EPA-AA-IMS/80-11
                           Data Summary Tables On The
                     Effects Of Specific Maintenance Types
                             On The Emissions From
                           In-Use  Light Duty Vehicles
                          Failing Idle Test Outpoints
                                 December,  1980
                                     Notice

Technical Reports  do not necessarily  represent final  EPA  decisions or  posi-
tions.  They are  intended  to present technical  analysis  of issues 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.
                                David Brzezinski
                          Inspection/Maintenance Staff
                      Emission Control Technology Division
                 Office of Mobile Source Air Pollution Control
                      Office of Air, Noise, and Radiation
                      U.S.  Environmental  Protection Agency

-------
The Tables in  this  report were compiled  from  data selected from  the  computer
data records from  several testing programs.  Except in  the  Portland Study NOx
Analysis Tables, only  vehicles  which received at  least  one repair  and  retest
sequence were  selected from the  testing  programs  for summary  in  this report.
No effort was  made to create a sample which would  contain a  specific mix of
model  years  or  vehicle  types.    Caution  should be  used in extrapolating any
measured  changes  from this  report  to  real  world  changes  which  might  be
observed in an in-use fleet.

Vehicles which  did not receive all  test  sequences in programs with more than
one repair and retest  step  have had  their emission levels  from their  previous
test sequence carried  forward to  any missing  test  sequence.   This  reflects the
fact that  the  repair in  the missing sequence was not  judged as  necessary in
the testing  program and  therefore the  previous  test sequence  would represent
the properly "repaired" emission  levels of that vehicle for the  missing test
sequence.  This assumption affects Tables  1 through 6.

The "as-received"  column  in Tables  1  through 18  represent  the emissions and
rates  for  only  those  vehicles  which received at  least  one repair  and  retest
sequence in  the  testing program.  This may not reflect the overall  emission
levels and rates for the test program sample as a whole.

-------
INDEX

Table
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

Program
Restorative Maintenance
Restorative Maintenance
FY77 Emission Factor
FY77 Emission Factor
FY77 Emission Factor
FY77 Emission Factor
Portland Element II
Portland Element II
Portland Element II
Portland Element II
Portland Element III
Portland Element III
Portland Element II
Portland Element II
Portland Element II
Portland Element II
Portland Element III
Portland Element III
Model
Years
1975-76
1975-76
1975-79
1975-79
1975-80
1975-80
1972-74
1972-74
1975-77
1975-77
1975-77
1975-77
1972-74
1972-74
1975-77
1975-77
1975-77
1975-77
Idle Cutpoints
IHC(PPM)/IC(%)
225/1.0
300/3.0
225/1.0
300/3.0
225/1.0
300/3.0
225/1.0
300/3.0
225/1.0
300/3.0
225/1.0
300/3.0
225/1.0
300/3.0
225/1.0
300/3.0
225/1.0
300/3.0

Repairs
Three Step Restorative Maintenance
Three Step Restorative Maintenance
Carburetor Idle Mixture Adjustment
Carburetor Idle Mixture Adjustment
Three Step Restorative Maintenance
Three Step Restorative Maintenance
Carburetor Repairs
Carburetor Repairs
Carburetor Repairs
Carburetor Repairs
Carburetor Repairs
Carburetor Repairs
Typical I/M Maintenance
Typical I/M Maintenance
Typical I/M Maintenance
Typical I/M Maintenance
Typical I/M Maintenance
Typical I/M Maintenance
Portland Study - FTP and HFET NOx Measurements
19
20
21
22
23
Effect of Typical I/M Repairs
Comparison of NOx Measurements
Comparison of NOx Measurements
Comparison of NOx Measurements
Significance of Changes in NOx
on NOx Measurements
on 1972-74 Vehicles
on 1975-77 Vehicles
on 1975-77 Vehicles
in Portland.
in Eugene and
in Eugene and
in Eugene and

Portland Element II at Quarterly Intervals.
Portland Element II at Quarterly Intervals.
Portland Element III at Quarterly Intervals.
Measurements Between Quarterly Tests in Oregon.

-------
                                      Table  1.
                           Restorative Maintenance  Sample
                         (195 1975-1976 Model Year Vehicles)
                           Average Mileage:
8070 Miles
Idle
Idle
HC Cutpoint:
CO Cutpoint:
(Idle Scores Measured
As
(195
Idle Test:
Average Idle HC (PPM)
Average Idle CO (Z)
IHC Pass Rate (Z)
ICO Pass Rate (Z)
Idle Test Pass Rate (X)
Federal Test Procedure:
Average FTP HC (GM/MI)
Average FTP CO (GM/MI)
Average FTP NO (GM/MI)
FTP HC Pass Rate (%)
FTP CO Pass Rate (Z)
FTP NO Pass Rate (Z)
FTP Test Pass Rate (Z)
Highway Fuel Economy Test:
Average HFET HC (GM/MI)
Average HFET CO (GM/MI)
Average HFET NO (GM/MI)
Clayton Key Mode:
High Cruise HC (PPM)
High Cruise CO «)
High Cruise NO (PPM)
Low Cruise HC (PPM)
Low Cruise CO (Z)
Low Cruise NO (PPM)
Received
Vehicles)5

158.1
1.86
75.9
52.8
51.3

1.64
28.0
3.11
56.9
41.0
56.9
11.3

.37
4.75
3.55

37.7
.114
1346
42.6
.126
897
225 PPM
1.0 Z
in Neutral
or Park Gear)
Vehicles Which
Test As Received
RECV

281.1
3.70
50.5
3.2
0.0

2.32
46.3
2.75
26.3
7.4
72.6
2.1

.47
7.68
3.34

42.7
.182
1335
50.1
.186
927
AFT2_1
255.6
3.21
57.9
15.8
9.5

2.13
41.1
2.49
35.8
12.6
85.3
9.5

.44
6.81
3.04

39.5
.164
1211
46.5
.150
814
Fail Idle
(95 Vehicles)*
AFT32
82.7
.28
93.7
90.5
87.4

