EPA-AA-IMS-81-18
Technical Report
Emissions Reductions From Inspection and Maintenance:
Vancouver Versus Portland Snapshot
by
R. Bruce Michael
August, 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
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Table of Contents
Section
1.0
Heading
INTRODUCTION
2.0
SUMMARY AND CONCLUSIONS
3.0
REPRESENTATIVENESS OF VANCOUVER VEHICLES FOR THIS
COMPARISON
3.1
3.2
3.3
3.4
3.5
3.6
Maintenance Habits
Driving Habits
Amount of Driving
Vehicle Age
Effect of Knowledge of the Portland I/M Program
on Vancouver Vehicle Repairs
Summary of Factors
5
6
8
3
8
9
4.0
4.1
4.2
4.3
4.4
RESULTS
Atypically Low Emissions From 1978 Model Year
Vehicles in Both Cities
Federal Test Procedure, Idle Emissions and
Fuel Economy Results
State Inspection Test Failure Rate
Effect of Time Since Last State Inspection Test on
Emissions of Portland Vehicles
10
10
14
16
18
5.0
COMPARISON OF ACTUAL EMISSIONS VERSUS PREDICTED
EMISSIONS FROM MOBILE2 PROGRAM
21
APPENDIX
A. VEHICLE LIST FOR EACH GROUP
B. TESTS PERFORMED
C. BRIEF DESCRIPTION OF TESTS
22
23
24
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1.0 INTRODUCTION
Test Group No. 9 of EPA Contract No. 68-03-2829 with Hamilton Test Systems
compared the emissions of similar cars in Portland, Oregon and Vancouver,
Washington, which are neighboring cities. The purpose of this study was to
compare the emissions from vehicles subject to Inspection/Maintenance (I/M) in
Portland with emissions from non-I/M vehicles (Vancouver). EPA reasoned that
the proximity of these two cities would make a suitable controlled
comparison. No prior study had been performed which would yield a comparison
with as much confidence.
The study design called for two groups of 100 vehicles each to be tested. One
hundred vehicles were to be recruited from Vancouver and then one hundred from
Portland, with vehicle pairs matching by both vehicle type and odometer. The
vehicles were of 1976 and 1978 model years and were similar by type to the
national population mix. These years were chosen so that Portland vehicles
would have been inspected in the prior 12 months, thus representing an annual
I/M program. This was necessary because the Portland I/M program is
biennial. Portland vehicles were also to be evenly distributed over time
since their last I/M inspection, representing a "snapshot" situation of an
annual I/M program in which the vehicle fleet is evenly distributed over time
since the last inspection. Testing was conducted in the latter part of 1980,
so the 1976 model year vehicles were between four and five years old when
tested and the 1978 vehicles were between two and three years old.
The Federal Test Procedure (FTP) and several emissions short tests were
performed on each vehicle in the as-received condition only. Vancouver
vehicles which failed the State Inspection Test entered Test Group No. 10, a
task to investigate the effect of specific repairs on emissions.*
* "Effect of Specific Repairs on Emissions of Vehicles from, Vancouver,
Washington", EPA-AA-IMS/81-19, R. Bruce Michael, July, 1981.
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2.0 SUMMARY AND CONCLUSIONS
Results indicate the following:
1. The comparison of maintenance, driving habits, and the similarity of
the vehicles supports the use of Vancouver as a non-I/M version of
Port land.
2. For the 1976 model year, Portland I/M vehicles had Federal Test
Procedure (FTP) HC emissions 272 lower and CO emissions 22% lower than the
non-I/M vehicles.*
3. Predictions for the emission levels of the 1976 model year using
MOBILE2 agree closely with study results for both the I/M and non-I/M
cities. This supports the accuracy of the MOBILE2 I/M emission reduction
benefits.
4. Vancouver 1978 vehicles were unexpectedly clean, having as low
emissions levels as the Portland 1978 vehicles. On the surface, this
would suggest that there was no I/M effect on the Portland vehicles.
