EPA-AA-TEB-81-8
An Evaluation of Sealed Idle Mixture
Adjustment on 1977 Buicks
by
Karen E. Marschall
November 1980
Test and Evaluation Branch
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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-2-
ABSTRACT
This report describes the results of an EPA program conducted on 48 in-
use passenger cars. Each of these vehicles was a 1977 Buick equipped
with a 350 CID engine and a four barrel carburetor. Some of these
engines were equipped with special carburetors which had lead plugs
covering their idle mixture screws to prevent maladjustments. The
purpose of this program was to gather information on current vehicles
which will allow EPA to project the effectiveness of similar systems
after they have been employed on future vehicles. The program included
direct, mail solicitation, a parking lot survey, and complete FTP
testing. This work was conducted in the Detroit area and at EPA's
laboratory in Ann Arbor during the summer of 1980.
The results indicate that this technique for sealing the idle mixture
screws is an effective method for preventing the adjustment of the idle
mixture. Average idle emission test results for the sealed carburetor
vehicles were similar to the results for untampered vehicles with
conventional carburetors. Average idle emissions from vehicles with
broken or missing limiter caps were substantially higher.
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-3-
INTRODUCTION
Over the past, several years, the results of various programs have shov/n
the significant effect that idle mixture adjustment has on exhaust
emissions as measured by the Federal Test Procedure (FTP). A major study
of three hundred 1975 and 1976 passenger cars (Reference 1) concluded
that, carburetor maladjustment was the greatest single reason that caused
vehicles to fail their standards. Once maladjusted idle mixture and
speed were adjusted to manufacturers' specifications, the average HC and
CO emission levels for the entire fleet were reduced by 30% and 56%,
respectively. On a subset of properly tuned cars in the same study, it
was found that an idle mixture adjustment performed using the classic
"lean best idle" technique would double HC emissions and triple CO
emissions when the vehicle was tested over the FTP.
Based on these and other findings, the EPA has published regulations
which are designed to limit the range of adjustable parameters which have
been found to affect emission levels. These rules begin to take effect
with light-duty vehicles of the 1981 model year. The purpose of these
regulations is to help ensure that in-use vehicles maintain the low level
of emissions established by prototype and production vehicles from the
certification process.
In anticipation of these regulations, many manufacturers have chosen to
incorporate preliminary designs for limited adjustability in their
current models. General Motors, for example, has employed rivets instead
of screws in the attachment of the thermostatic coil cover to make choke
adjustments more difficult, and have redesigned carburetors to use steel
caps over recessed idle mixture screws. The adjustments are made prior
to installation on the engine. This method to prevent idle mixture
maladjustment, is the subject of this test program.
General Motors first employed recessed screws and a capped access on a
sample of 5000 Buicks during the 1977 model year. These carburetors were
identical in all other aspects to standard models which were equipped
with conventional plastic limiter caps. These cars were at least three
years old and averaged approximately 40,000 miles at the time of the test
program.
PJJRPOSE
The overall purpose of this project was to evaluate the relative
effectiveness of this system to prevent idle mixture maladjustments.
This was to be accomplished by examining three areas of interest:
1) whether the average emission test, results of the vehicles witn
sealed carburetors (Group Aj differed from the average emission
test results of the vehicles with regular carburetors (Group B),
2) to compare the percentage of broken or missing limiter caps to
the percentage of broken or missing lead plugs, and
3) to determine whether a non-adjustable idle mixture could cause
any engine performance problems or result in owner
dissatisfaction.
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-4-
The information will be used for projections of overall effectiveness of
such devices once they have been in widespread use for several years.
PROGRAM DESIGN
The program used two different methods to gather data. The first method
involved direct contact with the vehicle by an EPA employee. This
included short tests and underhood inspections and was supplemented by
complete FTP testing on some vehicles. The second method was a mail
survey, in which owners were asked to inspect their own vehicle and mail
us the information.
