over the same time period.
No attempt is made herein to attach a dollar value to such costs /benefits
as better health, greater visibility, convenience, mobility, etc. The costs
of training, surveillance, garage and mechanic licensing, and enforcement
programs are not included as they vary widely from program to program
and, in some cases, are omitted entirely.
The 5-year period was used for cost amortization purposes only. The
change in vehicle age distribution throughout this period was not
considered.
2-54
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2.6.2 I/M Program Costs
2.6.2.1 Inspection Costs
Determination of the inspection cost per vehicle for the various
I/M strategies requires detailed consideration of the fixed and operating costs
associated with the operation of emission inspection facilities, as well as the
rate at which vehicles can be processed through the facility for different
inspection procedures. Cost estimates given here are restricted to State-
owned and operated lanes; only Idle and Key Mode emission inspection pro-
cedures are considered.
Component costs per lane are shown in Table 2-16 for the
inspection building and grounds, emission measurement instrumentation, and
annual operating expenses. The facility and instrumentation costs were pro-
fated over a 15-year period, with 1/10 of the total cost being annualized to
account for the interest factor. As shown, it is estimated that the annualized
fixed plus operating costs per lane are about $55,700 per year for an idle
emission inspection and about $56,500 per year for a loaded mode emission
inspection. It is important to note that in developing these costs it was
Assumed that emission inspection was the sole function of the facility and that
it was not added to or part of a safety inspection system. The values given in
Table 2-16 may differ from EPA estimates previously presented as they repre-
sent updated cost information generated in 1974 by EPA.
In order to determine the inspection cost per vehicle, it is also
necessary to know the average rate at which vehicles pass through the lane.
Calculation of the inspection rate requires a number of assumptions regarding
the time needed to conduct the emission measurements, the failure rate, and
the fraction of the time that the facility is occupied. Estimated values for
these quantities are given in Table 2-17.
The cost per vehicle inspected is obtained simply by dividing the
total annual cost per lane by the average effective vehicle inspection rate. The
inspection costs for Idle and Key Mode inspection are shown below for rejection
rates between 10 and 50 percent.
2-55
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Table 2T16. Emission Inspection Lane Costs
Component Co sis'
Test Procedure
Idle Test ($)
Key Mode Test ($)
Facility (not including instrumentation)
Emission measurement
instrumentation
Annual operation
Annualized fixed cost
Total Annual Cost
43,750
13,360
50,000
5,711
55,711
45,250
19.3601
50,000
6,461
$56,461
Costs per test lane in a two-lane test facility.
Includes variable power absorption dynamometer and associated
instrumentation.
•»
"HC, CO, NOX gas analyzers with semiautomatic readout; no NO
analyzer needed for idle test. x
Assumes a two-man operating crew for each lane with supporting facility
and instrumentation!maintenance, plus required supervision and:
administration.
'Initial facility and instrumentation costs are annualized as 1/10
of total each year (includes interest factor)
2-56
-------
Table 2-17. Inspection Lane Utilization Data
Item
Test Procedure
Idle Test
Loaded Test
Inspection time (minutes/vehicle)
Pre-test
Emission test
Post-test
Total
Average inspection time with
two-man crew (minutes/vehicle)
Maximum vehicle inspection
rate/lane
Inspection rate /year
Five 8-hr days/week
67% occupancy factor
Effective inspection rate/year,
including retests
30% rejection rate
1.5
1.0
0.5
3.0
2.0
30 vehicles/hr
41,800
32,200
1.5
2.0
0.5
4.0
3.0
20 vehicles/hr
27,800
21,400
2-57
-------
Failure Rate (%)
10
20
30
40
50
Maintenance- Related
Idle
1.47
1.60
1.73
1.86
2.00
Costs
Inspection Cost ($)/vehicle
Key Mode
1.47
1.60
1.73
1.86
2.00
2.23
2.43
2.64
2.84
3.05
2.6.2.2
The maintenance-related costs that are of interest in
evaluating the cost effectiveness of I/M programs are the expenditures
required to repair rejected vehicles and the fuel savings resulting from the
improved state-of-maintenance of the vehicle population due to the I/M pro-
gram. Repair costs have been discussed previously in Section 2.4.2.
It is generally agreed that better maintenance of vehicles leads
to improved fuel economy. Therefore, any fuel cost savings would partially
offset the costs of inspection and repair incurred in a mandatory I/M pro-
gram. Fuel savings due to the repair of the rejected vehicles are given
in Table 2-18. These savings are based upon calculations using the stan-
dard carbon-balance method used by EPA to relate fuel economy and CO,,
Lf
CO, and HC emissions. The values in the table represent the average fuel
savings at the time of the maintenance. If the assumption of linear deteriora-
tion to the pretuned condition over a one-year period used to determine the
time-averaged emission reduction is applied to these fuel savings, they should
be divided by two to determine the time-averaged fuel savings.
2.6.3 Comparison of the Cost Effectiveness of Various
I/M Approaches
Cost effectiveness criteria and methods of determining the
sion reductions from and the costs associated with various I/M approaches
have been discussed in previous sections. These methods were used to
2-58
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Table 2-18. Fuel Economy Changes of Repaired Vehicles
Test Fleet
• No. of
Vehicles
Repaired
Decrease in Fuel
Consumption
(em/mi) •
Carbon Balance'
California Key Mode (controlled,
1966-197 l)b
California Key-Mode (uncontrolled,
pre-1966)b
Michigan Key-Mode (controlled,
1968-1971)b
Michigan Key-Mode (uncontrolled,
pre-1968)b
17
22
15
16
70
17.4 (7.5%)
22. 5 (9. 75%)
12. 8 (5. 5%)
24.1 (10.4%)
19.6 (8.4%)
1972 CVS FTP used to obtain emissions data;( ) %
fuel savings based on 12 mpg, which is the approxi-
mate average fuel e'conomy for the combined fleet.
Data taken from Ref. 2- 1.
2-59
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calculate the emission reduction and cost effectiveness values given in
Tables 2-19 and 2-20. Values are given in the tables for idle and loaded
emission test/repair type programs, as well as for the mandatory mainte-
nance type of program that has no separate inspection phase. The cost effec-
tiveness ($/lb) is given both excluding and including the effect of fuel savings
that result from the improved maintenance of in-use vehicles. These cost
effectiveness values were determined by dividing the total per vehicle cost
for a given emission control strategy by the corresponding values of per
vehicle emission reduction for each emission specie (HC, CO). Thus they
do not represent any attempt to prorate or apportion control costs among the
vehicle emissions considered. Some other studies have reported cost effec-
tiveness values that apportion control costs on an arbitrary basis (e.g. , by
assigning 50 percent of the per vehicle control costs to HC control and 50 per-
cent to CO control, where a given control system reduces both HC and CO).
For comparison with other study results, the values given in Tables 2-19 and
2-20 can be easily adjusted by apportioning control costs on the same basis
as the study being compared.
For reject rates of less than 80 percent, the HC and CO emis-
sion reductions achieved both increase as the fraction of vehicles receiving
mandatory maintenance increases; the cost effectiveness of the HC and CO
emission control decreases as more vehicles are serviced. The cost effec-
tiveness of I/M programs for reducing HC emissions varies in the range
$0.20 to $1.50/lb, while the range for CO is $0.04 to $0. 13/lb.
The results given in Tables 2-19 and 2-20 indicate that the
loaded (Key Mode) test approach yields a greater emission reduction at a
correspondingly better cost effectiveness than the idle test approach for both
HC and CO emissions. It should be noted that all the cost effectiveness value*
given in the tables depend directly on the emission reduction and costs assume
for the various programs so that any change in emission reduction will chang*
the cost effectiveness of a program proportionately.
As expected, the cost effectiveness of all the I/M programs is
better for uncontrolled than for controlled vehicles. This is primarily due to
2-60
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Table 2- 19. Summary of I/M Emission Reduction and Cost Effectiveness for
Idle Emission Test/Repair and Mandatory Maintenance
to
Rejection
Rate (%)
Idle Test
10
20
30
40
50
Mandatory
Maintenance
Idle Test
10
20
30
40
50
Mandatory
Maintenance
Hydrocarbon Emissions3"
% Reduction**
6
8
10
11
11
13
6
8
10
11
11
19
Cost Effectiveness ($/lb)
Excl. Fuel
Savings
Incl. Fuelc
Savings
Carbon Monoxide Emissionsa
^% Reduction13
Cost Effectiveness ($/lb)
Excl. Fuel
Savings
Controlled Vehicle sd (1968-1971)
0.83
1.03
1.12
1.25
1.46
4.04
0.59
0.71
0.79
0.91
1.09
3.67
3
6
8
9
10
12
Uncontrolled Vehicles (pre-1968)e
0.50
0.63
0.68
0.76
0. 87
1.48
0.29
0.35
0.39
0.47
0.56
1.21
3
6
8
9
10
14
0.132
0.109
0. Hi
0.121
0.127
0.347
0.099
0.083
0. 084
0.091
0.095
0.199
Incl. Fuelc
Savings
>
0.094
0.075
0.078
0.088
0.095
0.315
0.057
0.047
0.049
0.056
0. 061
0.162
All emissions related to 1975 CVS FTP.
bAll emission reduction values taken from Appendix N of 40 CFR 51 or
linear deterioration method.
cFuel cost: $0. 50/gal
Average emissions from controlled vehicles: HC - 4.75 gm/mi, CO -
eAverage emissions from uncontrolled vehicles: HC - 8.9 gm/mi, CO
obtained using the
60 gm/mi.
- 90 gm/mi.
-------
Table 2-20. Summary of the I/M Emission Reduction and Cost Effectiveness
for Key Mode Emission Test/Repair Procedures
Rejection
Rate (%)
Hydrocarbon Emissions
% Reduction15
Cost Effectiveness ($/lb)
Excl. Fuel
Savings
Incl. Fuel*"
Savings
Carbon Monoxide Emissions
% Reduction
Cost Effectiveness (S/lb)
Excl. Fuel
Savings
Incl. Fuelc
Savings
Controlled Vehicle sd (1968-1971)
10
20
30
40
50
8
11
13
14
15
0.72
0.82
0.93
1.05
1.13
0.47
0.54
0.63
0.72
0.80
4
7
9
11
12
0.113
0.102
0.106
0.106
0.112
Uncontrolled Vehicles6 (pre-1968)
10
20
30
40
50
8
11
13
14
15
0.42
0.49
0.56
0.63
0.67
0.21
0.25
0.30
0.35
0.39
4
7
9
11
12
0.084
0.077
0.080
0.080
0.083
0.075 ,
0.067
0.071
0.072
0.079
0.042
0.039
0.043
0.044
0.048
IV)
o
ro
1A11 emissions related to 1975 CVS FTP.
^Emission reduction values taken from Appendix N of 40 CFR 51
"Fuel Cost: $0.50/gal.
Average emissions from controlled vehicles: HC - 4.75 gm/mi, CO - 60 gm/mi.
2Average emissions from uncontrolled vehicles: HC - 8.90 gm/mi, CO - 90 gm/mi.
-------
the fact that uncontrolled vehicles have higher emission levels than controlled
vehicles and the percent emission reductions achieved by maintenance are at
least as high for the uncontrolled vehicles as for the controlled vehicles.
Cost of maintenance does not seem to vary much between the two vehicle
groups.
2-63
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2.7 I/M PROGRAM IMPLEMENTATION CONSIDERATIONS
In selecting which of the I/M approaches is most advantageous
for a given State or AQCR and then in planning for the timely and effective
implementation of the selected I/M strategy, a wide variety of technical,
social, and economic factors must be considered and appropriate administra-
tive and legislative decisions made. For example, Table 2-21 lists the major
steps that would be involved in the eventual implementation of a full-scale
I/M program. This delineation of major steps represents the case where a
State (or AQCR) has not yet begun or completed initial planning and tradeoff
studies, and includes a pilot (or demonstration) program phase prior to imple'
mentation of the full-scale I/M program. Each of the major steps of Table
2-21 is discussed in detail in later sections.
These discussions do not address any aspects of tradeoff
studies or other activities related to comparisons of candidate emission
reduction measures within the overall area of transportation control strategi6*
(e.g., retrofit, gaseous fuel conversion, control of hydrocarbon refueling
emissions, traffic control, etc.). For purposes of discussion, it is assumed
that these studies and comparisons have been made and that it has been
determined that an I/M program is either necessary or advantageous in orde*
to meet the emission reduction requirements of the area in question.
Technical information and other assistance is available from
EPA to aid States or other government agencies involved in planning for I/M
program implementation. Therefore, EPA should be contacted (through the
appropriate office) to obtain other available or supplementary information
not contained in this report.
2.7.1 Initial Planning and Tradeoff Studies
A number of initial planning and tradeoff study activities are
required to assess and evaluate those factors whose characteristics could
affect:
a. The success or failure of the program
b. The emission reduction effectiveness of the program
c. The costs and cost effectiveness of the program
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Table 2-21. Major Steps Involved in Implementation of I/M Program
• Initial Planning and Tradeoff Studies
/ Selection of Basic I/M Approach
/ Relationship to Other Existing or Planned Programs
/ Training, Licensing, and Quality Control Aspects
/ Enforcement and Vehicle Owner Requirements
/ Coordination Between Involved Agencies
/ Program,Planning and Cost Estimation
• Development and Passage of Enabling Legislation
• Engineering and Administrative Studies
• Pilot Program Construction and Procurement
• Pilot Program Operation
• Planning for Full-Scale Program
• Full-Scale Program Construction and Procurement
/ Recruitment and Training
/ Manpower Development
• Full-Scale Program Operation
• Ongoing Licensing and Quality Control Program
/ Public Information Program
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In addition, such preliminary studies are needed to identify any special test
program activities that should be a part of the pilot I/M program or which
should be conducted prior to the pilot program.
Also, there are numerous broad administrative and legislative
policy decisions conceriling the specific I/M approach selected that must be
made before it is possible to consider the management and implementation of
the program in detail. These policy decisions, for the most part, can signi-
ficantly affect the impact of the program on the citizens involved and thus
influence their acceptance of it. As a consequence, the attitude and support
of legislators regarding the program can be affected also. In most cases, a
general discription of the I/M program, together with the specification of
many policy-oriented provisions, would be expected to appear in the enabling
legislation. Thus, the information resulting from the initial planning study
is necessary to enable the drafting of effective enabling legislation.
In Sections 2. 1 through 2. 6, the data and information that are
currently available have been summarized for use in initial planning and
tradeoff studies related to I/M approaches for light duty vehicles. The major
factors and considerations that should be treated in the initial study phase
are discussed and highlighted in the following sections (2.7. 1. 1 through
2.7.1.6).
2,7.1.1 Selection of Basic I/M Approach
There are basically two types of I/M programs to consider.
One type involves the inspection/repair sequence in which only vehicles
rejected in some type of emission and/or engine parameter inspection are
repaired. The other type involves a periodic maintenance of all vehicles
regardless of their emission levels or state of maintenance. This second
type of program may be simpler and less costly to administer because it
requires only the specification of maintenance procedures and some method
of checking that they are being followed by the automotive repair industry.
In effect, the mechanic who does the maintenance is also the inspector.
While this is a simplifying step, it could result in more maintenance being
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performed than is needed to achieve the desired control of emissions from
the in-use vehicle population. In the inspection/repair type of program, the
State would be involved with the inspection phase of the program, as well as
the specification of repair procedures and supervision of the repair industry.
The setting of inspection rejection rates and the associated failure criteria
are two of the most difficult aspects of establishing such an I/M program. In
addition, if the inspection is done in State-owned and operated lanes, the
State must finance the initial capital costs for land, buildings, and equipment,
and determine satisfactory locations for the inspection sites.
Other approaches to providing inspection are to have it done in
private garages as is customary for safety inspections in many States, or to
have a random highway inspection performed by specially trained officers
using mobile equipment. These latter two means of inspection involve less
initial costs to the State than inspection lanes, but also are less effective in
consistently identifying high emitters and/or poorly maintained vehicles.
Whether it is practical to perform the inspection in private garages and/or
at mobile sites on streets and highways depends to some extent on the type of
test procedure to be used. For example, an idle test can be performed rather
easily in a private garage or at a mobile site, but a loaded test requiring a
dynamometer might be restricted to inspection lanes.
Deciding between the use of the idle and loaded test inspection
Procedures has proved to be a source of considerable discussion. The relative
simplicity of the idle test and the ease with which it can be done without ex-
Pensive equipment in private garages and service stations have been the
Primary reasons for its being favored by the repair industry. The relative
complexity of the I/M process, its statistical character, and the large varia-
tion in the performance of the mechanics in the repair phase of the I/M studies
conducted to date have tended to make it difficult to quantify the relative
Advantages of loaded test procedures over the idle test. However, where the
**o procedures have been compared, the loaded mode procedure has been
shown to be from 15 to 40 percent more effective than the idle mode procedure
l|* reducing HC and CO emissions.
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Because of the several basic I/M options available and the
impact of the choice of I/M program on emission reduction levels, costs,
etc., the process of identifying and selecting the basic I/M program approach
considered most appropriate for any given State or AQCR should encompass
the analysis and tradeoffs of a number of factors.
2.7.1.1.1 Selection of Vehicles to be Included in Program
A major factor affecting both program scope and emission
reductions to be expected is the fraction of the vehicle population (by model
year and type) to be included in the program. In this regard, a trade-off
analysis that compares the cumulative I/M emission reductions of potentially
included vehicle classes (e.g., pre-1968, 1968 to 1969, 1970 to 1972, etc.)
vs the motor vehicle emission reductions required in the State or AQCR to
meet prescribed air quality standards may be necessary to justify the i
of specified vehicle groups. However, in the New Jersey idle mode I/M pro-
gram, all in-use light duty vehicles are required to participate. Even new c*
dealers are required to verify (via an idle emissions test) that all vehicles
sold meet the required emission levels of the I/M program.
Another category of consideration in planning an I/M program
involves how vehicles of differing age (model year) and level of emission
control are to be treated in the program. Because of the progressively
tightened new vehicle emission standards over the past years, there is a
wide variation in the emission levels and emission control systems on
vehicles currently in use. Both inspection failure criteria and maintenance/
repair procedures should reflect these differences. Where insufficient sur-
veillance test data exist to adequately characterize expected I/M emission
reductions, it may be necessary to implement special vehicle test
to provide this information. An alternative course of action would be to
the best possible estimate (based on similar data from EPA, other States,
etc.) and to provide for verification of the estimate during the pilot or del*10
stration phase of the overall program.
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2.7.1.1.2 Selection of Regional or Statewide Approach
Another major factor that similarly impacts both program
scope (and costs) and emission reduction benefits is the decision as to
regional or statewide applicability of the I/M program. Obviously, one key
factor to be considered in this decision option is how many AQCRs within a
given State require I/M emission reductions to meet air quality goals, and
what portion of the State's vehicles are located and/or used within the con-
fines of these specific AQCRs. If a sufficiently large percentage of the
vehicle population of the State (of the relevant vehicle groups) are directly
involved, it could be argued that statewide applicability would be both expedient
and equitable. On the other hand, if only a single AQCR were directly involved
'with motor vehicle emission reduction requirements, it could be argued that
statewide applicability would be nonequitable and would incur costs not neces-
sary to meet air quality requirements.
The issue of "fairness, " whether it be one of requiring every-
one to share the same burden with respect to I/M program requirements and
costs or be one of requiring participation only to the extent required by air
quality considerations, can be a major problem with regard to passage of
legislation. For example, consider the case of a State that had only one
county requiring a rollback in motor vehicle emissions. Residents of this
county might feel it unfair to permit vehicles from other counties to enter
their area unless they, too, were participating in the I/M program. The
residents of the other counties might not want to participate in an I/M pro-
gram since the air quality in their counties does not require it; on the other
hand, they might prefer to participate in the program in order to have the
Benefits of even cleaner air. Thus, the legislator is faced with balancing
many and perhaps conflicting interests in enacting legislation for an I/M
Program.
In either of the above two hypothetical cases, consideration
8hould also be given to the possible methods of program enforcement (see
Section 2.1, 1. 4 below) and their possible impact on resultant I/M emission
Deductions. For example, restriction of I/M program applicability to a
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single AQCR (or other regional subdivision) requires an enforcement technique
which assures that the appropriate vehicle classes or groups within the region
are indeed participating in the I/M program if I/M emission reduction benefits
are to be in fact achieved. In addition, there are instances where a single
AQCR encompasses land situated in more than one State, thus further com-
plicating the enforcement problem (as well as complicating the overall prob-
lems associated with I/M program initiation). In these cases, parallel or
joint programs involving two or more States may be required in order to
realize the air quality gains from I/M program implementation.
2.7.1.1.3 Selection of Idle or Loaded Mode of Testing
Various cities and/or AQCRs have proposed implementing
I/M programs with either idle or loaded emission testing. Although the
loaded testing mode appears to have advantages in terms of emission reduc-
tion and cost effectiveness ($/lb of pollutants reduced), the idle testing mode
offers advantages in the areas of simplicity of the test, lower program start-
up capital costs, lower equipment costs for repair garages, and greater ease
of combining emission I/M with existing safety I/M programs. Thus the
proper choice of idle vs loaded testing for a given city, State, or AQCR
be based on consideration of a number of factors. These include:
a. Mobile source emission reductions required to meet air
quality standards
b. Possibility of combination of emission I/M with an
existing safety I/M program
c. Availability of capital funds for program start-up
d. Previous experience in the licensing and supervision
of the auto repair industry.
Each of these factors is discussed further in the sections that follow.
2.7.1.1.3.1 Equipment Requirements
Development of emission controls has been closely related t
the availability of instrumentation and equipment for conducting emission
measurement tests. Because of this, a reasonably full range of emission^
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measuring instruments, computers, dynamometers, and engine parameter
analyzers are available to the States and the service industry. Within each
of these catagories a number of manufacturers are producing a variety of
models to satisfy the need of specific I/M programs. Consequently, a large
number of good instruments are now available. For example, Table 2-22
lists the infrared analyzers for HC and CO currently approved by New Jersey
for use in repair garages in connection with that State's idle inspection pro-
gram. Other lists are available. Although there is presently a lack of low-
cost NO measuring instruments and very low range HC and CO analyzers
for use with post-1974 emission controlled vehicles, past experience indi-
cates that such equipment should become available as the need increases.
2.7.1.1.3.2 Facility and Land Requirements^
*
The number of inspection facilities (and land) required depends
not only upon the selection of regional vs statewide applicability but also
upon the vehicle inspection processing rate associated with the specific
inspection test procedure selected and whether or not the emission I/M
Program is to be combined in any way with an existing safety I/M program.
Detailed planning studies for implementing I/M programs
been performed for several States. These studies have included the
of the inspection building and grounds and the estimation of the number
and location of the inspection lanes throughout the States. For example,
fetches of both an inspection lane and a mobile test unit for the Key Mode
loaded test inspection procedure are shown in Figure 2-8. The number of
test lanes required depends on the vehicle population density and the rate
at which vehicles can be processed through an inspection facility of either
the idle or loaded test procedure. Mobile inspection units could be used to
inspect vehicles in rural areas where a low vehicle density perhaps would
n°t justify building an inspection station. The information found in Refs. 2-14
and 2-15 may be useful to aid in the preliminary planning of inspection
facilities, but current vehicle population data for the specific region of
interest (city, State, AQCR) would have to be used to determine the number
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Table 2-22. New Jersey-Approved Manufacturers of Low Cost Infrared
Analyzers Suitable for Use in Repair Garages (Ref. 2-13)
Supplier
Allen Electric Company
American Motors Corporation
American Parts Company
Atlas
Autoscan, Incorporated
Barnes Engineering Company
Beckman Instrument Company
Chrysler Corporation
Ford Motor Corporation
Kal -Equip
Marquette Manufacturing Corporation
NAPA Balkamp
Horiba Instruments Limited
Peerless
Stewart -Warner
Sun Electric Corporation
Womaco-Yanaco
Model
Emission Analyzer Model 23-060
series and 23-070 series
AMserv Model 23-067 series and
23-077 series
Powerready Infrared HCKO Analyzer
Model 370-400
Exhaust Emission Tester Model 340
CO and HC Analyzer Model 710
and 4030
Emission Analyzer Model 8335
HC/CO Vehicle Emissions Analyzer
Model 590
Technican Service Equipment
Program; Model DCE-75, 23-066
series and 23-076 series
Rotunda Equipment Program;
Rotunda Analyzer Model BRE-42-730
and BRE-42-731
HC/CO Infrared Emissions Analyzer
Model 4094-C
Emissions Analyzers Model 42-151
and 42-153
Infrared HC/CO Emissions Analyzer
Model 14-4787
Engine Exhaust Analyzer Models
CSM-300 and Mexa-300
Infrared Exhaust Gas Tester Model 600
Infrared Gas Analyzer Model 3160-A
SunEET-910. U-912. U-912-I, and
EPA-75 Exhaust Emission Testers
Exhaust Gas Analyzer Model EIR-101
Available only in new car dealers of the company.
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IN
--*-1i _:t
i—7 ^~~*^ r*1 -'-• '.
nf^r E£T?I
OUT
KEY MOOE 1YPE
«***^<^J*
Double-Lane Configuration
Mobile Test Facility
Figure 2-8. Key Mode Double-Lane Configuration and
Mobile Test Facility
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and location of inspection stations needed in that region. In addition, the
potential of combining emission and safety 1/M programs could greatly affect
the number of inspection facilities required.
2.7.1.1.3.3 Emission Reduction Effectiveness
One of the most important characteristics of any I/M program
is the reduction achieved in emissions from serviced vehicles. The test
procedure used in the I/M program can affect the emission reduction achieved
in at least two ways. First, the relative ability of the test procedures to
consistently identify those vehicles that would have high emissions if they
were tested using the Federal Test Procedure. Such vehicles can potentially
benefit most from repair. Second, the ease with which the average mechanic,
after reasonable training on making emission-related repairs, can use the
emission inspection results as an aid in correctly diagnosing the cause of
high emissions in a particular vehicle. The I/M studies to date have shown
that the loaded test procedure is superior to the idle test procedure when the
failure criteria used rejected the same fraction of vehicles and when the
mechanics in both programs were instructed with the same thoroughness.