1.09
11.7
2.61
84.2
82.1
88.4
66.3

.27
3.72
3.05

34.6
.144
1234
37.2
.048
845
AFT43
76.9
.30
94.7
91.6
88.4

1.02
10.7
2.46
89.5
87.4
92.6
75.8

.25
3.18
2.89

32.8
.131
1145
36.4
.071
764
1:  After correction of any disablements and maladjustments other than idle
    air/fuel mixture and idle speed.*

2:  After adjustment of idle speed and idle air/fuel mixture.*

3:  After replacement of any defective components and a major tune-up.*

4:  Some vehicles do not complete all test sequences.  The emission values for
    these vehicles are carried forward from the previously completed test sequence.

5:  The total Restorative Maintenance program included 300 1975-1976 vehicles.
    These 195 vehicles are those which have received at least one additional test
    sequence besides the as-received tests.
  All repairs performed by laboratory mechanics.

-------
                                       Table 2.
                            Restorative Maintenance Sample
                          (195  1975-1976 Model  Year Vehicles)
                             Average Mileage:
       8070 Miles
                              Idle HC Outpoint:     300 PPM
                              Idle CO Outpoint:     3.0  %
                    (Idle Scores Measured in Neutral  or Park Gear)
                         As Received
                        (195 Vehicles)5
Idle Test:

Average Idle HC (PPM)       158.1
Average Idle CO (Z)           1.86

IHC Pass Rate (Z)            81.5
ICO Pass Rate (Z)            70.8
Idle Test Pass Rate (Z)      67.2
     Vehicles Which Fail Idle
  Test As Received (64 Vehicles)4
                                            RECV
362.9
  4.60

 28.1
  3.1
  0.0
                                                     AFT21
322.2
  3.86

 40.6
 17.2
  9.4
                     AFT32
97.0
  .33
92.
87.
                     84.4
                       AFT43
94.0
  .35

92.2
90.6
85.9
Federal Test Procedure:

Average FTP HC (GM/MI)        1.64
Average FTP CO (GM/MI)       28.0
Average FTP NO (GM/MI)        3.11

FTP HC Pass Rate «)         56.9
FTP CO Pass Rate (Z)         41.0
FTP NO Pass Rate (Z)         56.9
FTP Test Pass Rate (%)       U.3
  2.62
 52.6
  2.75

 12.5
  4.7
 78.1
  1.6
  2.32
 45.2
  2.40

 25.0
 12.5
 93.8
 10.9
 1.12
12.5
 2.59
79.
79.
92.
            65.6
 1.06
11.1
 2.41

85.9
85.9
95.3
75.0
Highway Fuel Economy Test:

Average HFET HC (GM/MI)        .37
Average HFET CO (GM/MI)       4.75
Average HFET NO (GM/MI)       3.55
   .53
  8.91
  3.37
   .48
  7.73
  2.97
  .28
 4.50
 3.06
  .26
 3.66
 2.83
Clayton Key Mode:

High Cruise HC (PPM)         37.7           51.7     46.2       38.6       37.3
High Cruise CO (%)             .114           .240     .213       .187       .165
High Cruise NO (PPM)         1346           1516     1333       1386       1265

Low Cruise HC (PPM)          42.6           60.9     55.0       40.9       41.6
Low Cruise CO (Z)              .126           .248     .196       .050       .079
Low Cruise NO (PPM)          897            1037     872        937        841
1:  After correction of maladjustments and disablements other than idle
    air/fuel mixture and idle speed.*

2:  After adjustment of idle speed and idle air/fuel mixture.*

3:  After replacement of any defective components and a major tune-up.*

4:  Some vehicles do not complete all test sequences.  The emission values for
    these vehicles are carried forward from the previously completed test sequence.

5:  The total Restorative Maintenance program included 300 1975-1976 vehicles.
    These 195 vehicles are those which have received at least one additional test
    sequence besides the as-received tests.
* All repairs performed by laboratory mechanics.

-------
                                       Table  3.

                             Emission Factor FY77 Sample



Idle Test;
Average Idle HC (PPM)
Average Idle CO (%)
IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (Z)
Federal Test Procedure;
Average FTP HC (GM/MI)
Average FTP CO (GM/MI)
Average FTP NO (GM/MI)
FTP HC Pass Rate (Z)
FTP CO Pass Rate (Z)
FTP NO Pass Rate (Z)
FTP Test Pass Rate (Z)
Highway Fuel Economy Test
Average HFET HC (GM/MI)
Average HFET CO (GM/MI)
Average HFET NO (GM/MI)
Federal 3-Mode Test:
High Cruise HC (PPM)
High Cruise CO (Z)
High Cruise NO (PPM)
Low Cruise HC (PPM)
Low Cruise CO (Z)
Low Cruise NO (PPM)
(71 1975-1979 Model
Average Mileage:
Idle HC Cutpoint
Idle CO Cutpoint
As Received
(71 Vehicles)*
397.3
3.55
39.4
32.4
23.9

2.44
37.8
2.06
25.4
12.7
70.4
1.4
.71
9.54
2.55
(20 Vehicles)3
100.5
.409
720
98.7
.507
824
Year Vehicles)
25003 Miles
: 225 PPM
: 1.0 Z
Vehicles Which Fail
Idle Test As Received (54 Vehicles)
As After
Received Maintenance^
499.7 241.5
4.59 .42
20.4 68.5
11.1 87.0
0.0 59.3

2.75 1.43
42.2 14.6
2.10 2.10
13.0 70.4
9.3 72.2
70.4 75.9
0.0 40.7
.73 .51
8.76 6.48
2.54 2.29
(10 Vehicles)3
95.4 74.1
.244 .456
867 730
87.4 116.9
.352 .410
865 788
1: Those vehicles in the FY77 Emission Factor Program which were  tested  after  only
carburetor air/fuel mixture related repairs.*

2: Adjustment of the carburetor air/fuel mixture and related adjustment  (timing,
idle speed).*

3: Only some of the vehicles selected for this analysis also received  the  loaded
mode testing.
* All repairs performed by laboratory mechanics.