Parking Lot Survey
The first step of the program was to conduct short inspections and
four-speed idle tests on a small sample of both Group A and Group B
vehicles. General Motors supplied the VIN's of Detroit area Buicks
equipped with sealed carburetors. The R. L. Polk Company used these
VIN's to supply the names and addresses of 108 owners of vehicles with
sealed carburetors (Group A), plus the names and addresses of 200 owners
of vehicles which were identical with the exception that they had been
equipped with standard carburetors (Group B). Direct mail solicitation
(Appendix A) was used to invite Buick owners from the Detroit
metropolitan area to bring their vehicles to a parking lot survey held at
Eastland Mall. This is a large shopping center located in Harper Woods,
a suburb adjacent to Detroit. Owners who attended this survey were
offered a check for ten dollars. Owners which were not able to attend
the parking lot survey were invited to bring their vehicles directly to
EPA's Motor Vehicle Emission Laboratory (MVEL) in Ann Arbor. These
owners were, offered a check for ten dollars and a full tank of fuel.
Once the owner arrived at the parking lot or at the MVEL, he was
interviewed to determine the date of the last tune-up and any engine
performance problems experienced with the vehicle. This information was
recorded on the Vehicle Owner Questionnaire (Appendix B). A visual
underhood inspection was performed to determine which category (sealed or
standard) the carburetor fell into, whether the limiter caps or lead
plugs had been removed or broken, and if all the emission components
appeared to be in proper operating condition. A brief exhaust emissions
test was performed using a portable garage-type analyzer. This test is
known as the four-speed idle test, and consists of measuring the
concentrations of HC and CO at 1) idle speed in neutral, 2) 2500 RPM in
neutral, 3) idle speed again in neutral, and 4) idle speed in drive.
This information was recorded on the inspection form (Appendix C).
Laboratory Tests
From the vehicles which received short cycle tests, 16 were selected to
be brought in to the MVEL for more extensive testing. Owners of vehicles
which were to undergo this testing were contacted by phone. These owners
were mailed a $50 United States Savings Bond, given a leaner vehicle for
their use while their vehicle was being tested, and had their vehicle
returned with a full tank of fuel. Vehicles were tested at a rate of two
per week. The following test sequence was performed twice on each
vehicle:
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1) The 1975 Federal Test. Procedure (exhaust emissions only).
2) The Highway Fuel Economy Test (HFET).
3) The Four-Speed Idle test.
4) The Loaded Two-Mode. This short test consists of two operating
conditions. At the end of a two minute idle period, the vehicle
is operated at 30 mph and at 9 actual horsepower. Immediately
following sampling in this mode, the exhaust is sampled at idle
with the transmission in neutral. The garage-type analyzer is
used for these measurements.
Of the 32 total sequences, 1 was aborted due to engine noise and 5 were
voided due to suspected exhaust leaks.
Mail Survey
In order to obtain additional information on the number of maladjusted
limiter devices, owners of Detroit area Buicks which were not inspected
were included in a mail survey. The only owners which were excluded in
this second Detroit-area mailing were those whose letters had been
returned to us as undeliverable or those who had sold their vehicle. The
owners were again invited to bring their vehicles to the MVEL or to
perform an inspection of their carburetor themselves. In the latter
case, they were instructed to simply match the appearance of their
carburetor to one of four pictures which were sent with the letter. The
owner filled in his response on the enclosed reply card and returned the
card to us. This allowed us to determine whether or not the limiter
device had been removed. The contents of this package are attached as
Appendix D. This mail survey was also extended to include approximately
200 owners from Houston and Chicago, although names and addresses were
only available for owners of vehicles with sealed carburetors. These
results will be addressed in a supplement to this report when comparable
results are received for vehicles with regular carburetors.
RESULTS
Parking Lot Survey
A total of 308 letters were mailed to Detroit area Buick owners inviting
them to our parking lot survey. Nineteen owners attended the survey. A
chart giving the complete response breakdown is attached as Figure 1. In
addition to these nineteen vehicles, ten more owners brought their
vehicles directly to MVEL. Thus, a total of 29 vehicles were given short.
inspections and a four-speed idle test. Fifteen of these vehicles had
sealed carburetors (Group A), and fourteen had conventional carburetors
(Group B). The average odometer readings for the two groups were 38,400
and 41,000, respectively. Complete results on these vehicles are
attached as Appendix E. Group A's average four-speed idle emissions are
lower than those for Group B. These results are listed in Table 1.
Table 2 divides Group B's results into the results of those vehicles with
removed limiter caps and those with intact limiter caps. The idle
emissions of the vehicles with limiter caps intact are similar to Group
A's idle
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-6-
emissions. The idle emissions of the vehicles with broken or missing
limiter caps are substantially higher than Group A's idle emissions.