Of course, the superior emission reduction effectiveness of the loaded test
procedure has to be balanced against its more severe requirements in the
areas of equipment, facilities, costs, etc. In many cases, it may not be
necessary to utilize the loaded test procedure where desired emission reduc-
tions can be obtained with the less effective, but simpler, idle test procedure.
2.7.1.1.3.4 Flexibility With Regard to Advanced Emission
Control Systems
Consideration should be given to whether or not the selected
inspection test procedure will be appropriate for use as additional groups of
vehicles are added to the I/M program (e. g., vehicles with NO control and/
or oxidation catalysts, etc.). In this regard, the idle test procedure is not
applicable for NOx emission inspection. There is insufficient data to ascertain
whether or not idle tests are appropriate for catalyst-equipped cars; however,
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the low exhaust flow rates at idle would argue against it applicability.
Loaded test procedures are required for NO emission inspection and are
JC
expected to be suitable for catalyst-equipped cars.
2.7.1.1.3.5 Costs and Cost Effectiveness
Both costs ($) and cost effectiveness ($/lb of pollutant elimi-
nated) can be key factors in selecting the most advantageous emission inspec-
tion test procedure. With regard to cost, one should consider both the inspec-
and repair costs. The inspection fee (which might be in the range of $1 to $3
per vehicle tested) is relatively small compared with the registration fee
for the vehicle and the repair bill for rejected vehicles regardless of which
short test procedure is used. The major difference in the inspection costs,
as they affect the choice between loaded and idle tests, is in the initial capital
(start-up cost) that is needed to set up the inspection lanes and/or inspection
phase of the program. Even though the equipment costs per lane are only
slightly greater for a loaded test, the primary factor in increasing the initial
capital requirements for the loaded test is the fact that the loaded test takes
longer to perform and hence the number of inspection lanes needed to
a given number of vehicles using the loaded test is about 50 percent
greater than using the idle test. Thus the magnitude of the initial funding
Deeded to start an I/M program using a loaded test can be nearly twice as
as that needed using the idle test, when both the increased number of
s and more expensive equipment are considered.
The time required to perform the emissions test is so short
it can even be added to a safety inspection lane without significantly
effecting the testing rate. This has been done successfully in New Jersey
a minimum additional cost. In California, an idle test for emissions has
added in a similar manner to the random highway safety inspection pro-
conducted by the highway patrol. This would not have been practical
Usi*ig a loaded test, however, because of the need for a chassis dynamometer,
is a bulky piece of equipment. Thus, in determining costs for imple-
an emission I/M program, the possibility of integrating it with an
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existing safety I/M program can greatly affect the costs associated with the
overall program. This consideration -can also affect the decision regarding
loaded vs idle test procedures.
The cost effectiveness of an I/M strategy depends both on the
costs incurred and the emission reduction achieved for that cost. When the
loaded and idle test procedures are compared on this basis, the loaded test
approach is usually superior because the repair costs from both approaches
are almost the same and much greater than the inspection cost. Also, the
emission reductions achieved using the loaded test/repair procedures are
significantly greater than those achieved using the idle test/repair procedures-
Hence, the loaded test approach yields a significantly greater emission reduc*
tion at only slightly higher cost to the consumer. This may also be true eve*1
in a state such as New Jersey, which has an established lane-type safety
inspection program. In that case, however, the differences in the initial
start-up costs of the loaded vs idle programs were so large that it would have
been difficult to use a cost effectiveness argument to justify the loaded test
approach.
2.7.1.1.4 Selection of Rejection Rates and Failure Criteria
The primary objective of the inspection phase of the I/M
program is to determine which vehicles in the total population have high
emissions that can be reduced by proper maintenance/repair. Failure
criteria can be set for each of the candidate short test procedures such tha*
a specified fraction of the various classes (precontrolled, controlled, etc.)
of vehicles inspected are rejected. The basic assumption is that the reject^
fraction of vehicles would also have the highest emissions if they were tea*6
using the Federal Test Procedure (FTP). Inspection data taken in various
I/M studies have indicated that on the average the assumption relative to
loaded and idle tests and FTP emissions is valid but that a fraction of the
rtfi$
rejected vehicles have lower FTP emissions than some of the vehicles pas*
by the short test procedure (errors of commission). This results in the *e'.
quired repair of vehicles with relatively low FTP emissions. Also, a
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of the passed vehicles have higher FTP emissions than some of those rejected
(errors of omission). In this case, .vehicles that actually require maintenance
to reduce emissions are simply not identified. Experience in the I/M studies
conducted to date have indicated that, at least for rejection rates up to about
80 percent, even those rejected vehicles which in a strict sense would be
classified as errors of commission have relatively high emissions that can
be significantly reduced by repair. Hence, in nearly all the I/M studies using
both the idle and loaded test procedures, significant average emission reduc-
tions have been achieved in the serviced (rejected) vehicles.
On the basis of available data, the errors of commission
appear to be somewhat less for the loaded test than for the idle test (especially
for CO). Also, it would be expected that the loaded test would have fewer
errors of omission (passing vehicles with high emissions) than the idle test,
because it utilizes emission results from additional engine operating modes.
In addition, the loaded test can detect vehicles with high NO emission while
Jt
the idle test can not.
In any event, the initial failure rate must be selected in order
to estimate the number of failed vehicles and their impact on repair facility
pequirements, emission reductions, costs, etc. It may be necessary, or
Prudent, to conduct additional fleet test programs to acquire more test data
Ort in the alternative, to plan for such data acquisition in the pilot phase of
the I/M program. Such data can be used to revise failure criteria for later
Phases of on-going, full-scale I/M programs. For example, in the New Jersey
*'M program, the initial failure criteria were established to fail about 10
Percent of the vehicles that were tested. More stringent emission failure
stahdards were planned for subsequent years of the program.
Considerable care will have to be exercised by inspection
Personnel as vehicles subject to different failure criteria are inspected. In
Edition, it is likely that the rejection rate will be higher for older vehicles
'higher mileage), which are in many cases owned by those less able to bear
the cost of repair. The problem of how to handle the cases of high-mileage
vehicles that may need costly repairs before they can pass the emission
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inspection has been the topic of considerable discussion. One approach to
providing an equitable'solution to this problem is to limit the maximum repair
cost for emission reduction that must be borne by the vehicle owner to some
percentage of the market value of the vehicle.
2.7.1.1.5 Retest Requirement Provisions
Another consideration in planning an I/M program is whether
or not to include a requirement for retest of failed (rejected) vehicles after
repair. Such a requirement impacts not only the total number of inspections
to be made in a given period of time but more importantly the quality of the
repair work done on rejected vehicles and thus the emission reduction effec-
tiveness of the program. Without a retest, there is no assurance that the
repair was done properly and that the vehicle emissions were actually reduce**'
Obviously a privately operated inspection program would be more prone to
excessive repair costs, incomplete repairs, direct sale of inspection sticker8'
and other fraudulent practices that result in higher costs to the public and
lower benefits to air quality.
In order for an I/M program to have public acceptance, it is
important that the vehicle owners be confident that the repair work and/or
periodic maintenance that they are paying for is done properly and will resul*
in the desired reduction in emissions. It is essential that rejected vehicles
after being repaired pass any emission retest with high probability. Repeated
failures would result in considerable public complaints even if the program
provided some type of guarantee of rework at no additional cost by the repa**
industry. It may be necessary to provide for an exemption procedure for
those few vehicles that are inherently high emitters and will not pass the
emission inspection even after proper repair and adjustment. In this latter
case, it should be noted that there could be difficulties in identifying such
vehicles and that several inspection-repair-retest cycles could be involved.
A retest requirement also impacts on the general problem °*
program evaluation (record keeping) and enforcement. These aspects are
discussed in a later section.
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2.7.1.1.6 Private vs State-Operated Inspection Facilities
Inspection facilities can be characterized under two general
classifications: State-operated and licensed private garages. The State-
operated inspections could be conducted in a system of State-owned or
franchised inspection lanes in which all vehicles would be checked periodically
(say annually) or at random sites on streets and highways by specially trained
officers using mobile equipment. If the random inspection approach were
used, only a fraction of the vehicles would be checked during each inspection
period. In a licensed garage system, the emissions testing would be per-
formed by private service or repair agencies within the automotive main-
tenance industry. Each such facility would have to be certified, licensed, and
supervised by an appropriate State or local agency.
In either case, private service garages and dealerships com-
prising the automotive repair industry would provide the requisite maintenance.
Although the selection of one approach over the other may not conceptually
have an impact on the effectiveness of an I/M program, it would have a sub-
stantial effect on (1) who provides the initial capital investment, (2) how
operating costs are determined and collected, (3) the relative difficulty in
Providing effective enforcement for the program, and (4) public acceptance
°f the program.
Public opinion surveys have shown that vehicle owners strongly
Prefer a State-owned and operated inspection lane system with only the
^intenance being done at private garages. In comparing the two approaches,
*t Would appear easier to maintain uniform and consistent inspection standards
and equipment calibration if the inspection is done by the State. In addition,
Enforcement of compliance by vehicle owners and supervision of the repair
lT*dustry may be simpler if the State performs the inspection phase of the
Program. The problem of program evaluation is also more easily handled
State obtains the emission inspection data directly at its facility. For
complex inspection test procedures that require more expensive equip-
nient, the arguments become stronger for a State-owned and operated system
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of inspection lanes. Hence, the arguments for State-operation of loaded test
inspection lanes are stronger than for State-operation of an idle test, which
can also be done at a private garage or at random inspection sites. On the
other hand, such direct State involvement requires additional State manpower*
new 6r revised organizations, increased funding, and expands the role of the
State into a new form of work.
2.7.1.1.7 Data Acquistion and Record Keeping
• Another factor that must be considered is the degree or extent
of data acquisition and record keeping to be incorporated in the program.
Once an I/M program has been implemented, the program must be monitored
and information reported to Federal, State, and local agencies, as appropria
The State and local agency reporting requirements will vary in detail and con*
tent between States and according to the type of I/M program implemented.
The evaluation of the effect of an emissions I/M program on
automobile emissions and air quality requires the compilation of exhaust
emissions data over a period of time (probably years). If the I/M program
includes an emission inspection phase conducted by the State, the inspection
data itself can be recorded, stored, and analyzed to determine the effect of
the program on vehicle emissions. A special effort will be needed and ex-
pense incurred, however, to use the inspection phase to evaluate the
as well as identify the vehicles needing repair. It will be necessary to
the short test procedure values to those based on the Federal Test Procedu?e
.-
(1975 CVS-CH) for purposes of emission inventory calculations and compa*1P
with new vehicle emission standards. (EPA is currently examining the cor-
relation characteristics of a number of short test procedures.) Analysis o»
the inspection data is also required to update the failure criteria needed to
yield the desired rejection rates. In those cases in which a separate inspec"
tion phase is not included in the program or inspection is done in private
garages, evaluation of the I/M program will require periodic automobile
surveillance emission tests in various sections of the State. At the presefl*
time, California is the only State that conducts such surveillance tests of
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automotive emissions. This later approach of obtaining emissions data for
program evaluation may be simpler and more cost effective even for those
States having a separate inspection phase; however, a much smaller sample
of vehicles will be tested and questions may arise regarding the adequacy of
the sample size and composition (type, make, and model year of the vehicles
tested).
Thus on the one hand, if records of all emissions tests per-
formed (including retests) are desired in order to (1) assure the necessary
statistical basis for determining the actual emission reductions being
accomplished, and (2) provide the data necessary to make meaningful adjust-
ments in emission test failure criteria as the program progresses, such data
acquisition and record keeping can be both time consuming and costly, as well
as require very large data storage facilities. On the other hand, it may be
acceptable to operate the program and evaluate emission ^reductions with less
Detailed data acquisition and record keeping measures. Thus, it is apparent
ttiat careful consideration should be given at the outset to this very important'
factor - the compilation and retention of data and test records. For example,
it may be both necessary and cost effective to consider an electronic data
Processing system to perform the data collection and retention function. If
s°> it may require equipment interfaces that impact both inspection equip-
^ent selection and facility design.
2.7.1.2 Relationship to Other Existing or Planned Programs
If the city or State has, or plans to have, other vehicle-related
Pr°grams, such as safety-inspection programs or emission control retrofit
Programs, it would appear both necessary and expedient to consider the im-
Pact of one program on the other and potential interfaces, including the
feasibility of combining functions and requirements. For example, if a
8afety inspection program incorporated the use of dynamometers for testing
Brakes, it might be possible to select a single dynamometer that is adequate
°r emissions and brake testing, thus permitting that portion of the safety
nspection program to be combined with the emission inspection program.
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Also, in the case of retrofit programs, similar equipment, facilities, and
testing techniques may be appropriate.
Today, 32 States have some form of periodic motor vehicle
safety inspection, and 8 additional States employ a spot check safety inspec-
tion system. Only New "Jersey, Delaware, and the District of Columbia
operate their own inspection stations; the remaining States use licensed
private garages. The Pennsylvania statewide vehicle safety inspection
program can be used to illustrate potential interactions and their ramifica-
tions. In the Pennsylvania safety inspection program, private garages are
licensed to perform the necessary vehicle inspections. Such individual
garages could also perform the inspection and maintenance phases of an I/M
program if the idle inspection testing mode approach were adopted in that
State. However, if the loaded inspection testing mode were selected, it is
unlikely that the private garages would or could acquire the necessary
dynamometers; therefore, the State would have to provide the necessary
inspection test facilities, probably in the form of inspection lanes.
In any event, where such similar programs exist (actual or
planned), the potential for combining the programs should be evaluated in
terms of potential savings in consumer time, costs, and minimization of
land use. However, in the case of private garage vs State -provided inspecti0
facilities, there is the additional consideration, as noted previously, of
customer acceptance of private garages for inspection purposes.
2.7.1.3 Training, Licensing, and Quality Control Considerations
One concern relative to the implementation and effectiveness °
I/M programs is that the automotive repair industry may not be capable of
performing cost-effective, emission-oriented repairs on the vehicles rejec*e
in the inspection phase of the program. Inadequacies in the repair industry
could lead to reduced effectiveness of the program and, if rejected vehicle8
are retested after repair, to vehicle owners experiencing the frustration ***
expense of repeated failures. If the I/M program involved emission
in private garages or facilities, similar reservations would apply. Hence*
2-82
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licensing and supervision of the automotive repair industry by a State agency
should be considered in regard to the implementation of all I/M programs.
Since the implementation of any form of an I/M program will
result in a significant increase in automotive maintenance/repair services
needed by the public, it is essential that these services can be obtained
conveniently and at a reasonable cost. Thus the implementation of the pro-
gram should also insure the availability of a sufficient number of repair
garages and mechanics and a relatively uniform demand for the services
over the year.
Various studies (Refs. 2-3 and 2-14) have been made of the
scope and length of instruction needed by mechanics to enable them to make
emission-oriented repairs and engine tuneups. All of the field studies
(Refs. 2-1 through 2-4) of I/M have found that the emission reductions achieved
by repair were dependent on the thoroughness of the instruction given the
participating mechanics. It has been also found that the certification and
standardization of exhaust gas analyzers are important. Both California
(Ref. 2-16) and New Jersey (Ref. 2-17) have set design and performance
criteria and accreditation procedures for HC/CO analyzers to be used in
vehicle emission repair stations.
2.7.1.3.1 Instruction of Mechanics on Making Emission-
Oriented Repairs
All of the I/M studies conducted to date have shown that unless
mechanics involved in the program had received thorough instruction on
engine malfunctions and maladjustments can result in high HC and CO
emissions, and how various engine diagnostic tests can be used to isolate
which of the possible malfunctions is present in a particular vehicle, the
6rnission reductions achieved by the repair of rejected vehicles is much less
than the potential reductions. The most beneficial instruction included actual
Demonstrations of how various malfunctions increased emissions using
v?hicles and exhaust gas analyzers. Supplying mechanics with written
and relying on written examinations to indicate that the material has
2-83
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been read was not nearly as effective as shop demonstrations. It has also
been found that having mechanics perform routine maintenance on vehicles
without providing instructions relating the various steps in the maintenance
procedures to emission reduction results in only a minimal emission
reduction. Actual measurements of emissions at as many engine operating
modes as available equipment permits was found to be the best procedure,
even in a mandatory maintenance program.
The subjects of the sensitivity of emissions and various engine
and control system malfunctions and maladjustments, related diagnostic testSi
and required equipment are discussed in detail in Section 2.3. 1. In addition*
various repair/tune-up and mandatory maintenance procedures are given in
Section 2.4. 1. Regardless of whether the I/M program to be implemented ifi
of the inspection/repair type or the mandatory periodic maintenance type, it
is necessary that the mechanics involved be knowledgeable concerning these
topics. Otherwise experience has shown that in most cases repair/maintena*1
costs will be relatively high and the emission reductions achieved will be quit0
low.
2.7.1.3.2 Certification of Exhaust Gas Analyzers
Experience has shown that the availability of reliable exhaust
gas (HC/CO) analyzers is critical to the success of any I/M program. Since
the implementation of an I/M program creates a relatively large market
such instruments, many of them have been developed with prices ranging
from several hundred to several thousand dollars. As would be expected,
the capabilities of these instruments vary significantly with respect to
sensitivity, accuracy, response time, warm-up time, etc. In order to
attain a high level of quality control on the repair/maintenance work done
the private garages and good relatability between emission inspection and
repair industry emission measurements, it is necessary to set minumum
specifications that must be met by all HC/CO analyzers used in an I/M
program.
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Both New Jersey and California have conducted gas analyzer
certification programs and have made available approved lists of instruments
to mechanics and service station operators. Specifications were set in the
following areas:
a. Range
b. Sensitivity
c. Accuracy and repeatability
d. Ease and reliability of calibration
e. Drift in calibration
f. Response'time and hang-up
g. Warm-up time
h. Maintenance requirements
Insuring that the exhaust gas analyzers used in the repair
lndustry are properly maintained and calibrated will not be a simple task
R '
andom spot checks by inspectors or local police may be necessary.
•'.1.3.3 Mechanic/Garage Licensing and Quality Control
A number of States currently have on-going programs in the
ea of mechanic/garage certification, licensing, and quality control. In
alifornia, the Bureau of Automotive Repair (BAR) is a part of the Department
Consumer Affairs and licenses both motor vehicle pollution control (MVPC)
stallation and inspection stations and device installers. All legally required
PC retrofit devices must be installed or approved by a licensed installer,
elfjJ
u employment of a licensed installer is a requirement for licensing of a
tton. Approximately 11,000 stations have been licensed after BAR inspec-
n visits to verify employment of a licensed installer and to verify that the
cessary tools and equipment are available. Device installers are required
to ..
pass a multiple-choice written examination and to provide verification of
"^Petence, either in the form of a recommendation by the station licensee
Of v
V evidence of satisfactory training (from school, device manufacturers,
2-85
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In Pennsylvania, the Bureau of Traffic Safety (BTS) is a part
of the Department of Transportation and is involved in a vehicle safety
inspection certification program. Approximately 17,000 official inspection
stations have been licensed to date. As in the California MVPC program, the
principal requirements are employment of a licensed mechanic and the
availability of tools and equipment. The mechanics are required to take a
training course and pass a written examination, as well as a practical test in
vehicle safety inspection. Approximately 70,000 mechanics have been
certified to date.
New Jersey has had a mandatory vehicle emissions inspection
program in effect since February 1974. However, there was no pre-existing
mechanic certification program. At present, the New Jersey Department of
Environmental Protection (DEP) is supporting an informal voluntary program
for training mechanics in the practical, hands-on aspects of emission control
systems. Efforts are underway to expand this program, possibly involving
the certification of mechanics.
Therefore, it would appear prudent to examine the training,
licensing, and quality control aspects of these on-going State activities, as
well as EPA programs in these areas, for consideration with regard to
similar requirements in an I/M program. On the other hand, many compete*1
individuals may prefer to do their own repair work, and some consideration
may have to be given to their situation.
2.7.1.4 Enforcement and Vehicle Owner Interfaces
A number of conceptual approaches are possible to ensure
compliance with an I/M program, including use of existing or modified car
registration procedures, control of car dealers, and car inspections.
2.7.1.4.1 Vehicle Registration
Since all States require annual registration of new and used
cars, a preregistration requirement that owners of cars to be used in con-
trolled regions show compliance appears relatively straightforward.
2-86
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Unfortunately, existing registration procedures in most States are not capable
of being used without some modification. In particular:
a. Very little effort is made to ensure that all cars are in
fact registered, nor are penalties for late registrations
severe. Enforcement is primarily through normal
police or highway patrol traffic activities, such as stopping
cars for speeding and reckless driving and in reporting and
investigating accidents.
b. Although all States require an address for car registration,
none is able to verify that such an address exists, and an
applicant's legal address is not required. For purposes of
car registration, a mailing address, post office box, second
home, or business address are all valid.
c. Only California requires that emission control compliance
(Equipment Installation Verification) be shown prior to
registration.
Thus, to use existing State car registration procedures for
ensuring compliance with an I/M program, expansion of State enforcement
capabilities would be required, as in the example of California.*
2-7.1.4.2 Dealer Control
While enforcement of new car emission levels is a function of
the Federal EPA, dealer control can be an effective enforcement tool for
controlling emissions of used cars at the time of change of ownership. In
nis approach car dealers could be required to verify that all cars being sold
fe in proper operating condition and properly equipped for the region in which
will be operated. Difficulties with this approach are:
a. Most dealers are poorly equipped to determine their
customer's legal residence or the primary area in
which the car would be used.
b. New legislation with strong enforcement provisions
might be required to ensure dealer compliance. ,
c. Fleet-car buyers who normally purchase and register in one
area for use in another might be required to register locally.
[? P?any states, all vehicle licenses expire at the same time, which makes
aj**fticult to incorporate a timely inspection with the purchase of a new
*«iual license. In such cases, a staggered licensing procedure that would
*o\v 1/12 of the licenses to expire each month would be helpful.
2-87
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2.7.1.4.3 Vehicle Surveillance
All cars in a given controlled region might be inspected
periodically or randomly to ensure that they are participating in the I/M
program. Such inspections could be physical in nature or be one of observa-
tion of a windshield or license plate color or number -keyed tag or sticker
issued by an I/M inspection facility. Thus, a number of procedures are
possible for ensuring successful compliance with an I/M program, including
tying compliance to car registration, providing compliance through controls
over car dealers, and enforcing compliance through car surveillance pro-
cedures. However, if widespread compliance is required, implementation
of these procedures will call for additional State legislation and expansion o*
State enforcement agencies,
2.7.1.5 Coordination Between Involved Agencies
As can be noted from the preceding discussions, the manage"
ment services required in the implementation of an I/M program may invoWe
the responsibilities and expertise of several State (and/or municipal) agenci*'
or departments. For example:
a. One agency may be charged with overall I/M program
management responsibility.
b. The Department of Motor Vehicles (or other agency
involved with vehicle registration) may be involved
in compliance assurance.
c. Police departments (State and/or local) may be involved
in physical inspections to assure compliance.
d. An environmental protection or air quality agency may
be involved to establish the inspection procedures and
standards and to determine results of the I/M program
on air quality.
e. A separate agency may be involved in the training,
licensing, and quality control activities.
f. Etc.
tat
Thus, it is imperative that the efforts of all included
or departments be carefully coordinated in the planning and operation of *n
2-88
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I/M program to ensure program success. In California, for example,
Senate Bill 479 makes such provision for interagency cooperation and sharing
of management responsibilities.
Some further insight into management of an emission I/M
program can be gained from looking at how States with safety I/M programs
have managed those programs. In most States having safety I/M programs,
Management of the program is centered in the Department of Motor Vehicles.
The enforcement function, both with respect to compliance of vehicle owners
and the investigation of complaints against licensed private inspection/repair
garages, is handled by the State Police. Public dissatisfaction with the
autornotive repair ihdustry has led in some states to the establishment of
Consumer Affairs Agencies within the State government to further license
ar*d supervise the repair industry. Management of emission I/M programs
should not be significantly different than the management of safety I/M
Pr°grams.
^•7.1.6 Program Planning and Cost Estimation
As a concluding part of the initial planning and tradeoff study
activityf it is necessary to estimate program costs, select a method for
financing the program, and prepare a time-phased program plan. These
eftorts are based on and thus include all the tradeoffs and resultant choices.
decisions as discussed in Sections 2.7. 1. 1 through 2.7. 1. 5.
As noted previously, the initial and operating cost require-
will vary with the inspection test procedure selected and the number,
and location of inspection facilities reduced. In general, however, an
ln8Pection fee of between $1 and $3 would be required to defray the cost of
tlie emission inspection. This fee could be collected at the time of the inspec-
ion or as an added vehicle registration fee. Adding the fee to the vehicle
^Sistration fee removes the money-handling function from the inspection
*tati°n, which may tend to reduce the incidence of inspector pay-offs. The
al cost of building and equipping the inspection stations could be covered
State bonds that would then be repaid using part of the revenue from the
fee.
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An example of a time schedule for implementing State -owned
inspection lane programs using idle or loaded-mode tests is presented in
Figure 2-9. The actual times required to accomplish each of the tasks
shown will vary greatly from one program to another. The times shown in
the figure are typical arid are for the purpose of illustration only. The time
scale starts from the point where legal authority and funding are granted, and
the acquisition phase is based upon the assumption that no facilities exist at
that time. The 14 months allowed for facilities and equipment acquisition
could be reduced if suitable test sites were readily available. If a great deal
of red tape is involved in acquiring land, this acquisition period could be
increased. Although the time to train inspectors can be predicted relatively
easily, the hiring of technically competent people at all levels can be a maj°r
variable. Pilot studies lasting from 3 to 6 months can provide not only an
opportunity to try out the proposed program but also a chance to obtain
valuable data on pass-fail criteria and other technical aspects of the test
procedure. Since it is more efficient from the viewpoint of both inspection
and maintenance to stagger participation over the full inspection cycle peri<^'
at least one cycle must be allowed before the total benefits of an I/M progra**1
can be realized.
Similar schedules can be constructed for licensed garage
programs, but again the extreme variability of the time required to compl«te
many of the tasks should be kept in mind in doing so. Each I/M program
should be treated separately in this respect, and predictions should be baS^d
upon the best available data for the specific program under consideration.