However, the Vancouver vehicles were far cleaner than similar vehicles EPA
has tested in other cities and far cleaner than EPA's MOBILE2
predictions. The reason for this is unknown and we do not try to
hypothesize one. Whatever the reason, one can presume that it affects
Vancouver and Portland vehicles equally.
The important question to consider is not why the Vancouver 1978 vehicles
were so clean, but why the Portland 1978 vehicles were not even cleaner,
as might be expected as a result of the I/M program. It is almost certain
that the Portland 1978 vehicle emissions would have been as low as the
Vancouver 1978 vehicle emissions even without I/M, due to the similarity
of maintenance, social habits, mileage, etc. (see Section 3.0). These
emissions averaged very close to the Federal standards. I/M then would
not have had much chance to reduce the emissions of the Portland 1978
vehicles, since I/M can only correct emissions which are substantially
higher than they should be. Therefore, the negative finding on the effect
of I/M on the 1978 model year vehicles can be explained in light of the
low non-I/M emission levels of these vehicles. The negative finding
should not be taken to mean I/M cannot be effective on typical 1978
vehicles or on vehicles of this age (2-3 years old). Rather, it merely
indicates that emphasis should be placed on the 1976 model year results.
* Since I/M is not intended to affect NOx emissions, comparisons of NOx
emissions are omitted in the text, but do appear in the tables.
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3.0 REPRESENTATIVENESS OF VANCOUVER VEHICLES FOR THIS COMPARISON
EPA believes Chat the comparison of vehicle emissions from these two cities is
valid for several reasons, and that it produces valuable results about the
impact of I/M.
3.1 Maintenance Habits
One factor which can affect vehicle emissions is maintenance. Cars which have
been well maintained and are in a proper state of tune will generally have
lower emissions than vehicles poorly maintained. Several items may affect
maintenance habits, such as social structure and economic conditions.
Although the cities in this study are in two different states, the city limits
are only about one mile apart. Many residents of Vancouver commute to work in
Portland. Therefore, it is likely that social beliefs and behavior are
similar for the cities. The economic status of the cities is also similar,
which contributes to the likelihood that vehicle maintenance habits are
similar.
Each vehicle owner was interviewed to find out when the vehicle had last
received a tune-up. Table 1 shows the answer to this question for the
Portland and Vancouver owners. The similarity in the owners' responses
support the assumption that Vancouver can be used as a non-I/M control site
for Portland.
Table 1
Recent Maintenance of Vancouver
and Portland Vehicles
Question Number of Responses
Due, But 0-6 6-12 Over Don't
Not Due Not Done Months Months 1 Year Know
How Long Ago Was
The Last Tune-Up?
Vancouver 11 4 55 25 3 2
Portland 4 3 50 29 11 3
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3.2 Driving Habits
A second factor affecting emissions is the type of driving performed.
Vancouver is a smaller city with a less congested downtown area. It is
therefore likely that the average Vancouver car is driven a smaller percentage
of the time in stop-and-go city traffic and a larger percentage in suburban
and highway driving than the average Portland car. The latter type of driving
causes less wear and deposit accumulation on engines and tends to keep
emissions low. This factor would therefore tend to make Vancouver cars
cleaner than Portland vehicles (and vehicles in other large cities) in the
absence of I/M. On the vehicle owner questionnaire, however, owners reported
very similar driving patterns and amount of driving per year. For example,
nearly all driving was performed mostly on major city streets, with 88% of
Vancouver owners and 79% of Portland owners reporting this type. Table 2
shows the owner responses to several questions.
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Table 2
Owner Response to Driving Habit Questions
For Vancouver and Portland (N-100 for both cities)
Questions
Number of Responses
Thousands of miles
driven per year
Vancouver
Portland
0-5
3
3
5-10
34
39
10-15
42
41
15-20
19
11
20-30
2
6
Where driving occurs
Vancouver
Portland
Mostly Major
City Streets
88
79
Some on
Other City Streets
87
86
Some on
City Expressways
92
89
How driving is done *
Vancouver
Portland
Mostly
to Work
53
47
Some for
Errands
61
57
Some for
Other Reasons
90
91
* The responses do not add up to 100, because .owners could respond to each
question with varying answers, such as "most", "some", "little or none". Only
the major responses are shown in the table.
