79-2
Technical Report
Evaluation of a Proposed Colorado State
Inspection/Maintenance Program
November, 1978
by
Thomas C. Bejma
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise and Pollution
U.S. Environmental Protection Agency
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Abstract
In response to a. request from the State of Colorado through EPA Region
VIII, a pilot test program was conducted to evaluate the effectiveness
of a possible Inspection and Maintenance (I/M) program at high altitude.
The work was performed in early 1978 by Automotive Testing Laboratories
(ATL) in conjunction with the FY77 Emission Factor Passenger Car Program
in Denver.
The vehicles which became part of this study were procured randomly from
private owners in the Denver area. Included were seventy-five 1977 and
twenty-four 1978 model year passenger cars. Thirty light duty trucks
(up to 8500 Ib. GVW) of the 1975 through 1978 model years were also
included. These 129 vehicles became part of the evaluation which included
the private repair facilities. The 1977 and 1978 automobiles repre-
sented the entire sample of these years in the Emission Factor Program.
Particular makes and models were chosen on a sales-weighted basis. The
trucks were procured separately from the Emission Factors Program but
were also chosen using sales-weighting techniques.
Each vehicle was subjected to an underhood inspection and a series of
emission tests both before and after maintenance. The maintenance was
performed at one of 10 selected commercial repair facilities. Infor-
mation on the costs associated with each maintenance action was also
collected. For comparison, data on 1975 and 1976 passenger cars which
underwent Restorative Maintenance as part of the basic Emission Factor
Program were also included in this report although all maintenance and
testing activities were performed by ATL. An additional fleet of thirty
1975 and 1976 models, each having accumulated more than 50,000 odometer
miles were also tested in an as-received condition only.
The results of this pilot effort confirm the poor emission performance
of relatively new, in-use passenger cars although 1977 and 1978 auto-
mobiles displayed better control than those prior to confirmatory
testing at high altitude. High-mileage vehicles exhibited higher HC and
CO emission levels than their lower-mileage counterparts but the budget
of the program precluded maintenance and retesting to help assess the
reasons. The underhood inspections revealed that many vehicles had been
subjected to various forms of maladjustments, primarily ignition timing
and idle mixture. The results of tests after maintenance at private
garages showed that a reasonable I/M program at high altitude would be
effective in identifying higher emitters and in reductions of HC and CO
emission levels.
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Introduction
Results of EPA's Emission Factor Testing Programs indicate that a large
percentage of in-use vehicles fail to meet their emission standards when
tested in an "as-received" condition. A major follow-up study, The
Restorative Maintenance Evaluation, was conducted to determine the
reasons for such failures. The results of this study indicate the major
reason for such failures is the maladjustment and disablement of the
control systems. One method which could minimize these actions is a
compulsory Inspection and Maintenance (I/M) Program. The State of
Colorado, in consideration of such a program in the Denver area, requested
EPA's assistance in the investigation of its feasibility. The two major
items which were to be evaluated were the reduction in atmospheric
pollutants and the cost to the consumer of these reductions.
The basic approach to the performance of this pilot program was developed
by the State of Colorado. At the present time, their primary plan is to
allow private repair facilities such as car dealerships and independent
garages to conduct emission inspections. This method would take advan-
tage of the safety inspection process currently in place. Each facility
would require a specific license to conduct these inspections and perform
any maintenance required. A license would be issued to a facility after
it was able to demonstrate appropriate capabilities both in equipment
and personnel to perform emission related testing and maintenance.
Mechanics would be required to undergo training such as that provided by
Colorado State University.
This method would eliminate the need for the state itself to conduct the
inspections or to contract for the performance of the inspections.
There is, however, the question of "conflict of interest" to be resolved.
With the private sector performing both the inspection and the main-
tenance, abuses could occur.
The program followed the same general strategy of past Restorative
Maintenance Programs except that failure of the idle test rather than
the FTP was the criteria used to enter a vehicle into the maintenance
and retest portion of this effort. A tiered approach was followed to
determine the reduction in idle emission levels at various stages in the
garage operations. This approach was used for evaluation purposes only.
Normally, a garage would perform any maintenance required to pass the
vehicle. Charges were in accordance with prevailing rates at each shop.
Repairs were generally limited to a maximum of $50.00 per vehicle for
this contract although a total of five vehicles were repaired at costs
ranging from $50 to $85.
Selection of Private Facilities
In order to best simulate the repair facility situation in a fully
operational I/M area, local garages and dealerships were screened to
identify those which possessed certain basic qualifications. These
qualifications were a current license to perform the State Safety
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Inspection, a heated work area, suitable HC/CO analyzer, tune-up tools,
and the willingness to send at least one person to an approved mechanics
training course. Of 120 facilities surveyed, 29 met the basic require-
ments and ten were ultimately selected. Three were new car dealerships,
three were independent garages and four were gasoline service stations.