Table 1
Average Emission Results from Parking Lot Survey
Four-Speed Idle Test
N HC CO
(ppm) (%)
Group A 15 121 .13
Group B 14 242 .65
2500 (N)
HC CO
(ppm) (%)
44
79
1.07
1.06
HC CO HC CO
(ppm) (%) (ppm) (%)
112
205
.09
.68
59
92
.08
.59
Table 2 lists the average 4-speed idle emission results from Group A and
from both the Group B untampered and tampered vehicles.
Table 2
Average Emission Results from Parking Lot Survey
Four-Speed Idle Test
2500 (N)
Group A
Group B
untampered
Group B
tampered
N
15
9
5
HC
(ppm)
121
255
219
CO
.13
.15
1.5
HC
(ppm)
44
90
60
CO
(%)
1.07
.99
1.19
(ppm) (%) (ppm) (%)
112 .09 59 .08
204
206
.11
76
1.69 121
.08
1.52
Of the fifteen vehicles from Group A, only one lead plug appeared to be
tampered. Of the fourteen vehicles from Group B,. five had their limiter
caps removed or broken.
The majority of the participants in the survey were satisfied with the
performance of their vehicle. The sealed carburetor did not appear to
cause more engine performance problems or owner dissatisfaction than the
regular carburetors. Of the 29 owners, 4 from each group indicated that
they were experiencing engine performance problems. The most common
complaint was that of engine noise or lifter noise, given as the problem
in 4 of 8 cases. A complete list of answers from the Vehicle Owner
Questionnaire is attached as Appendix F.
Testing at MVEL
Complete FTP, HFET, and short cycle test results are attached as
Appendix G. An indication of the condition of the emission-related
components is also included. The only notable finding from the underhood
inspection was the unexpectedly high failure rate of EGR valves. Figures
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-7-
2-4 are bar charts comparing average FTP HC, CO and NOx emissions of
Group A and Group B. Figure 5 compares the owners estimate of their fuel
economy to both the EPA Mileage Guide values and the FTP and HFET fuel
economy results. The average FTP emission results for Group A are higher
than for Group B for HC and CO, and lower for NOx. Both the city fuel
economy and the highway fuel economy are lower for Group A than for
Group B. The high FTP CO results for Group A are mainly due to one
vehicle. This vehicle had excessively high CO emissions, possibly from a
problem in the main metering circuit or power enrichment circuit of the
carburetor. When these results are excluded, Group A's average FTP
results are 1.30 g/mi HC, 19.17 g/mi CO, and 3.29 g/mi NOx. These
results are approximately equal to those of vehicles in Group B. Table 3
lists the average FTP emission and fuel economy results and the average
HFET fuel economy results for both Group A and Group B.
Table 3
Average FTP and HFET Results from Testing at. MVEL
FTP
HFET
Group A
Group B
1977 Federal
Standards:
N
5
8
Odom
47663
43342
HC
(g/mi)
1.54
1.24
CO
(g/mi)
35.26
20.57
NOx
(g/mi)
2.98
3.35
MPG
14.4
14.8
MPG
21.1
22.3
1.5
15
2.0
15*
22*
*EPA Mileage Guide values.
Vehicles in Group A were found to have lower average emissions than Group
B for all modes of both the four-speed idle and the loaded two-mode
tests. Table 4 lists the average four-speed idle and loaded two-mode
emission results for Group A and Group B.
Table 4
Average Short Cycle Test Results from Testing at MVEL
Group A
Group B
Four-Speed Idle
2500(N) I(N)
HC
Loaded Two-Mode
Loaded I(N)
HC CO HC CO HC CO HC CO HC CO HC CO
(ppm) (%) (ppm) (%) (ppm) (%) (ppm) (%) (ppm) (%) (ppm) (%)
113
142
.12 34
.69 46
.70 116
.81 132
.13 59
1.04 117
.17 44
1.03 81
.37
.56
130
141
Mail Survey
.09
1.08
A total of 269 letters were mailed, 92 of them to owners with vehicles from
Group A, and 177 from Group B. We received 19 valid responses. Five of these
were from Group A, and none indicated that their lead plugs had been removed.
