. EPA-AA-IMS/81-7
Low-Cost Approaches to
Vehicle Emissions Inspection and Mai'ntena ice
October 1981
Notice
This Report does not. necessarily represent final EPA decisions or positions.
It is intended to present technical analysis of the issue using data which are
currently .available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to inform the public of
technical developments which may form the basis for a final EPA decision,
position or regulatory action.
Inspection and Maintenance Staff
Emission Control 'Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise, and Radiation
U.S. Environmental Protection Agency
Ann Arbor, Michigan
-------
TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION AND SUMMARY 4
1.1 Introduction 4
1.2 Summary of Key Results 6
1.3 Example Designs For Low-Cost I/M Programs 22
1.3.1 Example Program A: 22
Areas Requiring Only CO Reductions 24
1.3.2 Example Program B:
Areas Requiring HC Reductions
1.3.3 Example Program C: Maximum Benefit Program 27
2.0 BACKGROUND ON CONVENTIONAL I/M PROGRAMS 31
2.1 Inspection and Reinspection 31
2.2 Types of Repairs Performed 32
2.3 Cost of Repairs 33
3.0 REDUCING REPAIR COSTS BY REDUCING INAPPROPRIATE 34
. AND UNNECESSARY REPAIRS
3.1 Improvement 1: Mechanic Training 34
3.1.1 Mechanic Training Courses 34
3.1.2 Information Distribution 35
3.1.3 Problem Facility Identification 37
3.2 Improvement 2: Public Awareness 37
3.3 Improvement 3: Price Competition 37
3.4 Improvement 4: Automated Analyzers 37
3.5 Improvement 5: Challenge Stations 38
3.6 Impacts on Costs and Emission Reductions 38
3.7 Conclusions 38
4.0 I/M FOR PRE-1981 VEHICLES USING ONLY IDLE CO 39
OUTPOINTS : .
4.1 Description and Summary of Impacts 39
4.2 Repair Types and Costs 42
4.2.1 Elimination of Idle HC-Only Failures 42
and Repairs
4.2.2 Simpler Repairs for Other Failed Vehicles 43
4.2.3 Net Effect on I/M Costs 46
4.3 Emission Peductions 46
4.3.1 Carbon Monoxide Emissions 47
4.3.2 Hydrocarbon Emissions 48
4.3.3 Deterioration Issues 49
4.3.4 Emission Reduction Benefits Model for 49
Idle CO I/M Programs for Pre-1981 Vehicles
4.4 Fuel Economy Benefits 50
-------
TABLE OF CONTENTS
(continued)
Section Page
5.0 I/M FOR 1981 AND LATER VEHICLES USING ONLY IDLE 55
CO CUTPOINTS
5.1 Background on 1981 and Later Vehicles 55
5.2 Idle CO I/M for 1981 and Later Vehicles 56
5.3 Emission Benefits Model for Idle'CO I/M 57
Programs for 1981 and Later Vehicles
6.0 OVERALL EMISSION REDUCTION BENEFITS FOR I/M PROGRAMS 60
USING ONLY IDLE CO CUTPOINTS
7.0 METHODS TO IMPROVE THE HC AND CO EMISSION REDUCTIONS 62
FROM IDLE CO I/M PROGRAMS
7.1 More Effective Test Procedure for 1981 and Later 62
Vehicles
7.2 Higher Failure Rate for Pre-1981 Vehicles 63
7.3 Better Repairs 63
7.4 Re-establishment of a Loose Idle HC Cutpoint 70
7.5 Tampering Checks 72
7.5.1 Background 72
7.5.2 Air Pump Checks 74
7.5.3 Evaporative Emission Control System Check 77
7.5.4 Catalyst Removal Check 79
7.6 Inspection and Maintenance for Light Duty Trucks 81
References 85
-------
1.0 INTRODUCTION AND SUMMARY
1.1 Introduction
The cost of automobile Inspection and Maintenance (l/M) programs is one of the
main topics in any discussion of I/M as a strategy for reducing in-use
automobile emissions of hydrocarbons (HC) and carbon monoxide (CO). While I/M
is a cost-effective means to reduce these pollutants in urban areas, there are
aspects of the most common or "conventional" approaches to I/M which
could be varied and which would reduce the cost of repairs necessary to pass
I/M and, in some cases, the inconvenience which I/M causes vehicle owners.
This report will focus on possible approaches to I/M which inherently can be
expected to have lower repair costs than the conventional approaches to I/M or
which can be expected to result in fuel savings which will offset some of the
cost of the I/M program. The report evaluates the emission reductions that
can be obtained from each of these approaches relative to the conventional
approach.
The low-cost forms of I/M are basically only modifications of the conventional
form, and fall into two categories. First, there are I/M programs which have
the same basic inspection and reinspection requirements as a conventional I/M
program but include improvements which aim at reducing the number of
inappropriate and unnecessary repairs, thereby lowering the average repair
cost to vehicle owners. I/M programs such as these will achieve lower costs
with no loss in emission reduction effectiveness.
Second, there are I/M programs which differ from conventional I/M in that no
HC cutpoint is used in the inspection and reinspection. This reduces the
number of vehicles which fail inspection and changes the type of repairs
required for failed vehicles to pass reinspection. The result is a lower
overall repair cost. This cost reduction is accompanied by a. partial loss.in
emission reduction effectiveness for HC. There are,, however, some improve-
ments and add-on procedures which are helpful in increasing the overall HC
emission reductions from this second type of low-cost I/M program and which
are discussed in this report. These improvements can make this type of I/M
program more acceptable as a substitute for a conventional I/M program in
urban areas which need HC reductions in order to attain the National Ambient
Air Quality Standard for ozone. Some of these improvements and add-on
procedures can also be used in a conventional I/M program to increase its HC
effectiveness, and are therefore of general interest.
Because both forms of low-cost I/M are only variations from the conventional
I/M program, the agency responsible for planning, implementing, and operating
a low-cost I/M program will need to perform all the tasks it would in a
conventional I/M program. These tasks include:
0 Development of an Implementation Schedule.
0 Preparation of draft legislation, if adequate legislative authority
does not yet exist or is not compatible with the low-cost approach.
0 Initiation of a Public Information Program.
-------
0 Initial notification of the repair industry of program plans and
schedule.
0 Development and award of any necessary contracts.
0 Construction of facilities if necessary (including challenge stations
in a decentralized program).
0 Adoption of testing procedures and guidelines.
0 Selection of geographic coverage, vehicles subject to inspection,'and
inspection cutpoints.
0 ' Licensing of test facilities and testing equipment.
0 Development of test facility auditing procedures and schedules.
0 Purchase and delivery of necessary equipment.
0 Initiation of mechanic training programs.
0 Hiring and training of inspectors.
0 Phase-in of mandatory program.
These tasks are defined in more detail in EPA's I/M policy memo of July 17,
1978 [l]r* In addition, the improvements which seek to lower repair costs by
eliminating inappropriate and unnecessary repairs require additional involve-
ment by the responsible agency.
In this report's discussion of various approaches to I/M there will often be a
distinction made between pre-1981 model year vehicles and 1981 and later model
year'vehicles. This distinction is necessary to account for the significant
technology differences between these two groups. These technology differences
cause differences in the frequency and types of emission control system
maladjustments and malfunctions and the types of repairs needed to correct
these problems. There are also differences in warranty coverage between these
two groups of vehicles. These differences are primarily caused -by the more
stringent Federal standards for CO and NOx emissions and the implementation of
Parameter Adjustment[2] .and Emission Performance Warranty regulations[3]
beginning in the 1981 model year. The effect of these differences will be
discussed in greater detail later in this report. There is more information
available at this time about the costs and effectiveness 'of various I/M
strategies on pre-1981 vehicles than on 1981 and later vehicles and this will
be reflected in the detail with which the two technology types are covered.
v^WI(B>i^^MfcV^W^H«M^KKa^^B^A«^BMmMKHHi^B«Hm_MMBVlv^_ . ' ' ( . '
*. Numbers in brackets refer to references at the end of the report
-------
It is expected that the failure rate of 1981 and later vehicles will be low
(5-10%) and some of the repair costs of these vehicles will be covered by the
new warranty regulations [2]. There will also be relatively few 1981 and
later vehicles in the fleet in the early years of a new I/M program.
Therefore as the programs begin the repair cost .for 1981 and later vehicles
will not be as important to the overall cost of an I/M program as the repair
cost for pre-1981 vehicles.
1,2 Summary of Key Results
The most far reaching conclusion in this report is that inspecting cars only
for carbon monoxide (CO) emissions will not reduce the CO emission reduction
of an I/M program and will reduce the HC emission reduction by only a moderate
amount.
Repairs will be much simpler and cost much less in an I/M program that uses
only idle CO cutpoints (the "idle CO I/M program"). Carburetor adjustments
will usually be the only necessary repair for pre-1981 vehicles. These will
cost between $6 and $10, compared to average repair costs from $18 to $30 in
conventional I/M programs. For 1981 and later vehicles, using only a CO
cutpoint means that only cars which are suffering a malfunction in the
computer-controlled fuel system will fail the inspection; in the conventional
program, some cars fail for high HC due to other types of malfunctions.
Repair of fuel system malfunctions causes a sizable fuel economy benefit,
while repair of other malfunctions often does not. Consequently, the same
overall fuel savings will be achieved in an idle CO I/M program as in the
conventional program but the failure rate, and consequently the total repair
cost, for 1981 and later vehicles will be less.
The bottom line for any low-cost approach to I/M programs is not only a more
favorable cost-effectiveness value, but an adequate reduction in total HC and
CO emissions from automobiles. This reflects the need of areas requiring I/M
programs to reduce these pollutants to attain the National Ambient Air Quality
Standards for ozone and CO. The tables in this section will provide informa-
tion which can help I/M program planners assemble a low-cost I/M program using
the idle CO I/M approach as a base and adding various emission or cost
enhancement options. Options can be selected from the tables in this section
to meet an area's individual needs regarding design, costs, and benefits.
Following sections of this report provide substantiation and derivation of the
benefits presented in these tables. . ..
The methods used in this section to compute the costs and emission benefits
from the various options are identical to those used in "Update on the
Cost-Effectiveness of Inspection and Maintenance".[4] The estimates of fuel
economy benefits are derived using the methods described in "Update on the
Fuel Economy Benefits of Inspection and Maintenance Programs".[5] Each table
assumes a standard fleet of one million light duty gasoline powered passenger
vehicles subject to the I/M program. All operating conditions (speed,
temperature, etc.) are national averages.
-------
Table 1 compares the basic idle CO I/M program to a conventional I/M program
using information from Section 6.0. Both programs would have the same idle CO
cutpoints, but since the idle CO program does not use an idle HC cutpoint, all
of the vehicles which would have failed for idle HC only in the conventional
I/M program will pass in the idle CO program. Therefore, while the
conventional I/M program has stringency of 20% for pre-1981 vehicles the idle
CO program has a stringency of about 13% using the same idle CO cutpoints.
Both programs use the idle test for 1981 and later vehicles.
Table 1
Comparison of Basic Idle CO and
Conventional I/M Programs
Stringency
for
Pre-1981
Vehicles
(Percent)
Percent
Benefit on
Dec. 31, 1987
HC CO
Five Year
Emission
Reduction
(Thousands of
Tons Removed)
HC CO
Five Year
Program Cost^
(Millions of $)
Cost-
Effectiveness
($/ton)
HC CO
Conventional
I/M 20
Idle CO 13
I/M
34.9 33.1 46.50 526.8l/ 54.10 581 5ll/
24.2 33.1 31.31 526.8 40.19. 642 38
1:
2:
3:
Costs include inspection fee ; and repair costs less vany; fuel economy
benefits from repairs.- . .- vV '".'''::"3;'.'' ~' ".'.' '''-~:?--'?-*':#-£'&'£'.'~'-zC.^-' .'-- '-""'
Program costs are divided equally between the two pollutants. :.,.*.;, ("v - - C:
These values have been recalculated and 'are nearly but, not. exactly the
same as reported in "Update on the Cost-EffectivenessV of .Inspection and
Maintenance". [4] . "."''" '''.'' ',;'"' " ';'-' ' ~:'"f ' .:-'.. '''."'':.-'?'
Since only those I/M repairs which effect. CO emissions will be required the
basic idle CO I/M program will provide the same CO benefit as the conventional
I/M program, but with overall repair costs for pre-1981 model year vehicles
reduced by about 70%. Since repair costs .are only one part of overall, program
costs, overall program costs in the basic idle CO.program are about .26% less
than for a conventional I/M program. This reduction-;, is entirely in
out-of-pocket repair expenses-to vehicle owners. The cost-effectiveness of
the basic idle CO program is better for CO than the conventional approach to
I/M and slightly worse for HC. An idle CO program, however, lends itself to
-------
several optimizations which will greatly increase the cost-effectiveness of
the program and will provide other unique benefits to vehicle owners. These
optimizations are described briefly in this section and example low cost. I/M
programs using these options are described in Section 1.3.
Overall, each enhancement option strives to increase the effectiveness and/or
cost-effectiveness of an idle CO I/M program. There are three basic methods
to achieve this goal: (1) achieve greater emission or fuel economy benefits
from each failing vehicle, (2) fail more of the vehicles which are inspected,
(3) inspect more vehicles in the I/M area. Each of the following options will
use one or more of these methods.
Better Test for 1981 and Later Vehicles
Although the basic idle CO I/M program provides the same CO benefit as a
conventional I/M program, there is a considerable shortfall in HC benefit.
One of the simplist ways to increase the HC benefit of idle CO programs is to
use an inspection test for 1981 and later vehicles which is more effective in
identifying vehicles with full-rich fuel system failures. This is discussed
in Section 7.1. Increasing the failure rate of these vehicles will provide
large HC and CO emission benefits for each repair dollar spent. Also, studies
have shown that repairs of vehicles with full-rich fuel system failures result
in a 15% fuel economy benefit.[6] The fuel savings from the repair more than
offset the expected average repair cost of about S30. Using the Two-Speed
Idle or Loaded Test for 1981 and later vehicles instead of the idle test is
expected to.increase the .identification rate of 1981 and later vehicles with
fuel system failures from 50% to 70%. Because at each inspection less than 5%
of 1981 and later vehicles are expected to have a fuel system failure, their
failure rate on the I/M test will still be only a few percent.
Table 2 presents the additional benefits associated with the use of a better
test for 1981 and later vehicles. When combined with the basic idle CO
program, the HC benefit is increased 2.4 percentage points from 24.2% to 26.6%
and the CO benefit increases 5.8 percentage points from 33.1% to 38.9%. The
averaged cost-effectiveness of the I/M program with this option is improved to
$527/ton for HC and &30/ton for CO (not shown in the table, but can be
calculated from the information in the tables). The overall HC benefit with
this enhancement alone is still less than for a conventional I/M program.
-------
Table 2
Better Test for
1981 and Later Vehicles2
in an Idle CO Program
Additional
Percent..
Benefit on
Dec. 31, 1987
H£ C£
2.4 5.8
Additional
Five Year
Emissions
Benefit
(Thousands of
Tons Removed)
HC CO
2.03 60.4
Additional
Five Year
Program Cost^
(Millions of $)
-5.05
Incremental
Cost-
Effectiveness
($/ton) of Option
NA3
1: Costs include additional repair costs less any fuel economy benefits from
repairs.
2: Using the Two-Speed Idle or Loaded Test instead of the idle test will
increase the identification rate of 1981 and later vehicles from 50% to
70%.
3: The 15% fuel economy benefit savings in fuel more than offset repair costs
for 1981 and later vehicles with full rich fuel system failures. Overall
program costs are reduced by the amount shown.
Increased Stringency . . .
Another way to improve the cost-effectiveness of an I/M program is to fail
more of the inspected vehicles. This can be done in an idle CO program by
increasing the stringency for pre-1981 vehicles. This is discussed in Section
7.2. This will not increase inspection costs but will increase overall repair
costs. Up to a point, the increase in stringency will result in increases in
HC and CO emission benefits at a lower incremental cost per ton than the basic
program, since the inspection costs have already been paid.
Table 3 presents the additional benefits from increasing the stringency in an
idle CO I/M program. The costs include only the costs resulting from
additional repairs. The basic idle CO program has already absorbed all of the
inspection cost. Note that increasing the stringency from 30% to 40% does not
substantially increase the HC and CO benefits but will cost as much as
increasing the stringency from 20% to 30%. This is the point where failing
more vehicles will result in less cost-effective emission reductions than in
the basic program. For this reason a stringency . of more .than 30% is not
recommended for an idle CO I/M program unless no other option to increase HC
and CO emission benefits is found acceptable. . +.*..'.,. . . ,,. .'. ..
-------
10
Table 3
Increasing Failure Rates
in an Idle CO Program
Got ion
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
Additional
Five Year
.Emission
. Reduction
(Thousands of
Tons Removed)
HC CO
Additional
Five Year
Program Cost*
(Millions of £)
Incremental
Cost-
Effectiveness^
($/ton)
HC CO
Higher Stringency for
Pre-1981 Vehicles
Increased from 13% to 20%
Increased from 20% to 30%
Increased from 30% to 40%
2.4 3.3
3.1 2.8
1.1 0.8
5.07
7.23
2.03
80.6
85.2
30.4
2.06
2.95
2.95
203 13
204 17
727 49
1: Costs include additional repair costs less any fuel economy benefits from
repairs.
2: Program costs are divided equally between the two pollutants.
Better Repairs for Pre-1981 Vehicles
Better repairs for pre-1981 vehicles deserve special attention primarily as a
cost-saving measure, although they are also an HC and CO enhancement. Better
repairs therefore deserve attention from any area considering an idle CO I/M
program, not just those that might need it as an HC or CO enhancement. Better
repairs for pre-1981 vehicles will produce fuel . economy savings on these
vehicles which will offset a large part of the cost of the I/M program.
EPA studies have shown that a fuel savings of 4% is achieved by carburetor
adjustments to pre-1981 vehicles which have failed an I/M test, even if the
adjustments are not performed precisely to specification. It is necessary
that adjustments be performed closer to specification than they would be in a
basic idle CO or conventional I/M program, and that other types of repairs
which can degrade fuel economy be avoided. Because carburetor adjustments
will usually be the only necessary repair for pre-1981 vehicles in an idle CO
I/M program, the types of repairs which can degrade fuel economy are naturally
avoided in this type of program. Section 4.4 describes a number of approaches
that I/M administrators can take to improve the quality of carburetor adjust-
ments, two of which are mechanic training and a. tight idle CO reinspection
cutpoint. The fuel savings which will result are well worth the effort, since
-------
11
an additional 4% savings for each pre-1981 vehicle which is failed and
repaired translates into a total annual savings of about £36. This offsets a
large part of the program costs. Also, a small improvement in the HC and CO
emission reductions accompanies the fuel savings. Section 7.3 discusses the
HC and CO benefits. The overall effect is a major further improvement in the
cost-effectiveness of the idle CO I/M program.
Table 4 presents the additional benefits of better repairs in an idle CO I/M
program. Once a stringency has been chosen, Table 4 will provide the
additional benefit that can be achieved with better repairs. For example in
the basic idle CO program with a 13% stringency the HC benefit in 1981 can be
increased 0.6 percentage points from 24.2% to 24.8% and the CO benefit can be
increased 2.7 percentage points from 33.1% to 35.8%. Overall costs can be
reduced $13.27 million as a result of fuel savings from repaired vehicles.
The result is an overall cost-effectiveness of $411/ton for HC and $22/ton for
CO (not shown in the table) . However, the HC benefit in 1987 from the basic
idle CO program with this option alone is still not as large as the HC benefit
of a conventional I/M program. One or more other HC enhancements are also
necessary to equal the HC benefit of a conventional program.
The benefits from better repairs for 1981 and later vehicles cannot be
estimated at present. It appears that the requirement for vehicles to pass
the reinspection test alone will force a high quality repair on these
vehicles, unlike the case for pre-1981 vehicles, leaving less room for
improvements via special programs of training, etc. This occurs because most
repairs to 1981 and later models involve parts replacement instead of
adjustments. . .
