&EPA
United States
Environmental Protection
Agency
Office of Air
and Radiation
Washington, DC 20460
February 1993
EPA 420-R-93-001
Motor Vehicle
Tampering Survey
1990
Printed on Recycled Paper
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CONTE1STS
EXECUTIVE SUMMARY. 1
Introduction ; 1
Conclusions 2
BACKGROUND „ 5
SURVEY METHODS 6
Site Descriptions 7
RESULTS , 12
Vehicle Tampering 12
Site and Aggregate Totals 12
~— — ^DO^ O [[[*-.
Types of Tampering 14
Vehicle Characteristics and Tampering 17
Manufacturer 17
Vehicle Type 18
Vehicle Age 20
Impact of I/M and Antitampering Programs 21
Tampering Trends for Selected Sites 23
Correlation Between Tampering and Idle Emissions 31
Fuel Switching 33
Fuel Switching Indicators and Overlap 33
Fuel Switching Trends 36
Fuel Switching by Vehicle Type 38
Fuel Switching and Catalyst Tampering 38
Gasoline Lead Concentrations 40
APPENDIXES
A. Relevant Portions of Clean Air Act .42
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FIGURES
1. Tampering rates for selected components by program type 3
2. (a) Overall tampering by vehicle age for vehicles not covered
by I/M and/or antitampering programs, 4
(b) Comparison of catalyst tampering by vehicle age between
vehicles covered and not covered by a catalyst inspection program 4
3. Breakdown of surveyed vehicles by condition and extent of tampering 12
4. Vehicle Manufacturers and Tampering.................................. ... .... . 17
5. Classification of 1990 survey sites by program type (and model year
coverage), with the resulting tampering and fuel switching rates for
each program type .22
6. (a)-(f) Comparisons of component-specific tampering rates by model
year among vehicles covered and not covered by ATPs 27 - 29
(a) Catalytic Converter .27
(b) Inlet Restrictor .27
(c) Air Pump System .28
(d) Evaporative System 28
(e) PCV System 29
(0 EGR System 29
7. Comparison of component-specific tampering rates among vehicles
both covered and not covered by ATPs (summary of Figures 6(a)-(f)) 30
8. Distribution of unleaded vehicles surveyed among tampering, misfueling,
and idle test categories 31
9. (a) Overlap of fuel switching indicators among misfueled vehicles
for which all three indicators were inspected 35
(b) Breakdown of misfueled vehicles in 9(a) by prevalence of each
indicator combination 35
10. (a) Overlap of indicators used by ATPs to detect missing/damaged catalysts.
Only includes vehicles for which all three indicators were inspected and are
not covered by an ATP with plumbtesmo testing 39
(b) Breakdown of vehicles in 10(a) by prevalence of each indicator combination 39
11. Distribution of lead concentrations in leaded fuel sampled from fuel switched
vehicles: 1984 • 90. Percentages based on all fuel switched vehicles, including
those using unleaded fuel (<0.05 gpg.) 41
-ii-
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TABLES
1. 1990 Tampering Survey Summary - Light-Duty Vehicles only 13
2. Prevalence of Tampering by Component 14
.3. Component-Specific Tampering Rates (%) by Survey Location 15
4. Condition of Gasoline Tank Cap by Survey Site 16
5. Tampering Percentage (and Sample Size) by Model Year
and Vehicle Age at Time of Survey 19
6. Percentage of Catalyst Removal (and Sample Size) among
Catalyst-Equipped Vehicles by Model Year and Vehicle Age
at Time of Survey 19
7. Comparison of 1990 Survey Sample to Actual Nationwide
Vehicle Fleet 23
8. Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs in ATP-only Areas
Surveyed between 1984 -1990 25
9. Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs in I/M + ATP Areas
Surveyed between 1984 -1990 26
10. Idle Test Failure Rates (Percent) by Pollutant and
Vehicle Condition 32
11. Mean Idle Emissions for Tampered and Okay Vehicles
Within Each Program Type 33
12. Fuel Switching Rates among Unleaded Vehicles by Site
and Indicator 36
13. Combined Tampering and Fuel Switching Rates 37
14. Prevalence of Fuel Switching Indicators by Program Type 38
15. Prevalence of Fuel Switching Indicators by Vehicle Type 38
-III-
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EXECUTIVE SUMMARY
INTRODUCTION
Under the direction of the Field Operations and Support Division (FOSD) of the
Environmental Protection Agency (EPA), contract personnel from Colorado State
University (CSU) conducted a survey of light-duty motor vehicle tampering in 14 cities
between March and August, 1990. The areas surveyed and the total number of vehicles
inspected are listed below.