-------
                                       Table 4.

                              Emission Factor FY77 Sample
                          (71 1975-1979 Model Year Vehicles)
                                   Average Mileage:     25003 Miles

                                   Idle  HC Outpoint:    300   PPM
                                   Xdle  CO Outpoint:    3.0    %
 Idle  Test:
 Average  Idle  HC  (PPM)
 Average  Idle  CO  (%)

 IHC Pass Rate  (%)
 ICO Pass Rate  (%)
 Idle  Test Pass Rate  (%)
                               As  Received
                              (71  Vehicles)1
   397.3
     3.55
    50,
    49,
                            Vehicles Which Fail
                     Idle Test As Received (44 Vehicles)
                          As        After
                       Received  Maintenance^
572.8
  5.30
 20,
 18,
    38.0
                         0.0
242.6
   .38

 81.8
100.0
 81.8
Federal Test  Procedure:

Average FTP HC  (GM/MI)            2.44
Average FTP CO  (GM/MI)           37.8
Average FTP NO  (GM/MI)            2.06

FTP HC Pass Rate  (%)             25.4
FTP CO Pass Rate  (%)             12.7
FTP NO Pass Rate  (%)             70.4
FTP Test Pass Rate  (%)            1.4

Highway Fuel  Economy Test:

Average HFET  HC (GM/MI)            .71
Average HFET  CO (GM/MI)           9.54
Average HFET  NO (GM/MI)           2.55
                         2.98
                        47.6
                         1.91

                         6.8
                         6.8
                        75.0
                         0.0
                          .74
                         9.41
                         2.20
              1.42
             15.2
              1.94

             72.7
             68.2
             79.5
             45.5
               .48
              6.88
              1.97
Federal 3-Mode Test:

High Cruise HC (PPM)
High Cruise CO «)
High Cruise NO (PPM)

Low Cruise HC (PPM)
Low Cruise CO (%)
Low Cruise NO (PPM)
(20 Vehicles)3

   100.5
      .409
   720

    98.7
      .507
   824
   (9 Vehicles)3
100.6
   .231
867

 85.3
   .380
814
   77.0
   .462
724

118.1
   .442
758
1: Those vehicles in the FY77 Emission Factor Program which were  tested after  only
carburetor air/fuel mixture related repairs.*

2: Adjustment of the carburetor air/fuel mixture and related adjustment (timing,
idle speed).*

3: Only some of the vehicles selected for this analysis also received the  loaded
mode testing.
* All repairs performed by laboratory mechanics.

-------
                                       Table  5.
                             Emission Factor FY79 Sample
                          (91  1975-1980 Model Year  Vehicles)
                        Average Mileage:

                        Idle HC Outpoint:
                        Idle CO Outpoint:
                         As Received
                        (91 Vehicles)5
                    20020 Miles
Idle Test:

Average Idle HC (PPM)      189.7
Average Idle CO (2)          2.02

IHC Pass Rate (%)           73.6
ICO Pass Rate (%)           56.0
Idle Test Pass Rate (%)     52.7
Federal Test Procedure:

Average FTP HC (GM/MI)       1.75
Average FTP CO (GM/MI)      27.6
Average FTP NO (GM/MI)       2.21

FTP HC Pass Rate (%)        47.3
FTP CO Pass Rate (%)        31.9
FTP NO Pass Rate (%)        58.2
FTP Test Pass Rate U)       0.0
Highway Fuel Economy Test:

Average HFET HC (GM/MI)        .42
Average HFET CO (GM/MI)      6.41
Average HFET NO (GM/MI)      2.67
Federal 3-Mode:

High Cruise HC (PPM)
High Cruise CO U)
High Cruise NO (PPM)

Low Cruise HC  (PPM)
Low Cruise CO  (2)
Low Cruise NO  (PPM)
(30 Vehicles)6

   40.1
     .112
  950

   56.7
     .385
  681
225 PPM
1.0 %
Vehicles Which Fail Idle
Test As Received (43 Vehicles)4
RECV
350.5
4.13
44.2
7.0
0.0
2.10
33.7
2.05
14.0
20.9
67.4
0.0
.50
6.41
2.49
52.2
.121
874
73.5
.463
667
AFT21
319.0
3.61
48.8
16.3
9.3
1.93
28.4
1.96
39.5
30.2
69.8
7.0
.45
5.23
2.45
/in
	 \ 19
44.5
.077
704
63.8
.422
504
AFT32
159.6
.64
88.4
88.4
79.1
1.27
13.7
2.04
74.4
60.5
69.8
39.5
.35
3.78
2.43
Vehicles)6—
27.5
.071
716
35.9
.235
511
AFT43
119.8
.58
86.0
86.0
76.7
1.17
13.2
2.03
74.4
67.4
72.1
44.2
.34
3.79
2.41
28.3
.071
739
35.7
.221
508
1:  After correction of any disablements and maladjustments other than  idle
    air/fuel mixture and idle speed.*

2:  After adjustment of idle speed and idle air/fuel mixture.*

3:  After replacement of any defective components and a major tune-up.*

4:  Some vehicles do not complete all test sequences.  The emission values for
    these vehicles are carried forward from the previously completed test sequence.