-------
12
Stringency
for
Pre-1981
Vehicles
(Percent)
13
20
30
40
Table 4
Better Repairs for Pre-1981 Vehicles
in an Idle CO Program
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
Additional
Five Year
Emission
Reduction
(Thousands of
Tons Removed)
HC CO
0.6
1.3
1.9
2.1
2.7
3.3
2.7
2.0
1.40
2.28
3.29
4.18
74.5
98.3
78.9
56.6
Additional
Five Year
Program Cost1
(Millions of $)
-13.27
-20.40
-30.60
-40.80
Incremental
Cost-
Effecti
(£/ton)
N/A
N/A
N/A
N/A
Costs include additional repair costs less any fuel-economy benefits from
repairs.
Since there is a net savings, no incremental cost-effectiveness has been
calculated. Overall program costs are reduced by the amount shown.
Tampering Checks
Table 5 presents the incremental benefits from the addition of tampering
checks to an. idle CO I/M program. These checks are discussed in detail in
Section 7.5. The costs shown in Table 5 are entirely repair costs, since none
of the tampering checks is expected to significantly increase the assumed
inspection costs. The checks may, however, pose administrative.problems which
can seem large to the I/M program managers.
As can be seen from the table, the air pump and evaporative cannister checks,
which consists of checking for the presence of these devices, are extremely
cost-effective. The incremental cost-effectiveness for the catalyst check for
the presence of the catalyst on all model year vehicles is higher than any
cost-effectiveness value presented so far in this summary, but is still lower
than for many non-I/M HC control strategies.[4] The cost of replacing missing
catalysts on older cars is the reason for the high cost-effectiveness value.
About 1.4% of vehicles originally equipped with catalysts have had them
removed. New OEM replacement catalysts cost from $172 to $320. If all
catalysts removed before the I/M program begins in 1983 are waived, and
catalyst presence is checked only for 1983 and later models from then on, only
very foolish vehicle owners would remove their catalysts knowing that they
will be checked. The repair costs for the. catalyst check would then be
insignificant.
-------
13
Table 5
Tampering Check Benefits
Dotion
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
Air Pump Check 1.5 4.3
Evaporative
Cannister Check 1.3 0.0
Catalyst Check
(All Vehicles) 0.9 0.5
Catalyst Check
(1983 and Later
Model Vehicles) 0.3 0.2
Additional
Five Year
Emission
Reduction
(Thousands of
Tons Retooved)
HC CO
2.56
1.94
68.0
0.0
1.35 10.7
0.20 1.6
Additional
Five Year
Program Cost*
(Millions of J>.
0.92
0.25
2.00
0.00
Incremental
Cost-
Effectiveness
($/ton)
HC _CO
180 7
129l/ -
741
93
NA4 NA4
1: Costs include any additional repair costs. '' . .
2: Program costs are equally divided between the two pollutants.
3: Since there is no CO benefit, all costs have been allocated to the HC
benefit. . ...... :.._ .... ... . . - ;;,i;.
4: Since there is no significant cost, no cost-effectiveness has been
calculated. ' . ' . .''' " : . ''' -'''. '="..-'". ^ "'.":-... "\:.'.:~ '.'"-'
Loose HC Cutpoints
Table 6 presents the additional benefits of including very loose idle HC
outpoints with an idle CO I/M program. . This option is discussed in detail in
Section 7.4. Data on vehicles with very high idle HC scores are very sparse
so that there is a very high degree of uncertainty in all estimates concerning
these vehicles. Section 7.4 does make some conclusions concerning these
vehicles, however, based on data and experiences with vehicles exhibiting
moderately high idle HC scores. ...
-------
14
Repairs of vehicles which fail only for idle HC in the Portland program ranged
in cost from zero to $207, averaging $41. These repairs range from cleaning
or replacing spark plugs to extensive ignition system diagnosis and replace-
ments. Program costs would be increased by the additional cost of these
repairs for any vehicles failing a high idle HC cutpoint used in an idle CO
program.
There is evidence, discussed in Section 7.4, that repair of severe spark
ignition misfire, which often causes very high idle HC measurements, can
result in substantial fuel economy benefits averaging from about 7% to 9%.
This would save vehicle owners who needed and received such repairs about $72
in fuel costs for that year.
Section 7.4 estimates that, in the best possible case, about half of the
vehicles which fail a 1000 ppm idle HC cutpoint will obtain a $72 fuel economy
benefit. The repair cost of $41 and the average fuel savings of $36
approximately cancel each other, so in the best case this op.tion has no net
effect on program costs. As Table 6 shows, there is an HC benefit. Repairs
for vehicles failing idle HC cutpoints in an idle CO program are not expected
to increase the CO benefit of the program.
Other factors, however, not considered above, may prevent the best case from
occurring and thus affect the cost of this option. There is reason to believe
that unnecessary repairs, essentially eliminated by use of only idle CO
cutpoints, can become a problem again if any HC cutpoint is used. In the
Port-land program there are, for example, ignition repairs performed on
vehicles which fail the idle test for only CO. Such ignition repairs are not
necessary,* but are sold to vehicle owners who are willing to allow mechanics
a free hand in performing repair to pass the reinspection. An idle CO program
without an HC cutpoint is expected to have very few instances of such
unnecessary repairs, since in virtually all cases the only necessary repair
will be a carburetor adjustment and vehicle owners can be readily made aware
of this fact. Including an idle HC cutpoint makes determination of which
repairs are necessary and which are not more unclear. The typical vehicle
owner will again be left essentially on his own in determining which repairs
should be performed. As a result, the amount of repairs performed, besides
carburetor adjustments, will likely be greater than what would be needed to
make cars which failed the HC cutpoint pass reinspection. These unnecessary
repairs will increase the program costs without significantly increasing HC
benefits. This will degrade the cost-effectiveness of this option. If, for
example, only 4% of the inspected vehicles receive unnecessary ignition
repairs (the same number as do need ignition repairs) and produce no
additional HC benefit, the cost per tori of HC for this option can climb from
essentially zero to over $3000/ton. Clearly, unnecessary .repairs can
drastically reduce the cost-effectiveness of. any I/M program. Section 3.0
discusses approaches which can be used to reduce unnecessary repairs.'
* This statement is possibly overly pessimistic, since it is possible that
ignition repairs performed by the mechanic which.would not have been necessary
to pass the I/M reinspection may prevent engine problems in the. future which
would cause an I/M inspection failure.
-------
15
Table 6
Loose Idle HC Outpoints
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
2.0 0.0
Additional
Five Year
Emissions
Benefit
(Thousands of
Tons Removed)
HC CO
2.59 0.0
Additional
Five Year
Program Cost^
(Millions of $)
0 - 8.98
Incremental
Cost-
Effectiveness
($/ton) of Option
0 - 3467
1:
Costs include additional repair costs less any fuel economy benefits from
repairs.
Inspection of Light-Duty Trucks
Table 7 presents the additional benefits from inspection and maintenance of
light-duty .trucks (LDT) as well as passenger vehicles. This option is
discussed in Section 7.6. Reduction in HC and CO emissions is not required of
LDTs under EPA policy, however any emission reductions gained from LDTs can be
used towards total emission reduction goals for passenger vehicles. Since the
technology used in most LDTs is very similar to that of passenger vehicles,
I/M for LDTs is very similar to I/M for passenger vehicles. A 4% fuel economy
benefit has been included for the cases of better repair of pre-1985 LDTs and
a 15% fuel economy benefit for 1985 and later LDTs. 'Starting in 1985,
light-duty trucks will have the types of emission controls used on 1981 and
later passenger cars.) Since use of a better test such as the Two-Speed Idle
or Loaded Test for 1985 and later LDTs effects very few LDTs by 1987, the
effect of selecting that option on the LDT benefits is insignificant. " .
*- niC* 1 t
-------
16
Table 7
I/M for Light-Duty Trucks
in an Idle CO Program
Stringency
for
Pre-1985
Vehicles
(Percent)
Basic
13
20
30
40
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
4.2
4.6
5.1
5.3
4.4
4.9
5.4
5.6
Additional
Five Year
Emission
Reduction
(Thousands of
Tons Removed)
HC CO
5.20
6.08
7.27
7.62
71.7
84.1
98.6
103.0
Additional
Five Year
Program Cost^-
(Millions of $)
3.34
3.53
3.77
4.02
Incremental
Cost-
Effectiveness ^
CO
38
35
33
33
HC
642
581
518
527
With Better
Repairs 3
13 4.3 4.9 5.58 84.1
20 4.9 5.6 6.61 100.0
30 5.6 5.9 8.11 111.4
40 5.8 6.0 8.58 113.6
2.29
1.86
1.25
0.62
410
281
154
72
22
15
9
5
1: Costs include additional inspection and repair costs less any fuel economy
benefits from repairs. These costs have been estimated from the
cost-effectiveness values, which in turn were assumed to be the same as
for passenger cars. ..._.. . . . ...
2: Program costs are equally divided between the two pollutants. These
values have been assumed to be equal to those for light-duty vehicles.
Once a stringency has been selected, only one row from the Table may be
used, determined by whether or not the program chosen will utilize
mechanic training or tight reinspection cutpoints.
3: These additional benefits correspond to basic idle CO programs using
tighter reinspection cutpoints or with full mechanic training programs.
-------
17
Exempting Pre-1975 Vehicles
Another way to improve the cost-effectiveness is to reduce the overall
inspection costs by inspecting fewer vehicles. This reduces emission
benefits, but they can often be restored by increasing the failure rate of the
remaining inspected vehicles and adding other options described in this
report. There is, of course, a limit to which this approach can be expected
to work. Restricting an idle CO program to only 1981 and later vehicles, for
instance, cannot be optimized to provide the same HC and CO benefit as a
conventional I/M program, even if all vehicles in need of repair could be
identified and repaired.
Table 8 presents the benefits of an idle CO I/M program which exempts pre-1975
vehicles from testing. An area requiring only CO reductions could use such a
program with a 30% initial stringency and receive as much CO benefit as a
conventional I/M program at a lower overall cost. Areas requiring reductions
in HC will find they must add even more options to their idle CO I/M program
if they are to achieve the same HC benefit as a conventional program. It is
possible however to achieve the same HC benefit as a conventional program with
an improved overall cost-effectiveness if enough cost-effective enhancements
are used. Since exempting pre-1975 vehicles will often reduce the effective-
ness of the options in reducing overall HC and CO emissions, Tables 9 through
12 have been calculated to be used with the results presented in Table 8. The
benefits for use of a better test for 1981 and later vehicles in Table 2 are
not affected by exempting pre-1975 vehicles and therefore can be combined
directly with the results in Table 8 if that option is desired.
Table 8
Idle CO I/M for 1975 and Later Vehicles Only
Stringency
for
1975-80
Vehicles '
(Percent)
Percent
Benefit on
Dec. 31, 1987
HO CO
Five Year
Emission
Reduction
(Thousands of
Tons Removed)
HC CO
Five ..Year1 .:
Program Cost
(Millions of
Cost- V ~.~ ."//,-
Effectiveness
($/ton) of Option 2
HC ' :' CO . -;; .-.,
13
20
30
40
22.4
24.3
26.6
27.5
28.6
31.6
34.0
34.7
29.26
32.87
38.08
39-81
435.7.
502.9
572.5
598.7
32.43
34.00
36.24
38.48
554'
.517
476'
483
37
34
32
32
1: Costs include, inspection fee and repair . costs less any. fuel economy
benefits from repairs. .
2: Program costs are divided equally between the two pollutants. - .
-------
18
Table 9
Better Repairs
in an Idle CO Program for 1975 and Later Vehicles Only
Stringency
for
1975-80
Vehicles
(Percent)
13
20
30
40
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
0.5 2.7
1.3 3.3
2.0 2.7
2.1 2.0
Additional
Five Year
Emission
Reduction
(Thousands of
Tons Removed)
HC CO
1.07 72.3
2.40 95.9
3.74 74.9
4.28 51.8
Additional
Five Year
Program Cost*-
(Millions of $)
-10.14
-15.58
-23.37
-31.16
Incremental
Cost-
Effectiveness2
($/ton)
NA
NA
NA
NA
Fuel economy benefits from repairs.
Since there is a net savings, no incremental cost-effectiveness has been
calculated. Overall program costs are reduced by the amount shown.
-------
19
Table 10
Tampering Checks
in an Idle CO Program for 1975 and Later Vehicles Only
Option
Air Pump Check
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
1.4
Evaporative
Cannister Check 1.2
Catalyst Check
(All Vehicles) 0.9
Catalyst Check
(1983 and later
models only) 0.3
3.9
0.0
0.5
0.2
Additional
Five Year
Emission
Reduction
(Thousands of
Tons Removed)
HC CO
1.78 49.0
1.43 0.0
1.35 10.7
0.20 1.6
Additional
Five Year
Program Cost
(Millions of
0.92
0.25
2.00
0.00
Incremental
Cost-
Effectiveness 2
($/ton)
HC_ C0_
258 9
1753
741
93
NA4
1: Costs include any additional repair costs. . ;
2: Program costs are equally divided between the two pollutants.
3: Since there is no CO benefit, all costs have been allocated to the HC
benefit. '-. ; .'-.'.. " ;" ' ':- -. " ;*v.';-" ."""
4: Since there is no significant . cost, no cost-effectiveness has been
calculated. '.;, - . .- . ". '- . .-..' '.
-------
20
Table 11
Loose Idle HC Cutpoints
in an Idle CO Program for 1975 and Later Vehicles Only
Additional
Five Year
Additional Emissions Additional Incremental
Percent Benefit Five Year Cost-
Benefit on (Thousands of Program Cost1 Effectiveness
Dec. 31, 1987 Tons Removed) (Millions of i) ($/ton) of Option
HC CO HC CO
1.9 0.0 2.42 0.0 0 - 8.39 ' 0 - 3467
1: Costs include additional repair costs less any fuel economy benefits from
repairs.
repairs
-------
21
Table 12
Idle CO I/M for 1975 and Later Light-Duty Trucks
Stringency
for
1975-85
LDTs
(Percent)
Additional
Percent
Benefit on
Dec. 31, 1987
HC CO
Additional
Five Year
Emission
Reduction
(Thousands of
Tons Removed)
HC CO
Additional
Five Year
Program Cost^
(Millions of $)
Incremental
Cost-
Effectiveness
($/ton) of Option2
HC CO
13
20
30
40
3.7
4.1
4.4
4.5
3.4
3.9
4.4
4.5
4.58
5.22
6.05
6.27
52.7
62.6
74.3
78.0
2.54
2.70
2.88
3.03
554
517
476
483
37
34
32
32
With Better
Repairs 3
13 4.0 4.0 4.96 64.4
20 4.4 4.5 5.79 77.6
30 5.0 4.9 6.92 86.2
40 5.1 4.9 7.27 87.6
1.82
1.51
1.07
0.60
367
261
154
83
22
15
10
"6
1: Costs include additional inspection and repair costs less any fuel economy
benefits from repairs. These costs have been estimated from the
cost-effectiveness values, which in turn were assumed to be the same as
for passenger cars. ... . . ; ;' . "...
2: Program costs are equally divided between the two pollutants. These
values have been assumed to be equal to those for "light-duty vehicles.
Once a stringency has been selected, only one row from the. .Table may be
used, determined by whether or not the program chosen will utilize
mechanic training or tight reinspection cutpoints. . . ' ,'.
3: These additional benefits correspond to basic idle CO programs using
tighter reinspection cutpoints or with full mechanic training programs.
-------
22
1.3 Example Designs For Low-Cost I/M Programs
The previous section of this report presented a number of options for reducing
the cost of an I/M program and for restoring its emission reduction effective-
ness when necessary. This section selects from among these options and
assembles them into two examples of low-cost I/M programs. The example
programs are tailored to two situations. Program A is an example for all
areas which need to obtain only CO reductions from I/M because they are
already in attainment with the ozone NAAQS or will attain it by 1982. Program
B is an example for areas which require HC reductions from I/M to attain the
ozone NAAQS.
The core of the two examples is the idle CO I/M program. Program B for areas
needing HC reductions incorporates HC enhancements, described in Sections 1.2
and 7.0. The examples both suggest improvements from Section 3.0 to reduce
further the incidence of unnecessary and inappropriate repairs. All
cost-effectiveness comparisons in this section use the conventional I/M
program described in "Update on the Cost-Effectiveness of Inspection and
Maintenance" [4] to represent a typical conventional I/M program and use the
methodology presented in that report. This methodology essentially consists
of accounting for all of the I/M costs and emission reductions for a five year
period from January 1, 1983 through December 31, 1987. Costs include
inspection and repair costs less any fuel savings from repairs.
I/M planners who. wish to construct their own example program may easily do so
using the information in Tables 1-7 or Tables 8-12. The stringency of the
program and whether pre-1975 vehicles will be inspected should be the first
tentative choice made; options should then be added in turn. When selecting
options, better repairs for pre-1981 ' vehicles (achieved through mechanic
training or stringent reinspection limits) and a better test for 1981 and
later vehicles should be considered first, since they yield net savings in
program costs. Then other options should be considered based on their
incremental cost-effectiveness, their ease of implementation and administra-
tion, and local preferences. If a satisfactory program in terms of emission
reduction benefits does not result, another choice regarding stringency and
inspection of pre-1975 vehicles should be made.
1.3.1 Example Program A; Areas Requiring Only Ambient CO Reductions
Example Program A has the following principal design features:
(l) Only 1975 and later model year vehicles are subject to mandatory
inspection and repairs.
(2) Idle CO cutpoints are chosen which will fail 13% of 1975 through 1980
model year vehicles at the initial inspection.[7]
(3) The Two-Speed Idle Test or Loaded Test for 1981 and later vehicles with a
1.2% cutpoint on both modes instead of the idle test. This will increase the
identification rate of vehicles with full rich fuel system failures from 50%
to 70%. Owners qualify for the Emission Performance Warranty .[3] if other
conditions are also met. -.'.. .
-------
23
(4) A stringent reinspection idle CO outpoint of 1.0% for 1975-80 vehicles.
This will force better carburetor adjustments resulting in significant fuel
economy benefits averaging about 4% as well as additional CO emission
reductions. (Similar results could be obtained using mechanic training
programs. However, it is difficult to reach every vehicle through mechanic
training because some commercial mechanics will not submit to training and
some vehicle owners will perform their own maintenance.)
(5) Any improvements from Section 3.0 which are -compatible with local
conditions.
Example Program A will produce somewhat greater CO emission benefit than, a
conventional I/M program or the basic idle CO program but with an improved
cost-effectiveness and a lower overall cost.. Table 13 presents the emission
benefit calculations for Example Program A.
Table 13 '
Comparison of Emission Reductions and Costs
of Example Program A and a
Conventional 20% Stringent I/M Program
Five Year
Percent Emission
Emission Reduction Five Year
. Benefit on (Thousands Program Cost Source
Program Dec. 31, ,1987 of Tons) (Millions of &) (Section 1.2)
HC CO HC CO
CONVENTIONAL I/M
PROGRAM:
(20% Stringency,; idle
test for 1981 and later
vehicles)
EXAMPLE PROGRAM A:
0 13% Stringent. Idle
CO I/M exempting
pre-1975 vehicles
0 More Effective Test
for 1981 and later
vehicles
0 Tight idle CO
reinspection cutpoint
for 1975-80 vehicles
Program A Totals
34.9
33.1 46.50 526.8
54.10
Table 1
22.4 28.6 29.26 435.7 . ..32.43 7
2.4
0.5
5.8
2.7
2.03 60.4
1.07 72.3
25.3* 37.1 32.36 568.4
-5.05
-10.14-
17.24 -V
-.Table 8 '
Table 2
Table 9
* Note: This example is not equivalent to a conventional I/M
program in regards to HC benefit. .