AIL personnel assisted these facilities in the initial calibration and
correlation of their analyzers and performed subsequent cross-checks
during the program.
Selection of Test Vehicles
The vehicles which became part of this study were procured randomly from
private owners in the Denver area. Included were seventy-five 1977 and
twenty-four 1978 model year passenger cars. Thirty light duty trucks
(up to 8500 Ib. GVW) of the 1975 through 1978 model years were also
included. These 129 vehicles became part of the evaluation which
included the private repair facilities. In addition, thirty 1975 and
1976 passenger cars with high mileage (over 50,000) were procured and
tested in "as-received" condition only due to budget constraints. The
1977 and 1978 automobiles represented the entire sample of these years
in the Emission Factor Program. Particular makes and models were chosen
on a sales-weighted basis. The trucks and the 1975 and 1976 model cars
were procured separately from the Emission Factors Program but were also
chosen using sales-weighting techniques.
Test Procedures
As standards or test procedures have not been established for an I/M
program in Denver, the decision was made to use a neutral curb idle
test. Based on experience with similar programs at low altitude,
cutpoints of 150 ppm HC (as Hexane) and .5% CO were considered accept-
able. These cutpoints were expected to fail about 50% of the sample.
Of 129 vehicles tested, 55 failed using these cutpoints. Sample size
was limited due to budget considerations.
The sequence of tests performed at the ATL laboratory included the 1975
Federal Test Procedure (FTP) for exhaust emissions only, the Highway
Fuel Economy Test (HFET), and three short cycle tests. These were the
Federal Three Mode, Federal Short Cycle, and the Two Speed Idle Test. A
thorough underhood inspection and a limited driveability evaluation were
also performed. The entire sequence was conducted both before and after
maintenance. Flow diagrams for the various classes of vehicles tested
in this program are shown in Figures 1, 2 and 3.
The garages performed only idle tests. "As-received" values and final
values were recorded, as well as the description and cost of any main-
tenance performed. Some vehicles were also sent to the garages even
though they passed the idle test at ATL. This was done to check their
ability to detect failed vehicles. Participating repair facilities were
given $5 in addition to the charges resulting from their normal repair
rates to cover the cost of completing the forms. This fee is not
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included in the cost of maintenance figures. In other cases, failed
vehicles were not sent to the garages because of the workload there or
because the vehicle owner was not willing to allow ATL to retain his
vehicle any longer.
Test Results
A summary of the test results for this program is found in tables at the
end of this report. Results on individual vehicles as well as more
details on the conduct of the program may be obtained from a copy of the
EPA Final Report No. 460/3-78-001, "Colorado Motor Vehicle Emission
Inspection - A Pilot Program." The State of Colorado, the customer for
this work, is also expected to produce an extensive analysis of these
results.
Table 1 describes the results obtained on the 1978 MY vehicles. Of the
24 vehicles included in the sample, 8 failed the idle test at the ATL
laboratory and were sent to the commercial garages. An additional 9
vehicles were sent to the garages even though they passed at ATL. Of
the 17 vehicles sent, 9 received maintenance (one vehicle received
maintenance even though it had passed its idle test at ATL). In general,
these vehicles performed poorly in relation to the federal standards but
did show improvements in emission levels when they were repaired by the
private facilities.
The results on the 1977 model year vehicles shown in Table 2 indicate a
majority passed the idle test. Passenger cars of this model year were
the only ones fully certified at high altitude and in most cases had
idle CO levels below .5%. Although these vehicles were a year older
than the 1978 models, a greater percentage of them were able to meet the
applicable federal standards both before and after maintenance.
Thirty trucks, up to a gross vehicle weight of 8500 pounds, were also
tested in the I/M portion of this program. Only two of the 30 trucks
passed the idle test. However, since it was originally intended to send
only 15 through the inspection and maintenance procedure,\no further
trucks were sent after the first 19 were delivered. Cutpoints for these
vehicles were too stringent. Where specified, most idle CO values were
in excess of the cutpoints. These results are shown on Table 3.
The 1975 and 1976 model year passenger cars shown in Table 4 were not
included in this pilot I/M evaluation but were maintained and retested
at the ATL laboratory under the Restorative Maintenance portion of the
basic EF contract. These results are provided for information only.
A group of 30 "high mileage" 1975 and 1976 model year passenger cars
were procured for this program and underwent only an "as received" test
sequence. This was due to cost constraints. The results of these tests
are shown on Table 5. Each vehicle in this group was to have an odometer
reading of at least 50,000 miles. The range was from 52,000 to 147,000
miles.