5:  Only those vehicles in the FY79 Emission Factor Program which received at least
    one of the subsequent repair sequences were chosen for this analysis.

6:  Only some of the vehicles selected for this analysis also received  the
    loaded-mode testing.
* All repairs performed by laboratory mechanics.

-------
                                       Table 6.
                             Emission Factor FY79  Sample
                          (91 1975-1980 Model Year Vehicles)
                        Average Mileage:

                        Idle HC Outpoint:
                        Idle CO Outpoint:
                         As Received
                         (91 Vehicles)5
                    20020 Miles
Idle Test:

Average Idle HC (PPM)      189.7
Average Idle CO (%)          2.02

IHC Pass Rate (%)           78.0
ICO Pass Rate (%)           74.7
Idle Test Pass Rate (%)     69.2
Federal Test Procedure:

Average FTP HC (GM/MI)       1.75
Average FTP CO (GM/MI)      27.6
Average FTP NO (GM/MI)       2.21

FTP HC Pass Rate (Z)        47.3
FTP CO Pass Rate (%)        31.9
FTP NO Pass Rate U)        58.2
FTP Test Pass Rate (%)       0.0
Highway Fuel Economy Test:

Average HFET HC (GM/MI)       .42
Average HFET CO (GM/MI)      6.41
Average HFET NO (GM/MI)      2.67
Federal 3-Mode:

High Cruise HC (PPM)
High Cruise CO (%)
High Cruise NO (PPM)

Low Cruise HC (PPM)
Low Cruise CO (%)
Low Cruise NO (PPM)
(30 Vehicles)6

   40.1
     .112
  950

   56.7
     .385
  681
300 PPM
3.0 %
Vehicles Which Fail
Idle
Test As Received (28 Vehicles)4
RECV
465.9
5.41
28.6
17.9
0.0
2.33
36.2
1.90
35.7
28.6
78.6
0.0
.46
4.45
2.29
61.6
.068
813
79.3
.273
674
AFT2*
426.5
4.75
46.4
32.1
14.3
2.09
28.7
1.96
39.3
35.7
71.4
3.6
.39
3.25
2.47
-(12 Vehi(
54.9
.058
774
62.0
.188
576
AFT32
209.3
.92
89.3
85.7
78.6
1.34
13.0
2.06
75.0
64.3
71.4
42.9
.29
1.82
2.43
33.8
.058
784
38.4
.140
584
AFT43
145.0
.82
85.7
89.3
78.6
1.18
12.6
2.04
75.0
75.0
71.4
50.0
.30
2.14
2.39
33.8
.055
816
35.9
.111
598
1:  After correction of any disablements and maladjustments other than idle
    air/fuel mixture and idle speed.*

2:  After adjustment of idle speed and idle air/fuel mixture.*

3:  After replacement of any defective components and a major tune-up.*

4:  Some vehicles do not complete all test sequences.  The emission values for
    these vehicles are carried forward from the previously completed test sequence.

5:  Only those vehicles in the FY79 Emission Factor Program which received at least
    one of the subsequent repair sequences were chosen for this analysis.

6:  Only some of the vehicles selected for this analysis also received the
    loaded-mode testing.
* All repairs performed by laboratory mechanics.

-------
                                       Table  7.
                              Portland  Element  II  Sample
                          (16 1972-1974 Model Year Vehicles
                     Which Received Only Carburetor Maintenance)
                        Average Mileage:

                        Idle HC Cutpoint:
                        Idle CO Cutpoint:
              50970 Miles

               225 PPM
               1.0  %
Idle Test;

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (16 Vehicles)
465.9
  5.01
 37.5
  6.3
  0,0
                         Vehicles Which Fail
                  Idle Test As Received (16 Vehicles)
                       As     After Carb.
                    Received  Maintenance*
465.9
  5.01

 37.5
  6.3
  0.0
260.9
  1.06
 62.
 62.
 43.8
Federal Test Procedure:

Average FTP HC (GM/MI)           3.53
Average FTP CO (GM/MI)          61.7
Average FTP NO (GM/MI)           2.87

FTP HC Pass Rate (%)            50.0
FTP CO Pass Rate (%)             6.3
FTP NO Pass Rate U)            75.0
FTP Test Pass Rate (%)           0.0

Highway Fuel Economy Test:

Average HFET HC (GM/MI)          2.25
Average HFET CO (GM/MI)         21.44
Average HFET NO (GM/MI)          4.24
                      3.53
                     61.7
                      2.87

                     50.0
                      6.3
                     75.0
                      0.0
                      2.25
                     21.44
                      4.24
              4.35
             36.2
              3.28

             68.8
             68.8
             75.0
             31.3
              2.33
             13.87
              4.75
* Repairs performed by field mechanics.

-------
                                       Table 8.
                              Portland Element II Sample
                           (16 1972-1974 Model  Year Vehicles
                     Which Received Only Carburetor Maintenance)
                        Average Mileage:

                        Idle HC Cutpoint:
                        Idle CO Cutpoint:
              50970 Miles

               300 PPM
               3.0  %
Idle Test;

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (16 Vehicles)
465.9
  5.01
 37.
 12.
                         Vehicles Which Fail
                  Idle Test As Received (15 Vehicles)
                       As     After Garb.
                    Received  Maintenance*
  6.3
492.0
  5.17

 33.3
  6.7
  0.0
272.0
  1.07

 80,0
 93.3
 73.3
Federal Test Procedure:

Average FTP HC (GM/MI)           3.53
Average FTP CO (GM/MI)          61.7
Average FTP NO (GM/MI)           2.87

FTP HC Pass Rate (%)            50.0
FTP CO Pass Rate (%)             6.3
FTP NO Pass Rate (%)            75.0
FTP Test Pass Rate (%)           0.0

Highway Fuel Economy Test;

Average HFET HC (GM/MI)  .        2.25
Average HFET CO (GM/MI)         21.44
Average HFET NO (GM/MI)          4.24
                      3.50
                     57.8
                      2.86.