-------
24
From Table 13 it is simple to calculate .the overall program cost-effectiveness
of Example Program A in reducing CO emissions. The total five year program
costs are divided by the total five year CO emission reductions resulting in
an overall CO cost-effectiveness of &30 per ton. This is about a third the
cost per ton for CO of the conventional I/M program. Table 14 compares the
benefits and cost-effectiveness of conventional I/M, the basic idle CO I/M
program, and Example Program A.
Table 14
Comparison of I/M Programs for
Areas Requiring Only CO Reductions
CO Emission Benefit on Cost-Effectiveness*
Program December 31, 1987 (S/.Ton. CO)
Conventional I/M . 33.1 102
Basic Idle CO I/M 33.1 76
Example Program A 37.1 30
* All costs have been allocated to the CO benefits.
It may be of interest to point out that since the fuel savings from repairs
more than offset repair and inspection costs when tight reinspection cutpoints
(or mechanic training programs) are incorporated in the idle CO program,
increasing the failure rate for pre-1981 vehicles over the 13% used in Example
Program A would actually reduce the overall cost of the program and the cost
per ton of CO. For example if the stringency in Example Program A were
increased to 20%, equal to the stringency of the conventional I/M program, the
CO emission benefit on December 31, 1987 would be increased to 40.7%
eliminating 659.2 tons, of CO during the five year period. The total program
cost, including the fuel savings, would be reduced to $13.37 million resulting
in a cost-effectiveness of $20/ton of CO. It has been assumed in this example
that there are local reasons for keeping the failure rate as low as possible
and that there is no need for CO benefits beyond the minimum required amount.
1.3.2 Example Program B: Areas Requiring HC Reductions
In areas requiring HC reductions, HC enhancement options from Section 7.0 (and
described briefly in Section 1.2) are necessary to make idle CO I/M an
acceptable substitute for conventional I/M. Since all of the HC enhancements
combined would more than fully compensate for the loss in HC reduction which
occurs from eliminating the HC cutpoints, I/M planners can choose among the
enhancements based on convenience, practicality, and local preferences. There
will be no need for CO emission enhancements, although many of the HC enhance-
ments will also increase CO benefits. The centralized or decentralized
-------
25
formats will make some of the enhancements more convenient and practical than
others. High failures rates are not desirable, for example, in a centralized
program since each failure implies a fair degree of inconvenience to owners
who must make two trips as a result, one to a repair facility and another back
to the inspection station. On the other hand, using a tighter CO reinspection
cutpoint to force higher quality carburetor adjustments would be quite simple
in a centralized program. Tampering checks are also appropriate in a
centralized program. It is easier to train the relatively few centralized
inspectors to perform tampering checks than it would be to train every
operator of a licensed inspection station in a decentralized program. The
example program described below is just one possibility. The reader should
have no difficulty in constructing other examples. All that is necessary is
to select a combination of HC enhancements, which will restore HC effectiveness
back to that of a conventional program.
Example Program B has the following principle design features:
(1) All model year vehicles 1968 and later are inspected.
(2) Idle CO cutpoints which will fail 30% of pre-1981 vehicles at the initial
inspection.[7]
(3) A reinspection cutpoint of 1.0% CO for pre-81 vehicles. This will achieve
the same effect as a mechanic training program that reaches every vehicle.
(4) The Two-Speed Idle Test or the Loaded Test for 1981 and later vehicles
with a 1.2% CO cutpoint on both modes, increasing the identification rate
of high emitters among these vehicles. Owners of 1981 and later vehicles
qualify for the Emission Performance Warranty [3] if other conditions are
also met.
(5) An air pump inspection.* As described in Section 7.5.2, this is a simple
check to perform. Although an air pump check will require opening the
engine compartment, this check is prefered over other simple checks such
as a catalyst check because the low expected cost of repair of air pump
disablements. The extra time needed to open the hood will be unimportant
in a decentralized program. . , ,-... _;. ..>..-.-. ->., i" '. '-, : -
(6) Improvements from Section 3.0 which are compatible with local conditions.
Example Program B is approximately equal in HC reduction effectiveness and
exceeds the CO reduction effectiveness of a conventional I/M program with a
20% stringency for pre-1981 vehicles. This \is illustrated, in : Table 15.
Although the pre-1981 failure rate in Example Program B is half again as large
as in the conventional I/M program, the much lower per-vehicle repair cost and
fuel savings will result in a less costly program overall. This is illustrat-
ed in Table 16. . . : .. '%'..' -
* Any one of the three tampering checks (catalyst, air pump, evaporative
control) described in Section 7.5 could be used in this example. Tampering
checks for air pumps and evaporative- emission control systems would require
opening the engine compartment hood on all vehicles. Program B as described
here would require the hood to be opened on 1981 and later vehicles anyway if
the Two-Speed Idle Test is used instead of the Loaded Test. -; - . .
-------
26
Table 15
Comparison of Emission Reductions and Costs
of Example Program B and a
Conventional 20% Stringent I/M Program
Program
CONVENTIONAL I/M
PROGRAM:
(20% Stringency, idle
test for 1981 and later
vehicles)
EXAMPLE PROGRAM B:
0 Basic Idle CO I/M
0 More Effective Test
for 1981 and later
vehicles
0 Increased Pre-1981 .
Stringency
-13% to 20%
-20% to 30%
0 Tight idle CO
reinspection cutpoint
for'pre-1981 vehicles
0 Air pump disablement
check
Five Year
Percent .^Emission
Emission Reduction Five Year
Benefit on (Thousands Program Cost Source
Dec. 31, 1987 of Tons) (Millions of t) (Section 1.2)
HC CO HC CO
34.9 33.1 46.50 526.8
54.10
24.2 33.1 31.31 526.8 40.19
2.4 5.8 2.03 60.4 -5.05
Table 1
Table 1
Table 2
2.
3.
1.
1.
4
1
9
5
3.
2.
2.
4.
3
8
7
3
5.
7.
3.
2.
07
23
29
56
80.
85.
78.
68.
6
2
9
0
2.
2.
-30.
0.
06
95
60
92
Table
Table
Table
Table
3
3
4
5
Program B Totals
35.5
52.0 51.49 899.9
10.47
-------
27
Table 16
Cost-Effectiveness Comparison
Between Example Program B
and a Conventional I/M Program
With CO and HC Cutpoints
Program HC Cost-Effectiveness* CO Cost-Effectiveness*
Conventional I/M $581/ton $51/ton
Example Program B $102/ton $ 6/ton
* Some areas which are implementing I/M to achieve HC reductions are doing so
only for that reason, i.e., they do not need CO reductions. In such cases,
since the costs are equally distributed between the two pollutants in this
table, the HC cost-effectiveness number would-be doubled.
1.3.3 Example Program C: Maximum Benefit Program
As an exercise to demonstrate the maximum potential benefits of an idle CO
program and as a method to show how to apply each of the Tables in Section
1.2, Example Program C will use all of the emission enhancements discussed in
this report. -
Example Program C has the following principle design features: ' " " -: -
(l) All model year vehicles 1968 and later are inspected. ' ^- - ~" :.- .;-.;.
(2) The Two-Speed I'dle Test or Loaded Test for 1981 and later passenger
vehicles and 1985 and later light-duty. trucks with a 1.2% CO cutpoint in both
modes increasing the identification rate of high emitters among these
vehicles. Owners of 1981 and later vehicles qualify for the Emission
Performance Warranty [3] if other conditions are also met. . :.. .;
. ' " . . . _. '..-'.' -- /. --'' 3, : , ;' -;
(3) Idle CO cutpoints which fail 30% of pre-1981 vehicles at the initial
inspection.[7] Although a 40% stringency program would provide greater
benefits, 30% is probably closer to what most I/M programs consider desirable
as a failure rate. . : .. '. ..". .-.
(4) The reinspection cutpoint of 1.0% CO for pre-1981 passenger car and
pre-1985 light-duty trucks. This will achieve the same effect as a mechanic
training program that reaches every vehicle.
(5) An air pump check. :. .
-------
28
(6) An evaporative cannister check.
(7) A catalyst check for all inspected 1975 and later passenger cars.
(8) An idle HC inspection cutpoint of 1000 ppm.
(9) Inspection and maintenance for all light-duty trucks below 8500 Ibs. GVW.
Example Program C achieves a 45% HC benefit and a 58% CO benefit, much larger
than the conventional I/M program with a 20% stringency. This is illustrated
in Table 17. The cost-effectiveness of Example Program C is calculated and
presented in Table 18. These cost-effectiveness values are slightly more than
for Example Program B, but are still well below the conventional I/M program.
-------
29
Table 17
Comparison of Emission Reductions and Costs
of Example Program C and a
Conventional 20% Stringent I/M Program
Program
CONVENTIONAL I/M
PROGRAM:
(20% Stringency, idle
test for 1981 and later
vehicles)
EXAMPLE PROGRAM C:
0 Basic Idle CO I/M
0 More Effective Test
for 1981 and later
- vehicles
0 Increased Pre-1981
Stringency
13% to 20%
20% to 30%
0 Tight idle CO
reinspection cutpoint
0 Air pump check
0 Evaporative System
check
0 Catalyst Check
0 Loose HC cutpoint
0 Light-Duty Truck I/M
Percent
Emission
Benefit on
Dec. 31, 1987
HC CO
Five Year
Emission
Reduction
(Thousands
of Tons)
HC CO
Five Year
Program Cost
(Millions of $)
Source
(Section 1
.2)
34.9
24.2
2.4
33.1 46.50 526.8
54.10
33.1 31.31 526.8
5.8
2.03 60.4
40.19
-5.05
Table 1
Table 1
Table 2
2.
3.
1.
1.
1.
0.
2.
5.
4
1
9
5
3
9 :
0
6
3
2
2
4
0
'-..- 0
o
.. 5
.3
.8
.7
.3
.0
.5
.0
.9
5.
7.
3.
2.
1.
1.
2.
8.
07
23
29
56
94
35
59
11
80.
85.
78.
68.
0.
10.
0.
111.
6
2
9
0
0
7
0
4
2.
2.
-30.
0.
0.
2.
0.
1.
06
95
60
92
25
00
0
25 .
Table
Table
Table
Table
Table
Table
Table
Table
3
3
4
5
5
5
6
7
Program C Totals
45.3 58.4 65.48 1022.0 13.97
-------
30
Table 18
Cost-Effectiveness Comparison
Between Example Program C
and a Conventional I/M Program
Pro gram' HC Cost-Effectiveness* CO Cost-Effectiveness*
Conventional I/M $581/ton $51/ton
Example Program C $107/ton $ 7/ton
* Some areas which are implementing I/M to achieve HC reductions are doing so
only for that reason, i.e., they do not need CO reductions. In such cases,
since the costs are equally distributed between the two pollutants in this
table, the HC cost-effectiveness number would be doubled.
-------
31
2.0 BACKGROUND ON CONVENTIONAL I/M PROGRAMS
Since 1972 when New Jersey added emission analyzers to its safety inspection
stations, I/M has existed as a feasable, effective means to reduce in-use
emissions from automobiles. Congress added T/M to the requirements of the
Clean Air Act Amendments in 1977 as a reasonable and required air pollution
control strategy for those urban areas with serious air quality problems. In
all, 30 states are expected to implement some type of I/M by 1983. Some
states, such as Oregon, Arizona, and Rhode Island have already begun emission
inspection programs. These current programs, while differing from state to
state, do have many features in common. This section will describe what can
be called a "conventional" I/M program which best describes the type of
program now being used in those states with operating I/M programs. Following
sections will describe low-cost approaches to I/M primarily by noting the
aspects in which they differ from conventional I/M programs.
2.1 Inspection and Reinspection
All currently operating programs[8], both centralized and decentralized, use
an emission analyzer to measure the concentrations at idle and/or at a cruise
mode (usually only at idle) of hydrocarbons (HC) and carbon monoxide (CO)
coming from the tailpipe(s) of vehicles subject to inspection. These
measurements are compared to standard levels (cutpoints) for each pollutant
established for each vehicle age and type by the state or local agency
responsible for the program. If the measurement of either pollutant exceeds
its cutpoint, then that vehicle fails the test. The percent of vehicles which
fail the emission inspection is refered to as the failure rate. This failure
rate is typically 20 to 30 percent. The state or local agency can adjust the
program failure rate by adjusting' the cutpoints to fail more or fewer .
vehicles. Vehicles which fail the emission inspection must receive enough
repairs to reduce their emissions below the program cutpoints and pass a
reinspection. The reinspection cutpoints are identical to the original
inspection standards. Most failed vehicles pass tbe reinspection test on
their first try. : .
: . ' ' ' ' '. ' . ''. " '' /*
There are several ways to provide for inspection facilities. Decentralized
programs utilize existing repair facilities which are licensed to perform
emission inspections and reinspections. Centralized programs involve use of
facilities dedicated to high-volume, emission testing with repairs performed
elsewhere. These centralized facilities can either be operated directly by
the state, by a single contractor, or by multiple private companies under
licenses from the state. States should not feel constrained to use only these
options. New Jersey combines advantages of centralized and decentralized
approaches in their I/M program. All vehicles are inspected initially at
state-run centralized inspection facilities. Those vehicles which fail have
the option of either returning to the centralized facility for a- reinspection
or having the reinspection performed at a licensed repair facility. This
allows the reinspection to be performed where the repairs are performed in
some cases eliminating a trip back to the centralized inspection . facility
without loading the repair service industry with the initial inspection task.
-------
32
The inspection requirement is enforced either by withholding registration from
vehicles which have not passed their inspection or reinspection or by issuing
special stickers to cars when they pass the inspection and issuing citations
to cars with missing or expired stickers.
2.2 Types of Repairs Performed
In the majority of cases it has been found that a simple carburetor adjustment
on pre-1981 vehicles can reduce the idle emissions of HC and CO from most
vehicles sufficiently to pass the reinspection cutpoints used in operating
programs. When a carburetor adjustment alone is not enough to reduce both CO
and HC idle emissions to pass the program cutpoints then in many cases other
simple repairs like new spark plugs or a new air filter element can provide
the additional nece.ssary reductions. Other repairs may also be performed in
the same visit to the repair facility, at either the owner's or the mechanic's
initiative. Table 19 lists the frequency of various types of repairs done on
pre-1981 vehicles as observed in the Portland I/M program. Carburetor
adjustments are by far the most common repair.
Table 19
Typical Repairs Performed on Vehicles Failing
the Oregon State Inspection Test
Model Year Model Year
1972-74 Vehicles 1975-7? Vehicles
Total Number of Cars 95 252
Were the following items repaired, replaced, or adjusted? (yes)
Spark Plugs 35.8% 25.4%
Spark Plug Wires 14.7% 11.9%
Points and Condenser 31.6% 5.6%
Distributor Cap and Rotor 17.9% 6.3%
Spark Timing Control Devices 13.7% 10.3%
Carburetor (Idle Mixture Adjustment) 87.4% 89.3%
Choke 48.4% ' 21.8%
Intake System . 5.3% 4.0%
Air Filter 31.6% 31.0%
Engine Oil 21.1% 15.1%
Idle Speed ' 48.4% 73.4%
Timing -'-9.5% '^.02
Dwell 41.1% 26.6%
Air Injection System 5.3% 3.2%
EGR System 6.3% 4.8%
PCV System 6.3% " 7.5%
Valves 7.4% 0.8%
-------
33
2.3 Cost of Repairs
Average repair costs on pre-1981 vehicles h'ave be.in reported to be as low as
$18.71 per failed vehicle in the New Jersey program and as high as $35.00 per
failed vehicle in the Los Angeles program.[8] An analysis of repair costs in
1979 in the Portland, Oregon I/M program[9] showed an average repair cost of
$22.00 with half of the repairs costing less than $14.00. (Over 44 percent of
the collective repair bill was due to the 13 percent of the failed cars that
had repair costs more than $50.00.) These low average and median costs are
significant since the Portland program has the most stringent cutpoints of all
operating programs.
The low average cost of typical I/M repairs on pre-1981 model year vehicles is
a reflection of the simple adjustments necessary in most cases to reduce a
vehicle's emissions sufficiently to pass the reinspection test.
-------
34
3.0 REDUCING REPAIR COSTS BY REDUCING INAPPROPRIATE AND UNNECESSARY REPAIRS
Most persons in the service industry are sincere in their efforts to provide
effective, low-cost I/M repairs 'to their customers. However, the service
industry is not perfect. Problems can occur which cause repair costs to
owners to be higher than they would need to be. Some problems result from a
lack of knowledge in the repair industry of proper diagnosis and repair
procedures for emission related components and systems. Misdiagnosis and
ignorance of proper repair procedures can lead to (1) replacement of parts
which have not failed, (2) unnecessary adjustments, (3) multiple repair trips
to finally correct the emission problem, (4) continued non-compliance with
emission inspection standards possibly requiring a waiverj and (5) encouraging
the vehicle owner to attempt to acquire a certificate of compliance without
completing necessary emission repairs (cheating). In addition, there may also
be some cases where (1) a mechanic will knowingly perform more repairs than
necessary to pass the emission inspection, some of which would not be
considered necessary or useful by any standard, (2) the vehicle owner will be
persuaded to purchase services the owner would not have sought otherwise
(i.e., brake job, lube, wiper blades, tires, etc.), (3) higher rates will be
charged for the repairs than can be justified by the parts and labor costs,
and (4) when the emission inspection is performed in the service facility, as
in decentralized programs, the vehicle may be deliberately failed incorrectly
to generate repair business.
These potential problems increase the repair cost'vehicle owners must pay and
reduce the cost-effectiveness of the I/M program. It is not possible to
determine exactly how frequently these problems may occur, but it is necessary
to consider the possibility of these problems in the overall design of an I/M
program. If these problems can be made less frequent, the cost of the I/M
program can be reduced.
3.1 Improvement 1: Mechanic Training
The most straightforward way to deal with problems associated with emission
repairs is to assure that mechanics are able to diagnose the problem and
perform the repairs correctly, and that they are aware of the benefits to
their customers and their business of correct diagnosis and repair of emission
related problems. With this information conscientious mechanics will be
better able to avoid any unnecessary or inappropriate repair work during
emission related repairs.
3.1.1 Mechanic Training Courses
A short, practical course has been designed by the National Center for Vehicle
Emissions- Control and Safety of Colorado State University (CSU) which provides
mechanics with the basics of diagnosis and repair for vehicles failing I/M
test cutpoints. The course was designed to be a maximum of 16 hours in length
and could, for example, be taught over several evening sessions. A program to
provide this course or a similar course to all mechanics who will perform
emission repairs will improve the knowledge of the service industry in vehicle
emission control. In addition, EPA is convinced that mandatory mechanic
-------
35
training can result in increased, emissions reductions and fuel savings from an
I/M program.
3.1.2 Information Distribution
Another, less ambitious, method to inform mechanics of proper I/M diagnosis
and repair procedures is to include advice to the mechanic directly on the
inspection form. The advice would take the form of a list of the repairs
which are most likely needed based on the type of I/M failure (HC-only,
CO-only, or both). Table 20 is an example of the type of advice which can be
included on the inspection forms. (A portion of the advice in Table 20 is
specific to pre-1981 vehicles, but corresponding advice can be developed for
1981 and later vehicles.) In this way the mechanics who will actually perform
repairs will have diagnosis and repair information available to them at the
time of repair. This information can be supplemented by a full-scale training
program or by distribution of more detailed I/M diagnosis and repair manuals.
-------
Table 20
Diagnostic Advice for Use on Inspection Forms
For each emission problem condition, perform the checks and maintenance in the
sequence as listed until the idle measurements for both HC and CO are
sufficiently below the idle emission standards to assure passing a
reinspection.
Condition: Fail Both Idle HC and Idle CO.
Diagnosis: Begin with the maintenance described to correct the idle HC
problem. When the idle HC measurement is acceptable, begin
performing maintenance described to correct idle CO problems as
necessary.
Condition: Fail Idle HC.