14 of the responses were from Group B, and 5 indicated that their limiter caps
had been removed or broken.
Combining these results with those from the parking lot survey gives a total
of 20 vehicles from Group A and 28 vehicles from Group B. One of the Group A
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-8-
vehicles had its lead plugs removed, and ten of the Group B vehicles had their
limiter caps removed or broken. Table 5 lists these results, plus the number
of broken or missing limiter devices as a percentage of the total group.
Table 5
Total Broken or Missing Limiter Devices
Number Number Percent
in Sample Disabled Disabled
Sealed Carburetors 20 1 5.0%
Conventional Carburetors 28 10 35.7%
With a 95% confidence level, a statistical analysis shows that the proportion
of removed or broken limiter devices is higher for the conventional
carburetors than it is for the sealed carburetor.
CONCLUSION
Based on the results of this study, restricting access to the idle mixture
screws has proven to be effective in preventing mixture adjustments. The
inability to adjust, the idle mixture screws does not seem to cause engine
performance problems or result, in owner dissatisfaction. The average idle
emissions of the vehicles with sealed carburetors are lower than the average
idle emissions of those with standard carburetors. On the other hand, the
results of the idle test vehicles which had their caps in place were
approximately equal to the results on vehicles with sealed carburetors.
Reference
1. J. T. White, "An Evaluation of Restorative Maintenance on Exhaust
Emissions from In-Use Automobiles", SAE Paper 780082, March 1978.
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Figure 1
EVALUATION OF SEALED IDLE MIXTURE ADJUSTMENT ON 1977 BUICKS
Letters
Mailed
308
Special
Carburetors
108
Returned
Undeliverable
Regular
Carburetors
200
Delivered
194
Returned
Undeliverable
Ho
Buick
1
Contact
Owner
!_
Not
Attend-
ing
Attend-
ing
_!!_
No
Response
87
No
Response
148
Attend-
ing
13
Not
Attend-
ing^
Contact
Owner
7_
No
Buick
7
RESPONSE CHART
FOR
PARKING LOT SURVEY MAILING
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EVALUATION OF SEALED IDLE MIXTURE ADJUSTMENT ON 1977 BUICKS
AVERAGE FTP EMISSIONS OF GROUP A AND GROUP B
2.0-i
Fig. 2
1.5-]
HC(g/m)
.1.0-J
0.5-J
Fig. 3
401
30H
C0(g/m) 20-|
Fig. 4
3H
N0x(g/m)
H
GROUP A
(sealed carburetors)
GROUP B
(regular carburetors)
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Figure 5
EVALUATION OF SEALED IDLE MIXTURE
ADJUSTMENT ON 1977 -BUICKS
Comparison of Owner Perceived MPG to
Test and Fuel Economy Guide Values
30-
25-
20 —
§ 15-
o
10 H
CO
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Appendix A
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ANN ARBOR. MICHIGAN 48105
OFFICE OF
AIR. NOISE AND RADIATION
June 17, 1980
Dear Buick Owner:
As you know, the nation's air pollution problem is a very serious matter. As
a concerned citizen, you can contribute significantly toward its control and
be rewarded for your cooperation.
The U.S. Environmental Protection Agency (EPA) is currently conducting a
survey in the Metropolitan Detroit area which requires us to obtain
information on certain passenger cars. Your car has been identified as a
possible candidate for testing.
In order to determine if your car'qualifies, a technician must perform a 10
minute inspection on your 1977 Buick. We will be conducting inspections at
Eastland Mall on Saturday, June 28 from 10:00 a.m. through 5:00 p.m. Enclosed
is a map with specific directions on where we will be located. We will have a
white van with a blue EPA symbol on the side. In return for your
participation in this program, you will be mailed a check for $10.00.
We are also prepared to conduct inspections at our laboratory in Ann Arbor
anytime between the hours of 8 a.m. to 8 p.m. on Monday, June 23 through
Friday, June 27. If this is more convenient for you than our Saturday hours,
you are invited to call us at the number given below and an appointment will
be made at your convenience.
Within two weeks after the inspection, you will be notified as to whether your
vehicle qualifies for further testing at our laboratory in Ann Arbor. If
your car does qualify and you are willing to participate further, you will be
offered additional incentives which we will discuss with you then.