2.7.2 Development and Passage of Enabling Legislation
Passage of appropriate enabling legislation is, of course, a,
necessary and key milestone in the implementation of an I/M program, and
a considerable period of time can be involved in assuring that such legi
adequately treats all aspects of the desired I/M program. To remedy thi*
situation, the EPA has prepared model I/M legislation formats that should
greatly assist the States in this important element of I/M program
inplementation.
2-90
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STATE TASKS
PLANNING AND EVALUATION
?SSUTIE$
OF INSPECTORS
IDLE MODE
ONGOING
14
14
^ n LOADED MODE
IL«I 4IUDY
>- •_ LOADED MODE
IRS|VEAR TEST CYCLE*
""-^_ IDLE MODE
*^^_ LOADED MODE
SERVICE INDUSTRY TASKS
(
^**"^Jb f OR REPAIRS
9 17
W//////////4
10 13
n
10 It
1 !
14
1
26
^////////////////m
17
wm
14
1
1 1
S 12 11
TIME, months
'////M
PROG
FULL
IMPLE
24'
1.
^
i_r~~
i
MENTED
30
je
re 2-9. Estimated Time Required for Implementation of State-Owned
Inspection Lanes Using Idle or Loaded Mode Tests. (Shaded
bars represent critical path of tasks leading to full
implementation.) (Ref. 2-13)
2-91
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In the meantime, enabling legislation for I/M programs has
been prepared and passed by the legislatures in several states. New Jersey,
Arizona, Chicago, and California are a few examples. The New Jersey
legislation provided for a statewide Idle Inspection Program that was com-
bined with the existing safety inspection program done in State -operated
lanes. The California legislation provided for a demonstration Loaded
Inspection Program to be initiated in selected counties of the State. The
Arizona bill provides for State lane loaded mode inspections conducted by a
private contractor. The Chicago ordinance establishes idle mode inspection
in city -owned and operated facilities. All cases of the I/M legislation passed
to date treated special situations and hence none can be thought of as a model
to be followed in preparing future enabling legislation for I/M programs.
However, each bill provides an insight into what level of detail is likely to be
required. This is especially true of Senate Bill 479 in California, which
reflects the past experience of the California Legislature in preparing
legislation for automotive retrofit programs for emission control.
In the general case, however, the conduct of initial planning
and tradeoff studies, as discussed in Section 2.7. 1, should result in the
identification of the technical, social, and economic characteristics of the
desired I/M program, thus enabling appropriate administrative and legis-
lative policy decisions to be the basis for structuring effective enabling
legislation. The socioeconomic impact of legislation dealing with motor
vehicles is so great that legislators are reluctant to authorize such a
unless they have clearly in mind what is involved and can judge how the
is likely to react to it.
In this regard, some of the provisions that should be
for incorporation in enabling legislation are:
a. Adequate authority to adopt rules and regulations concerning*
1. Requirements for periodic inspection
2. Establishment of fees for providing the inspection
service
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3. Withholding vehicle registration for those vehicles
•that do not satisfactorily complete the inspection or
that do not comply with an applicable variance
4. Prohibition of tampering
b. Provisions for providing adequate funds for implementing,
monitoring, and enforcing the I/M program
c. Adequate authority to obtain pertinent data and information,
and require periodic reporting of emission information
d. Authority to make emission reports and information
available for public inspection
e. Authority to compel compliance with rules and regulations
supported by civil or criminal penalties
f. Provisions for injunctive relief where deemed necessary
? "7 1
•'•3 Engineering and Administrative Studies
Following adoption of the enabling legislation, it is necessary
° perform definitive engineering and administrative studies in order to
actually carry out the legislative mandate. These studies are now program-
8Pecific (i. e., concerned only with the specific I/M program adopted by the
egislature) and are concerned with the details of program implementation.
8 such, they are an expansion of the initial planning studies and result in
decisions as to the management and enforcement structure of the pro-
, specific sizes and locations of inspection stations, cost and financing
Procedures, etc. A key output of this study period is the identification and
°Ption of the pilot or demonstration phase of the overall full-scale program
n Efficient detail to permit construction of the inspection stations and
Procurement of equipment.
Also, a program for information transfer to the affected
e"icle owner, including details of requirements levied upon vehicle owners
compliance assurance measures to be used, should be implemented at
8 time. Because of the relatively recent advent of emissions as an im-
°rtant consideration in vehicle operations, the effect of maintenance and
. epai* on auto emissions is much less well understood and easily recognized
by «
tne public than the effect of maintenance on safety. Hence, enforcement
*0f f,
C0r*»pliance with emission I/Mis likely to be more difficult than for safety
2-93
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I/M, and the public is more apprehensive regarding the quality and cost of
emission-related repair/maintenance services. For these reasons, the
consumer affairs aspects of the implementation of emission I/M programs
are even more important than for safety I/M programs. For example, both
California and New Jersey have and continue to expend large efforts on the
consumer affairs areas of educating the public on the relationship between
vehicle emissions and maintenance and the licensing, training, and super-
vision of emission-related repair services and personnel.
By the end of this study period, the I/M program management
group should be functional, and all participating State agencies (e.g. , State
or municipal police, air quality boards, motor vehicle groups, etc. ) should
be involved with program coordination activities.
2.7.4 Pilot Program Construction and Procurement
In this phase of the program, those inspection stations involve^
in the pilot program are constructed and the necessary measurement and
recording equipment is procured, in accordance with final decisions made
previously (Section 2. 7. 3).
Facility construction and equipment procurement should be
monitored to assure that initially selected plans and designs are indeed
adequate for program needs. Where changes are required, this information
should be incorporated into the structure of the final full-scale I/M program
by the management staff.
2.7.5 Pilot Progra.m^ Ope ration
Operation of the I/M program on a pilot or demonstration
basis provides the opportunity to verify the adequacy of facilities and
equipment, observe personnel training requirements, finalize test and data
acquisition procedures, and verify the operability of selected compliance
assurance measures.
With regard to data acquisition, data taken in the pilot pro-
gram can be used to adjust rejection rates and/or failure criteria, exami«e
the desirability of the retest option, and preliminarily assess the degree o*
2-94
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emission reduction afforded by the I/M program. Also, initial testing may
indicate that record-keeping formats or procedures selected initially may on
the one hand be too lengthy or otherwise cumbersome and costly, or on the
other hand be inadequate or insufficient for purposes of emission reduction
records of compliance" assurance.
The training requirements of inspection facility personnel can
be finalized by direct observation under actual working conditions (i. e. ,
working with real vehicles, vehicle owners, and actual measurement and
recording equipment).
Any problems that occur in the pilot program can be resolved,
and any required modifications for the overall, full-scale I/M program can
be structured into the full-scale program with a minimum impact on cost
and time considerations.
2.7.6 Planning for Full-Scale Program
Final planning for the full-scale I/M program should proceed
hand-in-hand with the operation of the pilot program. All potential problems
Discovered in the pilot program should be resolved within the framework of
full-scale program, and modifications to management structure, enforce-
procedures, and facilities incorporated as appropriate to benefit the
-scale program.
The planning should consider to what extent the introduction of
full-scale program should be time phased in order to budget investment
c°sts and operating costs within funding allocation limits. Such time-phased
Plans are required also to assure the availability of trained inspection
acility manpower.
During this phase of the program, the adopted licensing
Pr°gram for garages and mechanics should be initiated in order to assure an
a(*equate supply of trained mechanics and repair facilities when the full-scale
p:Pogram is initiated. This effort would also include the certification of
Pproved emission measurement equipment.
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2.7.7 Full-Scale Program Construction and Procurement
In this phase of the program, the remaining inspection stations
are constructed and measurement and recording equipment is procured, in
accordance with the initial program plan and any changes occasioned by
problems or improvement areas discovered in the pilot program construction
and operation phases.
Of particular importance in this phase of the program is the
implementation of the training program and the adequate training of the
personnel who will man the inspection stations.
2.7.8 Full-Scale Program Operation
Full-scale implementation of the overall I/M program is the
final step or program phase. It is the culmination of all activities, com-
mencing with the initial planning and tradeoff studies, and extending through
the pilot program activities and final construction and manning of the comple*e
I/M station network. It is the final product of the enabling legislation, and
its success or degree of effectiveness is largely dependent upon the through-
ness with which all preceding steps have been made.
2.7.9 Ongoing Licensing and Quality Control Program
Concurrent with I/M program activities, per se, are a
of ancillary activities that also are critical to the success or failure of the
program. As discussed in Sections 2.7. 1.3 and 2.7. 1.4, these activities
include the implementation of selected procedures or techniques for licens
garages and mechanics, as well as adoption and implementation of a viable
mechanism/organization for assuring quality control of the licensing
Of equal importance is the establishment of effective techniques for
the public informed as to their requirements as vehicle owners and as to
measures being enforced under the I/M program to meet the public's
in the areas of air quality and effective vehicle maintenance procedures.
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2.8 I/M OF HEAVY DUTY VEHICLES
2.8.1 Introduction
In Sections 2.3 through 2.7, the I/M of light duty vehicles was
discussed in detail. The light duty vehicle category presently includes all
Vehicles with a GVW of less than 6000 Ibs. In this section, various aspects
°f the I/M of vehicles with GVW greater than 6000 Ib will be considered. *
The percentages of in-use trucks in the nation in the various weight classes
are shown in Table 2-23. The data given in the table were obtained from
8ales and truck registration information contained in Ref. 2-18. Note that
°Ver 60 percent of the trucks have a GVW less than 6000 Ib; hence, they are
Presently classified by EPA as light duty vehicles** and must satisfy the
8ame emission standards (gm/mi) as passenger cars. Starting with model
Vear 1975, the emission standards for light duty trucks (GVW < 6000 Ib) will
e higher than passenger car standards. This section of the report is con-
cerned with the other 35 to 40 percent of the trucks with GVW greater than
°0 Ib. As shown in Table 2-23, about 50 percent of this group of vehicles
al1 into the 6000 to 10, 000 Ib weight class, with the remaining vehicles dis-
*buted in weight classes up to and exceeding 33, 000 Ib. Current Federal
fission regulations for the heavy duty vehicles (GVW >6000 Ib) are given
terms of emission standards for the engines to be used in those vehicles
wier than for the vehicles themselves. Hence, for heavy duty vehicles,
18 the engine rather than the vehicle that is certified by EPA. The engine
1ssion tests are performed on an engine dynamometer using test cycles
411(1 Procedures specified by EPA (Refs. 2-19 and 2-20). The heavy duty
glne emission standards for both gasoline-fueled and diesel engines are
(rnot 8tty trucks, but there are increasing numbers of recreation vehicles
** ° mes and campers) that fall into this category.
Slf
'ng in 1975, EPA has designated a new class of vehicles, light duty
that will have different emission standards (gm/mi) than passenger
*8 n-
e
-------
Table 2-23. Percent (National Averages) of In-Use Trucks
in"Various Weight Classesa
GVWb Class
<6000
6-10,000
10-14,000
14-16,000
16-19,000
19-26,000
26-33,000
>33, 000
GVW Class as %
of all Trucks0
•63.0
18.5
0.3d
1.3
4.5
6.5
2.0
3.9
Trucks with GVW
>6000 Ibs (%)
-
50.0
0.8
3.5
12.2
17.6
5.4
10.5
1972 and 1973 Motor Truck Facts (Ref. 2-18)
GVW = gross vehicle weight rating, Ib
°There were approximately 20 million trucks registered in
1973.
As of 1970, before the recreational vehicles sales showed
a marked increase in this weight class.
summarized in Table 2-24. The engine must satisfy the cited standards
after a prescribed durability test of 1000 to 1500 hr.
The wide variation in the types, weights, and uses of
heavy duty vehicles as contrasted with the corresponding much smaller
variation for light duty vehicles, plus the basic difference in the emission
regulation approach taken by EPA for the two vehicle classes, makes it
advisable to treat the I/M of heavy duty (GVW > 6000 Ib) and light duty
vehicles separately. Various aspects of vehicle emissions, maintenance,
and alternative I/M approaches for heavy duty vehicles are considered in
the next subsections.
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Table 2-24. Federal Emission Standards
for Heavy Duty Engines
Gasoline-Fueled Engines3
1970-73
HC - 275 ppm C6
CO - 1.5% (volume)
Diesel Enginesb
Smoke:
1973
40% opacity - acceleration mode
20% opacity - lugging mode
1974
HC + NO - 16 gm/bhp-hr
Ji
CO - 40 gm/bhp-hr
1974
HC + NO - 16 gm/bhp-hr
j£
CO - 40 gm/bhp-hr
Smoke:
20% opacity - acceleration mode
15% opacity - lugging mode
50% opacity - peaks
'-mode (2000 rpm, range of manifold vacuum) (Ref. 2-19)
Urteen-mode (intermediate and rated rpm, range of loads) (Ref. 2-20)
2-99
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2.8.2 Heavy Duty Vehicle Emissions
There have been several recent studies of exhaust emissions
from heavy duty gasoline-fueled trucks using both chassis dynamometer
driving cycles and road routes (Refs. 2-21 and 2-22). Those studies indicate
that truck emissions increase significantly with vehicle weight (curb-weight
plus payload) and that even in the 4000 to 6000 Ib inertia weight range vehicles
(1970-1973) equipped with engines certified using heavy duty test procedures
and emission standards seem to have emission levels much above those for
light duty vehicles at the same inertia weight. This is illustrated in
Figure 2-10, which shows the HC, CO, NO emissions (gm/mi) for medium
j£
duty vehicles tested using the 1975 CVS-CH FTP at EPA and the Southwest
Research Institute (SWRI) (Ref. 2-21).
Few measurements of exhaust emissions from heavy duty
vehicles equipped with diesel engines have been made as yet. Predictions
of emissions from diesel trucks have been made, however, in Ref. 2-23
based on diesel engine emission measurements (Ref. 2-24) (gm/bhp-hr
at various engine loads and rpm) and calculated engine load factors in urban
driving. Those predicted diesel emissions indicate that diesel HC and CO
emissions are much lower than those for gasoline engines and that the NO^
emissions from a diesel engine can be either lower or higher depending on
the type of fuel injection used (prechamber or direct injection). Because
diesel HC and CO emissions are much lower than for a gasoline engine,
the emission problems usually associated with diesel engines are those of
smoke and odor.
2.8.3 Mobile Source Emission Impact of Heavy Duty Vehicles
The contribution of heavy duty vehicles to mobile source
emissions has been studied in some detail in Ref. 2-25 for several AQCRS*
The importance of truck emissions compared with those from light duty
vehicles depends on the number of each class of vehicles in the AQCR and
the miles traveled by each class. The mix of vehicles and the average
miles traveled per day by each class can be quite different in the
2-100
-------
2 4 6 8 fo"
INERTIA WEIGHT - klb
MEAN REGRESSION LINE
95% CONFIDENCE LINE
I
12
4 6 8 10 12
INERTIA WEIGHT - klb
I
4 6 8 10
INERTIA WEIGHT - klb
12
Figure 2-10. Variation of Emission Levels with
Inertia Test Weight (1970 through
1973 trucks and motorhomes)
(Ref. 2-23)
2-101
-------
various regions. The^projected percentage contributions of the light duty
and heavy duty vehicle classes to the total mobile source emissions in
some AQCRs for the period 1970 to 1990, assuming that only the presently
*
promulgated emission standards for light duty and heavy duty vehicles
are implemented in that period, show that although at the present time
the emissions from light duty vehicles are dominant this will gradually
change in the next 20 years because the promulgated emission standards
for light duty vehicles are much stricter than those for heavy duty vehicles.
Unless the heavy duty engine emission standards are significantly tightened
beyond those set forth for 1974 (Table 2-24), by 1990 the total exhaust
emissions from trucks will be comparable to or greater than those from
light duty vehicles (Ref, 2-25). Hence, even though the control of emissions
from in-use trucks by I/M or retrofit strategies would not have nearly as
large an impact on mobile source emissions at the present time as the same
strategies applied to light duty vehicles, future projections indicate that this
will not be the case in 10 years or even sooner in some AQCRs.
2.8.4 Surveillance Studies of Heavy Duty Engine Emissions
As noted previously, emission standards pertinent to
heavy duty vehicles are not set for the vehicle itself, but rather for the
engines to be used in such vehicles. Hence, emission surveillance studies
of heavy duty vehicles involve emissions testing of engines after they
have been in service in heavy duty vehicles for a specified time or mileage.
Since removing the engine from the vehicle for testing on an engine dynamo**1'
eter is both expensive and time consuming, studies have been done at SWRI
to demonstrate that the engine can be emission tested while it is in the
vehicle by the use of a chassis dynamometer (Ref. 2-26). The same set of
'For light duty vehicles, it was assumed that the interim 1975 and final
HC and CO standards are implemented as scheduled. For heavy duty
vehicles, it was assumed that the 1974 heavy duty standards are implemented
and will remain unchanged until 1990.
2-102
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steady-state engine .test conditions (the nine-mode test procedure for gaso-
line engines) is used in the chassis dynamometer test as would be used if
the engine were tested alone on an engine dynamometer. All of the engine
emission surveillance results discussed in the following paragraphs were
obtained using the chassis dynamometer test procedure.
The engine emission surveillance program reported in
TN it
Ref. 2-26 involved the testing of about 150 1970-71 trucks ' with GVW between
°000 and 34, 000 Ib. The emission tests were to be performed every 4
Months over a period of about 2 years or 50, 000 miles. Results are presently
Published for only the first 12 months of the program. At the start of the
Program, the engine in each truck was tuned to the manufacturer's specifica-
tions. Subsequent emission tests were conducted in the "as-received" condition
after which the basic ignition time and idle rpm were checked. If they
found to be outside tolerance (±3° for timing and ±100 rpm), they
adjusted and the engine emissions test repeated. The timing and rpm
reset at the as-received values before the truck was returned to the
/
°wner. It is of interest to compare the initial emissions characteristics
0;f the trucks with those found after 12 months of service. This comparison is
shown in Table 2-25. As would be expected, some deterioration of emissions
was evident, with an increase in the average fleet HC emissions of 14 percent
and an increase in CO emissions of 11 percent. The fleet average NO
Missions remained essentially unchanged (less than 1 percent) during the
ll>st 12 months of the surveillance program. Determination of whether
Ule heavy duty engines continue to deteriorate with mileage or stabilize
1 the higher levels measured after the first year of the program must
wait publication of the data from the second year. At the end of the first
ar of the program, the CO emissions were above the Heavy Duty Engine
•^ndard of 1. 5 percent and HC emissions was very near the HC Standard
Of275ppm.
he initial mileage on most of the trucks was less than 10, 000.
2-103
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Table 2-25. Surveillance Study of Heavy Duty Engine
Emissions Over 12 Months (Ref. 2-26)
Months After
Tune-Upb
0
4
8
12
No. of
Trucks0
152
148
148
145
Emissions3
HCd
(ppm)
239
264
261
273
cod
(%)
1.61
1.73
1.89
1.79
NO •
(ppm)
1701
1873
1911
1703
aNine-mode test procedure with vehicle on a chassis dynomometer.
Vehicle given tune-up, and all components adjusted to manu-
facturer's specification.
C1970-71 heavy duty vehicles - 6000 < GVW < 32,000 Ib.
d!970 Federal Heavy Duty Engine Emission Standards: HC - 275
CO - 1.5 percent.
As mentioned previously, the ignition timing and idle rpm
of each truck was checked after it had been emissions tested in the as-
received condition. At each testing period, about 20 percent of the trucks
were found to be out of specifications, with early timing being the most
frequent maladjustment. Unfortunately, idle CO or air /fuel ratio was not
checked. The relatively high CO emissions of the fleet indicate that it is
likely a number of the trucks needed a carburetor adjustment at idle or
possibly at loaded conditions.
Voluntary Maintenance of Trucks and Other
Heavy Duty Vehicles
2.8.5
The group of vehicles being considered in this section
very nonhomogeneous in size, shape, weight, use, and approach to
nance. In discussing the maintenance of these vehicles, it is advantage0*1
2-104
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to consider the following categories: commercial and noncommercial, fleet
and nonfleet operated, recreational, and gasoline-fueled and diesel engines.
As indicated in Table 2-26, the approach to and level of maintenance can be
expected to vary considerably from category to category (Ref. 2-27). In
general, commercial vehicles are likely to be better maintained than non-
commercial vehicles of the same type because minimizing lost time due to
vehicle breakdowns and reducing fuel costs are important factors in con-
ducting a profitable business. Owners of recreational vehicles would
probably also maintain them better than the average passenger car because
breakdowns away from home while traveling and/or vacationing would be
both expensive and inconvenient. The best maintained vehicles are probably
those operated as part of a fleet, for which the cost and inconvenience of
scheduled and preventative maintenance is much less than if the same work
were done at a private garage or dealer.
Detailed surveys of the maintenance practices and associated
costs for the various truck and multipurpose vehicle categories are not
Presently available. However, limited inquiries to truck owners have
that most of the maintenance performed is directed toward safety
and lubrication. Engine tune-ups that are needed less frequently
seldom, if ever, done for any other reason than to improve vehicle
Performance and driveability. Except for reducing smoke from diesel
ei*gines, emission reduction is not a consideration. Even well-equipped,
^set-operated shops do not presently have exhaust gas analyzers. The
marked increase in the concern of vehicle owners for fuel economy
tend to improve the situation relative to scheduled engine tune-ups,
6ven for individual and small fleet owners. As in the case of the tune-up
repair of passenger cars, truck mechanics will need considerable
concerning emission-oriented tune-ups and the use of emission
periodic safety inspection of commercial vehicles is required by law in
°me States. Random highway inspections by State Police or Highway Patrol
llcers are conducted in other States.
2-105
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Table 2-26. Maintenance of Trucks and Other
Heavy Duty Vehicles (Ref. 2-27)
Vehicle Categories
Level of
Maintenance
Place of
Maintenance
Light duty trucks (GVW < 6000 lb)
Noncommercial
Commercial (nonfleet)
Commercial (fleet)
Gasoline-fueled heavy duty vehicle
(GVW > 6000 lb)
Noncommercial
Commercial (nonfleet)
Commercial (fleet)
Recreational
Diesel heavy duty vehicle
(GVW > 20, 000 lb)
Commercial (nonfleet)
Commercial (fleet)
Fairb
Fair/good
Goodd
Fair
Fair/good
Good
Fair/good
Good
Good
Independent
garage/dealer
Independent
garage/dealer
Company facility
Independent
garage/dealer
Independent
garage/dealer
Company facility
Independent
garage/dealer
Independent
garage/dealer
Company facility
All light duty trucks are gasoline fueled.
•*•
3Maintenance comparable to passenger cars.
*
"Somewhat better than for passenger cars.
Scheduled and preventative maintenance.
2-106
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measuring instruments in making repairs before the present rather
extensive voluntary maintenance program can be expected to result in
significant emission reductions from trucks.
Since trucks operated in fleets are on the average the best
maintained, it is of interest to know how many and what type of trucks are
operated in fleets and what maintenance schedules are followed. The
larger the fleet, the more likely it is that scheduled maintenance (safety
lube and engine tune-up) procedures are followed, and that the work is
performed by experienced, qualified personnel. The minimum size fleet
that is likely to have a shop and a qualified mechanic is one having about 10
vehicles. Data given in Ref. 2-18 indicate that about one-third of the in-use
trucks are operated in fleets of that size or larger. The number, type,
and use of vehicles in fleets of 10 or more vehicles are shown in Figure
2-11. It is common for the gasoline-fueled vehicles in such fleets to
Deceive safety/mechanical checks and lubes every 4000 miles (or 3 months)
9-nd major engine tune-ups (replacement of spark plugs, points, etc.)
every 12, 000 miles (or 6 months). Engine maintenance of diesels is done
much less frequently than for gasoline engines, with the period between
major engine work being 50, 000 miles in some cases. Including an
emission inspection procedure as part of existing fleet maintenance programs
^ould seem to be a logical step.
2.8.6 I/M Approaches for Trucks
^•8.6.1 General Considerations
In assessing the applicability of various I/M approaches to
tl>ucks, especially heavy duty trucks (GVW > 6000 Ib), the following factors
^d special circumstances pertinent to the use and maintenance of such
Vehicles are important and should be considered:
a. The number and density of heavy duty vehicles in the region
being considered.
b. The range of sizes, shapes, and weights included in the
vehicle population.
2-107
-------
o
00
Number of Vehicles
7,000,000 Vehicles
Figure 2-11. Vehicles in Fleets of 10 or more (Ref. 2-18)
-------
c. The Federal emission standards and test procedures
applicable to the in-use vehicles at the time they were
produced.
d. A large part of the heavy duty population is operated
for commercial purposes. Lost time and the cost
of unscheduled maintenance are more significant to
the owners of heavy duty vehicles than for most owners
of light duty vehicles.
e. Fleet operation and maintenance are more common
with heavy duty than with light duty vehicles.
f. Heavy duty chassis dynamometers are expensive and
their availability is limited; therefore, experience
with dynamometer testing of heavy duty vehicles is
quite limited.
2.8.6.2 I/M Alternatives for Trucks
Various I/M approaches as they relate to light duty vehicles
(primarily passenger cars) were discussed in Sections 2.1 through 2.7.
The approaches considered fall into two broad categories: (i) an emission
°r engine parameter inspection, usually performed in State-owned and
°perated lanes, followed by the repair of rejected vehicles at an inde-
pendent garage or dealer; and (2) mandatory periodic engine and emission
control system maintenance, with the entire procedure being done at an .
independent garage or dealer. It was found that for light duty vehicles
cost effectiveness of the first approach (emission inspection/repair)
significantly better than that of the second (mandatory periodic mainte-
nance) primarily because it is possible in the case of light duty vehicles
to identify by a lane inspection those vehicles having high emissions that
^ould benefit most from repair. For the reasons delineated in Section
•8.6. lf the lane inspection approach does not seem practical for heavy
^Uty vehicles. In addition, it is generally much more difficult to perform
a Meaningful emissions test on the larger vehicles in the heavy duty class
h*t is both low in cost and of short duration. Hence, the circumstances
Urrounding truck operation indicate that mandatory periodic maintenance
aV be the I/M approach best suited for heavy duty vehicles. This approach
2-109
-------
would be equally applicable to individual truck and recreation vehicle
owners and fleet operators. In addition, maintenance procedures could
be specified for both gasoline-fueled and diesel engines. This flexibility
in application is important because of the nonhomogeneity of the vehicles
in the heavy duty class.