Diagnosis: 1. Improper Ignition Timing: Compare with manufacturers
specification.
2. Faulty Ignition or Misfire: Check for arcing or disconnected
wiring, fouled or damaged spark plugs and insufficient spark
voltage.
3. Vacuum Leaks: Check for damaged, missing, or disconnected
hoses and check for leaks around the intake manifold and base on
the carburetor.
4. EGR System Incorrectly Operating at Idle: Check for proper
valve operation.
5. Idle Speed Set Too Low: Compare with manufacturers
specification.
6. Air/Fuel Mixture Set Too Lean: Check or set using
manufacturers specified procedures. Check the balance in two and
four barrel carburetors.
7. Worn Piston Rings or Valves: Perform compression check.
Condition: Fail Idle CO. . - ...
Diagnosis: 1. Dirty Air Filter: Clean or replace if necessary.
2. Choke Stuck: Check for proper operation and adjustment.
3. PCV Svs tern'PI ugged: <"heck valve and hose.s for restriction.
4. Air Pump and Control Valve Inoperative: Check belt, bypass
valve, hoses, etc.
5. Idle Speed Set Too Low:
specification.
Compare with manufacturers
6. Air/Fuel Mixture Set Too Rich:
manufacturers specified procedures.
Check
set using
-------
37
3.1.3 Problem Facility Identification
If those mechanics who are most in need of emission repair training can be
identified, then the training effort can be more effectively focused on this
smaller number of individuals. These repair facilities can be identified by a
survey of vehicle owner complaints, average repair costs, or waiver rates for
service facilities performing emission repairs. Those facilities which
deviate the most from the norm could be required or encouraged to send their
mechanics for training. This approach could be used as a method to eventually
train all the service industry, starting with those most in need of training.
3.2 Improvement 2: Public Awareness
One simple way to protect vehicle owners from inappropriate or unnecessary
repairs is a strong public awareness program. This effort should be aimed at
telling the vehicle owner what repairs are appropriate for his/her vehicle
given it has failed the I/M test in a certain way (HC, CO, or both) and what
charges are reasonable for these repairs. This information can be included on
the inspection form. Armed with this information, vehicle owners would be
better prepared to enquire about and understand the type of repairs mechanics
propose to make and to know better to refuse any unnecessary repairs.
3.3 Improvement 3; Price Competition
The repair industry may take advantage of the lack of information about
appropriate repairs and their costs in the beginning of a mandatory I/M
program to sell repairs at inflated prices.
An effort could be made as part of the I/M program to encourage comparison
shopping by vehicle owners in need of emission repairs. Repair facilities
could be encouraged to advertise their fees for various emission related
repairs and give accurate estimates of possible repair costs. This
information could be made mandatory. The program could also publish the
average repair costs from each facility at frequent intervals to promote price
competition by repair facilities and comparison shopping by vehicle owners.
3.4 Improvement 4: Automated Analyzers '".-. . :.'-;» S'l:'L:.4.-".^ : . ' -'
In decentralized programs, the possibility of vehicles_being deliberately
failed incorrectly to increase a service facility's repair business is a worry
to some vehicle owners. Even if the instances of such dishonest}' are few, the
bad publicity and distrust such instances wi 1.1 generate should be avoided.
All decentralized programs should have some method to respond to consumer
complaints about specific instances of fraud and should also conduct auditing
and surveillance programs to detect other instances. However, "any method
which can make fraud more difficult from the start is also desirable.
Computerized emission analyzersflO] offer a new tool for a decentralized
program to reduce errors in the passing and failing of vehicles in an I/M
program. These sophisticated analyzers are less prone to improper use. These
analyzers can make it nearly impossible for a service facility to deliberately
fail a vehicle incorrectly if the vehicle owner at least makes .certain that
-------
38
his own vehicle is being tested by the analyzer. These instruments can also
reduce administrative costs by automating data collection and reducing the
amount of program auditing required. With an automated analyzer, the audit
period can be lengthened from one to three months, with a corresponding
reduction to the number of auditors which are required!11].
EPA has been impressed by the performance and possibilities inherent in
computerized emission analyzers for decentralized I/M programs, and recommends
their use over the traditional garage analyzers. In addition, to make it
feasible for I/M programs to acquire these analyzers, additional lead time for
implementation of a decentralized I/M program using them may be granted if
requiredfl1].
3.5 Improvement 5; Challenge Stations
"Challenge Stations" are state-operated or closely supervised emission
inspection stations which can be used by vehicle owners to verify their
inspection results received at private garages in a decentralized program.
These challenge stations will allow vehicle .owners who are suspicious of the
results they have received from their emission inspection at private garages
to be retested by the state before they invest in emission repairs.
Challenge stations increase confidence in the fairness of the I/M program and
provide a means to identify inspection stations which are incorrectly failing
vehicles through incorrect testing procedures, poor equipment maintenance, or
deliberately. By reducing the number of incorrect failures, total repair
costs to owners will be reduced. These stations also provide a means for
distribution of public awareness material directly to vehicle owners 'most
concerned about the program.
Because of the importance of the challenge function, EPA requires some form of
it in any decentralized I/M program. In this sense, challenge stations are an
essential part of a conventional I/M program and not an optional improvement.
However, an I/M program does have the option of placing far more emphasis on
the challenge function than required by EPA.
3.6 Impacts on Costs and Emission Reductions
None of the improvements outlined .in this section will decrease emission
reductions from the I/M program. Indeed, mechanic training programs can
increase emissions reductions. They will reduce the costs of the program to
the motoring public, and thus improve the overall cost-effectiveness of the
program. The size of the cost savings cannot be quantified, hut it is
reasonable to assume it will outweigh the administrative costs to the I/M
program of implementing the improvements.
3.7 Conclusions
All of the improvements outlined in this section can be applied in one form or
another to any I/M program including any "conventional" I/M program and
should be considered whether the program is being designed, implemented, or is
already operating.
-------
39
4.0 I/M FOR PRE-1981 VEHICLES USING ONLY IDLE CO OUTPOINTS
4.1 Description and Summary of Impacts
The improvements described in Section 3.0 attempt to reduce I/M costs by
reducing the number of inappropriate, unnecessary, and ineffective repairs.
Such repairs constitute "fat" in a conventional I/M program and can be cut
without reducing program effectiveness. Further reduction in I/M costs can be
achieved only by eliminating some properly performed repairs that are
appropriate in a conventional I/M program and which do produce useful emission
reductions; this is cutting "lean" from the I/M program. Clearly, the
objective of such cuts should be to eliminate or reduce types of repairs that
are costly in relation to the emission reductions they produce (less
cost-effective) and to maintain or even increase repairs which are cheap in
relation to their emission reductions (more cost-effective).
The number and types of repairs which are appropriate in a conventional I/M
program are determined by the design of the program, specifically by the
inspection and reinspection test procedure and cutpoints. Consequently, the
only approach which might have the effect of reducing the number of less
cost-effective repairs is to modify the test procedures or the cutpoints.
This section examines one such modification: simply eliminating the idle HC
cutpoint and retaining only the idle CO cutpoint, with no change in the idle
test procedure itself. An I/M program with this modification will be referred
to as an idle CO I/M program. The goal of using only an idle CO cutpoint is
to virtually eliminate the occurrence of all repair types other than idle
mixture and speed adjustments, because idle mixture adjustments appear to be
the most cost-effective type of repair in a conventional I/M program for
pre-1981 vehicles. .
Idle mixture and speed adjustments can be performed cheaply, because there is
no need for diagnosis beyond the results of the idle test itself and no
replacement parts are needed. This is in contrast to most other types of I/M
repairs (excluding perhaps spark timing adjustments), particularly ignition
system repairs, in which time .consuming diagnosis is needed to pinpoint the
exact problem and the fix involves installing a replacement- part such as a set
of spark plugs or wires, a distributor cap, or-a new vacuum hose."'-"; -;---:~-~~
In addition to being relatively inexpensive, idle mixture adjustments produce
very sizable emission reductions for both HC and CO on catalyst-equipped
vehicles. On such vehicles, a rich idle mixture maladjustment causes the
engine to produce higher concentrations of HC and CO. .It also depletes oxygen
from the engine's exhaust, so the catalyst is less able to convert the HC.and
CO to harmless C07 and water vapor. Correcting the idle mixture " therefore
has a two-fold effect in reducing HC and CO emitted at the tailpipe.*' -
* On cars without catalysts, i.e. ,. those sold before 1975, an idle mixture
adjustment also has a large effect on CO but its effect on HC'is much less.
. ' . . -( ..-;...>'- -'. . -;' ......... TO--- # »-.. « i - " - _, .-i
re
-------
40
Table 21 shows a number of examples illustrating how effective idle mixture
adjustments are for catalyst vehicles which have failed idle HC and/or CO
cutpoir.ts. The examples differ from one another with respect to how the
samples were selected and the procedure used in the idle mixture adjustment;
the specific details for each example are given in footnotes to the Table.
All of the examples support the general effectiveness of this type of repair.
Reductions in FTP HC range from 34.1% to 55.6%. Reductions in FTP CO range
from 51.8% to 71.5%. For comparison, Table 21 also presents the results
achieved by the typical mix of "conventional" I/M repairs performed by field
mechanics in the Portland I/M program.
Eliminating repairs other than idle mixture adjustments will decrease the HC
emission reductions of an idle CO I/M program compared to a conventional I/M
program. Not all of the HC reductions are lost, since idle mixture
adjustments account for some of the HC emission reductions in a conventional
I/M program.
The fuel economy aspects of an idle CO I/M program will also differ from those
of a conventional I/M program, because of the differences in the types of
repairs performed. Proper correction of a rich idle mixture maladjustment
should always improve fuel economy. If there are no other repairs performed
which can decrease fuel economy, a net fuel savings should result from the I/M
program.
The following sections examine in more detail the issues of repair types and
costs, emission reductions, and fuel economy improvements in an idle CO I/M
program. The conclusions from these sections can be summarized as follows:
Repair Types and Costs - Virtually all cars which fail inspection in an idle
CO I/M program will be capable of passing the reinspection after having
received only an idle mixture adjustment. The average repair cost is expected
to be $6 to $10, compared to the range of $18.71 to $35 in the currently
operating conventional I/M programs. There will also be a reduction in the
failure rate, since cars will no longer fail for high HC emissions. Together
these two changes will have a large impact on the overall cost of the I/M
program. The total repair cost for pre-1981 cars will be reduced by about
70%, which will in turn reduce the overall cost of a typical I/M program by
19% during the period from 1983 through 1987.
-------
41
Table 21
Emission Reductions
From Carburetor Adjustments
(1975-1980 Model Year Vehicles)
Program
FY77
Emission Facto'r*
Program
Portland Study2
Carburetor Repairs
Only
Houston Program-^
Study
Houston Program^
Study
Restorative
Maintenance^-
FY79 EF
Program^-
Portland Task
Group
Portland Study&
Vehicles
Receiving
Adjustments
(54)
(76)
(97)
(97)
(95)
(43)
(31)
FTP
Pollutant
HC
CO
HC
CO
HC
CO
HC
CO
HC
CO
HC
CO
HC
CO
., ~
Before
Carburetor
Adjustment
(g/mi)
2.75
42.2
2.50
39.4
3.54
59.7
3.54
59.7
2.13
41.1
1.93
28.4
3.26
. 47.5 -
.* . "... .
Conventional
After
Carburetor
Adjustment
(g/mi)
1.43
14.6
1.65
19.0
1.57
20.9
1.87
26.5
1.09
11.7
1.27
13.7
1.90
. 20.6 ': /
V '. : . . - " . . ...
Percent
Change
48.0
65.4
34.1
51.8
55.6
65.0
47.2
55.6
48.8
71.5
34.2
51.8
41.8
:56.7 ..
T d
I/M (for comparison)
(310)
CQ
2.82 : 1.56 , . ;44.7
39.63 -- .19.72 -. ..- :' 50.2
1: Carburetor adjustment performed by contractor mechanics to manufacturer
specifications. Idle HC cutpoint: 225 ppm; Idle CO cutpoint: 1.0% . '
?.: rarburetor repairs performed by field mechanics. Vehicles failing Oregon
DEQ outpoints. .
3: Carburetor adjustment performed by contractor mechanics to manufacturer
specifications. Vehicles failing Houston Program cutpoints.
4: Idle mixture adjusted so that idle CO is 0.5%. Vehicles failing Houston
Program cutpoints.
5: Idle mixture adjusted so that idle CO is 0.2%. Vehicles failing Oregon
DEQ cutpoints.
6: Typical mix of conventional I/M program repairs. Vehicles failing Oregon
DEQ I/M inspection presented here for comparison. ~,--....,:,-<-. ,
-------
42
Emission Reductions - The CO emission reductions from pre-1981 vehicles in an
idle CO I/M program will be virtually the same as those from a conventional
I/M program which uses the same idle CO cutpoints. The HC emission reductions
will be significantly less, but still 75% or more of what they would be in a
conventional I/M program. The reduced HC benefits are due to the absence of
ignition system and other HC-oriented repairs in the idle CO I/M program.
Fuel Economy Improvements - A fuel economy improvement of about 4 percent can
be expected from an idle CO I/M program, if.appropriate mechanic training is
conducted or if the I/M program has soirie other mechanism to ensure that idle
mixture adjustments are performed approximately correctly. There has been no
conclusive evidence that there is any fuel economy benefit associated with
conventional I/M programs. This is primarily due to repairs performed in
conventional I/M programs which degrade fuel economy offsetting the fuel
economy benefits associated with carburetor adjustments alone.
4.2 Repair Types and Costs
4.2.1 Elimination of Idle HC-Only Failures and Repairs
The most obvious effect of eliminating the idle HC cutpoint for pre-1981
vehicles from a conventional I/M program is that cars which would have failed
the inspection only for high idle HC emissions will now pass inspection and
will not be repaired. Consequently, these cars' contribution to the average
repair cost is eliminated. To quantify this effect, the number .of HC-only
failures and their average repair cost in a conventional I/M program must be
known.
In its study of the Portland I/M program, EPA found that among 1975-1977
vehicles, 8 percent of'cars failing the idle test in 1978 failed for HC only.
This number should not be considered typical of most other I/M programs, for
two reasons. First, the Portland program has an unusually low (stringent)
idle CO cutpoint, so many cars which would be HC-only failures in other states
are HC-and-CO failures in Portland. Second, the cars in EPA's sample were
relatively new when they began I/M. The I/M programs which will begin
operation in 1982 or 1983 will find that malperformances which cause high HC
will be more common due to the greater average age of catalyst-equipped
pre-1981 vehicles. Consequently, if they use an HC cutpoint, the fraction of
all failing cars which fail only for HC will be larger. EPA estimates that
for conventional I/M programs starting in 1982 or 1983 the HC-only failure
rate will be about 25% of the overall failure rate.
The impact on average repair cost of eliminating HC-only failures will be
greater than suggested by their number. THis is because HC-only failures have
a higher average repair cost than the remaining failed cars. In EPA's
Portland sample, the 1975-1977 HC-only failures had an average repair cost of
$31.05. The average for the other failed cars was $23.86. This pattern of
costs makes sense, since most of the cars that fail only the HC cutpoint
require some sort of ignition system repair. This involves time consuming
diagnosis to pinpoint the specific parts in need of replacement, or else
replacement of more parts than really necessary. Ignition system repairs
should be less frequent among the other failed cars, since idle mixture
-------
A3
maladjustment is the only cause of idle test failure for many of them. This
explanation is supported by type-of-repair data from the Portland study.
Spark plugs and spark plug wires were replaced more o'ften (about twice as
often) on the HC-only failures than on other failed cars.
The figures given above for the number of HC-only failures (about 25% of all
failures) and for their relative repair cost ($31 versus $24) mean that
eliminating HC-only failures should reduce the total I/M repair bill for
pre-1981 vehicles by about 30%.
4.2.2 Simpler Repairs for Other Failed Vehicles
Because the vehicles that do fail the idle test in an idle CO I/M program do
not have to pass an HC cutpoint on reinspection, in principle they should
require simpler repairs than in a conventional I/M program. The only repairs
that are possibly needed are those which reduce idle CO emissions; repairs
which would reduce idle HC emissions are not necessary. In fact, for
virtually all failed cars the only repair that is needed is an idle mixture,
and possibly idle speed, adjustment. Argument and evidence in favor of this
contention are given in the following paragraphs.
It is well known that the engine parameter which has the largest impact on
idle CO is the idle mixture setting, since this is the primary control for the
idle air/fuel ratio. Most catalyst-equipped vehicles with a properly adjusted
idle mixture have an idle CO level near zero. A rich maladjustment causes
idle CO to increase far enough for the vehicle to fail a typical idle CO
cutpoint. Even partial correction of the maladjustment will reduce idle CO to
below che cutpoint. There are some other malperformances which can increase
idle CO, such as blockages and leaks inside the carburetor, defective
carburetor floats, severely plugged air filters, crankcase oil which is
heavily contaminated with gasoline, and disabled air pumps. Surveillance
studies have repeatedly found that such problems are infrequent compared to
idle mixture maladjustments [12,13,14]. Consequently, they should be needed
only rarely in either a conventional or idle CO I/M program.
Additional evidence to support the claim that idle mixture adjustments are
almost always sufficient to allow vehicles which have failed an idle CO
cutpoint to pass on reinspection comes from several EPA test programs.* These
programs and their findings are summarized in Table 22. All of the programs
showed very high pass rates on the idle CO test after an idle mixture
adjustment, in the range of 96.4 to 99.0 percent. . . ' ."*'"...';
* With few exceptions, the report will treat 1973-1980 vehicles as though they
are typical of all vehicles made before the 1981 model year. In fact they are
not; there are important differences between these and older vehicles.
However by 1987 the date EPA uses to evaluate the effectiveness of I/M
programs - 1975-1980 vehicles will acount for 83.7% of the inspections and
83.4% of the emissions of all vehicles made before the 1981 model year. Hence
their behavior in an I/M program will far. outshadow the remaining older cars.
In addition, comparatively little data is available on pre-1975 ve'hicles, so
the focus on 1975-1980 vehicles is unavoidable. Where essential,.distinctions
will be drawn based on the best available information. : . : ;
-------
44
Program
Restorative
Maintenance Evaluation
FY79 Emission
Factor Program 1
Houston Program
Study !
Houston Program
Study 2
Portland Task
Group 10 3
Table 22
Idle CO Pass Rate
After Carburetor Adjustment
Idle CO Pass Rate
Initial at Reinspection After
Initial Idle CO Only Carburetor
Sample ..Failure Adjustment Among Vehicles
Size Rate Failing Initial Test
145 50.3 97.3
64 43.8 96.4
480 21.7 99.0
480 21.7 96.5
102 38.2 97.1
1: Carburetor adjustment performed by contractor mechanics to manufacturer
specifications.
2: Idle mixture adjusted so that idle CO is 0.5%.
3: Idle mixture adjusted so that idle CO is 0.2%.
As Section 3.0 suggested, it is not necessarily enough to arrange things so
that only simple I/M repairs are needed. The lack of understanding by
mechanics and owners and the economic interest of repair facilities can result
in unnecessary repairs being performed. This is illustrated by the types of
repairs which were performed by commercial repair facilities in Portland on
cars that had failed only the CO cutpoint. Virtually all of these cars could
have passed with only ar idle mixture adjustment. Table 22 shows the repairs
that were actually performed. The average repair cost ' for the vehicles was
S19.50. This is below the average for the cars that failed the ^C cutpoint or
both cutpoints, but it still reflects charges for maintenance in addition to
idle mixture adjustments.