Enclosed is a postage-paid reply card which we ask you to complete and return
at your earliest convenience. The information obtained from this inspection
is for survey purposes only and will not be used in any legal action.
We are looking forward to seeing you on June 28. If you have any questions or
would like further information, you may contact Karen Marschall at EPA's Motor
Vehicle Emission Laboratory, 2565 Plymouth Road, Ann Arbor, MI 48105. The
telephone number is (313) 668-4430 during normal business hours.
Sincerely,
John T. White, Project Manager
test and Evaluation Branch
Enclosure
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Appendix B
Vehicle Owner Questionnaire
1977 Buick Survey
Vehicle # Owner's Name
Address
Zip
VIN License Plate #
1. How long ago was the last tune-up (spark plugs, timing, etc.)?
approximate date no tune-up
2. Who performed this tune-up?
dealer garage tune-up clinic yourself or friend
no tune-up
3. Have you had any repairs to your vehicle for the correction of driveability
problems?
yes no
4. What repairs were performed on your vehicle to correct the driveability
problems?
no repairs
5. Were these repairs effective in correcting the driveability problems?
yes no no repairs
6. How long ago were your idle mixture and speed adjusted?
approximate date not adjusted
7. Do you now experience any engine performance problems with this
vehicle?
yes no Description:
8. Approximately what fuel economy do you obtain from this vehicle?
city highway combined
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Appendix C
VEHICLE NUMBER
A) System Inspection
1. Induction System
*a. Is the outside air duct, air cleaner assembly, and filter
intact and complete?
b. Is the heated air door and motor intact and complete?
c. Does the heated air door respond to external vacuum?
*d. Are the vacuum lines connected, unrestricted, and properly
routed?
2. Garb and Fuel System
*a. Are the plugs which seal the idle mixture screws present
and unaltered?
b. Is the choke assembly intact and complete?
c. Has the fuel filler neck been altered?
*d. Are the vacuum lines connected, unrestricted, and properly
routed?
3. Ignition System
*a. Are the spark plugs, spark plug wires, and distributor
cap intact and complete?
*b. Is the vacuum advance line connected, unrestricted, and
properly routed?
c. Does the advance unit respond to external vacuum?
4. EGR System
*a. Is the EGR valve intact and complete?
b. Is there a RPM drop when external vacuum is applied?
c. Is the vacuum line connected, unrestricted, and properly
routed?
5. EFE System
*a. Is the EFE valve intact and complete?
b. Does the valve respond when external vacuum is applied?
*c. Are the vacuum lines connected, unrestricted, and properly
routed?
6. PCV
*a. Is system intact and complete?
b. Does valve "rattle" when shaken?
c. Is the vacuum line connected, unrestricted, and properly
routed?
7. Evap
a. Is the s>stem intact and complete?
B) Adjustable Parameter Check
1. Check idle speed with A/C off and transmission in drive.
Yes
No
Comments
2. Propane gain procedure: Administer propane into snorkel
of-the air cleaner. Increase flow until maximum rpm is
achieved.
3. Check fast idle speed on high step, of the cam, with the A/C
off,, the EGR disconnected and plugged, the air cleaner in place
and the transmission in park.
4. Check timing at 600 rpm with the hose to the vacuum advance unit
disconnected and plugged.
5. Check choke adjustment.
Spec.
550 rpm
50 rpm-
1800 rpm
Measured
12°BTDC
1 NR
* These checks should always be performed.
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Idle
MODE
IDLE(N)
2500 (N)
IDLE(N)
IDLE(D)
HC (ppm)
COCO
RPM
2500
Page 2
10 If I
TO CARBURETOR
TO TEE
•O EGR VALVE
*TVS routing
purple >
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Appendix D
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ANN ARBOR. MICHIGAN 48105
OFFICE OF
AIR. NOISE AND RADIATION
Dear Buick Owner:
We are sorry you were unable to attend our parking lot survey at the
Eastland Mall on June 28. However, we are still interested in conducting
a short inspection of your 1977 Buick. We can conduct these inspections
here at our laboratory in Ann Arbor anytime Monday through Friday, from
8 a.m. to 5 p.m. If it is possible for you to bring your vehicle here,
please contact me to schedule an appointment. For your participation in
this program, you will receive a full tank of gasoline and will be
mailed a check for $10.00. Enclosed is a brochure on our laboratory and
a map indicating its location. Also enclosed is an EPA mileage calculator
for your personal use.