Since, as discussed in Section 2.8. 5, many trucks receive
scheduled safety checks and lubrication, and, in addition, a significant
fraction receive periodic engine tune-ups, implementation of a mandatory
periodic maintenance program for trucks directed toward engine emission
reduction would not result in major changes in the maintenance schedules
of some truck owners. The primary effects of a State specifying engine
and emission control system maintenance procedures would be (1) that
all truck owners would be subject to the same set of procedures and standa*
and (2) that the mechanics doing the engine tune-up and repair work would
necessarily become conscious of engine emission requirements. Enforce-
ment of the mandatory engine maintenance regulations could be done by
requiring evidence of compliance at the time of registration of the vehicle
each year.
In contrast with the extensive studies of I/M related to light
duty vehicles, there have not been any similar studies concerned with heavy
duty vehicles. Since gasoline engines used in some heavy duty vehicles
essentially the same as those used in light duty vehicles, some of the i
mation developed in the light duty vehicle studies may be applicable to
these vehicles. However, since the power-to-weight ratio of heavy duty
vehicles tends to be much less than that for light duty vehicles and as a r
suit the engines in trucks operate at high loads a greater fraction of the
the incremental effect on emissions (gm/mi) of most engine and emissio*1
control system malfunctions and maladjustments is likely to be greater
than for light duty vehicles. Because of this, it is probable that idle
emissions are an even less reliable indicator of road emissions for heavy
duty than for light duty vehicles, and the use of chassis dynamometer
2-110
-------
testing becomes the only reasonably reliable approach to short emission
testing of heavy duty vehicles. This is unfortunate, as a heavy duty dyna-
mometer capable of simulating both the inertia and road horsepower of a
heavy truck is expensive ($30, 000 to $40, 000) and not many are available.
It is likely that a procedure for heavy duty vehicles analogous to the Key
Mode test for light duty vehicles can be developed that would require a
dynamometer with only power absorption capability. Possibly even a
"beefed-up" light duty vehicle dynamometer could be developed for this I/M
application. Emission inspection of heavy duty vehicles could be included
as part of a mandatory maintenance program or be conducted at a stationary
°r mobile site as a random check on the emissions of such vehicles.
2-111
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REFERENCES
2-1. Effectiveness of Short Emission Inspection Tests in Reducing
Emissions Through Maintenance, EPA Contract No. 68-01-
0410, Olson Laboratories (July 1973).
2-2. Mandatory Vehicle Emission Inspection and Maintenance, Cali-
fornia ARB Contract No. 1522, Northrop Corporation (June 1971).
2-3, An Evaluation of the Effectiveness of Automobile Engine Adjust-
ments to Reduce Exhaust Emissions, California ARB Contract
654, Clean Air Research Company (June 1973).
2-4. A Study of Mandatory Engine Maintenance for Reducing Vehicle
Exhaust Emissions, Vol. IV. APRAC Project No. CAPE-13-68
(July 1972).
2-5. New Jersey/Clayton Key Mode Demonstration Pro.ject, Clayton
Manufacturing Company (April 1971).
2-6. A. J. Andreatch, J. C. Elston, and R. W. Lahey, Tune-Up at
Idle, APCA Journal (December 1971).
2-7. Letter from W. Godsey, Government of the District of Columbia,
Department of Motor Vehicles.
2-8. Exhaust Emission and Cost Evaluation of the State of California
Road Side Idle Emission Inspection Program, Scott Laboratories*
Report SRL 2125-04-1273 (December 1973).
2-9. Feasibility of Meeting the 1975-76 Exhaust Emission Standards.
in Actual Use, Report on Panel on Testing, Inspection, and
Maintenance for National Academy of Sciences (June 1973).
2-10. J. Panzer, Idle Emissions Testing - Part II. SAE Paper 740133
(March 1974)
2-11. Kev Mode Truth Chart. Clayton Manufacturing Company (February
1971).
2-12. Control Strategies for In-Use Vehicles. U.S. Environmental
Protection Agency, Office of Air and Water Programs, Mobile
Source Pollution Control Program (November 1972).
2-1.12
-------
2-13. Inspection and Maintenance of Light-Duty Gasoline -Powered
Motor Vehicles; A Guide to Implementation, EPA-450/2-74-QQ5r
U.S. Environmental Protection Agency, Office of Air and Waste'
Management, Office of Air Quality Planning and Standards
(August 1974).
2-14. Mandatory Vehicle Emission Inspection and Maintenance^ Vol. V,
Part 2, "Technical Analysis and Results, " Northrop Corporation*
prepared under contract ARE 1522 with State of California Air
Resources Board (December 1971).
2*15. Vehicle Emission Inspection and Control Program, Vol. II,
"Technical Analysis and Results, " Olson Laboratories, prepared
under contract with State of Colorado, Department of Health
(November 1972).
2-16. Performance Criteria, Design Guidelines, and Accreditation^
Procedures for Hydrocarbon (HC) and Carbon Monoxide (CO)
Analyzers Required in California Official Motor Vehicle Pollution
Control Stations, Bureau of Automotive Repair (July 1973).
* Motor Vehicle Dealer Approved Automotive Service Exhaust
Gas Analyze rs. Department of Environmental Protection, Division
of Environmental Quality, State of New Jersey (November 1973).
2~18. 1972 and 1973 Motor Truck Facts, published by Motor Vehicle
Manufacturers Association of the United States.
**9.
-20.
"Emission Regulations for New Gasoline -Fueled Heavy Duty
Engines, " Subpart H, 37 Federal Register 24279 (November 15, 1972)
"Engine Exhaust Gaseous Emission Regulations for New Diesel
Heavy Duty Engines, " Subpart J, 37 Federal Register 24307
(November 15, 1972).
""**• Medium Duty Truck Emissions Data, Environmental Protection
Agency, Ann Arbor, Michigan (1973).
22. K. J. Springer and M. N. Ingalls, Mass Emissions from Trucks
Above 6000 Ib GVW -- Gasoline Fueled, Southwest Research
Institute (August 1972).
3- L. Bogden, A. Burke, and H. Reif, Technical Evaluation of
Emission Control Approaches and Economics of Emission
Reduction Requirements for Vehicles Between 6000 and 14,000
Pounds GVW. EPA-460/3-73-005 (November 1973).
2-113
-------
2-24. W. F. Marshall and R. D. Fleming, Diesel Emissions Re-
Inventoried," Bureau of Mines Report RI 7530 (July 1971).
2-25. Medium Duty Vehicle Emission Control Cost Effectiveness
Comparisons, Vol. II, Technical Discussion, Aerospace Report
ATR-74(7327)-l (January 1974); also EPA Report 460/3-74-0046
(January 1974).
2-26. M. H. Ingalls and K. J. Springer, Surveillance Study of Control
Equipped Heavy Duty Gasoline-powered Vehicles, Southwest
Research Institute (October 1972),
2-27. Visit and Discussions with Southern California Service Manager,
Ryder Truck Company (February 1974).
2-114
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3. RETROFIT OF EMISSION CONTROL SYSTEMS/DEVICES
FOR IN-USE VEHICLES
-------
3. RETROFIT OF EMISSION CONTROL SYSTEMS/
DEVICES FOR IN-USE VEHICLES
3 * * INTRODUCTION
Continuing advances in vehicle emission control technology
suggest that retrofitting emission control devices or systems to in-use
Vehicles may be a useful approach to accelerate the reduction in vehicular
emissions while these vehicles remain in use. The three main sources of
Vehicle emissions and thus possibilities for retrofit are the control of
exhaust emissions, crankcase emissions, and evaporative emissions. A
summary of the years in which emission controls were first used on new,
Jight duty vehicles sold in the United States in order to comply with Federal
and California emission standards is presented in Table 3-1. In general,
retrofit approaches would be applied to vehicles not equipped at the factory
similar controls.
Thus, a retrofit approach is defined as the addition of a new
or system, or the modification or removal of an existing item of equip-
beyond that of regular maintenance that is made to'a motor vehicle
aft-
'•er its initial manufacture for the purpose of reducing emissions.
3 4 .
Control of Exhaust Emissions
In order to control exhaust emissions, retrofit devices may
ther treat the exhaust gases after they leave the combustion chambers
enter into the exhaust system, or decrease pollutant formation in the
n8ine by modifications to the induction, fuel, and ignition systems. Within
6se broad categories there are, as discussed in Section 3. 2. 1, a number
Of diw
^4«erent approaches that can be pursued.
3.1 ,
Control of Crankcase Emissions
Engine blowby results when the air/fuel mixture in the cylinder
i fj g
aPes past the piston rings during the compression and power strokes.
3-1
-------
Table 3-1. Light Duty Vehicle Emission Control Requirements
Control System
Model Year
for Which
Standards Were
First Applicable
First Year
Control Technique
Introduced
Exhaust Emissions
HC and CO
Engine modifications
Idle adjustments
Timing modifications
Air injection
Catalyst
NO
x
Engine modifications
Spark advance control
EGR
Crankcase Emissions
PCV
Evaporative Emissions
Fuel tank and carburetor
1968 (1966 Calif.)
1973 (1971 Calif.)
1968 (1963 Calif.)
1971 (1970 Calif.)
1967
1968 (1966 Calif.)
1968 (1966 Calif.)
1968 (1966 Calif.)
1975
1973 (1971 Calif.)
1973 (1971 Calif.)
1973 (1972 Calif.)
1963 (1961 Calif.)
1971 (1970 Calif.)
3-2
-------
The vapors enter the crankcase and subsequently escape to the atmosphere.
Crankcase control systems provide a means of mixing air with the blowby
gases in the crankcase and recirculating the mixture into the intake mani-
fold, usually through a variable orifice control valve. The flow rate through
the valve is controlled by intake manifold vacuum. Crankcase emissions
control is discussed in Section 3, 2, 2.
3.1.3 Control of Evaporative Emissions
These systems control emissions from fuel that is evaporated
from the fuel tank and carburetor. Gasoline tanks and carburetors are
Vented to the atmosphere on pre-1970 vehicles in California and on pre-1971
vehicles nationally. Losses from the tank result from diurnal temperature
cycling, which causes expansion of the vapors in the tank. Losses at the
c&rburetor occur almost entirely during the hot-soak period after shutting
off the hot engine. Residual heat causes the temperature of the fuel bowl
to rise to 150 to 200eF, which results in substantial boiling and vaporization
of the fuel. Control of evaporative emissions is discussed in Section 3. 2. 3.
3«1.4 Criteria for Evaluation of Retrofit Emission
Control Systems/Devices
The following criteria should be utilized to ascertain the
ea£»ibility of a retrofit emission control system:
a. The emissions reduction at low mileage and any change
in reduction effectiveness (deterioration) at extended
mileage.
b. The effects of the device on the driveability of the vehicle.
This would include such factors as hesitation, stumble,
surge, stall, or other factors affecting vehicle operational
safety.
c. The effect on fuel consumption attributable to the retrofit
system/device.
d. The cost of the device or system, including initial installa-
tion cost, annual maintenance cost, and any changes in
fuel costs resulting from the use of the device. These data,
in turn, can be used to determine the cost effectiveness
3-3
-------
of the device in terms of pounds of pollutants
removed per dollar of cost.
e. The impact of the device, if any, on engine durability
and reliability, such as might be caused by high
coolant or exhaust gas temperatures or carburetor
deposits.
f. The applicability of the device to the vehicle popula-
tion in terms of its potential use on pre-1968,
1968-1971, etc. vehicles.
g. The ease or complexity of installation and maintenance.
This evaluation can aid in determining the reasonable-
ness of the cost estimates.
3-4
-------
a.
3'2 EVALUATION OF RETROFIT EMISSION CONTROL
SYSTEM/DEVICES ~ ~" ~ •
3 £ 4
• l Exhaust Emission Control
The following classes of exhaust emission control system/
Devices have been evaluated:
Engine Parametric Modifications. This type of retrofit is
applicable to uncontrolled vehicles (pre-1968 nationwide
pre-1966 in California) and consists of carburetor, timine
and idle adjustments. B»
b. NOX Control. This retrofit system is especially directed
toward those vehicles having only hydrocarbons (HC) and
carbon monoxide (CO) controls (1968-1972 nationwide, 1966-
1970 in California), but could be also used on uncontrolled
vehicles. Two approaches are currently certified for use in
California. One type uses exhaust gas recirculation (EGR)
plus vacuum spark advance delay, while the other uses only
vacuum spark advance disconnect.
c. Air Bleed. These devices are applicable to all vehicles, but
are most effective on uncontrolled vehicles (see discussion,
p. 3-13). Additional air is bled into the intake manifold at
idle and part-throttle, thereby leaning the air/fuel ratio and
reducing the HC and CO emissions, while potentially increasing
NOX emissions.
d. Oxidation Catalytic Converter. This system utilizes an
oxidation catalytic converter for the reduction of HC and CO.
It could potentially be used on all pre-1975 vehicles capable
of lead-free fuel operation. In general, the use of an oxida-
tion catalyst requires an air pump to supply the oxygen to
complete the oxidation of HC and CO.
e« Combination Systems. Numerous combinations of the above
systems can be utilized to provide a particular combination
of emission reductions. These include an oxidation catalyst
and EGR, air bleed and vacuum spark advance delay, etc.
The Environmental Protection Agency (EPA) has provided
estirnates of reductions in exhaust emissions achievable through the
8t*Uati
of various types of retrofit devices on light duty vehicles
e 3-2). These estimates were provided in Appendix N of 40 CFR 51 for
i N ' El^ission Reductions Achievable Through Inspection
oi 3a nce and Retrofit of Light Duty Vehicles, " Federal Register,
' No. HO (Friday, June 8, 1973).
3-5
-------
Table 3-2. Estimated Emission Reductions for
Retrofit of Light Duty Vehicles**
Retrofit Option
Average Reduction Per
Vehicle (%)b
HC
CO
Precontrolled Vehicles
Lean idle air/ fuel ratio
adjustment and vacuum spark
advance disconnect
Oxidizing catalytic converter and
vacuum spark advance disconnect
Air bleed to intake manifold
Exhaust gas recirculation and
vacuum spark advance disconnect
25
68
21
12
9
63
58
31
NOX
23
48
0
48
Controlled Vehicles
Oxidizing catalytic converter
Exhaust gas recirculation
Oxidizing catalytic converter and
exhaust gas recirculation
rt
Air bleed to intake manifold
50
0
50
25
50 '
0
50
40
0
40
40
0
aAppendix N of 40 CFR 51 (Federal Register. Vol. 38, No. 110
(Friday, June 8, 1973)
Reductions are to be applied to a maintained vehicle baseline (i.e.,
applied after emission reduction claimed for inspection/maintenance).
cAddendum to Appendix N of 40 CFR 51 (Federal Register, Vol. 38,
No. 110 (Friday, June 8, 1973).
3-6
-------
transportation control measure planning purposes. The data and discussions
presented in the following sections are supplementary to that of Appendix N
and are a summarization of currently available information related to the
emission reduction performance and cost aspects of specific light duty vehicle
retrofit approaches th'at have been or are currently being considered.
3.2.1.1 Engine Parametric Modifications
i
Two engine parametric modifications generally employed by
the vehicle manufacturers in meeting Federal and California exhaust ernis-
8ions standards have been the leaning of air/fuel ratios and the modification
°f ignition (spark) timing. Therefore, the modification of these parameters
*fc precontrolled (pre-1968) vehicles can be used to reduce exhaust emissions
*lso. Because 1968 and newer vehicles have utilized these modifications to
8orrte extent to meet Federal emissions standards, this retrofit technique can
°nly be considered to be generally applicable to precontrolled vehicles.
3.2.1.1.1 Description
Basically, this retrofit approach consists of three adjustments,
*-e. , increased idle speed to reduce HC on deceleration, a leaner idle mixture
^4:1) to reduce HC and CO at idle, and vacuum spark advance disconnect
a&d/or delay (VSAD). Engine overheating protection can be provided by a
the r mo static vacuum switch that restores the normal spark advance if high
c°olant temperatures occur. The retrofit device referred to in the remainder
°* this section is this temperature sensing device.
3-2.1.1.2 Emission Reductions
Emission tests have been conducted (Ref. 3-1) on a group of
l<*62-1967 vehicles using the 1972 CVS cold start test procedure in four dif-
e*ent configurations. The first was the "as-received" or baseline configura-
The vehicles were then tested again after installation of the retrofit
. Following this, the vehicles were tuned, the retrofit device detached,
the "tuned" configuration tested. The final test was made with the retrofit
reinstalled and tested in combination with the tuned configuration.
3-7
-------
The tune-up procedure consisted of the replacement of spark
plugs, spark plug wires, distributor rotor, distributor cap, ignition points,
condenser, and air filter element. As a part of the major tune-up, the idle
mixture setting was set to give the best manifold vacuum at idle. All other
tune-up settings were as specified by the vehicle manufacturer.
The relative effectiveness of the various procedures for re-
ducing emissions is presented in Tables 3-3 and 3-4. As one would expect,
the tuned plus retrofit configuration showed the greatest overall emission
reduction.
Table 3-3. Emission Reduction from As-Received Baseline (Ref. 3-1)
Emission
HC -mean
95% confidence
CO -mean
95% confidence
NO -mean
95% confidence
No. of vehicles in
test sample
Emission Reduction (%)
Retrofit Alone
26
24 to 29
16
14 to 17
22
15 to 30
110
Tune -Up
15
11 to 18
11
9 to 13
-4 inc.
-18 to 10
85
Tuned with Retrofit
34
33 to 38
18
17 to 20
20
13 to 27
110
Table 3-4. Emission Reduction from Tuned Baseline (Ref. 3-1)
Emission
HC -mean
95% confidence
CO -mean
95% confidence
NOx-mean
95% confidence
No. of vehicles in test sample
Emission Reduction
Due To Retrofit (%)
25
22 to 28
9
6 to 11
23
1 5 to 29
85
/
3-8
-------
Durability tests conducted on this system to 25,000 miles
indicated essentially no deterioration in emission reduction effectiveness for
HC and nitrogen oxides (NO ). A deterioration in CO reduction was noted
Jt
and was attributable to an increase in idle enrichment, thus pointing up the
need for annual maintenance to insure that the installed idle speed and mix-
ture ratio are maintained.
3.2.1.1.3 Fuel Economy
Fuel consumption penalties associated with these devices have
been reported to range from 2 to 6 percent, largely due to the ignition timing
Codifications.
3.2.1.1.4 Installed Cost
Kits containing parts needed for this retrofit have been
riUrketed for approximately $10. The labor cost for installation is also
about $10, bringing the total initial cost to the consumer to about $20.
3.2.1.1.5 Safety
There are no known adverse safety effects associated with this
Retrofit system.
•2.1.1.6 Driveability
No serious driveability problems are associated with this
Profit system.
3<2-1.1.7 Reliability
The hardware used in these devices is not expected to present
ny reliability or durability problems, as it is similar to hardware used on
Deduction vehicles.
'^•1.1.8 Maintenance
Annual maintenance is essential with this system, since the
&sic effectiveness in reducing emissions is contingent upon maintaining the
48 .
-installed idle speed, timing, and idle mixture. Annual maintenance costs
3-9
-------
associated with the carburetor adjustment and timing check are expected to
be about $5 per year.
3.2.1.1.9 Applicability to Vehicle Population
This system is applicable to all pre-1968 domestic cars on a
nationwide basis with the exception of those few not utilizing a centrifugal
advance mechanism and similarly most pre-1966 cars in California. This
amounts to approximately 40 percent of the U.S. passenger cars in operation*
based on model year distribution data for 1973 (Ref. 3-2).
3.2,1.2 NOX Control
Historically, the introduction of emission controls to reduce
HC and CO (1966 in California, 1968 nationally) resulted in a significant
increase in NO emissions. The development of retrofit devices to reduce
Ji.
the NO emissions has been directed, therefore, primarily toward applica-
Jt
tion to those vehicles currently having only HC and CO emission controls.
This includes those cars sold in California from 1966-1970 and those sold
nationally from 1968-1972, inclusive.
3.2.1.2.1 Description
Retrofit devices designed to reduce emissions of NO are
J%r
generally of two types. One relies entirely on spark timing retard and
accomplishes this through VSAD or electronic modulation of the timing.
Additional adjustments may be required at the time of installation of the
device. These might include idle mixture adjustment to 1. 5 to 2 percent
CO and retard of the basic timing. This type of device may also incorporate
provisions for overtemperature protection in the form of either an overspeed
switch that restores full vacuum advance above a preset vehicle speed or a
temperature sensing device that restores vacuum advance when the engine
coolant reaches a certain temperature.
The other type of NO emission reduction device utilizes a
ff x
combination of EGR and VSAD. The EGR is accomplished by metering a
3-10
-------
quantity of exhaust gas from a connection to the engine exhaust system through
a control valve to a T-connection with the positive crankcase ventilation
(PCV) line leading to the intake manifold. The control valves differ sub-
stantially, but, in general, are responsive to a vacuum signal that controls
valve operation. A vacuum delay element is used to provide varying degrees
of spark retard under different operating conditions but allows full advance
during cruise conditions to minimize fuel economy penalties. Since this type
of device employs a delay rather than full vacuum disconnect (VSAD), over-
temperature protection is not required. No change is required from the
basic idle rpm or timing, but adjustment of mixture ratio to best lean idle
is necessary in some cases,
3.2.1.2.2 Emission Reductions
Emission reductions from the NO control devices are based
Ji
primarily on emission measurements taken in support of manufacturers'
applications for certification of the devices in the State of California (Ref. 3-3).
The test data are based on the averages of 16 to 24 car fleets tested using the
hot start 1972 CVS test procedure. Baseline vehicles were adjusted to manu-
facturers' specifications.
Average emission reductions at zero miles resulting from the
installation of the VSAD type devices were 26 percent HC, 4 percent CO, and
45 percent NO . The average emission reductions for the EGR plus VSAD
vvere 12 percent HC, 20 percent CO, and 53 percent NOx-
It should be pointed out that these devices were designed
primarily to reduce NO *. As a result, the extent of NO^ reduction is fairly
consistent among the various devices, but a wide variation exists in their
effectiveness in reducing HC and CO. For example, average emission reduc-
tion variation ranges for the EGR type devices were: HC from 4 to 15 percent,
from 16 to 43 percent, and NO from 47 to 54 percent. Similar variations
Jt
*
The California retrofit program for 1966-1970 vehicles was directed toward
Deducing NOX emissions by at least 40 percent without increasing HC and
emissions.
3-11
-------
for the VSAD type device were: HC from 22 to 31 percent, CO from -3 (an
increase) to 9 percent^ and NO from 42 to 50 percent (Ref. 3-3).
Jt
Only limited data are available on the emission reduction
effectiveness of these devices at extended mileage. The EGR type device
has been operated to 12,-QOO miles with no significant change in NO^ reduc-
tion. No extended mileage data is available on the VSAD only devices.
3.2.1.2.3 Fuel Economy
Fuel economy changes associated with the NO retrofit devices
Ji
have exhibited a wide variation on a car-to-car basis. Representative aver-
age values have been reported (Ref. 3-4) to range from a 3 to 7 percent
penalty for the EGR type devices to a 6 to 10 percent penalty for the VSAD
type devices, although actual fuel economy improvements were measured
on a few individual vehicles.
3.2.1.2.4 Installed Cost
Both types of NO devices are required by law in California
to have an installed cost of not more than $35. It is assumed that the devices
would be available on a nationwide basis at a similar cost.
3.2.1.2.5 Safety
There are no apparent safety hazards associated with these
devices.
3.2.1.2.6 Driveability
No significant driveability problems were reported for the
EGR type devices. Minor deterioration was reported for some VSAD devices,
but driveability was considered acceptable.
3.2.1.2.7 Reliability
Both types of NO devices are expected to have an estimated
Jt
useful life of at least 50,000 miles, although actual durability tests have not
been conducted.
3-12
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3.2.1.2.8 Maintenance
The systems employing EGR are potentially susceptible to
deposit formation in the EGR system and require annual maintenance of
the EGR valve. The VSAD systems are susceptible to maladjustment of
the basic timing settings and should also undergo annual maintenance. The
VSAD systems have been shown (Ref. 3-4) to cause an increase in exhaust
gas temperature (200 to 250°F at 60 mph), and a small percentage of
the cars (approximately 5 percent) experienced coolant overheating under
severe conditions. In this regard, it is of interest to note that a study has
recently been completed by the California Department of Transportation
(Ref. 3-5) in which the vacuum spark advance was disconnected on approxi-
mately 200 vehicles in normal motor pool use. No other modifications were
made to these vehicles, which were in operation for approximately 11 months.
Results indicated that there was no serious impairment of vehicle drive -
ability nor could any adverse effects on needed engine maintenance be attri-
buted to VSAD. Caution should be exercised in interpreting the results of
this test program, however, since the effects of prolonged use at highway
speeds and loads were not fully investigated.
Annual device-related maintenance cost for the NO devices
xx
has also been set by statute in California at not more than $15. Actual costs
are not expected to exceed this.
3.2.1.2.9 Applicability to Vehicle Population
The NO retrofit devices have been specifically designed to
x
be used on that portion of the vehicle population that has some degree of HC
and CO control but no NO control. Specifically, this means the 1966-1970
Vehicles in California and the 1968-1972 vehicles nationally. There is no
reason, however, why these NO retrofit systems could not be used on
JL
Precontrolled cars as well.
3.2.1.3 Air Bleed Devices
The HC and CO emissions can be reduced by leaning the
ai*/fuel ratio at part-throttle conditions and during deceleration by introducing
3-13
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additional air into the intake manifold. This technique is applicable to some
degree to all light duty vehicles; however, because of the increasingly lean
air/fuel ratios on later model controlled vehicles, this retrofit technique
can be expected to become less effective and in some cases may lead to
lean misfire effects on later model vehicles.
3.2.1.3.1 Description
Retrofit devices of this type operate on the principal of bleeding
air into the intake manifold in response to the manifold vacuum (difference
between intake manifold and atmospheric pressures) to increase the air/fuel
ratio. The additional air provides more complete oxidation of the CO and,
to a lesser extent, HC during the combustion process. NO emissions tend
Jt
to increase unless other controls are used in conjunction with the air bleed
devices. Adjustment of the idle mixture ratio at the time of installation is
required for some, but not all, devices.