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3.3 Amount of Driving
A third factor affecting emissions is the amount of driving performed.
Generally, vehicles with more mileage have higher emissions than vehicles with
low mileage. This factor has no affect on the present comparison, however,
due to the design requirement which made matched-pair vehicle mileages be
similar. The average mileage of the two city groups, shown in Table 3 on page
11, is nearly identical.
3.4 Vehicle Age
A fourth factor affecting emissions is vehicle age. Because vehicles were
matched by age (as well as several other things) this possible factor also has
no affect on the comparison.
3.5 Effect of Knowledge of the Portland I/M Program on Vancouver Vehicle
Repairs
A fifth factor which could affect the emissions of the Vancouver cars is that
some of these cars may receive I/M-type low emission repairs despite the lack
of an I/M program in Vancouver. This would be due to the proximity of the
cities.
A few possibilities exist for Vancouver cars receiving low emissions repairs.
First, Vancouver owners may want to get low emission^ repairs having heard of
the I/M program and having an interest in clean air. However, it is very
unlikely that Vancouver mechanics would have success with giving low emission
repairs, because they are unfamiliar with the repairs and, mainly, because
very few facilities have the emission analyzers to check the adjustments.
Only one real possibility exists for their cars actually receiving low
emission repairs: • if they go to Portland repair facilities for normal
maintenance. Since it is also unlikely that Vancouver residents would take
their vehicles to Portland repair shops, this possibility should have an
insignificant effect.
Second, Vancouver mechanics may want to tune for low emissions having heard of
the Portland I/M program. For the reasons mentioned in the last paragraph,
however, it is unlikely that they would have much success.
Third, if Vancouver owners buy cars from Portland dealers, the dealership
warranty service may have an impact on emissions, since these dealers are
experienced in I/M. Oregon officials who were questioned felt that very few
Vancouver residents buy cars in Portland, however. There is no economic
incentive to do so and, except for a larger variety of foreign car dealerships
in Portland, there is a sufficient number of dealerships in Vancouver to serve
the residents there.
For the reasons mentioned, it is unlikely that a significant number of
Vancouver vehicles receive I/M-type repairs which would lower their emissions.
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3.6 Summary of Factors
Vehicle age and mileage are generally considered to be the most important
factors affecting emissions. Since these were controlled for the two groups
of vehicles, we can say with confidence that the only important difference
between the groups of .vehicles from the two cities is that one group has been
involved in I/M.
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10
4.0 RESULTS
4.1 Atypically Low Emissions From 1978 Model Year Vehicles in Both Cities
4.1.1 Discussion
Study results show that emission levels of the 1978 model year in both cities
were similar. They were both less than in other sites recently studied by EPA
and also both less than predicted by MOBILE2, an EPA computer program which
estimates fleet emissions with and without I/M. This phenomenon is discussed
first, because it has implications as to the meaning of the other results.
The cause of the unexpectedly low emissions is unknown. For whatever reason,
the meaning is that I/M had no significant opportunity to provide emission
reductions in Portland on 1978 cars, since the 1978 model year cars there
would have been relatively clean prior to their I/M test, as clean or cleaner
than the Vancouver cars. I/M can only have an impact on cars with high
emissions. Consequently, the 1978 model year results should be given little
weight. Results will show the two model years separately, as well as the
combined results.
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11
4.1.2 Emission Comparison of Portland/Vancouver Vehicles With Non-I/M Vehicles
in Other EPA Programs
In the ongoing EPA Emission Factors (EF) program, in-use vehicles are tested
in their as-received condition at many sites around the country. Vehicles of
the same model years as those tested in Vancouver and Portland were tested by
EPA in four major cities during 1979/80 for the FY79 EF program. That EF
program tested vehicles very similar to the Vancouver and Portland vehicles in
terms of make and model, although it had a slightly broader cross-section of
vehicle types and lower average mileage.