If you are not able to bring your vehicle to the lab, we ask that you
fill out the enclosed postcard and return it at your earliest convenience.
Enclosed is a sketch of the engine compartment with figures for several
types of carburetors. The carburetor on your 1977 Buick will match one
of the figures. Place an "X" in the appropriate box. Also, record your
car's vehicle identification number (VIN) on the card. This can be
found on your registration form or on the dashboard at the base of the
windshield on the driver's side. It is visible from outside the car.
Once this information is recorded, you may drop the card in the mail.
flo postage is necessary.
If you would like to schedule an appointment at our lab, or if you need
more information, you may contact me at EPA's Motor Vehicle Emission
Laboratory, 2565 Plymouth Road, Ann Arbor, Michigan 48105, or call (313)
668-4430 during normal business hours.
Sincerely,
Karen E. Marschall, Project Officer
Test and Evaluation Branch
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Appendix D
1977
CIA'S/JAM,
TTfe
OP THIS
4.
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-18-
Appendix D
EVALUATION OF SEALED IDLE MIXTURE ADJUSTMENT ON 1977 BUICKS
Mail Survey Reply Card
I have examined my car and have determined that the figure which
most closely resembles the appearance of the carburetor is
(check one):
/_/ Figure 1 /_/ Figure 2
j~~T Figure 3 I~J Figure 4
Vehicle Identification Number (VIN) _______
Name
Street
City/State
Telephone
Zip/
&EPA
Official Business
Penalty for Private Use
8300
United States
Environmental Protection
Agency
Karen Marschall
EPA, ECTD, TEB-20
2565 Plymouth Rd.
Ann Arbor, MI 48105
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
EPA FORM 1320-3* (2-791
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-19-
Appendix E
EVALUATION OF SEALED IDLE MIXTURE ADJUSTMENT ON 1977 BUICKS
PARKING LOT SURVEY RESULTS
Four-speed Idle
Tun*
Veh.*
or
02
OS
. 11
13
17
19
28
29
12
15
>'
21
23
03
04
06
07
08
09
10
14
18
22
24
25
26
27
20
Odoa
24872
45919
27379
30774
48201
38064
43085
35242
36643
40908
65746'
34122
46708
56900
16233
24141
41076
38109
36465
33267
48937
9499
26798
61000
47392
61831
21981
44470
65445
Croup
B
B
B
B
B
B
B
B
B
B
B
B
B
B
A
A
A
• A
A
A
j
A
A
A
A
A
A
A
A
A
T.apT
No
Ho
No
No
Ho
No
Ho
• Ho
Ho '
Ye*
Ye*
Ye*
Ye.
Ye*
So
No
Ho
Ho
No
Ho
Ho
Ho
No
No
No
No
No
Ho
Ye*
RPM
880
820
870
970
977
750
780
745
800
850
610
756
980
825
850
700
790
650
500
730
890
760
830
700
890
£90
754
620
825
HC(ppm)
1000
30
175
77
244
25
430
96
221
107
277
149
70
490
65
300
100
100
SO
120
71
207
13
ISO
160
186
37
35
190
CO(Z)
.08
.03
.12
.01
.22
.01
.90
0.0
0.0
.01
2.4
.02
.01
5.2
.02
.02
.02
.07
.01
.01
.03
.10
.03
.02
1.5
.02
0.0
.02
.02
RPM
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500.