                     53.3
                      6.7
                     80.0
                      0.0
                      2.32
                     19.81
                      4.29
              4.50
             35.7
              3.27

             66.7
             73.3
             80.0
             33.3
              2.44
             14.12
              4.76
* Repairs performed by field mechanics.

-------
                                       Table  9.
                              Portland  Element  II Sample
                          (26 1975-1977 Model Year Vehicles
                     Which Received Only Carburetor Maintenance)
                        Average Mileage:

                        Idle HC Cutpoint:
                        Idle CO Cutpoint:
              29821 Miles

               225 PPM
               1.0  %
Idle Test;

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (26 Vehicles)
248.5
  2.92

 57.7
 15.4
  7.7
                         Vehicles Which Fail
                  Idle Test As Received (24 Vehicles)
                       As
                    Received
264.8
  3.15

 54.2
  8.3
  0.0
          After Carb.
          Maintenance*
102.3
   .42

 91.7
 83.3
 75.0
Federal Test Procedure:

Average FTP HC (GM/MI)           2.27
Average FTP CO (GM/MI)          38.6
Average FTP NO (GM/MI)           2.61

FTP HC Pass Rate (%)            38.5
FTP CO Pass Rate (%)            26.9
FTP NO Pass Rate (%)            69.2
FTP Test Pass Rate (%)          11.5

Highway Fuel Economy Test:

Average HFET HC (GM/MI)           .67
Average HFET CO (GM/MI)          9.86
Average HFET NO (GM/MI)          3.71
                      2.39
                     40.9
                      2.63

                     33.3
                     20.8
                     66.7
                      4.2
                       .69
                     10.53
                      3.66
              1.70
             21.4
              2.74
             58.
             58.
             58.
             12.5
               .64
              9.29
              3.80
* Repairs performed by field mechanics.

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                                          10
                                      Table  10.
                              Portland Element II Sample
                           (26 1975-1977 Model Year Vehicles
                     Which Received Only Carburetor Maintenance)
                        Average Mileage:

                        Idle HC Outpoint:
                        Idle CO Cutpoint:
              29821 Miles

               300 PPM
               3.0  %
Idle Test:

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (26 Vehicles)
284.5
  2.92

 73.1
 50.0
 42.3
                         Vehicles Which Fail
                  Idle Test As Received (15 Vehicles)
                       As     After Carb.
                    Received  Maintenance*
339.0
  3;95

 53.3
 13.3
  0.0
128.3
   .41

 93.3
100.0
 93.3
Federal Test Procedure:

Average FTP HC (GM/MI)           2.27
Average FTP CO (GM/MI)          38.6
Average FTP NO (GM/MI)           2.61

FTP HC Pass Rate (%)            38.5
FTP CO Pass Rate (%)            26.9
FTP NO Pass Rate CO            69.2
FTP Test Pass Rate (%)          11.5

Highway Fuel Economy Test:

Average HFET HC (GM/MI)           .67
Average HFET CO (GM/MI)          9.86
Average HFET NO (GM/MI)          3.71
                      2.65
                     40.1
                      2.38
                     20.0
                     26.
                     73.
                      6.7
                       .73
                      8.44
                      3.25
              1.69
             16.9
              2.75

             60.0
             66.7
             53.3
              6.7
               .61
               6.90
              3.65
* Repairs performed by field mechanics.

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                                          11
                                      Table 11.
                             Portland Element III Sample
                          (55 1975-1977 Model Year Vehicles
                     Which Received Only Carburetor Maintenance)
                        Average Mileage:

                        Idle HC Cutpoint:
                        Idle CO Cutpoint:
               37732 Miles

                225 PPM
                1.0  %
Idle Test:

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (55 Vehicles)
 287.2
   3.71

  58.2
  18.2
  12.7
                          Vehicles Which Fail
                   Idle Test As Received (48 Vehicles)
                        As     After Carb.
                     Received  Maintenance*
 321.4
   4.22

  58.3
   6.3
   0.0
 101.5
    .40

  93.8
  85.4
  79.2
Federal Test Procedure:

Average FTP HC (GM/MI)           2.48
Average FTP CO (GM/MI)          37.2
Average FTP NO (GM/MI)           2.54

FTP HC Pass Rate (%)            30.9
FTP CO Pass Rate (%)            18.2
FTP NO Pass Rate (%)            72.7
FTP Test Pass Rate (%)          10.9

Highway Fuel Economy Test:

Average HFET HC (GM/MI)           .68
Average HFET CO (GM/MI)          9.21
Average HFET NO (GM/MI)          3.71
                       2.66
                      40.6
                       2.36

                      20.8
                      12.5
                      77.1
                       8.3
                        .70
                       9.61
                       3.41
               1.60
              18.4
               2.47

              54.2
              54.2
              68.8
              31.3
                .48
                6.34
               3.49
Federal 3-Mode Test:

High Cruise HC (PPM)
High Cruise CO (%)
High Cruise NO (PPM)

Low Cruise HC (PPM)
Low Cruise CO (%)
Low Cruise NO (PPM)
  63.8
    .373
1473

 100.3
    .720
 956
  65.2
    .377
1387

 106.2
    .792
 883
    53.2
    .275
1309

  70.4
    .333
 909
* Repairs performed by field mechanics,

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                                          12
                                      Table  12.
                             Portland Element  III  Sample
                          (55  1975-1977 Model  Year Vehicles
                     Which Received Only Carburetor Maintenance)
                        Average Mileage:

                        Idle HC Cutpoint:
                        Idle CO Cutpoint:
               37732 Miles

                300 PPM
                3.0  %
Idle Test;

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate U)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (55 Vehicles)
 287.2
   3.71