1976 Model Year - Emissions for each site are shown in Table 3 and Figure 1
for each model year. Emissions of the 1976 model year in Vancouver were
higher than the average EF emissions. The average mileage was also higher in
Vancouver, a factor which would tend to result in higher emissions, but not
enough to account for the total difference. It is interesting to note that
the Phoenix HC and CO emissions were quite a bit lower than the other EF
sites, which is only partly due to the significantly lower mileage of the cars
tested there. The I/M program in Phoenix may also explain some of the
difference. If Phoenix is removed from the comparison, HC emissions in
Vancouver are lower than the non-I/M EF sites, and CO emissions are nearly
equal.
1978 Model Year - HC and CO emissions of the 1978 model year in Vancouver were
much lower than the average EF emissions; its CO emissions were lower than any
of the EF sites, a surprising change from the 1976 year. No reasons are
apparent for this. Again, the average mileage was higher in Vancouver than
the EF sites.
Site
EF Average
Table 3
Emission Factors Program Compared With Vancouver and Portland
FTP Emissions by Model Year and Site
N
1976 Model Year
Mileage HC CO
NOx
1978 Model Year
N Mileage HC CO
75 42,798 2.50 25.4 2.84
EF Average
Without Phoenix 50
45,850 2.80 29.4 2.86
NOx
Phoenix
St. Louis
Wash. O.C.
Houston
25
25
0
25
36,693
50,715
-
40,985
1.92
3.00
-
2.59
17.3
30.0
-
28.8
2.79
2.31
-
3.41
75
75
75
75
13,
23,
20,
27,
258
543
383
529
1.12
1.94
1.68
1.73
16.4
27.8
20.6
23.8
1.83
1.34
1.92
2.26
300 21,170 1.62 22.2 1.96
225 23,818 1.78 24.1 2.01
Vancouver
Port land
50 53,650 2.56 30.7 2.90
50 55,169 1.88 24.0 3.25
50 32,705 1.33 15.1 2.45
50 33,177 1.30 15.3 2.41
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Figure 1
Emission Factors Program Compared With Vancouver and Portland
FTP Emissions by Model Year and Site
MC COMPARISON 1976 MTR
CO COMPARISON 1376 MTR
u.o
3.5
3.0
2.5
2.0
l.S
1.0
O.S
0.0
ST.L
X
HOUS ^
^S^ VANC
^^C\ r\
MOBILEZ^x^^ pJj~E ®
•
i i i i t
0 20000 40000 600
10000 30000 SOOOO
MILEAGE
KO
35
- 30
a.
»
" 25
520
o
in
x
IftJ
a 10
u
S
0
00
^xi^X xV"N
^^ 5T.L
^ — HOUS
PORT
PMOE
•
i i i i i
0 20000 KOOOO 600C
10000 30000 SOOOO
MILEAGE
x =• Emission Testing Site with no I/M
0= Emission Testing Site. .with. I/M
4.0
3.5
3.0
2.5
2.0
l.S
1.0
O.S
0.0
HC COMPBRJSON 1978 MTR
.
^^^HASH "°US
0 VANC
PMOE
i i i i i
HO
35
- 30
s
a.
ts
" 25
220
a
f^
2 15
JC
UJ
a 10
u
S
0
CO COMPARISON 1978 MTR
i ^^^^
^^^^ *HOU3
HASH
® 00RT
M VANC
i i i i i
0 20000 1(0000 SOOOO
10000 30000 50000
MILEAGE
0 20000 1(0000 60000
10000 30000 SOOOO
MILEAGE
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13
Other evidence also shows that the 1978 model year vehicles in Portland
and Vancouver had lower as-received emissions than expected. In the EF
programs, vehicles are sometimes given maintenance by contractor personnel
in order to lower their FTP emissions. Many vehicles from the FY77 EF
program are appropriate for comparison to the Portland and Vancouver 1978
model year vehicles. These EF vehicles were all certified to the same HC
and CO standards as the Portland and Vancouver vehicles, and had nearly
identical average mileages, although they were of 1975-77 model years.