This additional maintenance will be easier to eliminate in an idle CO I/M
program than in a conventional I/M program. In a conventional I/M program
there are enough failed cars which actually do need types of repairs other
than an idle mixture adjustment that many owners are not surprised and have no
recourse when told their vehicles is one of them. Some mechanics may not have
learned or may not bother to determine which vehicles do or do not. need more
-------
45
maintenance. However, in an idle CO program, owners and mechanics can be told
that in virtually all cases only idle mixture adjustments are required to pass
reinspection. Owners then have a much simpler job in protecting themselves
from repair facilities that recommend more maintenance. The number of cars
that require more maintenance will be so small that owners can be advised by
the I/M program to always seek a second opinion before agreeing to it. In
addition, price competition among repair facilities should be keener in an
idle CO I/M program because repairs are more uniform. The price competition
will be additional pressure on repair facilities to refrain from performing
unnecessary maintenance.
Table 23
Portland Program
Typical Repairs Performed on Vehicles Failing Only Idle CO
in the Oregon State Inspection Test
Model Year Model Year
1972-74 Vehicles 1975-77 Vehicles
Total Number of Cars 80 134
Were the following items repaired, replaced or adjusted? (yes)
Spark Plugs 28.8% 14.9%
Spark Plug Wires 11.3% 4.5%
Points and Condenser 23.8% 5.2%
Distributor Cap and Rotor 16.3% 3.7%
Spark Timing Control Devices 11.3% 6.0%
Carburetor 93.8% 92.5%
Choke 40.0% - 11.9%
Intake System 2.5% . 3.0%
Air Filter 26.3% . 24.6%
Engine Oil . ' ' ' 16.3% -.'..--..= 16.4%
Idle Speed '- - - T' 56.3% ' - - ; : - -;'""''V;: :-73.9% :.
Timing ...:....-...-...-. 42.5% - ' v-;''"=-^ ">-*->-34.3% -
Dwell .-.-- ;j :36.3% : '" . r-: ':.': <-:;' 20.1%
Air Injection System ?:'""." 3.8% " " -.' -:--^"-'' :-'=r 3.0% .: :
EGR System " . "* 3.8% -.' .' : ,:-: 3.7%
PCV System ' '6.3% ' '.. -''.' 4.5%
Valves .- 5.0% ' - -.-: -' ' '; :-0.0%
In conclusion, an idle CO I/M program which also adopts the improvements
discussed in Section 3.0 will very likely succeed in reducing repair costs for
pre-1981 vehicles to the amount which is legitimate for an idle mixture
adjustment only. Data from two sources indicate this cost should be in the
range of $6 to $10 per car. -In the Portland study, 58 1975-77 cars which
received only idle mixture and/or speed adjustments were charged an average of
$9.50 by the repair facilities. And for 313 1975-79 cars which were taken to
commercial repair facilities in various parts of the country as part of EPA's
-------
46
FY79 Emission Factors Program [14], the average charge for an idle mixture
adjustment was $6.29.
It should be mentioned here that passenger cars produced by General Motors
Corporation (GM) during the 1979 and 1980 model years were equipped with
carburetor idle mixture adjustment screws which are inaccessable without first
removing the carburetor. It can be expected that a carburetor adjustment on
these vehicles will cost more than has been estimated for other vehicles.
However, since the carburetor idle mixture of these vehicles cannot normally
be adjusted, the occurrance of idle mixture maladjustments will be lower. In
the Houston Program only 3.1% of the 98 1979 and 1980 GM vehicles tested
failed the program's idle CO cutpoints. In all, these vehicles will account
for only 11% of all pre-1981 vehicles in January of 1983 when all I/M programs
are scheduled to be in operation. It is not expected, then, that these
vehicles will have any significant effects on the overall repair costs being
estimated for idle CO programs.
4.2.3 Net Effect on I/M Costs
It was shown in Section 4.2.1 that by just eliminating HC-only failures, 30%
of the total repair bill for pre-1981 vehicles can be saved compared to a
conventional I/M program. The cost per vehicle for the remaining vehicles
will also be reduced, down to the cost of a carburetor adjustment, about $6 to
$10. Using the repair cost of $23..86 from Portland as typical for these
vehicles in a conventional I/M program and $10 for an idle mixture adjustment,
the net effect is that an idle CO I/M program will have total repair costs for
pre-1981 vehicles that are about 70% less than a conventional I/M program with
the same CO cutpoint.
EPA has recently estimated all the cost components for a typical
(conventional) I/M program design [4]. Averaged over the five years from 1983
through 1987, repair costs for pre-1981 vehicles account for 27% of the total
cost of the I/M program. Therefore, an idle CO I/M program costs will be
about 19% cheaper than a conventional I/M program with the same CO cutpoint as
the result of reduced costs for pre-1981 vehicles alone. Overall program
costs will be reduced about 26%, including the savings from 1981 and later
vehicles discussed in Section 5.2.
4.3 Emission Reductions
There are several operating programs, such as the Portland program, which
provide data that can be used to estimate emission reductions in conventional
I/M programs. 'Since there are no operating idle CO I/M programs, the emission
reductions that we can expect from such programs can only be estimated from
evidence gathered from a variety of sources that are each only partially
relevant. This section will examine the available data which may provide some
indication of the possible effects of idle CO I/M programs on HC and CO
emission reductions observed in conventional I/M programs.
In order to provide a convenient analytical framework for analyzing emission
reductions, a failure group approach will be used. That, is, the three groups
of "failed" vehicles will be analyzed separately: vehicles which would have
-------
47
failed HC only if there was an idle HC outpoint but will now pass instead
(HC-only failures), vehicles which would have failed HC and CO and will now
fail only idle CO (HC-and-CO failures), and vehicles which would have failed
idle CO only (CO-only failures).
4.3.1 Carbon Monoxide Emissions
HC-only failures - Any CO emission benefits from vehicles which fail only idle
HC cutpoints in a conventional I/M program will be lost in an idle CO I/M
program since these vehicles will pass their idle CO cutpoint. However, these
vehicles do not produce any CO benefits from repair even in conventional
programs and therefore dropping these vehicles from an idle CO I/M program
will not reduce the overall CO benefits of the program. This conclusion is
supported by data from the Portland Study. In .Portland, those vehicles which
failed only for idle HC had low FTP CO emissions to begin with and showed no
CO improvement from repairs.
HC-and-CO failures - Vehicles which fail both the idle HC and idle CO
cutpoints in a conventional I/M program will still fail for idle CO in an idle
CO I/M program. It is expected that the CO emission reduction from the repair
of these vehicles in an idle CO I/M program will be the same as the CO
emission reduction that would be observed from the same vehicles In a
conventional I/M program. This is expected since the same repairs used to
reduce idle CO emissions in the conventional program will still be needed in
the idle CO program in order to pass the idle CO cutpoints.
Also, the additional repairs which reduce idle HC emissions in a conventional
program do not significantly affect CO emissions. As mentioned earlier,
vehicles in Portland which failed only for idle HC and received repairs to
reduce their idle HC emissions showed no improvement in their CO emissions.
In an EPA test program where misfire was induced on a sample of eight pre-1981
vehicles an average 11% misfire drastically increased HC emissions but had
little effect on CO emissions. A correction of misfire on these vehicles
would have resulted in only a small reduction in FTP CO emissions. In the
Houston program[15] additional repairs other than carburetor adjustments
reduced FTP CO emissions only an additional 1.25 gpm after the carburetor
adjustment on those vehicles which failed both idle HC and idle CO.. These
additional repairs would only have increased the total CO emission reduction
from repairs by only 2.4%. .... . . ..-.^! . ,' ,-
CO-only failures - Those vehicles which would fail only .for idle CO. in a
conventional I/M program will also fail in an idle CO program'. These vehicles
will receive similar repairs and therefore tbe sane reductions in CO emissions
as in a conventional program since the retest requirements will.be the same..
The conclusion that can be drawn is that for pre-1981 vehicles, dropping the
idle HC cutpoints from a conventional I/M program, to arrive at an idle CO
program, will not reduce the overall CO benefits of the I/M program, despite
the elimination of idle HC only failures and the additional repairs performed
on some CO failures in a conventional I/M program to pass idle HC cutpoints.
-------
48
4.3.2 Hydrocarbons/Emissions
HC-only failures - In an idle CO I/M program all of Che HC emission benefits
from vehicles which would have failed the idle HC cutpoints but not the idle
CO cutpoint in a conventional I/M program will be lost since these vehicles
will not be failed in an idle CO program. For 1976-77 vehicles tested in
Portland during 1978 and 1979 in the Portland Study, only 11% of the total HC
benefit observed in the program came from the idle EC only failures. However,
the idle HC only failure rate and their contribution to the total HC benefit
of a conventional I/M program is expected to increase as the pre-1981 vehicles
age. By the time I/M programs begin operation in 1982 or 1983 it is estimated
that idle HC only failures will account for 26% to 27% of the total HC
emission reductions from pre-1981 vehicles in conventional I/M programs. By
1987 idle HC only failures will account for about 29% of the HC benefits from
these vehicles.
HC-and-CO Failures - The HC emission reductions from repair of vehicles which
fail idle CO in the idle CO I/M program but would have also failed idle HC in
a conventional I/M program are expected to be less than the HC reduction
observed in conventional I/M programs. Primarily this is due to the loss of
additional repairs} such as ignition repairs, necessary in a conventional I/M
program to reduce- idle HC emissions which will no longer be required in an
idle CO program.
While there is no precise information on how much of the HC emission reduction
benefit will be lost, this loss can be estimated by examining existing data
which compares the HC emission reductions produced by carburetor adjustments
and those produced by more complete tune-ups including ignition repairs on
vehicles which fail both idle HC and idle CO cutpoints. In the Houston
Program additional repairs after the carburetor adjustment increased the total
FTP HC emission benefit an additional 9.4% on a small sample of vehicles
initially failing both idle HC and idle CO. Also, additional repairs
increased che total HC emission benefit another 4.0% in a small sample of
vehicles failing both idle HC and idle CO in the FY79 Emission Factor
program[14] after a carburetor adjustment. The Restorative Maintenance
Evaluationf12] shows an additional 3.8% HC benefit in further repairs on
vehicles failing both idle HC and idle CO after a carburetor adjustment.
Vehicles in the Emission Factor and Restorative Maintenance samples were
reasonably new when testing was done and were not expected to have many
problems which would cause high HC emissions. Also, the vehicles in these
samples would have received less of Che additional repairs in a conventional
I/M program. To quantify Che Loss precisely would require new testing since
Che existing data only approximaces che expected effects of an idle CO I/M
program.
CO-Only Failures - Vehicles which fail only for idle CO in a conventional I/M
program will also fail in an idle CO program and will receive essentially the
same repairs. The HC emission reductions from these repairs in an idle CO
program will therefore be the same as in a conventional program.
-------
49
In conclusion, the total HC emission benefits possible from an idle CO I/M
program will not be as- great as from a conventional I/M program for pre-1981
vehicles. The loss in HC effectiveness is expected to be even greater on
pre-catalyst technology vehicles built prior to 1975, but there is
insufficient data to illustrate their loss. An idle CO I/M" program will
therefore achieve only partial HC emission reduction benefits for pre-1981
vehicles. Quantification of these benefits will be presented in Section 4.3.4.
4.3.3 Deterioration Issues
Between inspections the HC and CO. emission- reductions praduced; by an I/M
repair: will gradually deteriorate. The. reasons for this deterioration may
include/ emission component. failures due to general gradual. wear,
maladjustments, and tampering- occurring between- I/M inspections. The rate of
this deterioration affects the net HC' .and CO emission benefits that can be
expected from an I/M program. EPA has done extensive testing to quantify the
deterioration rate for conventional I/M programs, however, no testing program
has yet been conducted to measure deterioration in an idle CO program. Such a
testing program would be difficult to conduct with any validity since there.
are currently no operational idle CO I/M programs which can be evaluated.
One possible line of speculation is that the deterioration rate will be less
in an idle CO I/M program since mechanics will have no need to temporarily
adjust carburetors very- lean as a cheap way to pass- idle; HC cutpoints as is
sometimes done in conventional I/M programs. However, since a rich idle
mixture may be counteracting other, problems which may remain unrepaired in an
idle CO I/M program, the rate of deterioration of HC and CO emissions may be
higher than has been observed in conventional I/M programs if vehicles owners
maladjust their vehicles between I/M inspections. A survey of vehicle owners
in EPA's Emission Factor Programs a. week after they had had their vehicles
carburetors adjusted to manufacturers specifications indicates that most
vehicle owners are satisifed with the performance of their vehicles after such
repairs.[16] Although Emission Factor Programs do not simulate I/M programs
and although carburetor- adjustments to manufacturers specifications is not
exactly the repair at issue, it does indicate that: vehicle owners can be
satisfied with the performance of their vehicles even after the carburetor is
adjusted leaner than they have become accustomed to.
Lacking any relevant data, one can only assume the same deterioration behavior
for idle CO I/M programs as for conventional I/M for the purposes of this
report.
4.3.4 Emission Reduction Benefits Model for Idle CO I/M Programs
for Pre-1981 Vehicles
For pre-1981 model year vehicles, EPA's simulation model for conventional I/M
programs can be modified to approximate the effects of idle CO I/M programs.
First, the HC benefit attributable to vehicles which fail only HC in a
conventional I/M program are omitted. Secondly, the HC benefit attributable
to vehicles which fail both pollutants in a conventional program are reduced
based on assumptions concerning the cause of failure. An estimate is made of
the number of conventional HC-and-CO failures which have high idle HC for
reasons other than idle mixture maladjustment. These vehicles are then
modeled as receiving little HC reduction. The remaining vehicles in the
HC-and-CO group receive the normal (conventional) HC reduction. Finally, the
HC benefit attributable tc vehicles which fail only CO in -3 conventional
oro?ram is retained in its entirety.
-------
50
Figures 1 and 2 present sample results of this modified simulation. These
figures are based on a conventional I/M stringency of 20% and an idle CO I/M
stringency of 13%.* The two programs use the same CO outpoint. The
difference in stringency is due to the use of an HC outpoint in addition to an
idle CO cutpoint in the conventional I/M program. Figure 1 presents the
composite HC emission factor for pre-1981 vehicles without I/M and with each
of the two types of I/M. Figure 2 shows the percent benefits associated with
these programs for HC.
4.4 Fuel Economy Benefits
The Portland Study did not indicate any significant overall fuel economy
benefit as a result of I/M repairs [17]. This conflicts with data from
various restorative maintenance programs which show about a 4% improvement in
combined city/highway fuel economy after emission related maintenance[18].
The question is the following: what specific differences in the repair types
performed in Portland could cause the disparity.
One piece of the solution is the fact that carburetor adjustments, even when
they are not performed exactly as specified by the manufacturer, produce
sizable fuel economy benefits on pre-1981 vehicles. This makes sense
technically since a vehicle with an overly rich idle mixture is consuming more
fuel than it needs and any carburetor adjustment that results in a
significantly leaner idle mixture should result in less fuel consumption and
better fuel economy. Recent studies in Houston and Portland indicate that
significant fuel economy benefits between 1.1% and 4.6% can be obtained if
only carburetor adjustments are performed after failing an idle CO cutpoint.
Table 24 presents the results of those studies.
* The term stringency in this report will be used to refer to Che selection of
appropriate idle HC and CO outpoints in a conventional I/M program or Che
selection of idle CO outpoints in an idle CO I/M program such chat Che failure
rate in Che first year of Che I/M program will have a failure rate equal to
Che stringency, i.e., a twenty percent stringency means a twenty percent
failure rate in the first year. The outpoints selected are then used
Chroughout all years of Che program's operation.
-------
51
Figure 1
Comparison of HC Emission Seductions
For Pre-1981 Vehicles
5.50
CONVENT IONfiL
» / M
'0.0
30
30
-------
52
Figure 2
Comparison of EC Benefits
For Pre-1981 Vehicles
SO
45
40
uu
£
-------
53
Table 24
Fuel Economy Benefits
from Carburetor Adjustments to
Vehicles Failing Idle CO Cutpoints
(1975-80 Model Year Vehicles)
Program
Houston Program
Study1
Portland Task
Group 102
FY79 EF
Houston Site.
Number- of
Vehicles
Adjusted
Fuel
Economy
Before
Carburetor
Adjustment.
(mi/gal)
After
Carburetor
Adjustment
(mi /gal)
Percent
Change
(85)
(31)
(12.)
City
Hwy
Comb
City
Hwy
Comb
City
Hwy
Comb
13.79
20.57
16.19
14.39
20.14
16.51
14.22
21.71
16.92
14.61
21.01
16.93
14.70
20.03
16.70
14.74
22.29
17.39
5.9
2.1
4.6
2.1
-0.6
1.1
2.9
2.6
2.8
1: Idle mixture adjusted so that idle CO is 0.5%
2: Idle mixture adjusted so that idle CO is 0.2%
3: Carburetor adjusted by field mechanics; those
CO after carburetor adjustment.
vehicles passing 2.5% idle
If carburetor adjustments can produce sizable fuel economy benefits and
carburetor adjustments are the most common repair in conventional I/M
programs, the lack of significant overall improvement in fuel economy observed
in Portland must be the result of repairs other than carburetor adjustments
which degrade fuel economy and offset the fuel economy improvement provided by
the carburetor adjustment. Overly retarded ignition spark timing has been
identified as one such repair in the Port land. study [19]. Analysis of the
available data will continue in order to identify other repairs which may also
degrade fuel economy.
In idle CO I/M programs carburetor adjustments will be virtually the only
repair necessary to pass the reinspection idle CO cutpoint. It can therefore
be stated with confidence that an idle CO I/M program will obtain fuel economy
benefits. The size of the fuel economy benefit will depend on how close
repair mechanics will adjust carburetors to manufacturers specifications. We
do know that if mechanics adjust the carburetor such that the idle CO is 0.5%,
the fuel economy benefit may be as high as the 4.6% obtained in the Houston
program. This fuel economy benefit can provide significant savings in fuel
costs to vehicle owners who must receive emission related repairs.
-------
54
Mechanics will not normally be expected to adjust carburetors much leaner than
the program's idle CO cutpoint, since they only need a reasonable margin of
safety in order to be sure to pass the reinspection. In New Jersey, the
operating program has an idle CO cutpoint of 3.0% for 1975-80 vehicles and the
average idle CO measurement after repair is 0.9%. However, if the
reinspection cutpoint is tighter, mechanics will be forced to adjust leaner in
order to keep a reasonable margin of safety. In the Portland program most
1975-30 vehicles must pass a 1.0% reinspection cutpoint. The average idle CO
measurement after repair in this program is 0.2%. this means that one way to
assure that mechanics adjust carburetors so that the idle CO measurement after
repair is 0.5% is to impose an appropriately tight reinspection cutpoint. It
has been estimated that a reinspection idle CO cutpoint between 1.0% and 2.0%
will result in an average after-repair idle CO measurement of 0.5% or less
with no adverse side effects. (The Portland I/M program has been using a CO
cutpoint of 1% for many years.) This may mean having a reinspection cutpoint
which is different than the initial inspection cutpoint. (An initial
inspection cutpoint of 2.0% would result in a 37% stringency for 1975-80
vehicles, higher than desired by many I/M planners.) This should cause no
conflict, since the purpose of the two cutpoints is different. The initial
cutpoint is set to identify those vehicles most in need of repair. The
reinspection cutpoint assures that those repairs were effective in reducing
the vehicles CO emissions. The inspection cutpoint/, therefore, does not
necessarily need to be as tight as the reinspection cutpoint.
Another way to assure that most repair mechanics will adjust carburetors so
that the idle CO after repair is 0.5% is through mechanic training. Mechanics
who do repairs in the I/M program can either be instructed to adjust all cars
failing the idle CO cutpoints so that the idle CO is 0.5% as a matter of
course or they can be instructed to do so if the vehicle's idle CO measurement
exceeds 0.5% after adjusting the vehicles idle mixture using manufacturer
specified procedures. Additional information on overall carburetor
diagnostics and repair can also be included in the program.
If a tighter reinspection cutpoint or mechanic training is not possible a 0.5%
idle CO adjustment target can be mandated by the program as a requirement for
vehicles failing the idle CO cutpoint. This approach will require a periodic
statistical review by the program administrators of post-repair idle CO
measurement records from each repair facility to enforce the requirement. The
effectiveness of this approach will depend heavily on how well the requirement
can be enforced.