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Conclusions
There are a number of conclusions which can be drawn from the results of
this program. These are generally similar to those which were obtained
in the Restorative Maintenance Evaluation Project:
1. The great majority of the 1975-1978 light duty vehicles tested for
this pilot project were not able to meet federal standards when
tested in an as-received condition, although the 1977 and 1978
passenger cars did display control typical of late model year cars
at low altitude with 41% and 38% passing, respectively. However,
only 4% of the 1975 and 1976 models met the standards for these
years which preceded confirmatory Certification Testing under high
altitude conditions.
2. A large number of vehicles exhibited some amount of maladjustment
and disablement. Although a computer compilation of the data will
be required to accurately define the extent of the problems, it is
clear that basic timing advance is very prevalent in addition to
the idle mixture maladjustment which has been shown to be the key
problem at low altitude.
3. A proper I/M program at high altitude can be successful in reducing
vehicle emission levels without adversely affecting fuel economy.
The tables indicate a significant difference in the FTP and idle
emissions from vehicles which passed the idle test and those which
failed. Improvements after maintenance was performed on the
groups are also shown. Although this pilot project was more care-
fully controlled and monitored than the "real-world" situation it
was intended to simulate, the functions actually performed by the
participating repair facilities were not outside the capabilities
of typical garages equipped with a basic HC/CO instrument and a
mechanic with a modest amount of I/M training.
4. The average cost to repair each vehicle which failed the idle test
was approximately $20.00. This figure reflects the impact of
maladjustments and disablements on emission levels and the ease of
repair. Carburetor adjustments were the most common area.
5. The automotive service industry in the Denver area is not immedi-
ately prepared for the full scale implementation of even a basic
I/M program in the immediate future. The lack of proper equipment
and training of mechanics in areas related to emission controls are
the immediate drawbacks.
6. The 1975 and 1976 model passenger cars with higher mileage (over
50,000) exhibited higher emission levels than their lower mileage
counterparts. Unfortunately, cost considerations in the design of
this project ruled out maintenance and retesting. Thus, the mix of
reasons between inherent deterioration and greater exposure to
potential maladjustment and disablement actions cannot be determined
at this time.
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Figure 1
Colorado Pilot I/M Program
Test Vehicle Flow Diagram
1977 and 1978 Model Year Passenger Cars
Random
Selection
for
Quality
Idle
C Test
\Results
Maintenance
and
Idle Test
ATL
Garage
* These encircled numbers refer to line numbers on Tables 1
and 2 . They relate to .fleet average emission levels
at various steps in the program.
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Figure 2
Colorado Pilot I/M Program
Test Vehicle Flow Diagram
1975-1978 Light Duty Trucks (up to 8500 Ibs GVW)
ATL
Garage
Maintenance
and
Idle Test i
* These encircled numbers refer to line numbers
on Table-3 . They relate to fleet average
emission levels at various steps in the program.
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Plgure 3
Colorado Pilot I/M Program
Test Vehicle Flow Diagram
1975 and 1976 Model Year Passenger Cars
Note: All work performed
at ATL
* These encircled numbers refer to line
numbers on Table 4 . They relate to fleet
.average emission levels at various steps
in the program.