The EF vehicles used for comparison all would have failed the Portland
idle standards in their as-received condition. Table 4 shows that the
emissions of the EF vehicles after repair were very similar to the
Portland and Vancouver vehicle emissions as-received. This supports the
contention that the Portland and Vancouver vehicles had unusually low
emissions in their as-received condition and that there was little or no
room for improvement from I/M repairs, thus the observed similarity of
emissions of the Portland and Vancouver vehicles.
Table 4
Comparison of Repaired Emission Factor Vehicles
With 1978 Model Year Portland and Vancouver vehicles
Group N Mileage FTP HC FTP CO
EF Before Repair 142 31,970 3.09 44.8
EF After Repair 142 31,970 1.59 15.9
Vancouver 50 32,705 1.33 15.1
Portland 50 33,177 1.30 15.3
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14
4.2 Federal Test Procedure. Idle Emissions and Fuel Economy Results
The average vehicle inertia weight is 3795 pounds for all Vancouver vehicles
and 3793 pounds for Portland vehicles. The time since the last State
Inspection Test (SIT) for all Portland vehicles averages 6.3 months. Vehicles
are matched by make, model year, engine size, transmission type, fuel system
and (generally) odometers within 5000 miles of each other. A listing of each
group of 100 vehicle types is shown in Appendix A.
Average results of the Portland and Vancouver vehicle groups are shown in
Table 5. A statistical test at the .05 confidence level shows that the HC
emissions are significantly different between Portland* and Vancouver, but CO
and NOx emissions are not.
Table 6 presents the FTP emissions by model year. Note that essentially all
of the FTP HC and CO differences shown in Table 5 come from the 1976 model
year, as shown in Table 6. As stated earlier, the Portland I/M program has
had little opportunity to create a difference in the emissions of 1978
vehicles, because even without I/M these vehicles are remarkably clean.
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15
Table 5
As-Received Emissions and Fuel Economy Levels
(100 Matched Pairs)
Odometer
Federal Test
Procedure
Emissions
(grams per mile)
HC CO NOx
Idle Emissions *
(Using Garage-
Type Analyzer)
HC (ppm) CO (%)
Fuel
Economy
(miles
per gallon)
FTP HFET
Vancouver 43,178 1.95 22.9 2.68 230.0 1.53
Portland 44,173 1.59 19.6 2.83 166.4 1.18
Table 6
As-Received FTP HC and CO Emissions by Model Year
15.81 22.24
15.75 22.00
Percent
Difference +2.32 -18.52** -14.42 +5.62 -27.62 -22.92 -0.42 -1.12
1976 Model Year
N HC CO
1978 Model Year
N HC• CO
Va nc ouver
Portland
Percent Difference
50 2.56 30.7
50 1.88 24.0
-272** -222
50 1.33 15.15
50 1.30 15.31
-22 +12
* From the second idle portion of the State Inspection Test.
** Emission differences were statistically significant at the .05 confidence
level using a paired t-test.
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16
4.3 State Inspection Test Failure Rate
The overall State Inspection Test (SIT) idle emission failure rates were 39%
for Vancouver vehicles and 27% for Portland vehicles. Table 7 shows the
number of vehicles by pass-fail status for SIT idle HC and CO and their
associated FTP emission levels.
The 39 out of 100 Vancouver vehicles which failed the SIT ("Fail Any" column)
accounted for 60% of the total Vancouver HC emissions and 72% of the total CO
emissions. The 27 Portland vehicles which failed the SIT accounted for 41% of
the total Portland HC emissions and 49% of the total CO emissions. Concerning
the identification of excess emissions (emissions above the FTP standards),
the idle test identified 76% of the excess FTP HC emissions and 81% of the
excess FTP CO emissions from the total sample of 200 cars.