The emission benefits crom any of chess options which encourage leaner
adjustments Chan would be necessary merely Co pass Che iricial inspeccion idle
CO cutpoint will be discussed in Section 7.3.
-------
55
5.0 I/M FOR 1981 AND LATER VEHICLES USING ONLY IDLE CO OUTPOINTS
5.1 Background on 1981 and Later Vehicles
There are two significant technology differences between pre-1981 and 1981 and
later vehicles.. First, the: majority of 1981 and later vehicles are expected
to employ microprocessor-based, closed-loop, engine control systems. These
systems rely on a. network of, sensors to supply information on the: operating.
condition of the engine to an on-board microprocessor. .The microprocessor
analyzes this information- and: sends operational commands to various actuators
(primarily- solenoids) which: modify the air/fuel, ratio, control the deployment
of secondary air, determine spark- timing, and. on. some systems allow or
disallow exhaust gas recirculation (EGS). These systems represent a
significant departure from earlier, mechanically controlled systems.
Second, the Parameter Adjustment regulations[2] provide that the fuel metering
systems on 1981 and later vehicles be designed in such a way so as to
discourage tampering or maladjustment of the idle mixture and choke systems.
As is widely known, maladjustment of the idle mixture system has been the
cause of a significant share of the in-use emissions problem for pre-1981
vehicles. Although even the protected designs can still be maladjusted (after.
some effort), it iai expected, that the- 1981 and later fleet will be much less
subject: to idle mixture and. choke maladjustment.
Due to these technology differences, the general nature of the expected in-use
emission performance of 1981 and later vehicles is different than for earlier
model year vehicles. The in-use emissions performance of earlier model year
vehicles (pre-1981) is largely affected by the rate . of various forms of
maladjustment and tampering (chiefly idle mixture maladjustment) as well as
phenomena such as problems with the ignition system and catalyst deterioration
due to aging or misfueling. By comparison, while 1981 and later vehicles will
still experience ignition system problems and catalyst, deterioration to some
extent, .the main phenomenon affecting in-use performance is expected to be
failure of the microprocessor-based fuel control system. These failures often
result in very rich modes of operation with accompanying very high levels of
EC and CO and poor fuel economy. These HC and CO levels are high enough so
that even if only a small number of vehicles experience a fuel system failure,
they can dominate the emission inventory of the fleet and cause the average
emissions of the fleet to exceed the standards. The early data on the in-use
performance of microprocessor-controlled vehicles has given significant
indication that this type of behavior can be expected for the 1981 and later
fleet.
Rich failures of the microprocessor-based fuel control system primarily affect
CO emissionscausing them to rise dramatically. These failures also cause HC
emissions to rise, but to a somewhat lesser degree. Repair of these rich
failures result in significant fuel economy improvements averaging about
15%[6). The average in-use HC emissions of the 1981 and later fleet are also
largely affected by problems with the ignition system (e.g., misfire, fouled
plugs, faulty distributor components).
-------
56
Readers interested in gaining more information on the projected in-use
performance of 1981 and later vehicles should refer to "Derivation of 1981 and
Later Light Duty Vehicle Emission Factors for Low Altitude, Non-California
Areas"[20].
5.2 Idle CO I/M for 1981 and Later Vehicles
Given the preceeding discussion on the expected in-use emissions performance
of the 1981 and later fleet, it should come as no surprise that the emission
reductions attributed to I/M are expected to primarily come from the
identification and repair of vehicles with a rich failure of their
microprocessor-based fuel control system. Data from such vehicles in the
field indicate that some fraction of them will readily fail an I/M CO
cutpoint. The estimate used in this analysis is that 50% of those vehicles
with a failure of the microprocessor-based fuel control system will be
identified in an idle CO I/M program using the basic idle test. This is the
same estimate used for a conventional I/M program. This means that the CO
benefits in an idle CO program will be the same as in a conventional I/M
program. Since these vehicles also have high HC emissions, their
identification and repair in an idle CO I/M program will also result in
significant HC reductions. Ignition problems (the other main source of
projected HC emissions for the 1981 and later fleet) are not identified by a
CO cutpoint, and therefore an idle CO . I/M program will not get the HC
reduction benefits of their.repair.
A conventional I/M using an idle test program is expected to fail about 7% of
the 1981 ami later vehicle fleet. An idle CO I/M program using the same test
will only fail vehicles with microprocessor-based fuel control system
failures, or about 1.7% of the 1981 and later fleet. The other vehicles fail
in a conventional I/M program for idle HC emissions only. Since all of the
fuel economy benefits associated with repair of 1981 and later vehicles comes
from these vehicles with fuel control system failures, idle CO I/M programs
will achieve the same overall fuel economy benefits from 1981 and later
vehicles as conventional I/M programs. This amounts to an average 15% fuel
economy improvement for each vehicle experiencing a fuel system control
failure which is identified and repaired.
Repair costs for 1981 and later vehicles has been estimated to be about $30
per repair [4]. These repairs include ignition parts replacements as well as
repairs to the microprocessor-based fuel control system. For an idle CO
program these costs are assumed to be Che same, although only fuel control
system repairs will be necessary. However, since Che failure rate for an idle
CO program is only about ?5% of 'che failure rate of a conventional I/M program
for 1981 and Later vehicles, repair coses are reduced about 75%.
The following section will quantify the emission benefits expected for the
1981 and later fleet in an idle CO program. It will especially document the
loss of HC benefit due to not identifying vehicles with ignition problems.
-------
57
Readers interested in gaining more information on the methodology involved in
estimating I/M benefits for the 1981 and later fleet should refer to
"Derivation of I/M Benefits for Post-1980 Light Duty Vehicles for Low
Altitude, Non-California Areas"[21].
5.3 Emission Benefits Model for Idle CO I/M Programs for 1981 and
Later- Vehicles
The I/M emission, benefits attributed to a; conventional program- for 1981 and
later vehicles come from two sources: the: identification and repair of
vehicles with rich failures of their microprocessor control, system (yielding
HC anc CO benefits) and the HC benefits resulting from the identification and
repair of vehicles with ignition system problems. As. discussed above, the
first source of benefits is not diminished in an Idle CO I/M program although
the second source would be lost. EPA's computer model which calculates I/M
benefits for 1981 and later vehicles in a conventional I/M program can be
easily modified to account for this partial loss of HC benefits[20].
Figures 3 and 4- compare the HC and. CO emission reduction benefits from a
conventional I/M program and a idle CO I/M program. The benefits shown
represent those from, the 1981 and later fleet only.
-------
58
Figure 3
Later Vehicles
t.SO
'0.0
81 32 63
35 38 37
aa 33
30
-------
59
Figure 4
Comparison of EC Benefits
For 1381 and Later Vehicles
no
35
30
o2Q
a
-------
60
6.0 OVERALL EMISSION REDUCTION BENEFITS FOR I/M PROGRAMS
USING ONLY IDLE CO OUTPOINTS
The results from models for benefits of idle CO I/M programs for pre-1981
vehicles and 1981 and later vehicles as discussed in sections 4.3.4 and 5.3,
respectively, can be combined to determine benefits for the entire fleet.
Benefits for CO in an idle CO I/M program are expected to be the same as for a
conventional I/M program if the same idle CO cutpoints are used. The effects
for HC are presented in Table 20. The HC benefits on December 31, 1987 for
conventional and idle CO programs starting January 1, 1983 with no mechanic
training and a simple idle test for 1981 and later vehicles are shown. It
should be noted that the idle CO programs presented in Table 25 would have
higher CO benefits than the conventional programs since the idle CO cutpoints
for a given failure rate idle CO program are lower than the idle CO cutpoints
for a conventional program of the same stringency (failure rate).*
It can be seen in the table that areas with ozone non-attainment problems
using an idle CO program will likely need to implement measures to increase HC
benefits. Methods for increasing HC benefits are discussed in the next
section.
If the idle CO I/M program was restricted to only 19.75 and later vehicles, the
composite HC benefit for idle CO programs would be further reduced. Pre-1975
vehicles account for between 7.4% and 10.7% of the HC benefit in an idle CO
I/M program, depending on stringency. The HC benefit in conventional programs
would also be reduced if all pre-1975 vehicles were exempted from inspection.
Table 25 also presents the emission benefits of an idle CO program which
exempts pre-1975 vehicles.
* The term stringency in this report will be used to refer to the selection of
appropriate idle HC and CO cutpoints in a conventional I/M program or the
selection of idle CO cutpoints in an idle CO I/M program such that the failure
rate in the first year of the I/M program will have a failure rate equal to
the stringency, i.e., a twenty percent stringency means a twenty percent
failure rate in the first year. The cutpoints selected are then used
throughout all years of the program's operation.
-------
61
Table 25
Comparison of EC Benefits for Conventional and Idle CO
I/M Programs* Starting in 1983
Stringency for Percent. Benefit
Pre-1981 Vehicles on-December 31, 1987
(Failure' Rate) *"* Conventional Idle CO 1975-*- Idle CO
HC CO. H£ CO -' HC CO
13Z 32: 30 24 33 22 29
20Z 35 33 27 36 24 32
30% 38 36 30 39 27 34
40Z 39 38 31 40 28 35
* Further assumption about the I/M programs are no mechanic training and a
simple idle test for 1981. and later vehicles.
** At a given stringency (failure rate) , the idle CO I/M program has
numerically- lower CO outpoints- than the conventional program, but: has equal
stringency overall.
Using the model for emission benefits it is possible to calculate. the tons of
pollutants that are removed by an T/M program. The methodology for this
calculation is presented in "Update on the Cost-Effectiveness of Inspection
and Maintenance [4]. Table 26 presents the results of such a calculation for
idle CO programs. For comparison a conventional I/M program with a 20%
stringency for pre-1981 vehicles produces a 46,500 ton reduction in HC
emissions and a 526,800 ton reduction in CO emissions from a base of one
million vehicles.
Table 26
Five Year Emission Reductions -
Thousands of Tons Removed* by an Idle CO Program
Stringency for
Pre-1981 Vehicles All >fodel Years ' Only 1975 and Later
(Percent) H£ C£ HC CO
13 31.31 526.8 29.26 435.7
20 36.38 607.4 32.87 502.9
30 ^3.61 692.7 38.08 572.5
40 45.64 723.1 39.81 598.7
* A vehicle base of one million vehicles is used.
-------
62
7.0 METHODS TO IMPROVE THE HC EMISSION REDUCTION FROM
IDLE CO I/M PROGRAMS
As described generally in Section 4.3.2 and as quantified in Section 6.0, it
is expected that a conventional I/M program which simply eliminates the idle
HC emission requirements from the program will suffer some loss of
effectiveness in reducing HC emissions' from automobiles when compared to the
conventional progam. Table 20 showed that there is over a 20% percent loss in
HC effectiveness even if the CO cutpoint is tightened enough to bring the
overall stringency of the program back to that of a conventional I/M program.
This will have an impact on areas wifh ozone air quality problems which must
reduce the overall emissions of HC from automobiles and which may wish to use
the idle CO I/M program approach. For this reason, this section will examine
several methods which can be used to increase the effectiveness of an idle CO
program in reducing HC emissions. These methods include:
Using a more effective test procedure for 1981 and later vehicles.
Increasing the failure rate of pre-1981 vehicles.
Assuring better repairs on pre-1981 vehicles.
Re-establishment of a loose idle HC cutpoint.
Addition of tampering checks.
I/M for light-duty trucks.
Many of these improvements are also expected to increase the reduction of CO
emissions.
Most of these improvements can also be applied to conventional I/M programs if
additional reductions of HC and CO emissions are desirable.
7.1 More Effective Test Procedure for 1981 and Later Vehicles
One means of increasing the HC reductions from an Idle CO program is to use a
more effective test procedure for 1981 and later vehicles. The benefits
presented in Section 5.0 were based on the use of a basic idle-in-neutral test
for 1981 and later vehicles. This test is estimated to catch 50% of the
vehicles with rich failures of their microprocessor-based fuel control
system. The addition of other pass/fail vehicle operating modes to the
overall test procedure has been shown to increase this percentage. For
example, the addition of a 2500 rpm test mode (Two Speed Idle Test) or the
addition of a 30 mph/9.0 HP loaded test mode ("Loaded Test) has been shown to
result in a 70% identification rate of the vehicles with a fuel control system
failure[21!. This will increase Che failure rate for 1981 and later vehicles
from about L.7% to 2.4%. Either of these tests will still qualify vehicle
owners for coverage under the Emission Performance Warranty[3j. Since these
additional rich failures increase both HC and CO emissions, yet are readily
identifiable using only a CO cutpoint, any increase in the number of vehicles
identified by the CO cutpoint will cause the HC benefits to increase. Repair
of rich failures among 1981 and later vehicles has produced an average '15%
fuel economy benefit. The fuel savings from these repairs, therefore more
than offset the cost of an average repair cost of about $30.
-------
63
Figures 5 and 6 show the improvement in HC effectiveness which can be-achieved
by using the Two Speed Idle Test or the Loaded Test. For purposes of
comparison, the HC effectiveness of using the basic idle test is also
included. Figures 5 and 6- apply only to 1981 and later vehicles. In
fleetwide terms, the use of one of these more effective tests for 1981 and
later vehicles can increase- the- composite HC emission reduction from I/M as of
December 31, 1987 by 2.4- percentage points. For example, Table. 19 showed a
20% stringent idle CO I/M program will yield an HC reduction of: 27%, on this;
date. If- a more effective test is, used for 1981 and later vehicles, this,
reduction would be- improved to 29%. This option will increase the tons of HC
removed by an idle CO program by 2,030 tons and CO by 60,400 tons in. a. base
sample of one million vehicles.
7.2 Higher Failure Rates for Pre-1981 Vehicles
If the idle CO cutpoint is made more stringent more vehicles will fail their
initial idle CO inspection, more vehicles will receive repairs, and therefore
it is logical to expect that there will be an overall increase in the HC (and
CO) benefits of the idle CO I/M program. Also, if the reinspection idle CO
cutpoints are identical to the initital inspection cutpoints, tightening the
idle CO cutpoints will have the effect of forcing mechanics to adjust
carburetors on all failing cars leaner" than they would have with looser-
cutpoints. This effect is discussed in: Section 4-.4. Since these additional
failures will ail receive the same- repairs as the original failures
(carburetor adjustments), the increase in HC benefit to the program will not
be as large as the increase in the CO benefit. In addition, there are
diminishing returns from failing more vehicles as more and more relatively
clean vehicles fail the stringent initial inspection idle CO cutpoints and
produce very little HC or CO benefit from repairs. This is evident in Figure
7.
Figure 7 presents the effects of increasing stringency* on pre-1981 vehicles
subject to an idle CO I/M program. Figure 7 applies only to pre-1981
vehicles. Table 25 in Section 6.0 presents the HC and CO benefits of
increasing stringency on the pre-1981 vehicles and Table 26 presents the tons
of pollutants removed.
7.3 Better Repairs
On pre-1981 vehicles, mechanics will on the average only adjust carburetors to
just pass an idle CO reinspection cutpoint with a reasonable margin of
safety. If the reinspection cutpoint is fairly loose, vehicles after repair
* The term stringency in this report will be used to refer to the selection of
appropriate idle HC and CO cutpoints in a conventional I/M program or the
selection of idle CO cutpoints in an idle CO I/M program such that the failure
rate in the first year of the I/M program will have a failure rate equal to
the stringency, i.e., a twenty percent stringency means a twenty percent
failure rate in the first year. The cutpoints selected are then used
throughout all years of the program's operation.
-------
64.
Figure 5
Effect of a More Effective Test Procedure
on Che HC Emission Seductions
For 1981 and Later Vehicles
2.0
err
(U
,0.3
a
a.
s<
0.0
MO I/N
CONVENTlaNflL
I/M CS0231
IffLS CO
50231
Benefit from using
a better cest for
1981 and later vehicles.
SO 31 32 33 34 35 6*6
CflL£NOflB TEP.R
37
39
30
1: Idle CO Test (50Z Identification Sate)
2: Two-Speed Idle Test or Loaded Test (702 Identification Rate)
-------
65
Figure 6
Effect of. a. More Effective Test' Procedure
on Che HC Benefits.
For 1981. and Later Vehicles
40
3S
30
Ul
09
u
OS-
£lO
5
IOL£ cn I/M
IDLE Cff I/H
Benefit from using
a better cest for
1981 and later vehicles.
30
22 33
34 35 36
CflL£HOflH TEflH
37
39
30
1: Idle CO Test (502 Identification Rate)
2: Two-Soeed Idle Test or Loaded Test (707. Identification Hate)
-------
66
Figure 7
Effect of Increasing Idle CO I/M Stringency
on HC Benefits for Pre-1981 7ehicles
SO
45
40
-20
UJ
Sis
Ul
a.
10
CONVENTIONAL
I/H C20»*
IOLE CO I/H
IDLE CO I/M
(30X3*
IDLE CO I/M
30
92 33
34 35 36
CflLENOflfl TEflR
37
38
30
*?rogram Failure Rata in Che inicial program year.
-------
67
Figure 3
Effect of Better Repairs*
on the 1C Benefits
for Pre-1981 Vehicles
50
45
to.
£30.
tt
«25,
520
iu
Sis
LU
O.
10
CONYENTrONflL
I/H
IOLS: co I/M
IQL£ CO I/M
HITH «T*
80
81
32
33
3U 35
CfiLENOflfl
36
37
33 30
*Bectar Repairs are acqiiired either by eight reinspection idle CO outpoints or
"hrough aechanic training programs chat reach nearly, all repaired vehicles.
-------
68
will still have idle mixture's adjusted richer, than they would have been if all
carburetors were adjusted to manufacturer specifications. In New Jersey's
operating program the idle CO reinspection cutpoint for 1975-80 vehicles is
3.0%. After repair the average idle CO measurement of failed vehicles is
reduced to 0.9%. In the Portland program, most 1975-80 vehicles must pass a
1.0% idle CO reinspection cutpoint and the average idle CO measurement after
repair is 0.2%. The average idle CO measurement of vehicles failing the idle
CO outpoints in the Houston program which adjusted all vehicles using
manufacturer specifications had an average idle CO after adjustment of 0.15%.
This data indicates that there is some room for improvement in the manner in
which mechanics perform carburetor adjustments in I/M programs. Better
carburetor adjustments should result in greater HC (and CO) emission
reductions from the carburetor adjustments.
For 1981 and later vehicles, however, the logic that improved repair will
provide larger benefits does not apply in the same way. This can best be
understood by recalling the types of failures expected for 1981 and later
vehicles. These failures are truly "system" failures, where the failure or
disconnection of one or more of the components which make up the system causes
the entire system to malfunction. Proper operation of the system can only be
restored once the problem is diagnosed and the responsible components either
replaced or reconnected. For 1981 and later vehicles, if a vehicle has
experienced a fuel control system failure and fails the I/M test, its emission
will be high enough so that it will not be able to pass the I/M test until the
problem has been diagnosed and fixed. The benefits accompanying this repair
will be total. It will not be possible to increase the benefits by adjusting
closer to manufacturer specifications since no adjustments are involved.
Thus, it will not be possible to extract more HC benefit from 1981 and later
vehicles by striving to improve repairs. Repairs on these vehicles are of an
all-or-nothing nature. Improved repairs on 1981 and later vehicles will have
advantages in terms of lower repair costs (due to less wasted effort during
repair) and less owner inconvenience (due to fewer return trips to the repair
facility).
On pre-1981 vehicles, it will be possible to get mechanics to perform
carburetor adjustments closer to manufacturer specifications in three ways:
Mechanic training
Lower idle CO reinspection outpoints, and
Statistical review of idle CO reinspection results.