3.2.1.3.2 Emission Reductions
The emission reduction effectiveness of the air bleed devices
has been evaluated for both uncontrolled vehicles (pre-1966 in California,
pre-1968 nationally) and controlled vehicles (1968-1971). As expected, the
controlled vehicles, which operate at a leaner air/fuel ratio than the uncon-
trolled vehicles, show a somewhat lesser reduction in CO.
Typical emission reductions that might be expected with the
air bleed devices are 20 percent HC, 60 percent CO, and -5 percent NO
Jk,
(increase) when installed on precontrolled vehicles and 20 percent HC,
50 percent CO, and a neglible change in NO when installed on controlled
(1968-1971) vehicles.
Note: It should be pointed out that extensive and consistent
test data are not available on these devices; therefore, a reliable statistical
evaluation of their emission reduction capability is not possible.
3-14
-------
3.2.1.3.3 Fuel Economy
As was the case for emission reductions using air bleed
devices, a large variation (-4 to +13 percent) in their effect on fuel economy
has also been reported. A representative value for the pre-1968 vehicles
is approximately a 4 percent savings. It would be expected that the controlled
vehicles (1968-1971) would show a lesser improvement in fuel economy since
the baseline vehicles are operating at a leaner air/fuel ratio than the uncon-
trolled vehicles. However, this is not substantiated by the limited available
data, and the 4 percent fuel savings has been assumed for both groups of
vehicles.
3-2.1.3.4 Installed Costs
The installed cost of the air bleed devices ranges from
$20 to $60.
3-2.1.3.5 Safety
There are no apparent safety hazards associated with these
Devices unless severe lean misfire is encountered.
3-2.1.3.6 Driveability
No significant driveability problems were reported for the air
type devices, although some increase in acceleration times (approxi-
y 10 percent) was reported for one of the devices (Ref. 3-6). Theoreti-
, of course, these devices would be characterized by lean operation
tendencies, e.g., surge and hesitation. It should also be pointed out that the
*
nstallation of an air bleed device on any vehicles already operating near the
ean limit of combustion could result in misfire and possible severe adverse
effects on driveability (and safety) of those vehicles.
3'2-1.3.7 Reliability
No specific reliability problems are anticipated for the air
devices.
3-15
-------
3.2.1.3.8 Maintenance
Annual maintenance on the air bleed devices is not expected
to require more than changing the filter (if used by the device) and checking
the air/fuel ratio. Maintenance costs should not exceed $5 per year.
3.2.1.3.9 Applicability to Vehicle Population
The use of this device is applicable to both the uncontrolled
(pre-1968) and the 1968-1971 vehicles, although the percent reduction in
emission levels with 1968-1971 vehicles will be considerably lower than the
uncontrolled vehicles. Its applicability to the 1972-1974 model vehicles is
slight and therefore not recommended for application, since many of these
cars are already operating at the lean limit of combustion and the use of the
device would result in misfire and adverse driveability.
3,2.1.4 Oxidation Catalytic Converters
Oxidation catalysts as a retrofit device provide a means of
achieving reduction of both HC and CO emissions, with little or no effect
on NO emissions. Tests (Refs. 3-7 through 3-9) of retrofit catalytic
.X.
converters have been conducted in recent years. The most extensive test
program to date is one currently being conducted by the California Air
Resources Board involving a total to 100 vehicles (model year 1966 to 1972).
These vehicles are used by State employees for transportation required in
the conduct of State business and are tested every 4 months until each
vehicle has been in State service for 2 years.
3.2.1.4.1 California Test Program
3.2.1.4.1.1 Description
The catalytic converter used in the California test contains
approximately 170 grams of pellet catalyst (volume 33 cu. in.), with a loading
of approximately 1 percent or 1.7 grams of platinum per converter. One
converter is used on a six-cylinder engine and two on a V-8. The units are
mounted in the engine compartment just below the exhaust manifold.
3-16
-------
The 100 car test fleet was divided into groups A, B, and C as
described below:
a. Group A. Consists of 11 vehicles with factory installed air
pumps.
b- Group B. Consists of 29 vehicles without air pumps. For
this group, effective catalytic conversion is dependent on
adjusting the air/fuel ratio to a lean setting to provide the
excess air for conversion.
c. Group C. Consists of 60 vehicles to which air pumps were
added to provide the extra air needed for conversion. This
group is considered to be the most likely candidate for a
retrofit system.
3.2.1.4.1.2 Emission Reduction
The reported test results of November 1973 on the California
fleet are given in Table 3-5. Values shown are the average value for the
number of vehicles tested at each 4-month interval using the cold start 1972
CVS test procedure. The program is scheduled to continue until all vehicles
have been in service for 24 months. The Group A vehicles with factory-
installed air pumps experienced the largest emissions reduction, which
seemingly showed a stabilized reduction in HC and CO of 60 to 65 percent
after 12 months and an average of 10,000 miles. The Group B vehicles,
Without air pumps, exhibited relatively low emission reduction potential
early in the program when tested using a cold start and were phased out of
the program. The Group C vehicles with retrofitted air pumps have shown
HC and CO reductions of 65 to 70 percent at zero miles, but the reductions
deteriorated to about 35 percent after 12 months and an average of 12,600
miles.
It will be noted from Table 3-5 that both the A and C groups of
Vehicles experienced a substantial deterioration in emission reduction during
the first 4 months. As noted previously, the Group A vehicles (factory air
Pump) then remained fairly constant at 60 to 65 percent reduction in HC and
CO, while the Group C vehicles (retrofit air pump) exhibited an additional
Deterioration in the 8 to 12 month period.
3-17
-------
Table 3-5. Emission Test Results, 1972 CVS Cold Start California Fleet (Ref. 3-7)
I
l-»
00
Group
A (factory air pump)
Baseline
0 Months
4 Months
8 Months
12 Months
C (retrofit air pump)
Baseline
0 Months
4 Months
8 Months
12 Months
B (no air pump)c
Baseline
0 Months
4 Months
No. of
Vehicles
11
11
11
10
6
60
60
57
32
9
29
29
24
HC
gm/mi
3.73
0.69
1.32
1.31
1.47
3.52
1.09
1.77
1.86
2.28
2.89
1.43
2. 10
Reduction (% )
81.5
64.6
64.9
60.6
69.0
49.7
47.2
35.2
50.5
27.3
CO
gm/mi
44.64
4.95
17.01
17.30
16.04
42.23
14.39
23. 16
22.21
27.39
30.9
21.0
35.8
Reduction (%)b
88.9
61.9
61.2
64. 1
65.9
45.2
47.4
35. 1
32.0
-15.8
Average
Miles
;
10,000
12, 600
Number of vehicles shown tested after the various time periods varies due to differences in when the retrofitted
vehicles were placed in service and the status of the test program at the time referenced reports were written.
In addition, there have been seven catalyst failures (burn-out or mechanical problems) in Group C.
Negative value indicates an increase in emissions.
"This group was phased out of the program.
-------
Investigation indicated that the baseline emissions were
increasing as the 1966-1972 test vehicles accumulated additional mileage.
As reported in Ref. 3-10, 39 vehicles in Group C (with retrofit air pumps)
have received rebaseline tests after 16 months. Results of these tests,
shown in Table 3-6, indicate that these vehicles are maintaining HC and CO
reductions in the 40 to 45 percent range.
Table 3-6. Rebaselined Emissions, California Fleet
(June 1974)
Group C
3.
Rebaseline
Reduction
No.
of Cars
39
39
-
Exhaust Emissions
(gm/mi)
HC
1.86
3.29
43%
CO
29.7
54.2
45%
NOV
Average
Mileage
17,360
17,380
Without converters
In order for the oxidation catalytic converter to be an attrac-
tive retrofit device, it is necessary that the deterioration it experiences in
use be quite low. While sufficient data are available to conclude with some
confidence that the initial (zero miles) emission reduction on retrofitted
vehicles is high (70 to 90 percent) for both HC and CO, there is not sufficient
data at present to conclude that the needed low deterioration can be achieved.
In light of the promising deterioration results over 12, 000 miles in the
California tests for the vehicles with factory-installed air pumps and the
improving deterioration-resistant characteristics of catalysts on prototype
1975-76 vehicles (Refs. 3-11 through 3-13), there is certainly a reasonable
likelihood that the low deterioration requirement for retrofit converters can
be met in the not too distant future.
3-19
-------
It is certainly reasonable to assume that continued improvements
in the deterioration resistance of catalysts for new vehicles in the years ahead
will be reflected in potentially lower deterioration rates for retrofitted con-
verters. However, these improvements should not be accepted per se for
retrofit devices without'extensive testing because the configuration, location,
and engine system in which the original equipment and retrofit converters are
used are quite different. For example, currently the retrofit converters are
smaller in volume, have a higher loading of active metal, and are located
closer to the engine than converters used in new vehicles. In addition, the
retrofit converters will not benefit from the improved choke, ignition, and
carburetor systems used in 1975-76 vehicles. Further, it is difficult to pro-
vide comparable over-heat protection for the retrofit converters. In sumrnalff.'
it can be said that solving the catalyst deterioration problem for new vehiclgj!
does not necessarily mean the problem is solved for the retrofit of catalysts.
to in-use vehicles.
3.2.1.4.1.3 Fuel Economy
Results of the California tests indicate only that there have
been no reports of loss in fuel economy among the fleet vehicles. No quanti-
tative data on fuel consumption were reported. In this regard, however, it
should be pointed out that primarily fuel economy effects will depend largely
on the nature of parametric adjustments (timing, etc.), if any, made during
the installation of the retrofit system.
3.2.1.4.1.4 Installed Cost
The installed cost of the catalytic converter retrofit system
has been estimated from the manufacturers and other cost data presented in
Reference 3-6. For a V-8, these costs are:
Converters (2) $50.00
Converter installation 20.00
Conve rte r T otal $70.00
3-20
-------
Air pump $45.00
Air pump installation 40.00
Air Pump Total $ 85.00
Total Installed Cost $155.00
From the above, it can be seen that the air pump represents a significant
portion of the installed cost (and cost effectiveness of the system). Research
to develop alternatives for the currently necessary use of an air pump is
continuing.
3.2.1.4.1.5 Driveability
No adverse driveability problems, i.e., loss of performance,
has been reported.
3.2.1.4.1.6 Maintenance
Average maintenance costs associated with the catalyst (with
*ir pump) are not expected to exceed $15 per year. These costs would include
a*i annual replacement of any loss due to shrinkage and a possible complete
replacement of the catalyst (pellets only) every 25,000 miles. Replacement
costs for the pelletized catalytic material are uncertain, but a cost of $7 per
converter has been suggested by the manufacturer.
3-2.1.4.1.7 Applicability to Vehicle Population
The catalyst retrofit device would be applicable to those pre-
*°75 cars whose engines are capable (knock-free and without damage to valves)
of operating on lead-free 91 RON fuel. To insure against the use of leaded
Uel, consideration must be given to the retrofit of a fuel tank neck restriction
similar to that planned for the 1975 model year vehicles that will be catalyst
Quipped and also require lead-free fuel.
•2.1.5 Combinations of Retrofit Control Systems
Combinations of the systems discussed in the previous sections
the potential to achieve larger combined reductions in HC, CO, and
both uncontrolled (pre-1968) and controlled 1968-1971 vehicles than
**°8Bible with the individual systems alone.
3-21
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3.2.1.5.1 Air Bleed and NOX Control
One of the combination'systems employs an air bleed device
and either a vacuum delay valve for vacuum spark advance control or EGR.
3.2.1.5.1.1 Emission Reduction
Although only limited emission reduction data are available for
this combination system, projected emission reductions of 20 to 25 percent
HC and 40 to 50 percent CO are consistent with available data. NO reductions
of 10 to 20 percent for the air bleed plus vacuum delay and 30 to 40 percent
for the air bleed plus EGR are projected.
3.2.1.5.1.2 Fuel Economy
Fuel economy for the combined system is expected to show an
improvement over that for the NO device alone because of the leaning effect
of the air bleed device, which when used alone improves fuel economy by abou*
4 percent. Hence, the net effect of the two retrofitted devices together is
estimated to be only a slight fuel penalty of 1 to 2 percent at most. Test data
to confirm this estimate are not currently available.
3.2.1.5.1.3 Installed Cost
The installed cost of the air bleed and vacuum delay devices
has been quoted as approximately $25 (Ref. 3-14). The cost of the air bleed
and EGR combination is estimated to be about $40 to $50.
3.2.1.5.1.4 Applicability to Vehicle Population
This combined system could be used on most pre-1973 vehicle^
that did not have a factory-installed NO control system.
j£
3.2.1.5.2 Oxidation Catalyst and EGR
A second combination system that will be considered is the
oxidation catalyst and EGR. This system also requires a means of adding
additional air (oxygen) to the exhaust gases either by leaner carburetion or
by the use of an air pump. Systems have been tested with and without air
3-22
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pumps and in addition the possibility of using an air bleed device is currently
being studied. •
3.2.1.5.Z.I Emission Reduction
The combined system of oxidation catalyst and EGR has not
been tested using controlled light duty vehicles, but the initial emission
reduction characteristics (Table 3-7) of such a system can be estimated
using the characteristics of the separate systems given previously. These
estimates are thought to be appropriate, since the catalyst and NO control
systems do not interact significantly.
Table 3-7. Oxidation Catalyst and EGR Systems
Configuration
With air pump
Without air pump
Emission Reductions (%)
i
HC
70
50
CO
65
32
NO
X
53
53
*
Fuel Economy
Change (%)
-3
-3
All emissions relative to 1972 CVS-C FTP.
The data in Table 3-7 are for low mileage tests. The effect of deterioration
is likely to be important, but the rapidly changing catalyst technology and lack
°f fleet data for the new catalysts makes it impossible to assess retrofit
catalyst deterioration in a meaningful manner at the present time.
3.2.1.5.2.2 Fuel Economy
The fuel penalty for this combined system was estimated to be
.3 percent, which is slightly less than for the EGR system alone.
3.2.1.5.2.3 Installed Cost
The installed cost of this combined system can be determined
simply adding the costs of the individual systems because their installations
not interrelated. Hence, the installed cost would be $190, including an
3-23
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air pump, and $105 if the retrofitting of an air pump is not required for cars
already equipped with one.
3.2.1.5.2.4 Applicability to the Vehicle Population
This combined system would be most directly applicable to
1970-1972 vehicles that do not have NO control emission systems and can
operate on lead-free (low octane) gasoline.
3.2.1.6 Retrofit Emission Control at High Altitude*
It must be emphasized that much of the discussion of the retro-
fit at high altitude is based on the following: data from three sources only,
very limited sample sizes, hot start emissions tests, dissimilar vehicles,
and on device proponent's emissions data and cost estimates. There remains
considerable data to be gathered before the magnitude of the emission reduc-
tion by retrofit at altitude can be ascertained. It is strongly suggested that
before any high altitude retrofit program be initiated, a comprehensive and
thorough altitude retrofit evaluation be conducted on vehicles representing
the local high altitude vehicle population. Consideration must be given also
to the availability of devices optimized for high altitude retrofit, engineering
development problems associated with specialized high altitude retrofit, and
operation of a high altitude retrofit device at sea level. However, these data
are the only data available and are presented to complete the retrofit scenari0'
Differences in emission levels occur in gasoline-fueled vehicle9
when operated at high altitude. These changes are the result of fuel metering
enrichment due to the atmospheric pressure (and density) variations with
altitude. Since the air/fuel ratio is proportional to the square root of the air
density, operation of a motor vehicle at an altitude of 5000 feet would theo-
retically result in a decrease in the air/fuel ratio of 7. 2 percent. In the
normal operating ranges, this is equivalent to a decrease of approximately
one air/fuel unit. The effect of this, in general, can be seen in Figure 3-l>
which shows typical emission levels as a function of the air/fuel ratio. The
actual magnitude will vary, depending on the operating range of the vehicle-
*
High altitude means any elevation over 4, 000 feet.
3-24
-------
4000
— 20
§ 3000
o:
LU
a.
CD
^~~
ct
2
2000 —
1000 —
10
12
14 16
AIR/FUEL RATIO
18
20
22
Figure 3-1.
Typical Spark Ignition Engine Exhaust
Emission vs Air/Fuel Ratio (Gasoline)
(Ref. 3-15)
3-25
-------
Typical changes in emission levels for vehicles operating at
altitude are shown in Table 3-8. The changes are based on cold start 1975
results from CVS test results found in Denver, Colorado, (Ref. 3-16) and
compared to the average from similar tests conducted in low altitude cities,
* i V
Table 3-8. Emission Changes at Altitude (Denver, Colorado)
Model Year
Pre-1968
1968-1971
1972-1974
% Change Due to Altitude
HC
+ 16.7
+47. 8
+81.5
CO
+ 46.7
+ 71. 1
+ 121. 1
NOX
-46.6
-45.7
-37.9
It can be inferred from Table 3-8 that the retrofit of vehicles operating at
altitude should be directed toward the reduction of CO and HC. Vehicle
emission control programs for high altitude, including retrofit strategies,
are discussed inRefs. 3-17 and 3-18.
Additional problems associated with vehicle operation at high
altitude arise from the reduction in power due to the lower ambient air densi*/'
The power loss is proportional to the ambient density (Ref. 3-19), which
means approximately a 14 percent reduction in power at 5,000 feet. To com-
pensate for this, the vehicle must be operated at lower manifold vacuum and
higher rpm than at sea level to obtain the same output power from the engine-
The reduced power makes the effect of spark retard on engine operation moat
noticeable. Also, the lower manifold vacuum tends to reduce the amount of
air bled into the intake manifold through any particular air bleed valve
configuration.
3.2.1.6.1 Description
A number of control devices have been tested, either singly °r
in combination, in Denver, Colorado, to determine their effectiveness in
3-26
-------
reducing emissions at high altitude (Refs. 3-14, 3-17, 3-20). The systems
tested include the following:
a. Air Bleed. This is the same device previously discussed
in Section 3. 2. 1, 3 (Device A).
b. Air Bleed and a Vacuum Delay Valve. This is the same
system discussed in Section 3. 2. 1. 5.
c. Exhaust Gas Recirculation (EGR). This is the same system
discussed in Section 3. 2. 1. 2 (Device A).
d. EGR and Enleanment. The EGR unit (Section 3. 2. 1. 2,
Device B) was used in combination with enleanment
accomplished by installing an oversized PCV valve
(4-10CFM).
e. EGR, Enleanment, and an Oxidation Catalyst with an
Air Pump. The oxidation catalyst was the same type used
in the California test fleet (Section 3. 2. 1.4).
f. Manufacturer High Altitude Kits. For use on post-1967
vehicles.
3.2.1.6.2 Emission Reductions
Emission test results for each of the systems are presented in
Table 3-9. It must be noted that most of the tests were conducted using a hot
start 1972 CVS test procedure. Because of the small number of vehicles
tested and the fact that a hot rather than cold start test procedure was used, .
these results must be considered only as indicative of potential emission
reductions that may be achieved and not necessarily representative of a large
vehicle population in actual use. There are, however, several trends in the
data given in Table 3-9 that should be noted. First, and probably most im-
portant, it is apparent that for HC and CO emissions only the catalytic con-
verter reduces the emissions (gm/mi) at high altitude to levels equal to or
less than those experienced at sea level without retrofit devices. As indicated
in Ref. 3-17, the emission reductions found using manufacturer-supplied
high altitude kits were small, with only the Chrysler kit having a significant
effect on HC and CO but with a large increase of NO emissions. It would
Ji
seem that by changing carburetor jets and altering centrifugal advance
weights in the distributor to compensate for the effects of reduced ambient
3-27
-------
Table 3-9. Retrofit Emission Control at High Altitude
System
a. Air bleed
(Device A)
b. Air bleed and
vacuum delay
c. EGR (Device
A)
d. EGR (Device
B) and
enleanment
e. EGR (Device
B)
enleanment,
and catalyst
with air pump
f . Chrysler
high altitude
kit
No. of
Vehicles
1
1
1
1
5
1
1
1
15
Model
Year
1964
1972
1969
1970
1966-
1969
1966b
1969
1966
1968-
1973
Test
Procedure
Hot 72CVS
Hot 72CVS
Hot 72CVS
Hot 72CVS
Hot 72CVS
Hot 72CVS
Hot 72CVS
Hot 7 2 CVS
Cold 75CVS
Emission Reduction (%)
HC
52
15
25
15
16
75
81
61
26
CO
34
28
36
41
48
92
92
93
54
NOX
-36
48
45
28
36
30
51
72
-84
Source of
Data (Ref. )
3-14
3-14
3-20
3-20
3-20
3-17
00
A negative value indicates an increase in emissions.
This vehicle was not equipped with any enleanment device.
-------
density and manifold vacuum, it would be possible to reduce baseline engine
emisssions at high altitude to near sea -level values. This appears to be a
logical first step in a retrofit program for reducing emissions from in-use
vehicles at altitude.
Several conclusions can possibly be drawn from Table 3-9
regarding the effectiveness at high altitude of the various retrofit devices/
systems. First, air bleed is somewhat less effective in reducing CO at
altitude than it is at sea level (e.g., 34 percent CO reduction at altitude
vs 50 to 60 percent at sea level). And, because the baseline operation
°f the engine at altitude is on the rich side of stoichiometric, leaning the
mixture with an air bleed device results in a significant increase in NOX
emissions. It is apparent that the air bleed devices designed for use at sea
level do not permit the addition of sufficient air at altitude to even overcome
the effects of reduced ambient density; however, an air bleed device could be
designed to work at high altitude conditions. Second, the effects of both EGR
and VSAD on NO emissions are only slightly less at altitude than at sea level
even though the baseline NO emissions are lower at altitude. The effect of
on the HC emissions seems to be about the same at altitude as at sea
level. Third, a retrofit catalyst with an air pump apparently functions well
at altitude, which yields higher HC and CO emission reductions than at sea
level. It is likely that because of limitations on possible engine modifica-
tions to reduce emissions at altitude the catalyst system will be somewhat
m°re attractive at altitude than at sea level.
•2.1.6.3 Fuel Economy
Fuel economy data were not available on the systems tested
e*cept for the three vehicles equipped with the catalyst. Those vehicles
8howed an average fuel penalty for the combined system (catalyst and EGR)
°* less than 2 percent.
3-29
-------
3.2.1.6.4 Installed Cost
Installed cost of the various devices/systems tested are
summarized below:
a. Air Bleed. The installed cost of this device has been
estimated to be $20.
b. Air Bleed and Vacuum Delay. The installed cost of
this combination is between $25 and $35, depending
on the method of affecting the VSAD.
c. EGR (Device A). The cost of this device is $35.
d. EGR (Device B) and Enleanment. The cost of this
combination is between $40 to $45, depending on the
cost of the high flow rate PCV valve.
e. EGR (Device B), Enleanment, Catalyst, and Air Pump.
The^ installed cost of this system would be about $195
on a V-8 requiring two catalyst units. The cost of
catalysts and air pump alone are about $155.
f. Manufacturer's High Altitude Kits. The cost of these
kits installed is given as $8 to $13 in Ref. 3-17.
3.2.1.7 Summary of Emission Reductions and Cost Effectiveness
of ...Retrofit Exhaust Emission Control Systems
The emission reduction and cost effectiveness ($/lb of emissioia
reduction) characteristics of each of the retrofit devices/systems considered
are summarized in Tables 3-10, 3-11, and 3-12 for HC, CO, and NO ,
respectively. Each system is shown for the particular model years for whic*1
it is applicable. Incremental fuel costs over 50,000 miles for the model
years of interest have been calculated using the fuel economy values given
in Ref. 3-21 as the baseline (before retrofit) for the model years of intereS*
and the fuel economy change factors (percent of increase or decrease)
presented earlier in this section. The baseline fuel economy values were
adjusted to reflect 1975 FTP results using the procedure of Ref. 3-21. The
unit fuel cost was taken to be $0. 50 per gallon, and any change from this
value would require a re-evaluation of the total cost associated with a
device. Baseline emissions (without retrofit devices) were taken from
Reference 3-16.
3-30
-------
Table 3-iO.
Cost Effectiveness Summary, Light Duty Vehicles HC Emission Reductionsa
u»
I
OJ
System
1. Engine modifications
Pre-1968
2. Air bleed
Pre-1968
1968-197!
3, NO, device-VSAD type
Pre-1968
NO device -£GR type
P>e-1968
1968-1971
4. Oxidation catalyst
1968-1971
with air pump
w/o air pump
I97Z-1974
with air pump
w/o air pomp
5. Air bleed t vac delay
Pre-1968
1968-1971
6. Air bleed + EGR
Pre-1968
1968-1971
7. Catalyst + EGR
19.M-197I
w/o air pump
Installed
Cost (SI
20.00
20.00
20.00
35.00
35.00
35.00
155.00
70.00
15$. 00
70.00
Z5.00
25.00
35.00
3S.OO
105.00
50. 000 -Mile
Maint. Cost IS)
ZS.OO
25.00
25.00
25.00
ZS.OO
25.00
25.00
75.00
65.00
75.00
65.00
25.00
25.00
55.00
55.00
65.00
Fuel
Penalty (% lb
4
-4
-4
--
8
5
0
0
0
0
0
0
1
1
3
3
Fuel
Cost (s)b
74.00
-74.00
-79.00
__
157.00
98.00
0
0
0
0
0
0
19.00
20.00
59.00
59.00
HC
Baseline
Emissions
(gm/miy
8.9
8.9
4. 8
4.8
4.8
4.8
4.8
2.8
2.8
8.9
4.8
8.9
4.8
4.8
4.8
HC
',
Reduction
25
20
15
26
12
70
50
70
50
25
20
25
20
70
50
All emissions relative to 1975 CVS-C FTP.
HC
Reduction
(gm/mi)
2.2
1.8
0.7
1.2
0.6
3.4
2.4
J.O
1.4
2.2
1.0
2.2
1.0
3.4
2.4
HC
Emission Reduction
50, 000- Mile Cost (5/lb)
Excl. Fuel Incl. Fuel
0. 18
0.23
0. 57
0.44
0.95
0.62
0.5!