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17
Table 7
Pass-Fail Status of State Inspection
Test, and Associated FTP Emissions
FTP Standards: HOI.5, CO-15.0
1976 Model Year
Vancouver
Total N»50
Portland
Total N-50
No. Vehicles
FTP HC
FTP CO
No. Vehicles
FTP HC
FTP CO
Fail HC,
Pass CO
Pass HC,
Fail CO
0
-
—
2
3.16
28.2
6
1.89
33.0
8
2.01
33.5
22
3.74
51.1
10
2.88
39.7
28
3.34
47.2
20
2.56
36.1
22
1.57
9.77
30
1.43
15.9
1978 Model Year
Vancouver No. Vehicles
Total N-50 FTP HC
FTP CO
Portland No. Vehicles
Total N=50 FTP HC
FTP CO
2
2.27
23.4
0
-
-
1
2.04
18.0
1
2.28
42.1
8
2.22
32.4
6
2.11
31.7
11
2.21
29.5
7
2.13
33.2
39
1.08
11.1
43
1.17
12.3
1976 and 1978 Combined
Vancouver No. Vehicles
Total N=100 FTP HC
FTP CO
Portland No. Vehicles
Total N=100 FTP HC
FTP CO
2
2.27
23.4
2
3.16
28.2
7
1.91
30.9
9
2.04
34.5
30
3.33
46.1
16
2.59
36.7
39
3.02
42.2
27
2.44
35.3
61
1.26
10.6
73
1.28
13.8
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18
4.4 Effect of Time Since Last State Inspection Test on Emissions of Portland
Vehicles
Portland test vehicles are evenly distributed by time since their last State
inspection. The average time since inspection is 6.3 months with a standard
deviation of 3.5 months. The correlation between time and odometer is
extremely low; thus, odometer does'not influence the calculations.
A total of 107 vehicles were tested in Portland and 105 in Vancouver in order
to end up with the 100 matched pairs. For Section 4.4 all vehicles will be
used in analysis, since the importance of the matched sample is not present in
the regression equations of these sections.
I/M substantially reduces FTP emissions at the time of inspection and repair.
A logical assumption is that emissions then increase over time until the next
inspection. This behavior has in fact been observed by EPA in previous
studies conducted in Portland.* It is of interest to see if this behavior can
also be observed among the Portland vehicles in this study. In order to check
the emission deterioration of the Portland vehicles in this study, regression
equations were calculated for emissions versus time since inspection. Table 8
shows the constants and regression slopes for the Portland vehicles including
the 1976 model year separately. Regression equations show the expected
positive slope for both FTP HC and CO versus time since inspection. However,
none of the slopes are statistically significant, which is a common result
with relatively low sample sizes and quite variable emission levels. The
previous EPA studies were able to observed significant slopes because the same
vehicles were tested several times since inspection, resulting in much less
variability.
* 1. "Portland Study Element III Post-I/M Deterioration Study", EPA
Contract No. 68-03-2513, by Hamilton Test Systems, Inc., July, 1979.
2. "Analysis of Oregon's Inspection and Maintenance Program", Becker and
Rutherford, APCA No. 79-7.3, presented at 72nd Annual Meeting and
Exhibition, June 25, 1979.
3. "Update on EPA's Study of the Oregon Inspection/Maintenance Program",
Rutherford and Waring, APCA No. 80-1.2, presented at 73rd Annual
Meeting and Exhibition, June 24, 1980.
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19
Table 8
FTP Emissions
Regression Equation Results for
FTP HC and CO Versus Months Since
State Idle Test - Portland Vehicles
Regression
Sample Emission Constant Slope
1976 MYR HC 1.71 .020
N=52 CO 20.9 .266
All Portland HC 1.48 .016
N-107 CO 16.3 .464
Regression equations were calculated for idle emissions versus months since
inspection for all cars and cars by model year. The second idle portion of
the SIT was used in the calculations. Results are shown in Table 9.
As before, none of the equations shows a statistically significant
relationship between emissions and months since inspection. This again merely
indicates that the large vehicle-to-vehicle variations in idle emissions
overshadow any deterioration effect.