These approaches are described in Section ^.^. One or all of these approaches
can be applied co any I/M program to improve the carburetor adjustments
performed in the program. However, it is expected that none of these
approaches can do better than the results now being achieved in the Portland
program where most 1975-80 vehicles must pass a 1.0% idle CO inspection and
reinspection cutpoint. The average idle CO .measurement after repair of
1975-77 vehicles in Portland which fail for idle CO (excluding idle-HC only
failures) is 0.3%
-------
69
Better repairs for pre-1981 vehicles deserve special attention primarily as a
cost-saving measure, although they are also an HC and CO enhancement. Better
repairs therefore deserve attention from any area considering an idle CO I/M
program, not just those that might need it as an HC or CO enhancement. Better
repairs for pre-1981 vehicles will produce fuel economy savings on these
vehicles which will offset: a large part of the cost of the I/M program.
EPA studies have shown: that fuel savings; of 4Z, are achieved by carburetor-
adjustments to pre-1981, vehicles which have failed, an I/M-test, even if the
adjustments, are- not performed: precisely- to specification.. It is necessary
that adjustments be performed closer- to specification than they would be in a
basic, idle CO or- conventional I/M program^ and that: other types of repairs
which can degrade fuel economy be avoided. Because carburetor adjustments
will usually be the only necessary repair for pre-1981 vehicles in an idle CO
I/M program, the types of repairs which can degrade fuel economy are naturally
avoided in this type of program. Section 4.4 describes a number of approaches
that I/M administrators can take to improve the quality of carburetor adjust-
ments, two of which are mechanic training and a tight- idle CO reinspection
cutpoint. The- fuel savings which- will result are well worth the' effort, since
an additional 4Z savings foe each- pre-1981 vehicle which is failed and
repaired translates into a total, annual savings of about $36. This offsets a
large part of- the program, costs.- Also, a small, improvement: in the HC. and. CO
emission- reductions accompanies the fuel savingsv Section- 7.3 discusses the-
HC" and CO benefits. The overall effect, is a major further- improvement in the
cost-effectiveness of the idle CO I/M program.
The quality of adjustment observed in the Portland study is expected to be
achieved in a conventional I/M program with mechanic training. EPA's emission
model for conventional I/M programs with mechanic training reflects this
judgment and can therefore be modified in the same way as the basic model to
predict the maximum effect of better- repairs in an idle CO I/M program. This
process is described in Section 4.3.4.
Figure 8 presents Che maximum effect of better repairs performed in an idle CO
I/M program for pre-1981 vehicles. Figure 8 applies only Co pre-1981
vehicles. Table 27 presents the possible overall net effect in 1987 of better
repairs on pre-1981 vehicles.
Table-27
Efface of Better Repairs for Pre-1981 Vehicles
in an Idle CO I/M Program
Stringency for Percent Benefit on December 31, 1987
Pre-1981 Vehicles No Mechanic With Mechanic
(Percent) Training Training
HC CO HC CO
13 24 33 25 36
20 27 36 28 40
30 30 39 32 42
40 31 40 '33 42
-------
70
It can be assumed that the program costs associated with better repairs will
be minimal since any additional time required to perform a carburetor
adjustment more precisely would be insignificant compared to the basic charge
for setup and adjustment. When fuel savings are considered, better repairs
become a method to reduce overall program costs, since fuel savings from
repairs can be used to offset other program costs. These savings have been
calculated using figures from "Update on the Fuel Economy Benefits of
Inspection and Maintenance Programs" [5] and presented in Table 4 in Section
1.2. The additional tons of EC and CO removed through better repairs have
been calculated using the idle CO emission benefit model. These reductions
are al? o presented in Table 4. Exempting pre-1975 vehicles will reduce the
benefits of this option. Table 9 in Section 1.2 presents the costs and
benefits of better repairs without pre-1975 vehicles.
7.4 Re-establishment of a Loose Idle HC Cutpoint
Much of the loss in HC benefits of dropping the idle HC requirement from a
conventional I/M program was due to passing vehicles in an idle CO I/M program
which would have failed only for idle HC in a conventional program. These
vehicles provide a significant portion of the HC benefit in a conventional I/M
program. The effects are discussed in Section 4.3.2.
While re-establishing an idle HC cutpoint may at first seem to defeat the
basic idea behind an idle CO I/M program, it is at least worth considering
whether a reasonably loose idle HC cutpoint might identify the very worst HC
emitters, ones for which repairs to reduce idle HC would be very
cost-effective, without losing much of the attractive aspects of the idle CO
program.
In the Portland study, the vehicles failing only a hypothetical 500 ppm idle
HC cutpoint produced 77.5% of the total HC benefit from all vehicles failing
only for idle HC in the Portland study. The vehicles failing the 1000 ppm
cutpoint provided 61.3% of the total HC benefit from these vehicles. The two
vehicles failing only the 1000 ppm idle HC cutpoint provided this large a
percentage of the total HC benefit from the idle HC-only failures because one
of them was a vehicle with FTP HC emissions of 26.30 grams per mile. This is
more than 17 times the design standard. Although such vehicles are rare, they
are present in any fleet and produce very large HC emission reductions when
repaired. Because there are few such vehicles, their repair has negligible
impact on the overall failure rate and repair cost. Also, because very simple
problems, such as one disconnected spark plug wire, can cause very high HC
emissions, repairs can oftan be quite inexpensive.
In an idle CO I/M program with a loose idle 'AC cutpoint some additional
benefit might be obtained from vehicles which fail both the idle CO cutpoint
and the loose idle HC cutpoint if after the carburetor adjustment the
vehicle's idle HC emission still exceeds the idle HC reinspection cutpoint.
The level of HC benefit observed in the Portland study for loose idle HC
cutpoints may not be obtained in an idle CO I/M program, because in many cases
all of the repairs necessary to allow the vehicles to pass the stringent
-------
71
Portland idle HC cutpoints at reinspection will not be needed in order to pass
looser idle HC cutpoints. One possible way to assure that adequate repairs
are performed is to use a loose idle HC inspection cutpoint (1000 ppm) to
identify vehicles most in need of repairs related to high HC emissions, and
then apply a more stringent idle HC cutpoint (200-300 ppm) in the
reinspection. This approach would be very similar to the one described in
Section 4.4 for separate, idle CO inspection and reinspection cutpoints.
Using a special modification of its I/M- simulation model, EPA has estimated
that adding a 1000 ppm idle HC cutpoint to an. idle CO I/M; program may increase
the fleetwide HC benefit of the idle CO program as of December- 31, 1987 by as
many- as. two percentage points. For example, Table 25 showed that a 20%
stringent idle CO program- will achieve a composite HC reduction of 27% on
December 31, 1987. If air HC cutpoint- of 1000 ppm were added, this reduction
would be improved to 291. This is accomplished with a negligible increase in
the stringency of the program, about two to four percentage points.
A valid concern related to a loose idle HC cutpoint is the reintroduction of
uncertainty in the repair process. In the idle CO I/M program vehicle owners
can be assured that virtually all vehicles can be made to pass with a
carburetor idle mixture adjustment, possibly with an idle speed adjustment.
also. With the addition of even a. very loose idle HC cutpoint, some vehicles
owners will have to rely on the repair industry to properly diagnose and
repair their vehicle without- knowing for certain if the repairs- were indeed
necessary to reduce their idle HC emissions. The number of vehicle owners
with this problem will be small, however, since the failure rate for HC will
be quite low. In a centralized idle CO I/M program, owners of those vehicles
which fail a loose idle HC cutpoint could be given a choice of either passing
the retest of idle HC emissions or presenting a signed statement that a state
certified mechanic has performed specific ignition system diagnosis and has
performed repairs as necessary. This would be similar to the waivers provided
in some I/M programs after a specified "low-emission" tune-up by certified
mechanics. The suggestions outlined in Section 3.0 will also help reduce the
incidence of unnecessary repairs.
.A loose idle HC cutpoint may have fuel economy advantages since it would often
identify vehicles with severe ignition system misfire. Severe (11%) induced
misfire on 10 vehicles in an EPA test program decreased their overall fuel
economy 7.7%. The two vehicles in the Portland study identified as idle
HC-only failures by a 1000 ppm idle HC cutpoint obtained an overall fuel
economy benefit of 9.9% from repair. These instances indicate that there may
be a significant fuel economy benefit in the repair of many of the vehicles
which exhibit extremely high idle HC emissions. The reduction in fuel
consumption for such vehicles can offset: t'-e costs of the additional repairs
that will be necessary as a result of the addition of a loose idle HC
cutpoint. An 8% fuel economy benefit, for instance, provides about $72 per
year in fuel savings. Repair costs of the idle HC only failures in Portland
range from zero to $207, averaging $41. Not all vehicles requiring repairs as
a result of failing a high idle HC cutpoint are expected to receive such large
fuel economy benefits, however. Only about half of the vehicles failing a
1000 ppm HC cutpoint are expected to receive large fuel economy benefits from
repairs.
-------
72
The five year tons of HC emissions reduced have been estimated to be 2,590
tons in a vehicle base of 1 million cars. If pre-1975 vehicles are exempt
from the program the HC benefit will be reduced to 1.9% on December 31, 1987
reducing HC emissions by 2,420 tons.
Loose idle HC outpoints could also be instituted on a voluntary basis. An
idle CO I/M program could easily measure and report to the vehicle owner the
idle HC levels of each inspected vehicle. Vehicle owners whose vehicle's idle
HC levels were extremely high could be advised that their vehicle's HC
emissions were above normal and their vehicle probably was in need of
maintenance in addition to a carburetor adjustment. These repairs will
usually involve ignition problems. It could be expected that some vehicle
owners would voluntarily seek emission related repairs and reduce their HC
emissions.
Generally, the advisory HC limits could be considered as a service offered to
vehicle owners warning them when their vehicles are in need of repairs.
Emission reductions from this method would be sporadic and very hard to
quantify since all repairs would be voluntary and no idle HC retest would be
required. However, some vehicle owners would have repairs performed and some
HC benefits would be gained without significantly increasing the overall
program costs.
7.5 Tampering Checks
7.5.1 Background
Another means of obtaining additional HC reductions in an idle CO I/M program
is to perform a visual check of various emission control systems in
conjunction with the vehicle's idle CO test. The purpose is to identify those
vehicles which have had one or more of their emission control systems disabled
or removed. Requiring that these vehicles have their emission control systems
restored to proper operation can result in additional HC (and CO) emission
reductions.
Of equal importance, performing a tampering check as part of the I/M process
can discourage new instances of tampering. This deterrence value of a
tampering check can best be understood in qualitative, "common-sense" terms.
That is, it makes sense that vehicle owners will be less likely to remove or
disable any of the emission control systems on their vehicles if they know
Chat the presence of some or all of those systems will be checked in the I/M
program.
There are, however, several drawbacks to performing tampering checks as part
of the I/M test. First, the time required to properly perform a tampering
check slows down the inspection process and increases the manpower requirement
of the I/M station. This, of course, adds to the cost of the. I/M program.
Second, while most manufacturers equip at least some of their vehicles with
the emission control systems which are suggested below for inclusion in the
tampering check, they do not design those systems uniformly. There is
significant diversity in what the various systems look like and where they are
-------
73
placed on the vehicle. This will require that the inspectors performing the
tampering check receive special training. In addition, there will be a need
to determine which vehicles were originally equipped with the system in order
to accurately determine whether it has been removed. For example, many
vehicles from the 1975-1979 model years were not equipped with air pumps.. In
order for an air pump tampering check to. be made on these vehicles, it is
necessary to separate the; vehicles originally equipped with air- pumps from
those not so equippedv It should, be noted that these- considerations and the
difficulties, they present apply especially to decentralized programs.
Third, most of the emission: control systems recommended for- inclusion in the
tampering- check have been observed: in the field to have relatively low rates
of tampering (between 1-6Z).. This means that the number of cars failed in an
I/M program on the basis of the tampering check will likely be small. This
magnifies any added inspection cost per detected disablement.
Fourth, the replacement cost for some of the components on some systems can be
high (e.g. catalyst replacement). This is, of course, particularly
undesirable in. an I/M program designed with the goal of minimizing costs.
In light of these- considerations, tampering, checks should be limited., to an
inspection of: those, systems with a^ significant HC effect (based on both the
known incidence of tampering with the system and the pervehicle effect of
such tampering on HC emissions). In addition, systems should be included only
if they are easy to inspect, relatively cheap to repair and/or have a valuable
deterrent effect. The following sections will discuss the systems which best
meet these criteria: air pumps, evaporative emission control systems and
catalysts.
It is worth noting a fifth drawback of a tampering check. This is the
confusion it can cause among vehicle owners. An owner may not understand why
it matters if his older car fails the tampering check if the idle test shows
that the car has low emissions anyway. It can be difficult to explain the
different purposes of the tampering check and the idle test to a. layperson in
the noise and hurry of the I/M station. Therefore, EPA suggests that passing
the tampering check be a prerequisite to receiving a valid idle test. In this
way, the owner of a tampered vehicle will not receive the idle CO score from
his or her vehicle if it is below the cutpoint as this would only confuse him
or her. There is no harm in giving the owner a failing idle CO score,
however, and this may save him or her some inconvenience if the repair of the
tampering and Che carburetor adjustment are performed in Che trip Co a repair
facility.
One way to take advantage of the deterrence value of tampering inspections
without the drawbacks associated with inspecting all vehicles is to develop a
method to randomly select a sample of vehicles to be inspected for tampering.
Only the vehicles sampled would be checked for tampering and all other
vehicles would only be given the emissions test. This would greatly reduce
the resources needed to conduct tampering inspections. These few vehicles
could also be more thoroughly examined than in a program which mandated that
all vehicles be inspected for tampering and therefore would be somewhat more
likely to discover any disablements. The expected result would be less
tampering overall Chan without any Campering check since vehicle owners may be
-------
74
less likely to allow tampering with their vehicle's emission controls if there
is a chance, however small, that they will be detected. Likely there would be
more tampering than with an inspection of every vehicle, since at least some
owners may prefer to tamper and accept the low risk of being selected for the
inspection. If all owners did this, there would be no deterent effect from
the checks.
This random selection tampering inspection has drawbacks of its own, however.
(1) The program as a whole may be criticized as being "arbitrary" and, since
only some vehicle owners are singled out for the tampering inspection, may
criticize the program as not equitable. (2) If the number of tampering
inspections performed, is small, and if the associated penalty for detection is
only the repair cost, many vehicle owners may feel it is cheaper to take their
chances on being selected and discovered rather than correct any existing
tampering or refraining from future tampering.
For this analysis each tampering check it is assumed that once all instances
of disconnected or removed emission control components are discovered and
repaired in the first year of the program (e.g., a program starting in 1983),
only a few isolated instances of tampering will be discovered in following
years as vehicle owners become aware that their systems are being checked.
This does not reduce the HC.and CO emission benefits of the check, but limits
the repair costs to the cost of a one-time fix of all tampered systems at the
start of the program. Any increase in the inspection costs are considered
negligible.
7.5.2 Air Pump Checks
The purpose of the air pump is to supply air to the engine's exhaust in order
to promote the oxidation of EC and CO to harmless by-products. The air pump
performs this function on both catalyst and non-catalyst vehicles. The air
pump is driven by means of a belt which transmits power from the crankshaft as
it rotates. This method of powering the air pump is the same as that used to
run the alternator and air conditioner compressor. The air pump can therefore
be found near or on the same plane as the alternator or air conditioning
compressor. Its plumbing distinguishes it.
The percentage of vehicles equipped with air pumps varies by model year. The
percentages presented in Table 28 are the ones used in this analysis.
Table 28
Percent of Various Model Year Groupings Equipped
With Air Pumps
Mode 1 Year Grouping Percent Equipped With Air Pumps
1968-1975 100%
1975-1979 40%
1980 100%
1981* 95%
-------
75
There are three main ways the air pump can be tampered with. First, the belt
which drives the pump can be removed. Second, the entire unit pump, belt,
hoses, and even mounting brackets can be removed. Third, the output hose
from the air pump can be disconnected and/or the air routing valve can be
tampered with. This last form of tampering results in the air pump spinning
freely and no air being supplied, to the exhaust. AIL three- of these forms of
tampering can ba identified by trained inspectors in- an I/M: lane..
The repairs^ necessary for these various- forms of tampering are self-evident.
In most cases-,, repair can. be- accomplished by simply installing- a new belt or
reconnecting- a hose. An- average repair- cost of $20 has been assumed for this
analysis.
The rate of air pump tampering used in this analysis is that 6.6% of the air
pump-equipped fleet has a tampered air pump at any one time. This rate comes
from an in-use surveillance program conducted by EPA's Mobile Source
Enforcement Division in 1978 [22].*
While various surveillance programs have reported various rates of air pump
tampering, the rate from this program was chosen since the surveillance
techniques employed in the program should, have resulted in. the most random
vehicle sample from among the. various programs. In addition, the time spent
in inspecting each vehicle for tampering was roughly what might be spent in an
operating I/M program.
The HC and CO emission increases which accompany air pump tampering for
1975-1979 model year vehicles were quantified by examining data from. 11
vehicles (1975-1979 model years) tested with and without their air pumps
operational. Nine of. these vehicles came- from the 300 car Restorative
Maintenance program [12]. The other two came from a test program which
examined regulated and; unregulated exhaust emissions from catalyst
vehicles[23]. These data indicate that the average HC emission level
increases 1.2 g/mi upon air pump tampering and the average CO emission level
increases 28.0 g/mi. COne source of uncertainty in Che analysis has to do
with the fact that the 11 vehicles used to determine the emission effects of
air pump tampering were all in tuned-up condition. The emission increases due
to air pump tampering on vehicles in less perfect condition may vary.)
There is some uncertainty as to the HC and CO effects of air pump tampering
for pre-1975 model year vehicles. However, these vehicles contribute only a
very small share of the fleet's emissions at the date of interest to this
analysis (December 31, 1987^, They were assumed to show the same percentage
affect due to air pump tampering as 1975-1979 vehicles. This assumption is
reasonable and due to the small contribution made by these vehicles, does not
significantly affect the analysis.
* The rate of 6.6% is an overall rate for the air pump system and does not
appear in Reference 22, which gives rates only for individual components of
the air pump system. The rate of 6.6% was determined from the original data
base used to prepare Reference 22.
-------
76
For 1981 and later model year vehicles, Che effects of air pump tampering were
quantified by examining the results of EPA laboratory programs which took 4
vehicles representative of 1981 and later technology and tested them with and
without their air pumps operational. In addition, one representative 1980
Ford vehicle tested in an EPA surveillance program in California was found to
have its air pump disabled due to having one of the vacuum control hoses
kinked closed. This vehicle was tested as-received (air pump disabled) as
well as after having the air pump repaired (vacuum hose unkinked). Data from
these five vehicles indicate that the average EC emission level increases 0.5
g/mi upon air pump tampering for 1981 and later vehicles and the average CO
emission level increases 15.0 g/mi.
No comparable test data are available for 1980 model year vehicles. 1980
model year vehicles were assumed to have the same emission effects for air
pump tampering as 1981 and later vehicles. This is because the 1980 emission
standards (0.41 g/mi HC; 7.0 g/mi CO) are closer to the 1981 standards (0.41
g/mi HC; 3.4 g/mi CO) than to the 1975-1979 standards (1.5 g/mi HC; 15 g/mi
CO).
Given the assumed rate of air pump tampering (6.6%) and given the emission
increases which accompany air pump tampering for the various model year
groupings, fleetwide emission benefits and costs of identifying and repairing
tampered vehicles can be calculated. It is assumed that all vehicles with
tampered air pumps are identified and repaired.
The calculations involved in determining a fleetwide benefit will not be
presented. Basically the procedure involves calculating the emissions
projected to be contributed by the various model year groupings (i.e. pre-75,
1975-1979, 1980, 1981 and later) on December 31, 1987. The emission
reductions which would result from the repair of vehicles with tampered air
pumps is then calculated (also within each model year grouping at a December
31, L987 date). The final step involves calculating a fleetwide percent
benefit by taking the emission reductions due to repairing vehicles with
tampered air pumps and dividing it by the total (non-I/M) emissions of the
fleet. Table 29 presents these figures of percent benefit for both HC and
CO. For an example, Table 25 showed that an idle CO I/M program with a 20%
stringency will achieve a composite HC reduction of 27% on December 31, 1987.