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Table 1
Colorado Pilot I/M Program
00
1
(D
CD
(ft
G)
(&:
1978 Model Yeai
As Received
Passed Idle Test
Failed Idle Test
Sent to Garages
Received Maintenance
After Maintenance
N
24
16
8
17
9
9
Odom
3924
3437
4898
4315
4431
4431
HC
2.19
1.41
3.75
2.59
3.70
2.52
CO
26.9
27.9
24.9
42.3
56.2
25.1
NOxc
1.14
1.01
1.40
1.17
1.31
1.13
: Passenger Cars
Fuel Economy Met FTP
FTP HFET Standards
15.1
14.7
16.0
15.3
15.6
15.9
21.3
20.5
23.1
21.9
22.3
22.4
38%
50
13
29
11
22
Lab
HC
194
19
544
263
483
277
Idle Garage Idle Average
CO HC CO Cost
1.07
.04
3.13
1.49 371
2.81 664
.50 307
1.21
2.24
.13 $23.17
Fleet Average after
Maintenance
24 3924 1.77 24.6 1.20 15.3
21.3
33
177 .20
NOTE: FTP results are in grams/mile
Fuel economy values are in miles per gallon
Idle HC results are in ppm (Hexane equivalent)
Idle CO results are in mole percent
Numbers preceding each line refer to a portion of the fleet as described in Figure 1
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(T) As Received
(2) Passed Idle Test
(As received)
(3) Failed Idle Test
(4) Sent to Garages
(5) Received Maintenance
(6) After Maintenance
(T) Fleet Average after
Maintenance
Table 2
Colorado Pilot I/M Program
1977 Model Yeai
Tinrr*
N
75
56
19
18
16
16
Odom
12046
11549
13511
14648
14104
14104
HC
1.32
1.06
2.09
2.24
2.38
1.84
CO
23.8
18.6
39.1
41.0
44.4
33.7
NOxc
1.52
1.57
1.37
1.33
1.34
1.19
: Passenger Cars
Fuel Economy Met FTP
FTP HFET Standards
14.9
14.6
15.9
16.4
16.9
16.7
20.6
20.1
22.2
23.1
23.8
24.1
41%
48
21
16
19
38
Lab
HC
95
21
313
254
283
78
Idle Garage Idle Averag<
CO HC CO Cost
1.02
.03
3.97
3.53 323
3.97 354
.48 105
3.11
3.48
.26 $19.97
75 12046 1.22 22.1 1.48 14.8
20.5
45
51
.27
NOTE: FTP results are in grams/mile
Fuel economy values are in miles per gallon
Idle HC results are in ppm (Hexane equivalent)
Idle CO results are in mole percent
Numbers preceding each line refer to a portion of the fleet as described in Figure 1
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(lj As Received
(2) Sent to Garages
(3) After Maintenance
(4) Fleet Average after
Maintenance
Table 3
Colorado Pilot I/M Program
1975 through 1978 Model Year Light Duty Trucks
N Odom
8 21946
5 14744
5 14744
HC
3.89
4.67
3.92
1' 11
CO
70.7
77.7
59.8
Under
NOxc
1.69
2.09
2.01
6000 Ib GVW
Fuel Economy Met FTP
FTP HFET Standards
13.5 18.7 0%
13.5 18.3 0
13.5 18.5 0
Lab
HC
139
186
129
Idle Garage Idle Avera
CO HC CO Cost
3.13
3.90 226 3.50
1.58 68 .19 $41.2
8 21946 3.42 59.5 1.65 13.5
18.8
104 1.68
(I) As Received
(2) Sent to Garages
(3) After Maintenance
(4) Fleet Average after
Maintenance
22 21650
14 18932
14 18932 6.04
Over 6000 Ib GVW
7.70 111.3 2.85 12.2
8.28 118.9 3.09 11.8
92.4 3.00 12.0
22 21650 6.27 94.5 2.79 12.4
16.6
16.1
16.1
16.6
0
0
0
0
348 4.39
362 4.51
172 1.83
227 2.69
NOTE: FTP results are in grams/mile
Fuel economy values are in miles per gallon
Idle HC results are in ppm (Hexane equivalent)
Idle CO results are in mole percent
Numbers preceding each line refer to a portion of the fleet as described in Figure 2
574 5.74
132 1.13 $24.76
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(T) As Received
(2) Passed Idle Test
(as received)
(3) Failed Idle Test
(4) Before Maintenance
(5) After Maintenance
(6) Fleet Average after
Maintenance
Table 4
Colorado Pilot I/M Program
1975 and 1976
N
114
31
83
68
68
Odom
29663
27362
30522
33882
33882
HC
3.13
2.01
3.55
3.28
2.55
Model
1' Ir
CO
55.7
34.1
63.8
57.5
40.1
Year P
NOxc
1.83
1.65
1.90
1.89
1. 77
assenger Cars
Fuel Economy
FTP HFET
14.7
14.0
15.0
14.7
14.9
20.2
18.7
20.8
20.4
20.5
Met FTP
Standards
4%
13
1
0
0
Lab Idle
HC CO
252
45
329
241
124
2.57
.07
3.50
2.46
.30
114 29663 2.69 45.3 1.76 14.8
20.3
182 1.28
NOTE: FTP results are in grams/mile
Fuel economy values are in miles per gallon
Idle HC results are in ppm (Hexane equivalent)
Idle CO results are in mole percent
Numbers preceding each line refer to a portion of the fleet as described
in Figure 3
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i
C-l
Table 5
Colorado Pilot I/M Program
High Mileage 1975/1976 Model Year Passenger Cars
FTP Fuel Economy Met FTP Lab Idle
N Odom HC CO NOxc FTP HFET Standards HC CO
As Received 30 66302 4.33 88.5 1.69 12.2 17.1 0 351 3.36
NOTE: FTP results are in grams/mile
Fuel economy values are in miles per gallon
Idle HC results are in ppm (Hexane equivalent)
Idle CO results are in mole percent
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