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20
Table 9
Idle Emissions
Regression Equation Results for
Idle EC and CO Versus Months Since
State Idle Test - Portland Vehicles
Regression
Sample Emission Constant Slope
All Portland HC 169 -.252
N=107 CO 0.70 .027
1976 MYR HC 252 -5.98
N-52 CO 1.26 .011
1978 MYR HC 116 1.50
N=55 CO 0.38 .009
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21
5.0 COMPARISON OF ACTUAL EMISSIONS VERSUS PREDICTED EMISSIONS FROM MOBILE2
PROGRAM
An EPA computer program named MOBILE2 models the emissions performance of a
vehicle fleet over time, both with and without I/M. The I/M case assumes an
annual program. To estimate the emissions of the Portland vehicles, a
modification was made to the program, since Portland vehicles are subject to
inspection only once every two years. Table 10 presents the 'FTP HC and CO
emission comparisons for the vehicles in the study versus MOBILE2 predictions.*
Results show a similar phenomenon that was seen in Table 3, i.e., emissions of
the 1978 model year in Vancouver are much lower than expected making the
average Vancouver emissions also substantially lower than expected. Emissions
of 1978 vehicles in Portland are also lower than expected, making the average
Portland emissions slightly lower than expected. Emissions from the 1976
model year from both cities are very close to the predicted levels.
Table 10
Actual Versus Predicted
FTP Emissions for Portland and Vancouver Vehicles
Vancouver Portland
(No I/M) (I/M)
H£ C£ HC CO
1978 MYR
Actual 1.33 15.1 1.30 15.3
Predicted by MOBILE2 2.10 28.0 1.60 20.7
1976 MYR
Actual 2.56 30.7 1.88 24.0
Predicted by MOBILE2 2.85 35.3 1.85 23.1
Total
Actual 1.95 22.9 1.59 19.6
Predicted 2.48 31.8 1.72 21.9
* The MOBILE2 predictions shown here differ from published standard MOBILE2
predictions in that an adjustment to account for misfueling has been excluded
here. This is appropriate if the MOBILE2 predictions are to be compared to
vehicle samples without evidence of any misfueling, such as the Portland and
Vancouver samples in this study.
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22
APPENDIX A
VEHICLE LIST FOR EACH GROUP
1976 Model Year
1978 Model Year
Mfr
AMC
GM
Ford
Chrysler
Datsun
Honda
Toyota
VW
Make Qty
2
Buick 2
Cadillac 2
Chevrolet 1
Chevrolet 1
Chevrolet 3
Chevrolet 4
Chevrolet 2
Olds 1
Olds 4
Pontiac 2
Pontiac 1
1
1
2
3
4
3
3
2
1
3
2
50~
Descr.
258-A1
350-A4
500-A4
085-M1
250-A1
305-A2
350-A2
400-A4
260-A2
350-A4
350-A2
400- A2
140-A2
140-M2
250-A1
302-A2
351-A2
225-A1
318-A2
085-M2
091-M3
097-M2
097-M2
Mfr Make
AMC
GM Buick
Cadillac
Chevrolet
Chevrolet
Chevrolet
Chevrolet
Chevrolet
Chevrolet
Olds
Olds
Pontiac
Pontiac
Pontiac
Pontiac
Ford
Chrysler
Datsun
Honda
Toyota
VW
Qty
1
2
1
1
2
1
1
1
1
5
2
2
2
1
2
1
1
1
2
1
2
3
2
1
1
2
2
2
1
2
1
Jo
Descr.
258-A1
231-A2
350-A4
403-A4
425-A4
098-M1
151-A2
200-A1
250-A1
305-A2
350-A2
260-A2
350-A4
231-A2
301-A2
305-A2
400-A4
098-M2
140-M2
171-M2
250-A2
302-A2
351-A2
460-A4
105-A2
225-A2
318-A2
085-M2
091-M3
097-M2
08 9 -MO
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23
APPENDIX B
TESTS PERFORMED
The following tests were performed on the vehicles in the as-received
condition only. All tests except No* 6 were performed by contractor personnel.