If an air pump tampering check were added to the program the total HC
reduction would be about 29%. The total additional five year program cost has
been estimated to be SO.92 million for a fleet of one million vehicles.
Exempting pre-1975 vehicles will reduce the benefits. These benefits are
presented in Table 10 in Section 1.2.
-------
77
Table 29
Composite Percent Benefit due to Air Pump Tampering Check
Additional Five Year
Emission Reduction *
Pollutant December- 31. 1987 Percent Benefit (Thousands of Tons Removed)
HC 1.5* 2.56
CO : 4.33T 68.0
A vehicle base of one million vehicles is assumed.
7.5.3 Evaporative Emission Control System Check
The evaporative, control, system la intended, to capture the gasoline fumes which
are:, naturally given, off wherever gasoline is stored, and used* These fumes are
made- up of pure hydrocarbon- (HC) emissions. Although not. emitted from the
exhaust they represent a significant portion of a vehicle's total HC
emissions. The evaporative control system captures the fumes given off by
both gasoline in the fuel tank and the gasoline present .in the carburetor
(early systems dealt only with evaporative losses from the fuel tank). These
fumes are stored in a charcoal cannister mounted in the engine compartment and
then routed to the engine for burning at appropriate times.
Especially for early model year vehicles, on which evaporative controls were
first introduced, tampering with the system has been observed to be fairly
common. The 1978 Tampering Study(22] described earlier found 8.2% of
1973-1974 model year vehicles had tampered evaporative control systems and
1.3% of 1975-1977 model year vehicles had been tampered. This tampering can
take the form of disconnected or cut hoses, missing cannisters or removal of
the entire system. Once again, these forms of tampering are identifiable by
trained inspectors. An average repair cost of $10 has been assumed.
The calculation of the emission benefit due to the identification and repair
of vehicles with tampered evaporative control systems was performed in the
sane way as for air pump tampering. The fleet was broken down into
appropriate model year groupings, an HC emission increase due to evaporative
tampering and a tampering rate was assigned to each grouping and the fleetwide
benefit on January 1, 1988 was calculated. Since evaporative control
technology has evolved along a different timescale than air pump or catalyst
technology, the model year groupings used for the evaporative analysis differ:
pre-1971, 1971, 1972-1974, 1975-197"?, 1978-1980, 1981 and later.
-------
78
The emission increases assigned Co each grouping to represent a tampered
system come from an EPA emissions model MOBILE2 which models the
emission contributions ("both evaporative and exhaust) from all model years and
classes of mobile vehicles (e.g. passenger cars, trucks, motorcycles). The
assumption used to determine the increase in emissions due to tampering was
that any tampering would return the vehicle to uncontrolled levels (pre-1971)
of evaporative HC.
The rates of tampering used in the analysis were that 8.2% of 1971-1974
vehicles and 1.32 of 1975 and later vehicles are tampered. These rates
reflect the data from the 1978 Tampering Study[22]. A separate study
conducted in California confirmed the large difference in tampering rates
between pre-1975 and 1975 and later vehicles, although the exact rates were
not duplicated.
Given the above model year groupings, tampering rates and emission increases
due to tampering, a figure for cost and percent benefit on December 31, 1987
can be calculated. Once again, this calculation assumes that all instances of
tampering are identified and repaired. Table 30 presents the HC benefit which
results. (Obviously, since evaporative systems are only concerned with HC
emissions there is no CO benefit.) Five year program costs are expected to
increase $0.25 million.* Exempting pre-1975 vehicles from the program will
reduce these benefits to 1.2%, reducing emissions of HC by 1,430 tons.
Table 30
Composite HC Benefit Due to Evaporative Tampering Check
Additional Five Year
Emission Reduction *
Pollutant December 31, 1987 Percent Benefit (Thousands of Tons Removed)
HC 1.3% 1.94
* A vehicle base of one million vehicles has been made.
It is important to note that this benefit refers to the comparable percent
reduction of the fleet's exhaust HC emissions reprasented by the reduction in
evaporative HC emissions. As described earlier, the total HC emissions from a
vehicle come from both exhaust HC and evaporative HC. The percent benefit
presented in Table 30 is the gram-per-mile reduction in evaporative. HC divided
by the fleet's exhaust HC (in gram per mile) in the absence of I/M. While
most discussions of I/M emission reductions deal only with exhaust HC
emissions, it is equally valid to examine reductions in evaporative HC. This
is because the ultimate goal of the I/M program is to reduce total emissions
(exhaust and evaporative). Since I/M policy statements have traditionally
-------
79
been expressed in terms of percent reduction in exhaust HC, the HC reductions
due to an evaporative tampering check should be expressed in terms of the
comparable reduction in exhaust HC as has been done in Table 29. The HC
benefit in Table 30 can therefore be added to the HC emission reductions for
idle CO I/M programs in Table 25. For example, the 27% HC benefit for a 20%
stringency idle CO I/M program can. be increased to about 28% with the addition
of an evaporative emission control check.
7.5.4- Catalyst Removal Cheek
As is well known, automotive- catalysts lower HC and CO emissions in the.
exhaust by catalytically promoting- the. oxidation of HC and CO to harmless
by-products. (Catalysts on most 1981 .and later vehicles also help reduce NOx
emissions.) Catalysts are normally mounted on the underside of the vehicle,
along the exhaust pipe and before the muffler. Some vehicles have catalysts
mounted inside the engine compartment. If a catalyst is not observed by
checking underneath a 1975 or later model year vehicle, it will be necessary
to- open the engine compartment hood and either locate the catalyst, there or
confirm from, the emissions label put. on. every vehicle that the vehicle was not
equipped with a catalyst at the factory.
Tampering with the catalyst takes the form. of. simple: removal of the catalyst
and replacement with a straight exhaust pipe. Since- this is. very easy to
detect, it was assumed that all instances of catalyst removal are identified
through an I/M tampering check.
Repair of this form of tampering obviously requires installation of a new
catalyst (or reinstallation of the old one if it was saved). This could be a
relatively expensive repair. It was decided, however, to include it in this
report since many states might be interested in checking for catalyst removal
since it is such a flagrant form of tampering. In addition, a catalyst check
has a valuable deterrent effect which costs nothing. Hew catalysts now cost
between $172 and S320, most of which is dealer and distributor markup. A
market for lower-priced used catalysts may appear, if new catalysts are not a.
requirement of the program. In any event, lower-priced replacement catalysts
are possible if any demand is created by a catalyst check. An average cost of
$200 per catalyst has been assumed in this analysis.
The rate of catalyst removal used in this analysis was the rate observed in
the 1978 Tampering survey: 1.4%[22]. This rate was applied to the entire 1975
and later fleet.
The HC and CO emission increases f.;hich accompany catalyst removal were
determined by examining Che engine-out (before the catalyst) emissions of a
number of vehicles involved in several misfueling test programs. Before the
vehicles were misfueled, they received both baseline tests (all components
functional) and tests with the catalyst removed. -By comparing the results of
the two tests the percent increase in emissions which accompanies catalyst
removal can be calculated. Four vehicles from the 1975-1979 model year
grouping and six vehicles representative of the 1981 and later model year
grouping were tested. 1980 model year vehicles were assumed to have the same
percent increase as 1975-1979 vehicles. This was done because the catalysts
-------
80
used on 198C vehicles are more like Chose used on 1975--79 vehicles Chan Chose
used on 19<31 and later vehicles. The figures of percent increase were
combined wich the projected zero-mile emission levels of Che various model
year groupings in order Co calculate Che following figures of gram-per-mile
increase: 3.06 g/mi HC and 24.16 g/mi CO for 1975-1979; 0.67 g/mi HC and 7.36
g/mi CO for 1980; 0.93 g/mi HC and 7.11 g/mi CO for 1981 and later.
As was done for Che air pump and evaporative control analyses, the rate of
catalyst removal, the emission increases due to catalyst removal, and the
relative contributions of the various model year groupings were combined to
calculate figures of percent benefit at January 1, 1988. " Table 31 presents
Chose figures. As with the benefits presented in Tables 29 and 30, Che HC
benefit in Table 31 would be added to the HC benefit in Table 25, for example,
to find Che overall benefit of an idle CO I/M program chat includes a catalyst
removal check. Total five year program costs will be increased by about $2
million.*
Table 31
Composite Percent Benefit Due Co Catalyst Removal Check
Additional Five Year
Benefit on Emission Reduction *
Pollutant December 31, 1987 (Thousands of Tons Removed)
HC 0.9Z 1.35
CO 0.5% 10.7
One alternative way Co implement a catalyst check which helps avoid Che repair
cose problem mentioned earlier would be Co restrict Che check co Chose
vehicles sold after Che I/M program begins. That is, vehicle owners who had
removed Che caCalysC on Cheir earlier model year vehicles (before I/M
sCart-up) would not be required Co install a new catalyst, while owners of
newer model year vehicles would. This approach, if coupled with an effective
public awareness program, should provide an effective natural deterrent. Many
vehicle owners would be dissuaded from removing Cheir catalyst under such an
approach and those chat removed their catalyst anyway and were subsequently
identified in an I/M program would at least have been forewarned. There is
noc expected Co be, Cherefore, any significanC addicional program cost
associated wich this program.
* A vehicle base of one million vehicles is used.
-------
81
This approach does, of course, reduce the emission benefits associated with a
catalyst check. Table 32 presents the emission benefits which result if the
catalyst check is restricted to 1983-1988 model year vehicles (assumes a
January 1, 1983 I/M start-up).
Table. 3Z
Composite.' Percent Benefit Due to a Catalyst: Removal Check
Restricted to 1983 and Later Vehicles.
Additional Five Year
Benefit on Emission Reduction *
Pollutant December 31, 1987 (Thousands of Tons Removed)
HC 0.3% 0.20
CO 0.2% 1.6
* A vehicle base of one million vehicles is used.
7.6 Inspection and Maintenance for Light Duty Trucks
Light duty trucks (LDTs) such as pickups, vans, and light delivery vehicles
are susceptible to the same types of maladjustments and emission component
failures as most pre-1981 passenger vehicles. The HC and CO emissions from
LDTs are a significant fraction of emissions from all mobile sources in urban
areas. While EPA policy does not require inspection of LDTs in I/M programs,
any emission reductions from repairs of LDTs in an I/M program will contribute
towards attainment of air quality standards, just as do emission reductions
among passenger vehicles (LDVs). Therefore, an idle CO I/M program can
include LDTs and use the HC emission reductions from those additional vehicles
to improve the program's overall HC emission reduction benefits.
The most obvious advantage to this approach of enhancing an idle CO I/M
program is that it will require fewer additional design and administrative
complications than some of the other HC benefit enhancements in this section.
In addition, the added HC benefits will generally be larger than any of the
other HC enhancements since Che additional HC and CO emission reductions are
derived by testing more vehicles rather than by squeezing more benefits fron
the same vehicles.
LDTs can be broken down into two major subgroups which will be considered
separately. LDTs with gross vehicle weights (GW) below 6000 pounds will be
refered to in this report as LDT1. All LDTs between 6000 pounds and 8500
pounds GVW will be LDT2. In addition, in order to discuss the effects of
better tests and better repairs, the technology level of each LOT
corresponding to an equivalent LDV (passenger car) technology will be
determined. Table 33 presents the technology levels and the corresponding
model vears of LDVs, LDTls, and LDT2s which correspond to those levels.
-------
82
Table 33
LOT Technology Level Equivalents
Technology ' Model Years Included
Level LDV LDT1 LPT2
Pre-Catalyst. Pre-1975 Pre-1975 Pre-1979
Oxidation Catalyst 1975-1980 1975-1984 " 1979-1984
Three-Way Catalyst . 1981 and Later 1985 and Later 1985 and Later
LDV: Light duty gasoline vehicles
LDT1: Light duty trucks below 6000 pounds GVW
LDT2: Light duty trucks between 6000 and 8500 pounds GVW
The additional HC and CO emission benefits in tons of pollutants chat are
possible by including LDTs in an idle CO I/M program depend on the emission
reductions per LDT, the number of LDTs in the I/M area, and the number of
miles they drive. Table 34 presents the HC and CO emission benefits in an
idle CO program among the two groups of LDTs with and without other
enhancements.
-------
83
Table 34
HC Reductions Among Light Duty Trucks
in an Idle CO I/M Program
LDT1 (0-6000 pounds GVW):
HC
Stringency for
Pre-1985 Vehicles
(Failure Rate)
13
20
30
40
LPT2 (600Q-85QO pounds GVW):
Reduction on December 31,
Idle CO Test With
Alone Better Test *
CO
HC.
CO
29.6
32.8
36.8
38.1
35.4
40.1
44.5
45.7
30.0
33.2
37.2
38.5
36.2
41.0
45.4
46.6
Stringency for
Pre-1985 Vehicles
(Failure Rate)
13
20
30
40
Reduction on December 31,
Idle CO Test With
Alone Better Test *
HC
CO
HC
CO
22.1
24.2
27.3
28.2
32.1
34.9
37.8 -
38.5
23.2
25.3
- 28.4
29.3
34.6
37.4
40.3
41.0
1987
With
Be'tter Repairs **
HC CO
31.2 40.1
35.3 45.7
40.6 49.1
42.3 49.5
1987
With
Better Repairs **
HC CO
23.3
25.8
29.7
30.8
34.9
38.0
40.3
40.8
* Better Test: Two-Speed Idle Test or Loaded Test for 1985 and later LDTs.
** Better Repairs: Full mechanic training or more stringent reinspection
cutpoints for Pre-Catalyst and Oxidation Catalyst LDTs.
The emission reductions from LDTs in Table 34 can be converted into
passenger-vehicle-equivalent HC and CO emission reductions and applied to
overall passenger vehicle emission reduction goals. This is done by first
calculating the gram per mile reduction in the emission factors for HC and CO
from I/M on December 31, 1987. Next these reductions are weighted by the
vehicle miles traveled of LDTs versus passenger cars in Chat year. Finally
these weighted reductions are divided by the appropriate passenger vehicle
emission factors for the case without I/M giving the additional HC and CO
benefits from I/M for LDTs. Table 35 presents the results of such
calculations using standard national LOT densities and mileage accumulations.
Using the Two-Speed Idle or Loaded Test for 1985 and later LDTs provides only
an additional 0.1% benefit for both HC and CO emissions.
-------
84
Table 35
Passenger-Vehicle-Equivalent
Emission Benefits from Light-Duty Trucks
Stringency for Additional Percent Benefit on December 31, 1987
Pre-1985 Vehicles for Passenger Vehicle Idle CO I/M
(Percent) Idle CO Test With Better Repairs
HC CO HCT CO
13 4.2 4.4 4.3 4.9
20 . 4.6 4.9 4.9 5.6
30 5.1 5.4 5.6 5.9
40 5.3 5.6 5.8 6.0
For example, a basic idle CO I/M program from Table 25 in Section 6.0 with a
13% stringency can increase the program HC benefits by 4.2% and the CO
benefits by 4.4% for passenger vehicles by including light-duty trucks in the
I/M program. This would increase the benefits of a 13% stringency idle CO
program from 24.22 to 37.5% for CO. The five year program costs and tons
removed for this option have been estimated in Section 1.2 and presented in
Table 7. Exempting pre-1975 LDTs from the program will reduce both the HC and
CO benefits. Table 12 in Section 1.2 presents the benefits and costs of LOT
I/M exempting pre-1975 vehicles.
-------
85
References
1. "Inspection/Maintenance Policy." David G. Hawkins to EPA Regional
Administrators, EPA memo. July 17, 1978.
2. Federal Register, 44- FR 2960, January 12, 1979. (Parameter Adjustment
Regulations).
3. Federal Register, 45 FR 34802, May 22, 1980. "Motor Vehicles; Emission
Control System Performance- Warranty Short Tests and Warranty Regulations;
Final Rules."
4. "Update on the Cost-Effectiveness of Inspection and Maintenance." Tom
Darlington, EPA I/M Staff. April 1981. EPA-AA-1MS/81-9.
5. "Update on the Fuel Economy Benefits of Inspection and Maintenance
Programs." R. Bruce Michael, EPA I/M Staff. April 1981.
EPA-AA-IMS/81-10.
6. "Inspection and Maintenance for 1981 and Later Model Year Passenger
Vehicles". David W- Hughes, EPA I/M Staff. June 1981. Society of
Automotive Engineers, 810830.
7. "Recommendations Regarding the Selection of Idle Emission Cutpoints for
Inspection and Maintenance Programs Requiring Only Carbon Monoxide
Emission Reductions." Susan Vintilla, EPA I/M Staff.. May 1981.
EPA-AA-IMS/81-13.
8. "A Survey of Operating Inspection/Maintenance Program." R.F. Klausmeier
and O.K. Kirk, Radian Corporation, Austin, Texas. April 1980. No. DCN
80-230-146-09.
9. "Update on EPA's Study of the Oregon Inspection/Maintenance Program."
James A. Rutherford and Rebecca L. Waring, EPA I/M Staff, June 1980. Air
Pollution Control Association, No. APCA 80-1.2.
10. "Analysis of the Emission Inspection Analyzer". William B. Clemmens, EPA
ECTD, September 1980. EPA-AA-IMS/80-5-A.
11. "Implementation Issues Regarding EPA Recommended I/M Emission Analyzer
Specification." David G. Hawkins to EPA Regional Administrators, EPA
memo. September 24, 1980.
12. "An Evaluation of Restorative Maintenance on Exhaust Emissions of 1975-75
Model Year In-Use Automobiles." Jeffrey C. Bernard and Jane F. Pratt,
Calspan Corp., Buffalo, New York. December 1977. Three sites, four
volumes. EPA-460/3-77-021.
13. "A Study of Emissions from Passenger Cars in Six Cities." FY77.
Automotive Testing Laboratories, Aurora, Colorado. January 1979. Two
Volumes. EPA-460/3-78-011.
-------
86
14. "FY79 Study of Emissions From Passenger Cars in Six Cities." Two
Volumes. Automotive Testing Laboratories, Inc., September 1980.
EPA-460/3-80-020.
15* "Testing Support for an Evaluation of a Houston I/M Program." Automotive
Testing Laboratories, Inc., Aurora, Colorado. September 1980.
EPA-460/3-80-021.
16. "Final Results of the One-Week Follow-Up With Participants During the FT79
and FY80 Emission Factor Testing Programs." EPA Technology Evaluation
Branch, 1981. EPA-AA-TEB/81-27.
17. "Effects of Inspection Maintenance Programs on Fuel Economy." I/M Staff
Technical Report. Revised June 1979. IMS-001/FE-1.
18. "Restorative Maintenance Fuel Economy Analysis." Jim Rutherford to Janet
Becker, EPA I/M Staff memo. February 14, 1980.
19. "Portland Study Fuel Economy Analysis." Jim Rutherford to Charles Gray,
EPA I/M Staff memo. January 28, 1980.
20. "Derivation of 1981 and Later Light Duty Vehicle Emission Factors for Low
Altitude, Non-California Areas." EPA I/M Staff Technical Report.
November 1980. EPA-AA-IMS/80-8.
21. "Derivation of I/M Benefits for Post-1980 Light Duty Vehicles for Low
Altitude, Non-California Areas." David Hughes, EPA I/M Staff. January
1981. EPA-AA-IMS/81-2.
22. "1978 Motor Vehicle Tampering Survey." EPA Office of Enforcement.
November 1978.
23. "Regulated and Unregulated Exhaust Emissions from Malfunctioning
Non-Catalyst and Oxidation Catalyst Gasoline Automobiles." EPA ECTD,
1980. EPA-460/3-80-003.
------- |