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
2500
DC
430
12
70
19
82
80
90
9
19
52
85
54
30
80
40
20
19
30
40
15
129
79
£0
30
45
0.0
40
55
35
CO
.10
.67
1.50
.01
1.23
2.70
2.65
0.0
.03
1.05
2.81
.98
.02
1.1
.40
.20
.30
'.30
.32
.'02
6.50
2.20
2.65
.02
.85
.05
1.11
.90
.05
RPM
880
1020
850
878
979
770
810
805
800
890
630
820
1000
825
800
690
780
520
640
750
960
800
600
720
. 900
930
768
740
825
DC
800
30
155
'93
63
20
475
80
117
35
265
250
40
420
48
250
100
150
30
137
60
174
16
220
120
152
29
40
160
CO
.06
.02
.11
.01
.08
.05
.70
0.0
0.0
.54
2.83
.07
.01
5.0
.02
.02
.03
.07
.03
.02
.06
.14
.04
.02
.80
.01
0.0
.02
.02
RTH
6>0
690
620
660
680
560
600
591
650
620
470
600
650
600
640
400
600
520
S20
670
650
600
610
520
640
640
572
560
625
HC
100
22
150
44
43
14
230
37
44
•54
259
9
25
260
30
75
20
90
9
SO
40
163
10
100
140
51
15
36
50
CO
.02
.03
.07
.01
.02
.02
.53
0.0
0.0
.01
2.69
.01
.01
4.9
.01
.02
.02
.06
.01
.01
.02
.10
.02
.01
.89
.01
0.0
.02
.01
up?
DO
DO
ye*
y«»
ye*
ye*
ye*
ye*
no
ye*
7"
ye*
»"
ye*
no
y««
ye*
•»'\
7
DO
no
DO
ye*
ye.
y*.»
ye.
DO
y«
ye*
towaent.
no CCR tmt
no ECR cnmt
no ECR unit
no ECR wtmt
•
ECR
que.tion.bl*
V.CUUB line
repaired
HAD line'
di. connected
body work
oo ECR «>VBC
no ECR nut
DO ECR mvmt
new pi.toni
no ECR avat
dirty air
cleaner
no ECR omit
no ECR ttwt
no CCR mat
filler neck
punched out
choke
replaced
-------
Appendix F
Vehicle Owner Questionnaire Replies
o
CM
/
3
4
6
7
8
9
10
14
IS
20
22
24
25
26
27
1
2
5
11
12
13
15
16
17
19
21
23
28
29
f
/
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
B
B
B
B
B
B
B
B
B
B .
B
B
B
8
*
/
16233
24141
41076
38109
36465
33267
48937
9499
26798
65445
61000
47392
61831
21981
44470
24872
45919
27379
30744
40908
48201
65746
34122
38064
43085
46708
56900
35242
36643
A
•ft Q/
never
24
6
unknown
unknown
never
never
never
18
1
7
1
1
never
8
never
never
6
7
9
7
6
7
10
9
1
8
1
never
.4
/ j
/
dealer
dealer
unknown
unknown
-
-
-
dealer
dealer
dealer
owner
clinic
-
dealer
-
-
dealer
owner
ovncr
owner
clinic
dealer
dealer
dealer
owner
dealer
garage
unknown
' // / / /y // ,
*• . .. >» - i> „. !v A
Yea
No
No
No
No
Yes
Yea
No
No
Yea
No
No
No
No
Yea
No
No
No
No
No
No
No
No
Yea
. No
Yea
No
No
No
4^ '/
-------
-21-
Appendix G.
Evaluation of Sealed Idle Mixture Adjustment on 1977- Buicks
MVEL Short Cycle Test Results
Four Speed Idle -Loaded Two-node
I(N) 2500 I(N) I(D) Loaded " I(M)
Veh. ti Gfroup
1
10
11
12
13
roup
A
A
A
A
A
B
B
B
B
B
B
B
B
HC
40
380
360
10
40
20
30
80
60
45
100
170
220
10
20
600
350
130
121
180
110
55
45
60
50
CO
.01
.80
.17
.03
0
.02
.02
.02
.02
.03
.04
.70
.03
.01
.02
2.00
2.75
1.20
1.10
1.60
1.40
.02
.04
.02
.04
HC
105
50
50
10
30
10
30
20
0
103
100
10
20
0
20
20
40
70
20
50
40
60
50
60
70
CO.
3.60
1.40
1.20
.04
.001
.02
.02
.02
.02
4.80
4.00
.05
.01
.01
.02
.02
.25
1.25
.02
1.10
.04
.02
.04
.05
1.20
I!C
50
380
360
20
50
20
35
80
50
51
80
200
250
20
20
280
350
140
120
240
130
60
50
65
50
. CO
.01
.85
.24
.03
.001
.02
.02
.02
.02
.03
.01
1.30
.08
.01
.02
6.40
2.60
1.00
1.00
2.20
1.90
.02
.04
.03
.04
HC
30
195
190
10
30
10
25
20
20
19
30
160
155
0
10
260
290
170
140
215
220
55
50
50
45
CO
.01
.65
.75
.03
.001
.02
.02
.02
.02
.01
.01
1.10
.08
.01
.02
6.20
3.00
1.00
.80
2.05
2.00
.02
.04
.02
.04
IIC
26
95
105
20
50
20
40
20
20
40
95
110
98
0
10
80
95
120
100
120
130
60
55
" 60
120
CO
.03
1.75
1.25
.09.