1. Federal Test Procedure
2. 50 mph Cruise Test
3. Highway Fuel Economy Test
4. Four-Mode Idle Test
5. Loaded Two-Mode
6. State Inspection Test at a State Department of Environmental Quality
(DEQ) station
7. State Inspection Test at HTS laboratory.
8. Four-Mode Idle Test with one spark plug disconnected*
9. Four-Mode Idle Test on gasohol fuel*
10. Diagnostic Inspection
* These tests were performed for purposes unrelated to the Portland versus
Vancouver comparison. Results from the tests will be reported in later
reports.
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24
APPENDIX C
BRIEF DESCRIPTION OF TESTS
1. Federal Test Procedure
The Federal Test Procedure (FTP) is a non-repetitive driving cycle simulating
urban driving. The cycle covers 7.5 miles in 1372 seconds with an average
speed of 19.6 mph. The maximum speed in the cycle is 57 mph. Because the FTP
simulates some stop-and-go city driving, there is also considerable time spent
at idle - about 19Z of the time.
Each vehicle is driven on a chassis dynamometer which reproduces vehicle
inertia with flywheels,androad load with a water brake system. Vehicle
exhaust is collected,^gTluted^ and mixed with filtered background air to a
known constant volume flow. This procedure is known as Constant Volume
Sampling (CVS). The exhaust is analyzed for mass emissions of hydrocarbons
(HC), carbon monoxide (CO), oxides of nitrogen (NOx), and carbon dioxide
(002). Fuel economy calculations are also made from the exhaust
measurements, using a carbon balance technique.
2. 50 MPH Cruise Test
This test is run as part of the_ 3 minute 50 mph preconditioning for the
Highway Fuel Economy Test. ^UndilutecT) concentrations of HC, CO and NOx
emissions were measured. —•-<:—
3. Highway Fuel Economy Test
For this test, the vehicle starts from a warm, but engine-off condition and
then accelerates to highway speed. It maintains high speed until the cycle
ends in a deceleration back to idle. The high speed portion is not a steady
cruise condition, but varies _slightly. Average speed is 48.2 mph and the
cycle length is 10.2 miles. (^VS^/mass emissions are sampled from the start of
the engine until the vehicle is brought back to idle. Fuel economy is
calculated from the emissions.
4. Four-Mode Idle Test
This test has four modes for vehicles with automatic transmissions, and three
modes for others. The order of testing is: 1) idle in neutral (gear), 2) 2500
engine rpm unloaded^, 3) idle in neutral and 4) idle in drive (for
automatics). 0ndilutedyHC, CO and NOx emissions are sampled at all modes.
5. Loaded Two-Mode
This test consists of two operating conditions. The first condition is
constant 30 mph with a dynamometer load of 9.0 hp for all vehicles. Following
sampling in this mode the vehicle is returned to idle in neutral. ^TJndiluted
HC, CO and NOx emissions are sampled at both modes.
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25
6. State Inspection Test (SIT) at a Department of Environmental Quality
(DEQ) Station
Vehicles were taken by contractor personnel to a State operated inspection
station for this test. This test is the same as the first three portions of
the Four-Mode Idle Test, i.e., idle neutral, 2500 engine rpm, idle neutral.
HC and CO emissions are sampled by State personnel.
7. State Inspection Test (SIT) at the Hamilton Test Systems (HTS) Laboratory
The laboratory__personnel perform an identical test to the one at the DEQ
station. rUndiluteJ^HC, CO and NOx emissions are sampled.
^**~ i i. ....... -r**^
8. Four-Mode Idle Test With One Spark Plug Disconnected
This test is the same as the normal Four-Mode Idle Test except with one spark
plug disconnected.
9. Four-Mode Idle Test With Gasohol
Commercial gasohol fuel was used for this test.
10. Diagnostic Inspection
An engine diagnostic check was conducted using an Autosense Diagnostic
System. This system checks many parameters such as the electrical system,
engine timing, idle speed and emissions, and cylinder power contribution.
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