1.07
0.88
0.20
0.47
0.33
0.76
0.72
0.64
0.40
--
1.58
2.49
0.62
0. 51
1.07
0. 83
0.20
0.47
0.41
0.^4
0.88
0.87
Remarks
vehicle's.
11) Emission reductions at
zero mile 3. Deterioration of
age not included. (2) Requires
use of unleaded iWi, O) Costa
are forV_ft<&cyi. approxi-
mately S?0 leaiL
<1) Emission reduction! at
emission reduction with mile-
age not included. (2) Reauires
use of unleaded fuel. <3) Costs
are for V-8 (6 cyl. approxi -
mately $30 leas).
A negative „!„ Indicate, a saving.- fad penalty value, shown are approximate average values ba.ed on limited data with a sometimes wide car-tu-car variation.
-------
Table 3-11. Cost Effectiveness Summary, Light Duty Vehicles CO Emission Reductionsa
System
1. Engine modification*
Pre-1968
2. Air bleed
Pre-1968
1968-1971
3 , NO, device - VSAD type
Pre-1968
1968-1971
NO, device-EGR type
Pre-1968
1968-1971
4. Oxidation catalyst
1968-1971
with air pump
w/o air pump
1972-1974
with air pump
w/o air pump
5. Air bleed + vac. delay
Pre-1968
1968-J«»7I
6. Air bleed + EGR
Pre-1968
196B-197J
7. Catalyst + EGR
1968-1971
with air pump
w/o air pump
Installed
Co.t (S)
20.00
20.00
30.00
35.00
35.00
35.00
35.00
155. 00
70. 00
155.00
70.00
25.00
25.00
35.00
35.00
190.00
105. 00
50. 000 -Mile
Maint. Cost (Si
25.00
25.00
25.00
25.00
25.00
25.00
25.00
75. 00
65. 00
75.00
65.00
25.00
25.00
55.00
S5.0O
75. 00
65. 00
Fuel
Penalty (It )*
4
-4
-4
8
_„
5
0
0
0
0
0
0
1
1
3
3
Fuel
Cost,$)b
74.00
-74. 00
-79.00
157.00
98.00
0
0
0
0
0
0
19.00
20.00
59.00
59.00
CO
Baseline
Emission?
fgm/mit
94
94
61
61
61
61
61
30
30
94
61
94
61
61
61
CO
%
Reduction
9
60
50
4
6
65
32
65
32
55
50
40
40
65
32
CO
Reduction
(gm/mU
g 5
56.4
30. 5
2.4
__
3.7
39.7
19.5
19.5
9.6
51.7
30.5
57. 6
24.4
39.7
19.5
CO
Emission Reduction
•,0, 000-Mile Cost (S/lb)
Excl. Fuel
0.05
0.007
0.01
0.22
0. 15
0.05
0.06
0.11
0. 13
0.009
0.01
0.019
0.03
0.06
0.08
Incl. Fuel
0. 13
--
0. 18
0.39
0.05
0.06
0. 11
0. 13
0.009
0.01
O.OZ4
0.037
0.07
0. 11
Remarks
Insufficient data on pre- 1968
vehicles.
(1) Emission reductions at zero
miles. Deterioration of emis-
sion reduction with mileage not
included, (2) Requires use of
unleaded fuel. (3) Costs are
forV,8(6cyl. approximately
$30.00 less).
miles. Deterioration of emis-
sion reduction with mileage not
included. {2} Requires use of
unleaded fuel. (3) Costs are for
V -8 ( 6 c'yl. approximately
S30 less*.
All emissions relative to 1975 CVS-G FTP.
A negative value indicates a savings; fuel penalty values shown are approximate average values based on limited data with a sometimes wide car-to-car variation.
-------
Table 3-12. Cost Effectiveness Summary, Light Duty Vehicles NO Emission Reductions3
System
I. Engine modifications
Pre-11) 68
2. Air bleed
Pre-1968
19*8-1971
3. NO,, device -VSAD type
Pre - t^Wl
1968-mi
NO, device -EGR type
Pre-1968
I9fcli-I971
4. Oxidation catalyst
l<»fcB-l
3.63
1.60
5.04
2. 11
" 1.^4
0.45
0.81
0.47
1. 16
0.»2.
Reniarks
vehicle*.
miles. Deterioration of emis -
sion reduction with mileaj-e not
included. 75 CVS-C FTP,
A neg&tive value indicates a savings; fuel penalty values shown are approximate average values based on limited data with a sometimes wide car-to-car variation.
-------
The cost effectiveness ($/lb of emission reduction) of each of
the devices /systems has been evaluated in two ways. First, only the initial
installed cost and the incremental 50,000 mile maintenance cost were included
in the cost calculation. The second cost effectiveness value includes the fuel
penalty cost (or savings), as well as the initial and maintenance costs. This
has been done because of the sensitivity of the cost -effectiveness to uncer-
tainties in the fuel economy changes associated with the retrofit device/ system,
as well as the unit fuel price. This sensitivity is particularly strong for any
device, such as the air bleed, for which the fuel savings over 50,000 miles
may exceed the installation and maintenance costs. The cost effectiveness,
including fuel costs, is certainly the most appropriate value to consider in
the final analysis, but its uncertainty is also the largest at the present time.
Hence, it must be used with care and only after knowing what fuel penalty
(or savings) and unit cost have been included in its determination. Further,
these cost effectiveness values were determined by dividing the total per
vehicle cost for a given emission control strategy by the corresponding values
of per vehicle emission reduction for each emission specie (HC, CO, and
NO ). Thus they do not represent any attempt to prorate or apportion control
costs among the vehicle emissions considered. Some other studies have
reported cost effectiveness values that apportion control costs on an arbitrary
basis (e.g., by assigning 1/3 of the per vehicle control costs to HC control,
CO control, and NO control, where a given control system reduces HC, CO,
X
and NO ). For comparison with other study results, the values of Tables 3-1°'
Jt
3-11, and 3-12 can be easily adjusted by apportioning control costs on the
same basis as the study to which it is being compared.
3.2.2 C rankca Sje Emissions^
**1
Crankcase emissions have been estimated (Ref. 3-22) to
for approximately 3. 4 gm/mi of hydrocarbon emissions from an uncontrolled
motor vehicle. Installation of crankcase emission control devices has been
mandatory on new cars sold in California since 1961 and nationally since 19°
In addition, California requires a mandatory retrofit of all pre-1961 vehicle9
with such a device upon change of ownership.
3-34
-------
3. 2. 2. 1 Description
Systems to control crankcase emissions are classified as open
or closed. In open systems, ventilation air is taken directly from the engine
compartment through the oil filler cap and circulated to the intake manifold.
However, an open system will allow hydrocarbon evaporative emissions to
escape after engine shutdown. Closed systems receive ventilation air through
the carburetor air cleaner and are commonly referred to as positive crank-
case ventilation (PCV) systems.
3.2.2.2 Installed Cost
The installed cost of the PCV system is $35 to $40.
3.2.2.3 Applicability to Vehicle Population
The PCV system, as a retrofit device, would be applicable
only to those remaining cars not already equipped with such a device (pre-
1961 in California, pre-1963 nationally). This is approximately 8 percent of
the vehicle population as of 1 July 1973, and it is estimated to be approxi-
mately 5 percent by 1975. As a result, its overall effectiveness as a viable
retrofit device is small in terms of total emission reductions.
3.2.3 Evaporative Emissions
Carburetor and fuel tank evaporative emission control systems
could reduce total vehicle hydrocarbon emissions by approximately 3. 0 gm/mi
(Ref. 3-22). The use of evaporative emission control systems was initiated
in 1970 on new motor vehicles sold in California and in 1971 on new vehicles
8old nationally.
3.2.3.1 Description
Two fuel evaporative systems have been designed for new
vehicle production use. These are based on two different approaches to fuel
vapor recovery. One system stores the fuel vapor in the crankcase and the
°ther stores it in a carbon cannister during soak periods (engine off). The
are then purged from the crankcase or cannister when the engine is
3-35
-------
3.2.3.2 Discussion
Evaporative emission control systems are not currently
available as a retrofit system and are not a retrofit strategy actively pursued.
However, a recent study (Ref. 3-23) investigated the feasibility of an evapora-
tive control retrofit program for the South Coast Air Basin in Southern
California. The vehicle retrofit requirements as envisaged in the California
study would consist of both fuel tank and carburetor modifications. The
possibility of a partial retrofit of controls covering either the carburetor or
the fuel tank was also considered.
Fuel tank modifications would require the addition of an expan-
sion tank to the fuel tank, a means of directing evaporative emissions into
some convenient storage device, and a vacuum pressure relief gas cap. These
modifications to the fuel tank were estimated to cost approximately $60 for
domestic cars and $75 for the Volkswagen (the only import evaluated). The
carburetor must be rebuilt or replaced with a new carburetor suitable for use
in an evaporative emissions control system. Carburetor replacement/rebuilt
costs covered a wide range for domestic vehicles, depending on whether a
one-, two-, or four-barrel carburetor was involved, A typical layout for a
domestic car is shown in Figure 3-2, No carburetor retrofit costs were
required for the V-W since these cars (1961 to 1969) were equipped with
Solex downdraft carburetors. These carburetors have only an internal vent -
located at the top of the carburetor throat and vent to an oil bath type air
cleaner. This was assumed adequate to control carburetor evaporative losses-
Conclusive data is not available on the desirability of a partial
retrofit, i.e. , fuel tank or carburetor. Some insight into the relative effec-
tiveness of a partial retrofit can be gained, however, by considering that
typical carburetor hydrocarbon evaporative losses (using SHED techniques)
are 10 to 30 gm/test, while fuel tank evaporative losses are typically 50
test (Ref. 3-22).
SAE Procedure J171, Sealed Housing for Evaporative Determination
technique.
3-36
-------
•CARBON CANNI5TER
-PCV VALVE
EXPANSION TANK
Figure 3-2. Location of Evaporative Control System Components"
(Ref. 3-23)
3-37
-------
3. 2. 3. 3 Installed Cost
Based on estimates of the vehicle population and the distribution
of engine (and carburetor) types in the vehicle population in the South Coast
Air Basin, weighted (by vehicle age, make, and model) installation costs were
derived (Ref. 3-23) for this retrofit system. If the carburetor replacement
was required, the weighted average installed cost (including fuel tank modifi-
cations) was found to be $117. If rebuilding the carburetor was feasible, the
cost was estimated to be $95.
3.2.3.4 Maintenance
Annual maintenance costs to replace the charcoal cannister
were estimated to be approximately $5.
3.2.3.5 Applicability to Vehicle Population
This retrofit approach is potentially applicable to all pre-1971
vehicles nationally (pre-1970, California). However, the myriad of vehicle
configurations make this an extremely difficult retrofit approach to implement.
3-38
-------
3.3 IMPLEMENTATION OF RETROFIT STRATEGIES
FOR LIGHT DUTY VEHICLES
3. 3. 1 Introduction
The implementation of a retrofit strategy must take a number
of factors into consideration. In general, these would include the evaluation,
selection, and certification of devices/systems; analysis of the costs associ-
ated with each device, together with any attendant financing strategies; and
the development of installation strategies and schedules.
Many of the factors to be considered are similar to those
attendant to the implementation of an inspection/maintenance program.
These basic considerations were discussed at length in Section 2. 7 and are
not repeated here in the interest of brevity. Those implementation aspects
more singularly related to retrofit programs are summarized below.
3. 3. 2 Selection and Certification
The selection of emission control devices/systems should,
of course, be tailored to meet the ambient air quality requirements of a
particular State or Air Quality Control Region (AQCR). If, for example,
the primary problem is one of reduction of CO, a relatively simple and in-
expensive approach such as the air bleed device may be adequate. If, on
the other hand, a significant reduction of all three pollutants must be achieved,
then it may be necessary to consider one of the combination systems such as
the oxidation catalyst and EGR. Concurrent with this, the applicability of
the device/system to the vehicle population within the region of interest must
also be considered.
The emission reduction potential of a given device/system
should be based on a statistically significant sample size. To this end,
the EPA has published a set of proposed voluntary protocols for the eval-
uation of exhaust emission retrofit devices for motor vehicles (Ref. 3-24).
e purpose of that approach is to provide a centralized evaluation program
compile technical data on various exhaust emission control devices. The
3-39
-------
program will primarily address the effects of emission control potential,
applicability, durability and driveability, and fuel consumption of specific
retrofit devices presented for evaluation. Techniques are presented in the
protocol whereby the number of vehicles to be tested will be such that the
determination of the mean percent reduction (or increase) of HC, CO, and
NOX can be evaluated within a band of ±5 percent at the 90 percent confi-
dence level.
In addition to the emission reduction capability of a device/
system, other factors that must be considered in the selection and certifi-
cation are the durability or emission reduction effectiveness at extended
mileage, the impact on the driveability of the vehicle, possible safety con-
siderations, and the effect of the device/system on the fuel economy. It is
also necessary to be certain that the device is commercially available in suf-
ficient quantities to meet the requirements of a given State or AQCR. Con-
sideration must also be given to whether the device will be installed in pri-
vate garages or in Stated-licensed facilities. In the latter case, licensing
procedures would have to be designed and implemented.
3. 3. 3 Cost and Financing
The method of financing the initial cost must also be estab-
lished for the retrofit device/system selected. In the case of those devices
costing $20 to $35, this probably could be best treated as a one-time cash
expenditure by the vehicle owner. In the case of the more expensive cata-
lytic converter systems, however, this approach could impose a financial
burden on many car owners and other alternatives must be evaluated and
considered.
3. 3. 4 Implementation Scheduling
Several alternatives have been suggested as possible options
for implementing a retrofit program. It must be emphasized that the most
effective implementation strategies will depend upon several factors, includ-
ing the number of vehicles to be retrofitted, the availability of the devices i*1
3-40
-------
sufficient quantities, the availability of competent servicemen to make the
proper installation, the administrative mechanisms within a given State
or AQCR to ensure that the installations are made properly, and a consis-
tently strong will to accomplish retrofit at all levels of government.
The most viable implementation plans from an administrative
point of view are those involving vehicle registrations, and this could be ac-
complished either at the time of annual registration or on change of owner-
ship. A third strategy (to be used for NO retrofit in California) is to stag-
Ji
ger the retrofit program over a 10-month period with the implementation
date (month) being determined by the last digit of the vehicle license plate.
The California NO retrofit program for 1966-1970 vehicles has been rein-
Jt
stated (following a previous one-year delay).
3-41
-------
3 4 RETROFIT EMISSION CONTROL FOR TRUCKS
In several studies the same engine modifications and devices
that were discussed in Sections 3. 1 through 3. 3 for retrofit to light duty vehi-
cles were also considered for use on trucks (GVW > 6000 Ib). However, the
circumstances surrounding their use on trucks are sufficiently different that
it is advisable to consider retrofit strategies for trucks separately. These
considerations are summarized in this section, with the discussion divided
into the following parts: (1) the general characteristics of truck populations
that are important in the evaluation of retrofit control strategies, (2) the ef-
fectiveness of various retrofit emission control approaches and devices for
heavy duty gasoline and diesel engines, (3) the cost effectiveness of retrofit
strategies, and (4) implementation considerations.
There have been several recent studies that addressed the
characteristics of a separate vehicle class (GVW = 6000 to 10,000 or
14,000 Ib) within the overall truck classification of GVW > 6000 Ib. How-
ever, the data with regard to retrofit are not sufficiently explicit to justify
a separate consideration of this class at this time.
3.4.1 General Considerations
Various characteristics of the truck populations were dis-
cussed in Section 2. 8 in connection with the inspection/maintenance of such
vehicles. It was found that the heavy duty class of trucks is quite nonhomog"
eneous with respect to weight, size, use, and mode of operation and mainte-
nance, and that the emissions (gm/mi) from heavy duty vehicles increase
significantly with increasing vehicle weight and, in general, are much high«f
than for light duty vehicles. This difference in emissions has widened in ?e'
cent years and should continue to do so in the foreseeable future as long as
the emission standards for light duty vehicles are tightened to a greater ex-
tent than those for heavy duty engines. Hence, the potential for emission
reduction from the retrofit of heavy duty vehicles may be larger than for
light duty vehicles. This, coupled with the fact that the averag.e lifetimes
3-42,
-------
of trucks are significantly longer than those of passenger cars (Ref. 3-25),
indicates that retrofit strategies for heavy duty vehicles have the potential
to be effective in reducing mobile source emissions, especially in those
•»
Urban areas such as Los Angeles, New York City, Chicago, etc. , which
have large truck populations. Conversely1; if excessive hardware and/or
emission control deterioration were encountered, this would of course re-
duce the effectiveness of a truck retrofit strategy.
In assessing the effectiveness of a retrofit strategy in a given
AQCR, information is needed concerning the baseline emissions of vehicles
*n the various heavy duty weight classes, the number of vehicles in each
'class and model year in the region, and the miles traveled (in a given ref-
e*ence period) by the vehicles in each class. The latter two types of infor-
^ation vary significantly from region to region.
The baseline truck emissions, which'depend on weight, model
year, and fuel type, are common to all AQCRs, except for California and
fchose operated at high altitude. There are much less emissions data avail-
for trucks than for passenger cars (Refs. 3-26 through 3-28) and, in
, much of the available truck data pertains to recent.model vehicles
^970-73) and vehicles in the GVW < 14,000 Ib class. Also, many of the
heavier trucks (GVW > 26,000 Ib) are tractor-trailer combinations that often
86 diesel rather than gasoline engines.
For the heavy duty vehicle class as a whole (GVW > 6000 Ib),
8timates of emission characteristics and deterioration rates by applicable
^odel year have been provided by EPA in Ref. 3-25. However, with regard .
0 emission characteristics for specific subgroups within the overall heavy
utV vehicle class, a significant volume of data regarding emissions varia-
l°ns by model year is available only for the GVW category between 6000
^d 10,000 Ib. Average baseline HC, CO, and NOx emissions for this class
of vehicles for model years between 1965 and 1973 are given in Table 3-13.
Tk
nere is considerable scatter in this data (Refs. 3-26 and 3-29), and the
given in Table 3-13 represent an average of data from the baseline
3-43
-------
Table 3-13. Emission Values for Medium Duty Vehicles by
"Model Year (Ref. 3-Z9)
Model Year
Emissions (gm/mi)
HC
CO
N0x
Pickups, Vans, and Panel Trucks
(6000 to 10,000 Ib GVW)
1973
1972
1971
1970
1969
1968
1967
1966
1965
4.25
4.46
5.87
5.93
7.31
10.58
11.07
12.40
10.62
49.22
51.56
65. 52
71.78
93.59
125.35
126. 15
110.95
75.51
Conventional Motor Homes
(6000 to 14,000 Ib GVW)
1970 to 1973
Pre-1970
8.91
116.27
Insufficient data
4.95
7.49
8. 17
7.63
6.37
5.61
5.20
5.75
6,49
12.57
Chassis and Other Trucks
(6000 to 14,000 Ib GVW)
1970 to 1973
Pre-1970
6.78
12.20
72.05
113.82
8.52
9.43
3-44
-------
emission characterization program recently conducted by EPA (Refs. 3-29
and 3-30). For trucks in other weight categories, only scattered data points
are available (Refs. 3-27 and 3-28). In general, it can be stajted that the
emissions of all three pollutants for a given model year increase with in-
creasing vehicle weight (Ref. 3-29) and that HC and CO tend to decrease for
model years after 1970 (relative to pre-1970 levels) for all the truck
categories.
3.4.2 Retrofit of Gasoline-Fueled Trucks
3. 4. 2. 1 Introduction
The gasoline engines used in many trucks, especially those
with GVW less than 14,000 Ib are basically the same as those used in
standard-size passenger cars. Hence, the emission control systems on
these engines have reflected both the effect of tightened heavy duty engine
and light duty vehicle emission standards. The progression of emission
control systems on light duty vehicles has been summarized previously in
Table 3-1. As indicated in Table 3-14, these same emission control sys-
tems* are now being used on some 1973 heavy duty vehicles. Hence, in
retrofitting heavy duty vehicles, it is reasonable to consider the use of the
same retrofit devices and control technologies for light duty vehicles that
have been discussed in detail in Sections 3. 1 through 3. 3. Since the power-
to-weight ratio of trucks, especially those with GVW > 10,000 Ib, is much
*ess than that of passenger cars, the emission reduction effectiveness of
these retrofit devices when used on trucks could be quite different from that
°* the same device on a car. In addition, there are questions concerning
^hat emission test cycle is appropriate for the various categories of heavy
<*uty vehicles and how the different retrofit approaches are affected by the
A PCV system is required nationally, while an evaporative control system
is required by California if fuel tank capacity is less than 50 gallons.
3-45
-------
Table 3-14. Group Representative Vehicle-Engine Combinations
(Emission Control Devices - 1973 Models) (Ref. 3-30)
Vehicle Type
Pickup/camper
Van/passen-
ger van
Multistop
Chassis
Motor home
Make
Chev./GMC
I-H
Ford
Chev./GMC
Chev./GMC
Ford
Ford
Dodge
Model
C20/C25
1210
E300
P30/P35
C20/C25
F350
F500
M300/R400
Engine
V8-350
V8-345
V8-302
16-250
V8-454
V8-360
V8-330
V8-318
Emission Controls
Crankcase
PCV
PCV
PCV
PCV
PCV
PCV
PCV
PCV
Evaporative
GMECS
CAN
cc
--
GMECS
CC
CC
CAN
Exhaust
ccsa
EM,a EGR,
TLD
IMCOa
CCS
CCS.AI
IMCO, EGR
IMCO
EM
Notes
1
1,4,6
1
2
1,3
1,4
1
1,5
EM, CCS, and IMCO are basically engine modifications (carburetor, choke, compression ratio, and
spark retard) to reduce emissions. -.
Notes: 1 Evaporative controls only on California vehicles with fuel tanks £50 gallons.
2 This engine not sold in California.
3 Air injection (AI) only on California vehicles.
4 Exhaust gas recirculation (EGR) only on California vehicles.
5 Electronic Ignition on California vehicles, otherwise optional.
6 Throttle limiting device (TLD) only on California vehicles.
-------
test cycle. However, once an air-quality-related test procedure is developed
for heavy duty vehicle retrofit evaluation, that procedure should be used to
evaluate effectiveness, *
The performance of retrofit devices will be considered rela-
tive to the following emission test cycles: (1) 1975 CVS FTP, (2) an urban
short test cycle, and (3) a multimode (steady-state) engine test cycle. One
of these cycles should be appropriate for any heavy duty vehicle application
or retrofit program. The 1975 CVS FTP, which utilizes the EPA Urban
Dynamometer driving schedule, is appropriate for the smaller of the heavy
duty vehicles (GVW < 14,000 Ib) with inertia weights of 10,000 Ib or less.
These vehicles usually have a power-to-weight ratio that permits them to
be driven much like light duty vehicles. The short urban cycles, such as
the New York City Quick Cycle and the New Jersey Accelerate, Cruise,
Idle, Decelerate (ACID) cycle (see Fig. 2-1), have a maximum cruise veloc-
ity of 30 mph and a considerable period of idle. These cycles may be appro-
priate for heavy delivery or sanitation trucks (GVW > 20,000 Ib) operating
in a congested urban area such as Manhattan. Finally, since heavy duty
engines are certified relative to a multimode engine test cycle, it seems
reasonable to evaluate retrofit devices/systems for such engines on the
same engine cycle. Several engine cycles are currently in use, namely,
the 9, 13, and 23-mode cycles involving emissions testing at one or more
rpm and a range of engine loads. Both the composite and modal emissions
data from the testing of retrofit devices on heavy duty engines may be use-
ful to estimate their performance on the various classes of trucks.
There are three primary sources of information relative to
the effectiveness of retrofit devices on heavy duty vehicles: (1) the continu-
ing study by the New York City Department of Air Resources (Ref. 3-31),
(2) EPA tests of retrofitted medium duty trucks (Ref. 3-32), and (3) the engine
dynamometer tests of retrofitted heavy duty engines by the Southwest Research
Jnstitute (SWRI). The study by the New York City Department of Air Resources
ls directly applicable to the present discussion, as it involves retrofitting
a
-------
emission control devices /systems identical to those tested previously on
light duty vehicles. Vehicle emissions measurements are made before and
after the devices are installed, and a durability test program is also planned
for the most promising devices. The lighter trucks (GVW < 10,000 Ib) are
tested using the 1972 CVS-H test procedure, while the heavier trucks are
tested using the New York City Quick Cycle, which is thought to be more
appropriate than the 1972 CVS-H for heavy truck operation in congested
areas. One important limitation of the New York City (NYC) retrofit pro-
gram is that all the data were taken on a light duty dynamometer, which
means that the maximum inertia weight that could be simulated was 5500 Ib.
Because of this, the NYC data do not show the true effects of vehicle weight
on retrofit device performance. In addition, since the NYC program to date
has involved many retrofit devices, each of which was tested on only a few
vehicles at most in each weight class, it is difficult to separate out the ef-
fects of test cycle, vehicle size, and device characteristics. The NYC re-
sults are, however, helpful in developing a general format for examining
retrofit device performance, and in some cases are the only source of per-
tinent emission reduction information. The EPA and SWRI data (Refs, 3-32
and 3-33) can be used to interpret and augment the NYC retrofit data.
In the EPA program, emission measurements were made on
two 1972 trucks (5500 to 7000 Ib inertia weight), using the 1975 CVS-CH FTP'
as well as at selected steady-state modes (idle to 60 mph cruise). The SWR*
studies involved two 1972 V-8 engines (General Motors 350 CID and Ford 361
CID) often used in heavy duty vehicles. These engines, which were retro-
fitted (or modified) using various approaches to reduce their emissions, we*"6
tested using the 23-mode engine test cycle (Table 3-15) that includes a wide
range of operating conditions. This engine test cycle is particularly applica*
ble to heavy trucks, as it emphasizes high load conditions near maximum
engine torque. Tabulated modal data for several engine modifications and
retrofits are given in Ref. 3-34, as well as the composite cycle emissions
levels, for each of the engine configurations. The steady-state EPA and
3-48'
-------
Table 3-15. Experimental 23-Mode Emissions Test Schedule
* (Heavy Duty Gasoline Engines) (Ref. 3-33)
Mode
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Engine
Speed (rpm)
Idle
1200
1200
1200
1200
1200
1200
1200
1200
1200
Idle
1200
2300
2300
2300
2300
2300
2300
2300
2300
2300
Idle
2300
Power
Out (%)a
0
2
8
18
25
50
75
82
92
100
0
0 (CT)b
100
92
82
75
50
25
18
8
2
0
0 (CT)b
Mode
Time
3
3
3
3
3
3
3
3
3
3
3
12
3
3
3
3
3'
3
3
3
3
3
3
Cumulative
Time
3
6
9
12
15
18
21
24
27
30
33
45
48
51
54
57
60
63
66
69
72
75
78
Weighting
Factor
0.07
0.06
0.06
0.05
0.03
0.06
0.00
0.04
0.00
0.00
0.07
0. 12
0.025
0.055
0. 035
0.06
0.06
0.00
0.065
0.00
0.00
0.08
0.06
'Observed at the flywheel, percent of maximum at a given engine rpm.
b_
out is zero. Engine requires motoring in this mode.