  67.3
  40.0
  34.5
                          Vehicles Which Fail
                   Idle Test As Received (36 Vehicles)
                        As     After Garb.
                     Received  Maintenance*
 381.1
   4.98

  50.0
   8.3
   0.0
 108.2
    .46

  97.2
 100.0
  97.2
Federal Test Procedure:

Average FTP HC (GM/MI)
Average FTP CO (GM/MI)
Average FTP NO (GM/MI)

FTP HC Pass Rate (%)
FTP CO Pass Rate (%)
FTP NO Pass Rate (%)
FTP Test Pass Rate (%)

Highway Fuel Economy Test:

Average HFET HC (GM/MI)
Average HFET CO (GM/MI)
Average HFET NO (GM/MI)
   2.48
  37.2
   2.54

  30.9
  18.
  72.
  10.9
    .68
   9.21
   3.71
   3.01
  46.3
   2.34

  11.1
   5.6
  77.8
   2.8
    .77
  10.53
   3.35
   1.70
  19.6
   2.41

  47.2
  44.4
  69.4
  25.0
    .51
    7.08
   3.31
Federal 3-Mode Test:

High Cruise HC (PPM)
High Cruise CO (%)
High Cruise NO (PPM)

Low Cruise HC (PPM)
Low Cruise CO (%)
Low Cruise NO (PPM)
  63.8
    .373
1473

 100.3
    .720
 956
  70.0
    .414
1387

 122.4
    .992
 867
    57.2
    .294
1304

  77.4
    .406
 866
* Repairs performed by field mechanics.

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                                          13
                                      Table 13.
                              Portland Element  II  Sample
                          (62  1972-1974 Model Year Vehicles)
                        Average Mileage:

                        Idle HC Outpoint:
                        Idle CO Cutpoint:
              53735 Miles

               225 PPM
               1.0  %
Idle Test:

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (62 Vehicles)
406.7
  4.51

 38.7
  9.7
  0.0
                         Vehicles Which Fail
                  Idle Test As Received (62 Vehicles)
                       As        After
                    Received  Maintenance*
406.7
  4.51

 38.7
  9.7
  0.0
199.3
   .95
 75.8
 61.3
 50.0
Federal Test Procedure:

Average FTP HC (GM/MI)           4.07
Average FTP CO (GM/MI)          55.7
Average FTP NO (GM/MI)           3.22

FTP HC Pass Rate (%)            51.6
FTP CO Pass Rate (%)            22.6
FTP NO Pass Rate (%)            66.1
FTP Test Pass Rate (%)           9.7

Highway Fuel Economy Test:

Average HFET HC (GM/MI)          1.97
Average HFET CO (GM/MI)         15.95
Average HFET NO (GM/MI)          5.34
                      4.07
                     55.7
                      3.22

                     51.6
                     22.6
                     66.1
                      9.7
                      1.97
                     15.95
                      5.34
              3.12
             32.7
              3.31

             82.3
             72.6
             69.4
             45.2
              1.55
               12.20
              5.11
* Repairs performed by field mechanics.

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                                          14
                                      Table 14.
                              Portland Element II Sample
                          (62 1972-1974 Model  Year Vehicles)
                        Average Mileage:

                        Idle HC Cutpoint:
                        Idle CO Cutpoint:
              53735 Miles

               300 PPM
               3.0  %
Idle Test;

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (62 Vehicles)
406.7
  4.51

 59.7
 25.8
 14.5 .
                         Vehicles Which Fail
                  Idle Test As Received (53 Vehicles)
                       As        After
                    Received  Maintenance*
452.1
  4.91

 52.8
 13.2
  0.0
198.2
   .91

 84.9
 98.1
 83.0
Federal Test Procedure:

Average FTP HC (GM/MI)           4.07
Average FTP CO (GM/MI)          55.7
Average FTP NO (GM/MI)           3.22

FTP HC Pass Rate (%)            51.6
FTP CO Pass Rate (%)            22.6
FTP NO Pass Rate (%)            66.1
FTP Test Pass Rate (%)           9.7

Highway Fuel Economy Test:

Average HFET HC (GM/MI)          1.97
Average HFET CO (GM/MI)         15.95
Average HFET NO (GM/MI)          5.34
                      4.28
                     56.3
                      3.23

                     50.9
                     22.6
                     67.9
                      9.4
                      2.09
                     15.93
                      5.46
              3.22
             31.8
              3.38

             84.9
             77.4
             71.7
             49.1
              1.63
               12.55
              5.28
* Repairs performed by field mechanics,

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                                          15
                                      Table 15.
                              Portland  Element  II  Sample
                          (99  1975-1977 Model Year Vehicles)
                        Average Mileage:

                        Idle HC Cutpoint:
                        Idle CO Cutpoint:
              26050 Miles

               225 PPM
               1.0  %
Idle Test:

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (99 Vehicles)
329.0
  3.23

 42.4
 19.2
  7.1
                         Vehicles Which Fail
                  Idle Test As Received (92 Vehicles)
                       As        After
                    Received  Maintenance*
351.2
  3.45

 38.0
 13.0
  0.0
95.4
  .36

94.6
87.0
81.5
Federal Test Procedure:

Average FTP HC (GM/MI)           2.59
Average FTP CO (GM/MI)          37.2
Average FTP NO (GM/MI)           2.47

FTP HC Pass Rate (%)            31.3
FTP CO Pass Rate (%)            24.2
FTP NO Pass Rate (%)            73.7
FTP Test Pass Rate (%)          11.1

Highway Fuel Economy Test:

Average HFET HC (GM/MI)           .61
Average HFET CO (GM/MI)          8.46
Average HFET NO (GM/MI)          3.53
                      2.70
                     38.9
                      2.49
                     28,
                     20.
                     71.
                      7.6
                       .61
                      8.61
                      3.48
              1.53
             19.5
              2.60

             64.1
             59.8
             65.2
             31.5
               .51
               7.68
              3.50
* Repairs performed by field mechanics.