.15
.03
.03
.02
.02
.10
1.40
.95
.07
.01
.03
.20
.25
.75
.70
1.90
1.00
.02
.04
.20
1.40
11C
92
390
360
20
40
30
60
100
80
65
60
250
205
60
30
300
300
140
125
245
230
65
60
60
60
CO
.02
.38
.25
.03
.001
.02
.03
.02
.02
.01
.01
.30
.01
.02
6.00
3.10
1.30
1.00
2.35
1.90
.02
.04
.02
.04
-------
Appendix G
Evaluation of Sealed Idle Mixture Adjustment on 1977 Buicks
Parking Lot Results
MVEL Results
I
CM
CM
I
Idle (N) 2500 Idle(N) Idle(D)
Veh.# Group Tamp? HC CO KC . CO HC
IAN 71 .03 129 6.50 60
2 A N 50 .01 40 .32 30
3 A N . 100 .02 19 .30 100
4 AN 100 .07 30 .30 150
5 AY 190 .02 35 .05 160
6 B N 1000 .08 430 .10 800
7 B N 430 .90 90 2.65 475
8 B Y ' 70 .01 30 .02 40
9 BY 277 2.47 85 2.81 265
10 B N 244 .22 82 1.23 63
11 B Y 175 .12 70 1.50 155
12 B N 96 0.0 9 0.0 80
13 B N 25 .01 80 2.70 20
CO HC CO Odcm
.06 40 .02 50848
'
.03 9 .01 38407
.03 2C .02 42509
.07 90 .06 40077
.02 50 .01 66474
.06 100 .02 25342
.70 230 .53 44652
.01 25 .01 47030
2.83 259 2.69 72173
.08 43 .02 50809
.11 150 .07 29842
0.0 37 0.0 35852
.05- 14 .02 41040
HC(g/m) COCg/m)
2.76
2.21
2.23
i.99
.89
.81
.75
.73
1.47
1.54
.40
.43
1.72
1.91
.51
.51
2.32
2.04
1.30
1.31
2.44
2.21
' .54
.52
.76
.87
113
86
35
29
12
14
3
B
21
24
6
6
21
23
5
4
39
42
20
19
49
37
10
10
15
17
. 18
.08
.35
.93
.48
.16
.83
.43
.95
.21
.55
.88
.58
.27
.59
.43
.43
.12
.02
.14
.15
.59
.80
.03
.22
.21
FTP
NOxCg/m) MFC
T
1
1
1
4
4
5
5
2
2
4
4
4
4
1
2
1
1
4
4
4
4
1
1
3
3
.36
.65
.30
.32
.43
.06
. 39
.34
.13
.36
.58
.50
.36
.56
.99
.03
.24 •
.31
.97
.94
.20
.18
.71
.63
.72
.65
L2
13
14
14
15
15
15
15
13
13
16
16
15
15
13
14
14
14
14
14
14
15
13
13
15
15
. j
.9
.6
.3
.3
.3
.5
.7
.7
.2
.5
.2
.6
.3
.8
.2
.2
.2
.5
.4
.9
.1
.6
.6
.7
.6
HFET
MPG Comr-cn ts
T3"
19
21
2i
22
22
i •";
^.il
23
21
2i
24
24
23
22
21
21
21
21
22
22
22
23
20
20
23
23
. 2 no ECU irivmC
. 1 dirty air
cleaner
. 2
.5
. 8 no EGR mvnjt
.8
. 8 no EGRp mvmt
.C timing-3°
.2 Choke 3 KR; EFE Stuck
.3 HAD line plugged
.2 P.O SGR mvat
.1
. 0 no EGR mvxt
.6
.4
.6
.0
.2
.4
.0 No EGR ir.v-.r.t
. 6 No EGR snvir.t
.0
.1
.3
.3 No EGR mvmt
.6
------- |