3-49
-------
SWRI engine cycle data are summarized in Tables 3-16 and 3-17. In the
case of the SWRI tests (Table 3-17), it was found that both spark retard and
a 10-percent cold EGR flow rate resulted in sizeable reductions in maximum
hp output at test conditions of 1200 and 2300 rpm. For example, with the
Ford V-8 engine, a spark retard of 6 degrees reduced the maximum hp
about 13 percent, and a cold EGR of 10 percent reduced the maximum about
18 percent. These results and the vehicle cycle emissions measurements
Table 3-16. Summary of Emission Reductions at Various Steady-
State Operating Conditions Using Retrofitted Catalyst
and EGR Systems (Ref. 3-32)
J^
Operating Condition
Idle
GM 350 CID, 6500 Ib
Chrysler 318 CID, 7000 Ib
15 mph
GM 350 CID, 6500 Ib
Chrysler 318 CID, 7000 Ib
30 mph
GM 350 CID, 6500 Ib
Chrysler 318 CID, 7000 Ib
60 mph
GM 350 CID, 6500 Ib
Chrysler 318 CID, 7000 Ib
% Reduction at Zero
System Mileage
HC
85
98
87
93
88
90
93
98
CO
98
99
-
98
91
90
91
95
N0x
-
-
48
83
65
67
48
57
Vehicle operating in mode and inertia weight indicated - 6500 Ib, 50 mph,
road load, 32 hp; 7000 Ib, 50 mph, 37 hp
Emission reduction using a catalyst and EGR; any effect of catalyst
deterioration is not included.
3-50
-------
Table 3-17. Summary of SWRI Heavy Duty Engine Retrofit Data (Ref. 3-33)
Engine
Tested
Ford V-8
361 CID
*J \J £. ^v* 1 i f
GM V-8
350 CID
Retrofit Modification
a. None (baseline engine)
b. Engine modifications
1. Six-degree spark retard
2. Leaner air/fuel ratio (from
0.056-in. dia. main jets to
0.51 -in. dia.)
c. Baseline engine plus;
1. Ten percent "cold" EGR
2. Oxidation catalyst plus air injection
3. Oxidation catalyst plus air injection
plus 5 to 10 percent "hot"b EGR
a. None (baseline engine)
b. Engine modifications
1. Eight-degree spark retard
2. Leaner air/fuel ratio (from 0.073-
in. dia. main jets to 0.068-in. dia.)
c. Baseline engine plus:
1. Ten percent "cold" EGR
2. Oxidation catalyst plus air injection
3. Oxidation catalyst plus air injection
plus 5 to 10 percent "hot"b EGR
Fuel
Consumption
(Ib/bhp-hr)
0.72
0.86
0.77
0.88
0.78
0.83
0.63
0.79
0.64
0.75
0.61
0.67
Emissions
(gm/bhp-hr)a
HC
9.2
8.5
8.65
10. 1
1.43
1.31
7.3
6.2
7.2
7.2
0.85
2. 1
CO
72
116
44
143
49
19
56
66
32
37
18
16.6.
t
NO
8.7
f
5.5
9.7
2.2
6.22
4. 1
8.6
6.0
8.8
2.6
8. 1
6.2
OJ
I
Ul
23-Mode composite values.
Light duty vehicle approach using exhaust manifold crossover to extract exhaust and a
vacuum-actuated EGR valve.
-------
made by EPA and NYC form the data base currently available for the retrofit
emission control system characteristics (emissions reduction and fuel econ-
omy changes) given in the next section. In a few cases, expecially for pre-
1971 model year vehicles, light duty vehicle retrofit emissions data are also
used to estimate system" characteristics.
3.4.2.2
Emission Reduction Potential and the Cost Effectiveness
of Exhaust Emission Control Systems
The EPA has provided initial estimates of reductions in ex-
haust emissions achievable through the installation of various types of retro-
fit devices for trucks (6000 to 10,000 Ib GVW) (Table 3-18). These estimates
were provided in the Addendum to Appendix N of 40 CFR 51 (Federal Register/
Vol. 38, No. 110 (Friday, June 8, 1973) for transportation control measure
Table 3-18. Estimated Emission Reductions for Retrofit of the
6000 to 10, 000 GVW Classa
Retrofit Option
Exhaust gas recirculation (pre-1973,
plus 1973 and 1974 models without EGR)
Oxidation catalysts (1968 and later
not originally equipped with catalysts)
Air bleed to intake manifold (pre-1974
or pre-1973 California vehicles)
Average Reduction per
Vehicle (%)b
HC
0
50
15
CO
0
50
30
NO
X
40
0
0
Appendix N of 40 CFR 51 (Federal Register, Vol. 38, No. 110
(Friday, June 8, 1973).
Reductions are to be applied to a maintained vehicle baseline
(i.e. , applied after emission reduction claimed for inspection/
maintenance)
3-52
-------
planning purposes. The data and discussions presented below are supplementary
to that of Appendix N and are a summarization of current estimates related to
the emission reduction performance and cost aspects of specific retrofit
approaches for the truck GVW spectrum from 6000 Ib hy 26,000 Ib.
The same retrofit emission control systems that were dis-
cussed in Section 3. 2 for light duty vehicles are considered for heavy duty
vehicle applications in this section. Estimated values for the emission re-
ductions and fuel economy changes associated with each of the retrofit sys-
tems are given in Table 3-19 for the three test procedures (1975 FTP, short
urban cycle, and 23-mode engine cycle) appropriate to the various categories
of trucks. The values shown in Table 3-19 represent averages from the EPA,
NYC, and SWRI data previously discussed. Considerable uncertainty exists
regarding many of the values shown, but sufficient data does not exist to
evaluate the uncertainties quantitatively. In the absence of appropriate truck
data, light duty vehicle retrofit data were used and must be treated as an
estimate only. This latter approach was necessary primarily in the case of
engine modification for pre-1971 vehicles. The model years for which each
of the retrofit approaches is applicable are indicated in Table 3-19. Post-
1970 trucks were considered to be emissions controlled, while earlier model
years are termed uncontrolled.
The effect of the emissions test procedure on the performance
of the various retrofit devices/systems is due for the most part to differences
in engine loads experienced during the test cycles. High load test conditions
are particularly important if they require operation of the high-speed power
circuit of the carburetor because that results in higher HC and CO emissions
and higher specific fuel consumption than would normally be the case. Any
retrofit approach (such as spark retard or EGR) that significantly degrades
engine power output forces early use of the carburetor power circuit, result-
ing in lower emission reductions and a significant fuel economy penalty. Thus,
the influence of engine load on retrofit control system performance can be
very important and must be kept in mind when evaluating the use of such
systems on vehicles of significantly different GVW.
3-53
-------
Table 3-19.
Estimated Emission Reduction and Fuel Penalty
Characteristics of Retrofit Emission Control
Systems for Trucks
Retrofit Approaches
Engine modifications
Lean carburetionb
1975 FTP
Urban cycle
Engine cycle
Retarded timing
1975 FTP
' A
Urban cycle
Engine cycle
EGR
1975 FTP
Urban cycle
Engine cycle
EGR + lean carburetion
1975 FTP
Urban cycle
Engine cycle
Catalyst w/air putnp^
1975 FTP
Urban cycle
Engine cycle
Catalyst w/air + EGR8
1975 FTP
Urban cycle
Engine cycle
Applicable
to
Pre-1971
Post- 1970
Pre-1971
Post-1970
Post-1970
Percent Reduction
Emissions
HC
15
20
5
20
NAf
10
0
NA
-15
10
NA
-10
80
85
85
80
NA
75
CO
40
55
40
0
NA
-35
-5
NA
-10
30
NA
30
80
85
70
80
NA
70
N0x
-5
-5
-5
35
NA
35
40
NA
35
30
NA
35
-5
0
-5
40
NA
40
Fuel
Economy
-5
-3
5
8
NA
20
6
NA
15
0
NA
10
0
4
3
6
NA
10
Source for
Estimate
NYC (Ref. 3-31)
& LDV datac
NYC (Ref. 3-31)
SWRI (Ref. 3-33)
LDV data
--
SWRI (Ref. 3-33)
LDV data
--
SWRI (Ref. 3-33)
NYC (Ref. 3-31)
--
SWRI (Ref. 3-34)
& LDV data
NYC (Ref. 3-31)
NYC (Ref. 3-31)
SWRI (Ref. 3-33)
Ref. 3-32
.
SWRI (Ref. 3-33)
aMinus sign means an increase; this applies to fuel consumption also.
Increase in mean air/fuel ratio of about one due to air bleed or lean carburetion.
£
In all cases, LDV data refers to light duty vehicle retrofit emissions data previously
developed in Section 3. 2.
Retarded timing change of 4 to 6 degrees.
eUrban cycle is the NYC Quick Cycle; engine cycle is the 23-mode engine test cycle.
No data available.
8A11 values correspond to catalysts at low mileage; deterioration effects should be
accounted for separately.
3-54
-------
The cost effectiveness of selected* retrofit emission control
systems was studied for the three truck GVW categories (6000-10,000 Ib,
10,000-20,000 Ib, and 20,000-26,000 Ib). Two retrofit strategies for both
precontrolled and controlled vehicles were considered for each of the GVW
categories. One of the strategies is intended to reduce only HC and CO
emissions, while the second controls NO emissions as well as HC and CO.
X,
The baseline model year for the precontrolled vehicles was taken to be 1968,
and for the controlled vehicles, 1972. It was assumed that the 1975 FTP was
appropriate for evaluating emissions from trucks of 6000 to 10,000 Ib GVW.
and that the 23-mode engine cycle was most suitable for both the 10.000 to
20,000 Ib and 20.000 to 26,000 Ib categories. The baseline emissions, emis-
sion reduction factors, and fuel economy changes for each retrofit strategy,
test procedure, and truck category were obtained from Tables 3-13 and 3-19.
In assessing the cost effectiveness of each case, the same general approach
as followed in Section 3.2. 1.7 for light duty vehicles was used. The incre-
mental maintenance and fuel costs due to retrofit were based on 50,000 miles
of truck operation to facilitate direct comparisons with light duty vehicle re-
sults that were also based on 50,000 miles. All the costs, including the
initial cost of installation, were determined by starting with light duty vehi-
cle cost values and adding appropriate cost increments to account for the
larger sizes and/or increased durability requirements of heavy duty vehicles.
The results of the cost-effectiveness study are given in Table 3-20. Note
that cost-effectiveness values ($/lb) in the table are given excluding and in-
cjuding the effect of fuel economy changes due to retrofit devices. Since the
fuel consumption of heavy duty vehicles is much greater than for light duty
vehicles, the effects of a fuel economy penalty due to retrofit on the cost
eftectiveness is even greater for trucks than for passenger cars. Hence,
v '
The more likely combinations of retrofit systems for both precontrolled and
Controlled trucks were selected for the cost-effectiveness study.
3-55
-------
Table 3-20.
Estimated Cost Effectiveness of Various Retrofit Strategies for
Gasoline-Fueled Trucks
Retrofit Strategics
Precontrolled trucks
Lean earburetion
6 - 10*
10-20
20 - 26
Lean carburetion + EGR
6-10
10 - 20
20 - 26
Controlled trucks
Oxidation catalyst
with air"
6-10
10-20
20-26
Oxidation catalyst
with airh + EGR
6-10
10 - 2J
20 - 26
a
Costs
Initial
Cost
(S)
25
40
40
50
65
65
150
250
250
185
285
285
Maintenance
Cost
<*)
25
25
25
50
50
50
75
150
150
100
175
175
Incremental
Fuel Costb
(ft
-J25
+208
+278
0
+417
+557
0
+ 125
+ 167
+ 150
+417
+557
Emission Reductions and Cost Effectiveness
HC
Baseline
(gm/mi)
10.8
16.3
22.4
10.8
16.3
22.4
5.7
8.6
11.8
5.7
8.6
11.8
Reduc-
tion (%)
15
5
5
10
-10
-10
80
85
85
80
75
75
9/lbd
0.28,-E
0.72,3.0
0. 53.2.8
0.84,0.84
_
-
0.45,0.45
0.50,0.65
0.36,0.51
0.57.0.87
0.65. 1.25
0.57, 1.04
CO
Baseline
(gm/mi)
125
190
262
125
190
Z6Z
66
100
138
66
100
138
Reduc-
tion (%)
40
40
40
30
30
30
80
70
70
80
70
70
S/lb
0.009, -
0. 008,0.032
0.006,0.030
0. 025,0.024
0. 018,0.085
0.013,0.077
0.039,0.039
0.052,0.068
0.041,0.058
0. 049,0. 075
0.060,0. 113
0. 043,0. 096
NO..
Baseline
(gm/mi)
8.8
14.7
20 3
8.8
14.7
20. 3
8.0
13.4
18. 5
8.0
13.4 -
18. 5
X
Reduc-
tion (%l
-5
-5
-5
30
35
35
-5
-5
-5
40
40
40
f/lb
-
- t
-
0.34.0. 34
0.20,0 94
0. 15,0.86
-
-
-
0.81, 1.Z4
0.78, 1.49
0. 57, 1.25
OJ
I
Ul
*Costs for 50,000 miles of vehicle operation.
bBaseline fuel economy values used were 10, fc. 4. 5 mpg for the truck groups in the
6000 to 10,000, 10.OTO to 20,000, and 20, 000 to 26, 000 Ib GVW class, respec-
tively. Unit fuel cost was SO. 50/gal.
eBaseline emissions are for the 1968 model year in case of precontrolled vehicles
and 1972 in case of controlled vehicles.
^First value excludes the effect of incremental fuel costs, while the second value
includes the change in fuel costs.
elncrease in average air/fuel ratio of about one unit,
fGVW in 1000 Ib.
8Cost effectiveness is not meaningful if retrofit system results in an increase in
emissions of a particular pollutant or fuel savings cause the net cost to be
negative; hence, in these cases, no value for f/lb is shown.
All emission reductions correspond to a "new" catalytic converter: deterioration
is not included.
-------
a relatively small error or uncertainty in the fuel economy penalty can
significantly affect the cost effectiveness of a given retrofit system.
It is of interest to compare the cost Effectiveness of various
retrofit emission control strategies for vehicles of different GVW (from pas
senger cars to 26,000-lb trucks). This comparison is shown in Table 3-21
using the results previously given in Tables 3-10 to 3-12 and 3-20. The fol-
lowing conclusions can be drawn from Table 3-21.
a. All the retrofit emission control strategies for trucks less
than 10,000-lb GVW are at least as cost effective as they
are for light duty vehicles.
b. The oxidation catalyst with air injection retrofit system
maybe as cost effective for heavier vehicles (GVW up to
26,000 Ib) as for light duty vehicles. In general, the cost
effectiveness for HC and CO emission reduction increases
with increasing GVW, assuming that catalyst durability does
not become a problem at high engine loads.
s
c, Lean carburetion {or air bleed) retrofit is less cost effective
for precontrolled trucks greater than 10,000 Ib GVW than for
trucks less than 6000 to 10,000 Ib GVW and light duty
vehicles.
d. The fuel penalty due to EGR at high engine loads is the domi-
nant factor in reducing the cost effectiveness of retrofit emis-
sion control systems having NOX control on trucks greater
than 10,000 Ib GVW. NOX control on heavy vehicles is sig-
nificantly more difficult than on lighter vehicles because of
the fuel penalty and output power degradation associated with
EGR and spark retard near maximum power.
3-4. 3 Retrofit of Diesel Powered Trucks
Many of the larger trucks (GVW > 26,000 Ib) are powered by
Diesel engines. Most of these engines are of the open-chamber, direct-
ejection type, which have HC and CO emissions that are much lower (65 to
9fi
7U percent less) and NO emissions that are about 50 percent higher than
J»
result if a gasoline engine of comparable power were used in the vehi-
In addition to the gaseous pollutants, diesel engines can also exhaust
8r*ioke, aldehydes, and odorous compounds that are objectionable. Since
3-57
-------
Table 3-21. Comparison of the Estimated Cost Effectiveness of Various Retrofit
Strategies on Vehicles of Differing GVW
Vehicle
Precontrolled (pre-1971)
Lean carburetion
Excluding fuel
Including fuel
Lean carburetion + EGR
Excluding fuel
Including fuel
Controlled (post- 1971)
Oxidation catalyst
with air
Excluding fuel
Including fuel
Oxidation catalyst
with air + EGR
Excluding fuel
Including fuel
Cost Effectiveness ($/lb)
HC
LDVa
0.23
+c
0.24
0.32
0.62
0.62
0.72
0.88
6-10b
0.28
+
0.84
0.84
0.45
0.45
0.57
0.87
10-20
0.72
3.0
c
-
0.50
0.65
0.65
1.25
20-26
0.53
2.8
-
-
0.36
0.50
0.47
1.04
CO
LDV
0.007
+
0.010
0.015
0.05
0.05
0.06
0.07
6-10
0.009
•f
0.024
0.024
0.039
0.039
0.049
0.075
10-20
0.008
0.032
0.018
0.085
0.052
0.068
0.06
0.113
20-26
0.006
0.030
0.013
0.077
0.041
0.058
0.043
0. 196
N0x
LDV
-
-
0. 53
0.70
3.6
3.6
0.95
1.2
6-!0
t
-
0.34
0.34
-
-
0.81
1.24
10-20
-
-
0.20
0.94
-
-
0.78
1.49
20-26
J
-
-
0, 15
0.86
-
-
0.57
1.25
OJ
1
tjl
Oo
aLight duty vehicles, GVW < 6000 Ib.
b6000 to 10,000 Ib GVW category.
Plus indicates net cost savings; minus indicates retrofi-t device increased emissions.
rJo catalyst deterioration included.
-------
the HC and CO emissions of the diesel engine are quite low, it is possible
that any diesel retrofit program would be involved only with the reduction of
NOx emissions. Controlling smoke from diesels is not a matter of retrofit,
but rather one of proper adjustment and maintenance of the fuel injection and
•Mr*
timing systems. Unfortunately, the exhaust of odorous compounds is char-
acteristic of all lean-burning engines. However, two approaches for allevi-
ating the odor problem for such engines are known. These approaches are
the use of low-sac volume in injector tips and fuel-limiting devices.
There have been several studies of means of reducing NO
emissions from diesel engines (Refs. 3-35 through 3-38). The approaches
studied included, individually and in combination, fuel injection rate and pat-
tern variation, timing retard, turbocharging, exhaust gas recirculation (cold
and hot), and water injection (into the intake manifold and cylinder). NO
••t
emission reductions of 50 percent or more can be attained using these meth-
ods, but, as indicated in Table 3-22, in most cases the NO reduction is
Jt
accompanied by significant increases in CO emissions and smoke. In addi-
tion, in some cases, the associated fuel penalty is quite high and there are
potential maintenance problems with the retrofitted emission control systems
and/or the basic engine. The limited data and operating experience to date
indicate that EGR (cold) is the most promising approach for reducing NO
Jfc
emissions from diesel engines, but also dictate that additional testing and
Development are necessary.
3-4,4 Implementation of Retrofit Programs for Trucks
Many of the comments made previously in Sections 2. 8. 6 and
3V3 relative to the planning and implementation of I/M programs for heavy
duty vehicles and of retrofit emission control programs for light duty vehicles
are also relevant to the present discussion of the planning and implementation
of a retrofit program for heavy duty vehicles (GVW > 6000 Ib). In the interest
°* brevity, only the principal implementation considerations are delineated
ere. The implementation of such a program would involve the following
8teps and may require a time period of i to 2 years after the enabling legis-
afcion was passed.
3-59
-------
Table 3-22. Summary of Diesel Engine Emission Reductions Using Various
Retrofit Approaches (Ref. 3-38)
Retrofit Approach
Type
Engine
modification
Engine
modification
EGR
EGR
Water
injection
Water
injection
Description
Retard timing -
5°
Retard timing -
10°
Coldd - 7%
Coldd - 15%
20% of fuel
flow
50% of fuel
flow
o
Percent Reduction
NO
X
36
52
25 to
50e
35 to
65
10
25
HC
20
40
0
0
NAg
NA
cob
-40
-70
-10 to
-50
-20 to
-180
NA
NA
c
Smoke
-70
-150
-100
-250
NA
NA
Fuel
Economy
3
8
1
3
NA
NA
Potential
Problems
«
Corrosion and
deposit buildup
in EGR circuit
Corrosion and
deposit buildup
in EGR circuit
Corrosion and
fouling of
intake system
Corrosion and
fouling of
intake system
Based on the 13-mode engine cycle.
Negative sign indicates an increase.
»
"Opacity
Recirculated gases cooled to about 80°F; hot EGR
results in significantly lower NOX reduction and
greater fuel economy penalty.
Range indicates half load to full load.
Water injected into intake manifold.
not available.
-------
a. Promulgation of emission reduction, cost, and maintenance
specifications for acceptability of retrofit devices/systems.
b. Development of the certification procedures to be followed
by manufacturers of retrofit Devices/systems.
c. Certification of garages and fleet mechanics to install retro-
fit devices/systems.
d. Development of procedures for filing certificates of compli-
ance by vehicle and fleet owners.
e. Development of inspection procedures for checking the state
of operation of in-use retrofit devices/systems on heavy d\ity
vehicles.
3-61
-------
REFERENCES
3-1. Control Strategics for In-Use Vehicles, U.S. Environmental
Protection Agency, Office of Air and Water Programs, Mobile
Source Pollution Control Program (November 1972).
3-2. 1973/74 Automobile Facts and Figures, Motor Vehicles
Manufacturers Association of the United States, Inc. (Undated).
3-3. Applications for Accreditation of NOX Control Devices, State
of California, Air Resources Board (Undated)"!
3-4. Staff Report on Comparative Effects of NOX Retrofit Devices,
State of California, Air Resources Board (18 April 1973).
3-5. Final Report on Evaluation of Disconnecting Vacuum Spark
Advance, California Department of Transportation, Equipment
Branch (March 1974).
3-6. Analysis of Effectiveness and Costs of Retrofit Emission Control
Systems for Used Motor Vehicles, Vol. II, System Description,
Report 71Y233, Environmental Protection Agency (May 1972).
3-7. Report on Emisjions from Vehicles Equipped with UOP'S
Catalytic Device, Interim Report No. 2, State of California, Air
Resources Board (November 1973).
3-8. 50,000 Mile Standard and Abuse Durability Test, Universal Oil
Products (Undated).
3-9. An Evaluation of Catalytic Converters in Light Duty Vehicles,
City of New York, Bureau of Motor Vehicle Pollution Control,
Test Report No. 8 (Undated).
3-10. Status Report on Catalytic Device Equipped Test Fleets,
California Air Resources Board, Report No. 74-11-4
(12 June 1974).
3-11. Evaluation of GM Low Emission Fleet, Interim Report No. 2,
California Air Resources Board (April 1973).
3-12. Report on Emissions from Vehicles Equipped with GM.'s Advanced
Emission Control System, Interim Report No. 3, California Air
Resources Board (November 1973).
3-62
-------
3-13. Report on..Emis_sign_Te_st of Ford Catalytic Converter Vehicles,
Interim Report No. 1, California Air Resources Board
(November 1973).
•
3-14. Report on an Altitude jSyaluation of Emission Control Hardware
for STP Corporation, Automotive Testing Laboratories, Inc.,
Aurora, Colorado (Undated).
3-15. Hybrid Heat Engine/Electric Systems Study, Final Report, The
Aerospace Corporation, Report No. TOR-0059(6769-01)-2
(June 1971).
3-16. Automobile Exhaust Emission Surveillance, Final Report,
Calspan Report No. NA-5194-D-4, Calspan Corporation,
Buffalo, New York (August 1973).
3-17. High Altitude Vehicular Emission Control Program, Vol. II and
IV, TRW Environmental Services, Prepared for State of Colorado,
Department of Health, and EPA, Region VIII (December 1973).
3-18. Vehicle Emission Inspection and ContrjjjJProgram, Olson
Laboratories, Prepared under ContractTwith the State of
Colorado, Department of Health (November 1972).
3-19. C. F. Taylor, The Internal Combustion Engine in Theory and
Practice, Technology Press, M.I.T. and John Wiley and Sons,
New York (I960). .
3-EO. An Evaluation of Devices for the Control of Exhaust Emissions
at High Altitude, Clean Air Research Company, Pico Rivera,
California (19 February 1973).
3-21. T. C. Austin and K. H. Hellman, Passenger Car Fuel Economy -
Trends and Influencing Factors, Environmental Protection Agency,
SAE Paper 730790 (September 1973).
3-22. D. J. Patterson and N. A. Henein, Emissions from Combustion
Engines and Their Control, Ann Arbor Science Publishers, Inc.,
Ann Arbor, Michigan (1972).
3-23. Analysis of an Evaporative Controls Retrofit Program for the
South Coa st Ai r B a sin, EQL Memorandum No. 3, California
Institute of Technology, Environmental Quality Laboratory
(May 1973).
3-24. "Voluntary Retrofit Evaluation Program," Environmental
Protection Agency, U.S. Federal Register (March 27, 1974).
3-63
-------
3-25. D. S. Kircher and D. P. Armstrong, An Interim Report on Motor
Vehicle Emission Estimation, EPA Report No. EPA-450/2-73-003
(October 1973).
3-26. Medium Duty Truck Emissions Data, Environmental Protection
Agency, Ann Arbor, Michigan (1973).