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                                          16
                                      Table  16.
                              Portland Element II Sample
                          (99 1975-1977 Model Year Vehicles)
                        Average Mileage:

                        Idle HC Outpoint:
                        Idle CO Cutpoint:
              26050 Miles

               300 PPM
               3.0  %
Idle Test;

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (99 Vehicles)
329.0
  3.23

 55.6
 53.5
 35.4
                         Vehicles Which Fail
                  Idle Test As Received (64 Vehicles)
                       As        After
                    Received  Maintenance*
432.4
  4.15
 31
 28
  0.0
 99.2
   .31

 95.3
100.0
 95.3
Federal Test Procedure:

Average FTP HC (GM/MI)           2.59
Average FTP CO (GM/MI)          37.2
Average FTP NO (GM/MI)           2.47

FTP HC Pass Rate (%)            31.3
FTP CO Pass Rate (%)            24.2
FTP NO Pass Rate (%)            73.7
FTP Test Pass Rate (%)          11.1

Highway Fuel Economy Test:

Average HFET HC (GM/MI)           .61
Average HFET CO (GM/MI)          8.46
Average HFET NO (GM/MI)          3.53
                      3.12
                     43.0
                      2.36

                     15.6
                     15.6
                     73.4
                      4.7
                       .68
                      9.25
                      3.30
              1.57
             19.4
              2.49

             60.9
             59.4
             62.5
             26.6
               .54
               8.16
              3.30
* Repairs performed by field mechanics,

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                                          17
                                      Table 17.
                             Portland Element III Sample
                         (108 1975-1977 Model Year Vehicles)
                        Average Mileage:

                        Idle HC Outpoint:
                        Idle CO Outpoint:
               35756 Miles

                225 PPM
                1.0  %
Idle Test:

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate  (%)
                              As Received
                             (108 Vehicles)
 317.1
   3.80

  48.1
  12.0
   7.4
                          Vehicles Which Fail
                  Idle Test As Received (100 Vehicles)
                        As        After
                     Received  Maintenance*
 338.3
   4.09

  44.0
   5.0
   0.0
  95
,2
,33
  94.0
  89.0
  83.0
Federal Test Procedure:

Average FTP HC  (GM/MI)           2.78
Average FTP CO  (GM/MI)          42.0
Average FTP NO  (GM/MI)           2.29

FTP HC Pass Rate (%)            22.2
FTP CO Pass Rate (%)            14.8
FTP NO Pass Rate (%)            77.8
.FTP Test Pass Rate  (%)           9.3

Highway Fuel Economy Test:

Average HFET HC (GM/MI)            .85
Average HFET CO (GM/MI)         12.75
Average HFET NO (GM/MI)          3.27
                       2.91
                      44.4
                       2.18

                      16.0
                      11.0
                      80.0
                       7.0
                        .88
                      13.32
                       3.08
               1.55
              20.8
               2.40
              57.0
              53.0
              72.0
              31.0
                .51
                8.67
               3.29
Federal 3-Mode Test;

High Cruise HC (PPM)
High Cruise CO (%)
High Cruise NO (PPM)

Low Cruise HC (PPM)
Low Cruise CO (%)
Low Cruise NO (PPM)
  77.7
    .522
1285

 105.8
    .767
 844
  79.6
    .540
1226

 109.7
    .812
 801
    55.8
    .396
1190

  64.7
    .346
 867
* Repairs performed by field mechanics.

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                                          18
                                       Table  18.
                              Portland  Element  III  Sample
                          (108 1975-1977 Model  Year Vehicles)
                        Average Mileage:

                        Idle HC Outpoint:
                        Idle CO Cutpoint:
               35756 Miles

                300 PPM
                3.0  %
Idle Test:

Average Idle HC (PPM)
Average Idle CO (%)

IHC Pass Rate (%)
ICO Pass Rate (%)
Idle Test Pass Rate (%)
                              As Received
                             (108 Vehicles)
 317.1
   3.80
  58.
  41,
                          Vehicles Which Fail
                   Idle Test As Received (77 Vehicles)
                        As        After
                     Received  Maintenance*
 398.7
   4.70
  41.
  18.
  28.7
   0.0
 101.4
    .34

  97.4
 100.0
  97.4
Federal Test Procedure:

Average FTP HC (GM/MI)           2.78
Average FTP CO (GM/MI)          42.0
Average FTP NO (GM/MI)           2.29

FTP HC Pass Rate (%)            22.2
FTP CO Pass Rate (%)            14.8
FTP NO Pass Rate (%)            77.8
FTP Test Pass Rate (%)           9.3

Highway Fuel Economy Test;

Average HFET HC (GM/MI)           .85
Average HFET CO (GM/MI)         12.75
Average HFET NO (GM/MI)          3.27
                       3.28
                      50.3
                       2.16
                       6.5
                       5.2
                      80.5
                       1.3
                        .98
                      15.24
                       3.03
               1.63
              22.7
               2.36
              51.9
              45.
              72.
              26.0
                .55
                10.17
               3.16
Federal 3-Mode Test:

High Cruise HC (PPM)
High Cruise CO (%)
High Cruise NO (PPM)

Low Cruise HC (PPM)
Low Cruise CO (%)
Low Cruise NO (PPM)
  77.7
    .522
1285

 105.8
    .767
 844
  86.2
    .614
1204

 125.9
   1.003
 780
    60.3
    .449
1171

  70.3
    .417
 819
* Repairs performed by field mechanics.

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                                         19
                                        Table 19.