3-27. K. J. Springer and M. N. Ingalls, Mass Emissions from Trucks
Above 6000 Ib GVW -- Gasoline Fueled, Southwest Research
Institute (August 1972).
3-28. Exhaust Emission Analysis and Mode Cycle Development for
Gasoline Powered Trucks, Ethyl Corporation, Report GR 67-41
(September 1967).
3-29. Medium Duty Vehicle Emission Control Cost Effectiveness
Comparisons, Vol. II, Technical Discussion, Aerospace Report
ATR-74(7327)-l (January 1974); also EPA Report No. 460/3-74-0046
(January 1974).
3-30. L. Bogdan, A. Burke, and H. Reif, Technical Evaluation of
Emission Control Approaches and Economics of Emission
Reduction Requirements for Vehicles between 6000 and
14,000 Ib GVW, EPA Report No. EPA-460/3-73-005
(November 1973).
3-31. M. P. Walsh and N. Friberg, Retrofit Device Certification
Procedures for Medium and Heavy Duty Gasoline Fueled Vehicles,
New York City Department of Air Resources, Bureau of Motor
Vehicle Pollution Control, Presented before Manufacturers of
Emission Controls Association (March 1974).
3-32. H. Gompf, Evaluation of Dana Retronox EGR and UOP Oxidizing
Catalyst Retrofits on Two Medium Duty Vehicles, EPA Report
No. 74-10 DWP (September 1973).
3-33. K. J. Springer, Baseline Characterization and Emission Control
Technology Assessment of Heavy Duty Gasoline Engines, Southwest
Research Institute, Final Report on Contract EHS-70-110
(November 1972).
3-34. W. F. Marshall and R. D. Fleming, Diesel Emissions
Re-inventoried, Bureau of Mines Report RI 7530 (July 1971).
3-35. Characterization and Control of Emissions from Heavy Duty
Diesel and Gasoline Fueled Engines, Bureau of Mines, Draft of
Final Report on EPA-LAG-0129 (D) (October 1972).
3-64
-------
3-36. W. F. Marshall and R. W. Hurn, Modifying Diesel Engine
Operating Parameters to Reduce Emissions, Bureau of Mines
Report RI 7579 (October 7, 1971).
3-37. I. M. Khan, G. Greeves,"and C. H. T. Wang, Factors Affecting
Smoke and Gaseous Emissions from Direct Injection Engines
and a Method of Calculation, SAE Paper 730169 (January 1973).
3-38. W. U. Roessler, A. Muraszew, and R. D. Kopa, Assessment of
the Applicability of Automotive Emission Control Technology to
Stationary Engines, Aerospace Report No. ATR-74(7421)-1
(July 1974).
3-65
-------
4. CONVERSION OF IN-USE VEHICLES FOR GASEOUS
FUEL OPERATION
-------
4. CONVERSION OF IN-USE VEHICLES FOR
GASEOUS FUEL OPERATION
4. 1 INTRODUCTION
The modification of in-use vehicles to permit their operation
using gaseous fuels falls within the general definition of retrofit approaches
discussed in Section 3. However, the feasibility of gaseous fuel conversion
as an in-use vehicle emission control strategy depends not only on the
availability, emission reduction effectiveness, and cost of the required
hardware, but also on a number of other factors, such as the cost and
availability of the gaseous fuel, the feasibility of providing the necessary
fuel distribution system, and the impact of diverting the fuel from other uses.
This is not a highly viable approach to the control of emissions from in-use
vehicles in light of the availability problems presently being experienced with
such gaseous fuels as propane and natural gas.
There are three basic types of gaseous fuel conversions that
may be performed. These are (1) liquified petroleum gas (LPG), (2) com-
pressed natural gas (CNG), and (3) liquified natural gas (LNG). Differences
among the types manifest themselves principally in such areas as the type •
of conversion hardware required, conversion and fuel cost, and operating
convenience (e.g. , vehicle range). In addition to these three basic types of
conversions, a distinction can be made between single-fuel conversions in
which the vehicle is modified to operate exclusively on the gaseous fuel and
dual-fuel conversions in which the modified vehicle is equipped to operate
interchangably on either the gaseous fuel or gasoline.
4-1
-------
4.2 DESCRIPTION OF GASEOUS FUEL SYSTEMS
Conversion of a gasoline-powered vehicle for operation on a
gaseous fuel requires the installation of a new fuel tank designed to contain
the alternative fuel, new fuel lines and appropriate control valves and re-
gulators to ensure that the fuel reaches the engine at the required pressure
and only when it is running, and a new carburetor designed to meter the flow
of the gaseous fuel into the engine's induction system. Conversions for LPG
and LiNG also require the installation of liquid-gas converters that vaporize
the fuel. In single-fuel systems, the above components replace the original
fuel tank, fuel lines, fuel pump, and carburetor. In dual-fuel systems, the
new components are in addition to the original system. A typical schematic
diagram for dual-fuel operation with LPG and gasoline is shown in Figure 4-1.
In addition to the new equipment that must be retrofitted to an in-use vehicle
to permit its operation on a gaseous fuel, engine adjustments such as air/fuel
ratio and ignition timing are required to achieve proper operation with the
gaseous fuel. Optimization of engine adjustments is necessary if maximum
emission reductions are to be achieved with minimum impact on vehicle
performance and fuel economy. For vehicles not originally equipped with
hardened valve seats, installation of such seats may also be necessary to
prevent excessive wear.
A number of systems for conversion of light duty vehicles to
gaseous fuel operation are currently available. The operational consequences
of using gaseous fuels instead of gasoline result from the differences in the
physical and thermodynamic properties of the fuels. A summary of pertinent
properties for gasoline, LPG, CNG, and LNG is given in Table 4-1. For
vehicle applications, the most important properties are the state (liquid or
gas) of the fuel at ambient temperature and pressure, and its energy density
3
(Btu/ft ). These properties significantly affect the ease with which the fuel
can be stored on board the vehicle and at distribution stations. Tankage re-
quirements (weight and volume) and the corresponding vehicle range between
fueling stops are shown in Table 4-2. The advantages of gasoline over the
gaseous fuels in this regard are clearly indicated in Table 4-2.
4-2
-------
OPTION • "Y" OR "T" INTO EXBTNG CM HEATER HOSE TO THESE UNES
Figure 4-1. Schematic Diagram for Dual Fuel Operation with LPG and
Gasoline (Ref. 4-3)
4-3
-------
Table 4-1. Properties of Gasoline and Gaseous Fuel Alternatives
Property
Chemical formula
Normal boiling point (° F)
Storage temperature (° F)
Storage pressure (atm)
Heating value
Btu/lb
Btu/galC
Specific gravity
Liquid (water = 1)
Vapor (air =1)
Octane number (RON)
Ignition temperature (° F)
Flammability limits (% by volume)
Reference volume
Gasoline equivalent for same
energy (gal)
Fuels
Gasoline
(CHl 85)na
100-400
ambient
1
19,400
119,000
0.73
3. 3
85d
650
1-10
1 gal
1.0
Propane (LPG)
C3H8
-44
ambient
15
21,560
91,500
0.51
1.52
96
970
3-10
1 gal
0.78
Methane
Gas (CNG)
CH,
-
ambient
200
21,520
24, 300
-
105C
115
1170
5-15
100 scfe
0.20
Liquid (LNG)
CH4
-260
-260
2
21,520
80,000
0.45
0.52C
-
-
-
1 gal
0.67
aApproximate formulation; specific gasolines vary somewhat from this expression.
Lower heating value
°Fuel stored at pressure and temperature listed above.
"No additives (e.g. , lead alkyls to increase the octane number).
eStat\dard cubic ieet.
-------
Table 4-2. Tankage and Range Comparisons
Parameter ^
Weight (Ib)
Fuel alone
Fuel + tank
Volume (ft3)
Fuel alone
Fuel + tank
Range (mi)
Fuels
Gasoline
122
137
2.7
2.9
300
Propane (LPG)
85
162
2.7
3.5
230
Methane
Gas (CNG)
22
142
2.7
3. 1
60
Liquid (LNG)
75
162
2.7,
3.8
200
Basis
20-gal fuel volume, assuming 15 mpg for gasoline.
-------
4. 3 EMISSION REDUCTIONS ATTAINABLE THROUGH
GASEOUS FUEL CONVERSION
While a number of vehicles have been converted for operation
on gaseous fuels, evaluation of the emission reductions obtained by these
conversions has been limited. Most of the emissions tests have been done on
single vehicles converted by a particular manufacturer as part of a gaseous
fuel system development program or on a small fleet (usually less than 10
vehicles) of government-owned or leased vehicles. The emissions tests have
been conducted mainly by the Environmental Protection Agency (EPA) (Ref. 4-
1) and the California Air Resources Board (GARB) (Ref. 4-2). Most of the
data were obtained using the seven-mode test procedure [l970 Federal Test
Procedure (FTP)], while EPA used the 1972-CVS FTP. In addition, the EPA
tested a number of cars using both the 1970 and 1972 FTP (Ref. 4-1). Com-
parison of these two sets of data indicates that for gaseous fuel operation the
two test procedures yield emission levels that are not greatly different. Hence*
the two types of emission data were reviewed and assessed in a collective sefls
to draw conclusions concerning the effectivity of gaseous fuel conversions.
It may also be noted that most of the HC emissions data for
gaseous fuel vehicles reported by the CARB incorporate scale factors that
account for the reduced photochemical reactivity of the hydrocarbons in the -
gaseous fuel exhaust. Since EPA has not yet determined an appropriate basis
for developing reactivity correction factors for this purpose, the scale factor
was removed from the CARB data in compiling and reviewing the data on
gaseous fuel exhaust emissions.
Analysis of the data discussed above indicates that a signi-
ficant reduction in all three exhaust pollutants — hydrocarbons (HC), carbon
monoxide (CO), and nitrogen oxides (NO ) — can be obtained through a
X
conversion from gasoline to gaseous fuel operation. Reductions as high as
60 percent for HC and NO emissions and 90 percent for CO emissions have
J^
been obtained immediately following conversion to gaseous fuel when ignition
timing and air/fuel ratio are optimized. The actual emissions benefit
indicated by the data varies with a number of factors, including the type of
4-6
-------
conversion (LPG vs CNG/LNG) and the model year of the converted vehicle
(post-1971 vs earlier models). Also, while the data show that the levels of
CO emissions after conversion are consistently very low (often less than 5
gm/mi), the HC and NO emissions vary over a wide range. Depending on
Jt
the emission reductions desired* different tradeoffs may be made between
emissions, fuel economy, and vehicle performance. Therefore, it is neces-
sary in the evaluation of gaseous fuel conversion systems to have data on
fuel economy and vehicle performance, as well as emission reductions. Also,
the sensitivity of HC and NO emissions to engine adjustments makes it
1 JL
adviseable to have a periodic emission inspection to insure that operators
of gaseous-fueled vehicles do not alter the ignition timing and carburetor
settings to improve fuel economy and performance at the expense of higher
emissions.
The best attainable short-term (i. e. , without deterioration)
reductions that can be attained by gaseous fuel conversions when no consider-
ation is given to fuel economy are presented in Table 4-3.
In general, it is to be expected that dual-fuel conversions will
not be capable of achieving as large emission reductions as are possible using
single-fuel conversions, since compromises are required in various engine
adjustments to permit interchangable operation using both the gaseous fuel
and gasoline.
Data on the deterioration of emissions from vehicles converted
for gaseous fuel operation, as those vehicles accumulate time and mileage,
are extremely limited, and it is not possible to project with any certainty
what the trend will be.
4-7
-------
Table 4-3. Emission Levels and Reductions Obtainable Through
Single-Fuel Gaseous Conversion (Refs. 4-1 through 4-3)
Applicable Model
Years
1968-1971
-
1972-1974
Fuel
Gasoline (baseline)
LPG
LNG/CNG
Gasoline (baseline)
LPGa
LNG/CNGa
Emission Level
(1975 FTP)
HC
4.8
2. 1
1.7
2.8
1.5
1.0
CO
60.0
14.2
5. 1
30.0
2.7
2.0
NO
X
4.8
2.9
1.4
3.0
1. 1
0.7
Percent Reduction
From Gasoline
Baseline
HC
55
65
45
60
CO
75
90
90
95
NO
X
40 '
70
60
70
I
00
Best attainable, not the average, for 1972-1974 vehicles. In general, emission reductions
achievable with dual-fuel systems will be less than those shown.
-------
4.4 INITIAL AND OPERATING COSTS
In assessing the costs associated with gaseous fuel conversion,
it is advantageous to consider the initial costs and the operating costs
*
separately. The initial costs include the cost of the fuel conversion hardware
(under the hood), the fuel tank, and the labor to install the system. The
operating costs include the cost of fuel and maintenance. In the case of
operating costs, it is only the incremental costs compared to operation with
gasoline that are of interest.
The initial costs are summarized in Table 4-4. These values
reflect data obtained from manufacturers and distributors, and represent
costs as of March 1974. The tank sizes (volumes) cited in Table 4-4 are
either those required to achieve a vehicle range comparable to that with
gasoline or, as in the case of CNG, those that are customarily installed in
automobiles by companies in the business.
Since the initial cost of converting a vehicle to gaseous fuel is
quite high, it is advantageous if at least part of that cost can be offset by
reduced fuel and maintenance costs. It is generally agreed (Ref. 4-4) that
the maintenance costs (general repair, engine tune-ups, oil changes, etc.)
using gaseous fuels are less than those for operation with gasoline. On this
basis, it is considered reasonable to take credit for an estimated maintenance
savings of 0.0025 dollars per mile (1/4 ^/mi). There is less agreement
in the literature concerning the cost of gaseous fuels and the fuel economy
that can be expected by using them. Based on information provided in
Refs. 4-5 and 4-6, and on contacts with several companies concerned with the
establishment of gaseous fuel distribution centers, the fuel cost and fuel
economy data given in Table 4-5 were ascertained. The fuel costs shown for
natural gas, both CNG and LNG, are much higher than often used in some
previous studies, especially by utilities companies. The cost of the distribu-
tion and dispensing of the fuel was neglected in these studies. As in the case
of gasoline, this cost for natural gas is significant. The fuel costs given in
Table 4-5'do not include either Federal or State taxes as it can be expected
4-9
-------
Table 4-4. Initial Costs for Conversion to Gaseous Fuels'
Fuel
Gasoline
LPG
CNG
LNG
Total Cost
($) '
-
650
870
1020
Fuel Conversion
Hardware ($}
-
280
280
280
Fuel Tank ($)
- (23 gal)
230 (30 gal)
450 (1000 scf)
600 (30 gal)
Labor ($)
-
140
140
140
Costs as of March 1974 for converting a passenger car to single-
fuel gaseous system.
Table 4-5. Fuel Cost and Fuel Economy Data for Gaseous Fuel Operation
Fuel
Gasoline (regular)
LPG
CNG
LNG
Sales Unit
Gal
Gal
100 scf
Gal
Unit Fuel Cost
($/unit)a
0.33
0.28
0.20
0.28
Fuel Economy
(miles /unit )b
13
10
10
9
Fuel Cost
($/mile)
0.025
0.028
*
0.020
0.031
No Federal or State tax included, based on first quarter 1974 price levels.
Btu/mi for gaseous fuel operation assumed to be equal to that for operation
with gasoline.
4-10
-------
that an equivalent tax will be applied to all the fuels. In calculating the fuel
•**• %
economy for each fuel, it has. been assumed that the vehicle averaged 13 mpg
for gasoline and that the Btu/mi used for gaseous fuel operation was equal
to that required with gasoline. Except for CNG, it does not appear that the
fuel costs per mile vary much from fuel to fuel. The main disadvantage of
CNG is the reduced range resulting from the size and weight of the tanks
needed to store gas at 2000 to 3000 psi.
4-11
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4.5 COST EFFECTIVENESS OF EMISSION REDUCTION
THROUGH CONVERSION TO GASEOUS FUELS
Cost effectiveness information for attaining low emissions
from controlled vehicles (1968-1974) through conversion to gaseous fuels is
summarized in Table 4-6. The cost effectiveness is expressed as dollars
per pound of pollution eliminated ($ /lb) using the same general techniques as
outlined in Section 3. 2. 1. 7. The format of Table 4-6 is the same as that used
in Tables 3-10 through 3-12 in Section 3 so that a direct comparison can be
made between the cost effectiveness of the gaseous fuel conversion systems
and emission control retrofit devices for gasoline-fueled vehicles. In
general, it is found that gaseous fuel conversion systems compare unfavorably
in terms of cost effectiveness whether based on direct costs (initial cost and
maintenance savings) or on total costs, including fuel savings, unless the unit
cost of the gaseous fuel is much below that of gasoline. At the present time,
this seems to be the case for CNG only, and that system has the disadvantage
of a significantly reduced range (one-quarter to one-third that for gasoline)
and limited commercial availability of the fuel. The dominant factors in
assessing the cost effectiveness of gaseous fuel systems are the unit cost
of the fuel and the fuel economy of the vehicle when using the gaseous fuel.
In evaluating claims made for gaseous fuel systems, it is important to know
what assumptions have been made concerning these factors and to be certain
the values used are realistic.
4-12
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Table 4-6. Summary of Cost Effectiveness Information for Gaseous Fuel Conversion
Fuel
InitUl Cost {$)
Maintenance
Savings ($)*
LPG
CNG
JLNG
650
870
1020
LPG
CNG
ura
650
870
10ZO
125
125
125
125
125
125
Unit Fuel,
Price ($f
Savings ($)c
Emissions
(gm/mi- 1975 FTP)
HC
CO
Controlled Vehicles (1968-1971) has
HC = 4. 8, CO = 60, NO = 4
O.Z8/gal
O.ZO/100 scf
0.28/gal
-150
250
-300
2.1
1.7
1.7
14.2
5.1
S.I
Controlled Vehicles (1972-1974) has
HC = 2.8, CO = 30, NO = 3
0.28/gal
0.20/100 scf
0.28/gal
-ISO
250
-300
1,5
1.0
t.O
2.7
2.0
2.0
NO
Cost Effectiveness"1 (S/lb)
Initial Costs and
Maintenance Savings
HC
CO
N0x
Initial Costs and Maintenance
and Fuel Savings
HC
CO
NO
X
eline emissions:
. 8 gm/mi
2.9
1.4
1.4
1.81
2. 16
2.6
0. 11
0. 12
0. 15
2.52
i.99
2.39
3. 33
2.05
3.95
0.14
0.08
0.22
3.24
1.32
2.61
eline emissions:
gm/mi
1, 1
0.7
0.7
3. 18
3.77
4.5
0.18
0.24
0.29
2.52
2.95
3. S3
4.08
2.50
6.83
0.23
1
0. 16
0.44
3.24
1.-95
5.34
^Maintenance saving of 0.0025 $/mi for 50,000 miles.
No Federal or State tax ia included in the fuel coats.
GFuel savings in 50,000 miles compared with operation with g&soline; negative sign means an increase in fuel costs.
Lifetime of gaseous fuel conversion system is taken to be 50,000 miles.
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4.6 OTHER ASPECTS OF GASEOUS FUEL CONVERSION
Other factors that influence the feasibility of gaseous fuel
conversion approaches are the effects on vehicle performance and safety
considerations. In general, experience with gaseous fuel conversion fleets
has demonstrated that acceptable vehicle performance (though often reduced
from that obtained with gasoline) can be obtained with gaseous fuels. While
safety considerations have restricted the use of gaseous fuels in some areas
(e.g., in tunnels), enough experience has been accumulated with fleets of
gaseous fuel vehicles to demonstrate that the fuels, in general, can be used
safely. Various aspects of safety related to the use of gaseous fuels in
vehicles are discussed in Refs. 4-4, 4-5, and 4-7.
4-14
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4.7 USEFULNESS OF GASEOUS FUEL CONVERSION AS AN
IN-USE VEHICLE EMISSION CONTROL STRATEGY
In judging the usefulness of gaseous fuel conversion as an
emission control strategy for in-u*e vehicles, the following factors must be
considered: reductions in total vehicle population emissions achievable as
a function of time by the conversion strategy, cost of implementing the
strategy, and impact of the diversion of gaseous fuels for vehicle use on
other fuel requirements, including possible increases in emissions from
stationary sources through fuel switching.
Considerations of the cost of gaseous fuel conversions, the
limited availability and cost of refueling facilities, and limitations on the
availability of gaseous fuels in many areas have generally led to the conclu-
sion that gaseous fuel conversion is most practical when applied to certain
commercial fleets of vehicles. The overall effectiveness and cost of fleet
conversion programs are estimated in Ref. 4-8 for two cases of interest:
taxicab fleets in New York City and in Washington, D. C. The outcome of
that analysis indicates that emission reductions expected to result from
converting the pre-1975 model year taxicab fleets in those two cities to
gaseous fuels would be relatively small compared with the potential of other
emission control strategies for in-use vehicles and would be short lived.
In other analyses (Refs. 4-9 and 4-10), the overall emissions
impact of diverting natural gas from electric power generation to powering
commercial vehicles in New York City has been considered. It was determined
that to operate all commercial vehicles in New York City on natural gas would
require the diversion of approximately one-half of the quantity of that fuel
used for electric power generation. Replacing this fuel by 1 percent sulfur
fuel oil was estimated to produce an increase of emissions of sulfur oxides
equivalent to approximately 6 percent of the total New York City emissions
of that pollutant. This is an example of the type of pollutant control tradeoffs
that need to be evaluated in regions where supplies of gaseous fuels are
limited.
4-15
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It should be mentioned that the future availability of LPG as
an alternate fuel does not look encouraging for either the near term or the
longer term. In the near term, the production of LPG is tied directly to
the production rates at natural gas processing plants and gasoline refineries.
Though the production .of LPG is expected to continue to rise through the
1970's, the annual increase is expected to taper off to levels considerably
below those experienced in the 1960's. This is expected in large part to be
due to the use of more propane and butane in gasoline production to achieve
higher octane ratings in gasolines with low lead or no lead content.
With regard to natural gas supplies, a decrease in the pro-
duction of domestic natural gas is expected in the late 1970's and early
1980's, because the production of synthetic natural gas and the supply of
Alaskan gas will not grow fast enough. Therefore, a larger amount of
natural gas will have to be imported, with a possible impact on cost. Also,
while the continued limited use of natural gas for automotive applications
is not likely to be a critical factor in the U.S. natural gas energy use
balance, a major shift toward increased automotive consumption rates could
alter this balance so as to degrade critical supply/demand factors in other
consuming sectors. These ramifications on fuel supply and availability
must be carefully weighed in evaluating the relative merit of gaseous fuel
conversion as a control strategy for in-use vehicles.
4-16
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REFERENCES
4_1. H. L. Gompf, Exhaust Emissions from 10 GSA Rebels and 10 GSA
Falcons Equipped with LPG Conversion Kits. EPA, Ann Arbor,
Michigan (October 1970).
4-2. California Air Resources Board Emission Tests of Vehicles Converted
to Operate on Gaseous Fuels (series of memos during 1969 and 1970).
4-3. Beam Products Manufacturing Company, Los Angeles, California,
Brochure Form H-139A (March 1962).
4_4 Gas Power: The Fleet Owner's Gaseous Fuel Manual, California
Institute of Technology, Pasadena, California (March 1972).
4-5. Current Status of Advanced Alternative Automotive Power Systems
and Fuels, Vol. ill. Alternative Non-Petroleum-Based Automotive
Fuels, The Aerospace Corporation, Report No. ATR-74(7325)-2,
Prepared for EPA on Contract 68-01-0417 (March 1974).
4_6. R. W. McJones and R. J. Corbell, Natural Gas Fueled Vehicles -
Exhaust Emissions and Operational Characteristics, SAE, Automotive
Engineering Congress (January 1970).
4-7 E. F. Johnson, "Fire Protection Developments in CNG- Fueled Vehicle
Operations. " Fire Journal, Vol. 66, No. 6 (November 1972).
4_8 S. F. Hickey and J. Horowitz, The Effectiveness and Cost of
Conversion of Fleet Vehicles to Gaseous Fuel for Reducing Automobile
Emissions in Selected Regions, EPA, Washington, D.C. (November
4_9 Conversion of Motor Vehicles to Gaseous Fuel To Reduce Air Pollution,
Position Paper, Office of Air Programs, EPA, Washington, D.C.
(May 1972).
4 10 Emission Reduction Using Gaseous Fuels for Vehicular Propulsion,
' prepared under Contract No. 70-79 for EPA, Institute of Gas
Technology, Chicago, Illinois (June 1971).
4-17
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TECHNICAL REPORT DATA
(Please read Instructions on th\ reverse before completing)
1. REPORT NO.
EPA-460/3-74-021
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE •
A REVIEW OF CONTROL STRATEGIES
FOR IN-USE VEHICLES
5. REPORT DATE
December 1974
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
J. Meltzer, M.G. Hinton, T. lura, A. Burke,
L. Forrest, W.M. Smalley% F. Augustine
8. PERFORMING ORGANIZATION REPORT NO
ATR-74(7328)-l
I. PERFORMING ORGANIZATION NAME AND ADDRESS
The Environmental Programs Group
Environment and Urban Division
The Aerospace Corporation
El Segundo, California 90245
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-01-0417
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Air and Waste Management
Office of Mobile Source Air Pollution Control
Division of Emission Control Technology
Ann Arbor, Michigan 48105
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT ', ~~~~
A review was conducted of studies and evaluations made by the EPA and various
State agencies of the technical feasibility, emission reduction effectiveness, and
costs associated with implementing various approaches for reducing the emis-
sion of air pollutants from automobiles currently in use. These approaches
include: inspection/maintenance programs, retrofit programs, and the con-
version of in-use vehicles to permit the use of gaseous fuels. The emphasis
of this report is on providing emission reduction and cost data that maybe
useful to the States in evaluating the alternative approaches to in-use vehicle
emission control, as those approaches may be applied to their particular air
quality requirements. This report is supplementary to previous EPA pub-
lications covering these same topical areas.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Ficld/Gioup
Air pollution
In-use vehicles
Inspection/maintenance
Retrofit
Gaseous fuel conversion
Air pollution control
Mobile sources
Emissions «
Costs
Cost effectiveness
o. DISTRIBUTION STATEMENT
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
239
Unlimited
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
"A Form 2220-1 (9-73)
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