                              Effect of Typical I/M Repairs
                             on NOx Measurements in Portland
                          (Repairs  performed  by  field mechanics)
Initial Test
     Element III
(1975-1977 Vehicles)
Pass (179) Fail (108)
     Element II
(1975-1977 Vehicles)
Pass (123) Fail (117)
     Element II
(1972-1974 Vehicles)
Pass (113) Fail (95)
FTP NOx (gm/mi)
HFET NOx (gm/mi)
After Maintenance
2.44
3.49

2.29
3.27

2.62
3.72

2.47
3.52

3.42
5.09

3.15
5.13

FTP NOx (gm/mi)
HFET NOx (gm/mi)

Significance of
the Change*

FTP NOx
HFET NOx
              2.50
              3.45
              2.56
              3.55
              .0274
              .2143
              .3070
              .7543
              3.25
              4.96
              .2280
              .4565
* A value of .05 or less indicates a significant change.

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                                          20
                                    Table 20.

                         Comparison of NOx Measurements
                  in the Eugene  and Portland Element II  Samples
                              (1972-1974 Vehicles)
                           I/M Area
Initial Test         hJ     (Portland)   N

FTP NOx (gm/mi)      219      3.30      113
HFET NOx (gm/mi)              5.11

1st Quarterly Test

FTP NOx (gm/mi)      202      3.41       98
HFET NOx (gm/mi)              5.04

2nd Quarterly Test

FTP NOx (gm/mi)      197      3.41       93
HFET NOx (gm/mi)              4.75

3rd Quarterly Test

FTP NOx (gm/mi)      187      3.34       88
HFET NOx (gm/mi)              5.13

4th Quarterly Test

FTP NOx (gm/mi)      174      3.16       80
HFET NOx (gm/mi)              5.13
Non-I/M Area
(Eugene)

   3.63
   5.41
   3.70
   5.40
   3.56
   5.18
   3.53
   5.48
   3.40
   5.10
Significance of
the Difference*

    .0674
    .2432
    .0877
    .1893
    .3728
    .0905
    .3277
    .2416
    .1952
    .9450
* A value of .05 or less indicates a significant difference between the
  samples.

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                                         21
                                   Table 21.

                         Comparison of NOx  Measurements
                  in the Eugene and Portland Element II Samples
                              (1975-1977 Vehicles)
                           I/M Area
Initial Test         N     (Portland)   N

FTP NOx (gm/mi)      257      2.55      126
HFET NOx (gm/mi)              3.63

1st Quarterly Test

FTP NOx (gm/mi)      235      2.61      113
HFET NOx (gm/mi)              3.64

2nd Quarterly Test

FTP NOx (gm/mi)      221      2.58       95
HFET NOx (gm/mi)              3.46

3rd Quarterly Test

FTP NOx (gm/mi)      209      2.56       78
HFET NOx (gm/mi)              3.74

4th Quarterly Test

FTP NOx (gm/mi)      199      2.46       75
HFET NOx (gm/mi)              3.74
Non-I/M Area
(Eugene)

   2.70
   3.76
   2.73
   3.85
   2.53
   3.37
   2.72
   3.72
   2.51
   3.71
Significance of
the Difference*

    .2755
    .5327
    .4257
    .3664
    .7501
    .6992
    .3315
    .9368
    .7837
    .9039
* A value of .05 or less indicates a significant difference between the
  samples.

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                                          22
                                    Table  22.

                         Comparison of NOx Measurements
                 in the Eugene and Portland Element III Samples
                             (1975-1977  Model  Years)
                           I/M Area
Initial Test         N     (Portland)   N

FTP NOx (gm/mi)      292      2.40      126
HFET NOx (gm/mi)              3.44

1st Quarterly Test

FTP NOx (gm/mi)      276      2.44      113
HFET NOx (gm/mi)              3.31

2nd Quarterly Test

FTP NOx (gm/mi)      258      2.45       95
HFET NOx (gm/mi)              3.23

3rd Quarterly Test

FTP NOx (gm/mi)      229      2.52       78
HFET NOx (gm/mi)              3.73

4th Quarterly Test

FTP NOx (gm/mi)      228      2.55       75
HFET NOx (gm/mi)              3.61
Non-I/M Area
(Eugene)

   2.70
   3.76
   2.73
   3.85
   2.53
   3.37
   2.72
   3.72
   2.51
   3.71
Significance of
the Difference*

    .0356
    .1130
    .0562
    .0112
    .6135
    .5250
    .2494
    .9530
    .8070
    .6931
* A value of .05 or less indicates a significant difference  between the
  samples.

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                                                       Table 23.
                                               Significance of Changes in
                                              the NOx Measurements Between
                                               Quarterly Tests in Oregon

                     Init/lst Quarter*  1st Quarter/2nd Quarter*  2nd Quarter/3rd Quarter*  3rd Quarter/Ath Quarter*
Portland Element III
(1975-1977 Vehicles)

FTP NOx                   .3317
HFET NOx                  .1298

Portland Element II
(1972-1974 Vehicles)

FTP NOx                   .0622
HFET NOx                  .5553

Portland Element II
(1975-1977 Vehicles)

FTP NOx                   .4480
HFET NOx                  .9076

Eugene Sample
(1972-1974 Vehicles)

FTP NOx                   .8758
HFET NOx                  .9540

Eugene Sample
(1975-1977 Vehicles)

FTP NOx                   .6537
HFET NOx                  .8963
.0702
.7773
.5678
.0001
.3618
.0026
.0695
.1206
.0075
.0017
.0594
.0000
.1017
.0002
.8231
.0015
.5480
.0310
.0104
.0190
.3910
.2371
.0023
.9346
.0122
.7325
.1745
.0274
.0249
.9208
* A value of .05 or less indicates a significant difference between the samples.

-------