Beaumont, TX 500 Boston, MA 611
Covington, KY 610 Gary, IN 536
Greensboro, NC 570 Houston, TX 580
Huntington,WV 600 Knoxville,TN 575
Lexington, KY 610 Louisville, KY 951
Miami, FL 500 Raleigh, NC 525
Santa Barbara, CA 542 Tampa, FL 500
TOTAL 8,210 vehicles
The objectives of this survey were:
1. To make local measurements of the types and extent of tampering and fuel
switching.
2. To extend and update the knowledge gained from earlier surveys on:
a. The effect of vehicle inspection and maintenance (I/M) programs and
antitampering programs (ATPs) on tampering and fuel switching.
b. The relationship between tampering and vehicle idle emissions.
c. The distribution of tampering by vehicle age, type, manufacturer, and
other variables of interest.
To achieve these objectives, the inspection teams visually examined emission
control devices and measured the idle hydrocarbon (HC) and carbon monoxide (CO)
emissions of each vehicle. To provide information on fuel switching, the inspectors
sampled gasoline from the tanks of vehicles (for later laboratory lead analysis), tested
for lead deposits in tailpipes using Plumbtesmo®1 test paper, and checked the integrity
of the fuel tank filler inlet restrictors. Four categories were used to summarize the
condition of the inspected vehicles:
1. Tampered - at least one control device removed or rendered inoperative
2. Arguably Tampered • possible but not clear-cut tampering (i.e., may have
resulted from either tampering or malmaintenance)
3. Malfunctioning
4. Okay - all control devices present and apparently operating properly
Plumbtesmo is a registered trademark, and hereafter appears without the " ". It is manufactured by
Machery-Nagel, Duren, W. Germany, and is marketed by Gallard-Schlesinger Chemical Corp., Carle Place, New
York.
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Motor Vehicle Tampering Survey -1990 Page 2
CONCLUSIONS
These brief but thorough inspections were performed with the consent of the
vehicle owners in a variety of settings more fully detailed elsewhere in this report.
Site selection in these tampering surveys, especially more recent surveys, has
revolved more about the general objective of examining control program effectiveness
than that of tracking national prevalence of tampering. Thus the composition of the
survey sample by program type cannot be expected to match that of the national vehicle
population. This report will refrain from comparing the overall 1990 survey results with
those of prior surveys.
Tampering among vehicles not covered by I/M and/or anti-tampering programs
was 18%, compared to 15%, 16%, and 17% for those vehicles covered by I/M + ATP,
I/M-only, and ATP-only, respectively. Such comparisons between program categories
should be made carefully, since some of the control programs cover only newer model
years of vehicles, which historically have lower tampering rates than the older vehicles
not covered by the control programs. The I/M-only and ATP-only rates, for example,
are heavily weighted with programs inspecting 1979 and newer vehicles only.
Because of the large variation in program types and coverages, the vehicles are
classified based on the program restrictions within each site. In Covington, KY, for
example, only the 1980 and newer vehicles are covered by the area's antitampering
program; the 1975-1979 vehicles are thus classified as "non-I/M".
The 1988 and 1989 tampering survey reports noted a disparity in the effectiveness
of control programs to reduce certain kinds of tampering. In particular, tampering with
underhood components was less likely to be corrected by a control program than removal
of a catalytic converter. While this conclusion was generally true in 1990 as well,
Raleigh's control program was fairly effective in reducing PCV and EGR system
tampering (although air pump tampering rates went up slightly among vehicles covered
by the Raleigh program). These results and others will be discussed more thoroughly
later in this report.
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Motor Vehicle Tampering Survey -1990
Page3
Fuel-Related Tampering
The prevalence of vehicles with missing or damaged catalytic converters within each
program type is depicted in Figure 1. A vehicle can be considered to have a missing or
inoperative catalyst if the converter has been removed, the inlet restrictor is tampered, or
the plumbtesmo test is positive. (These three criteria are used by many antitampering
programs.) A missing or damaged converter can increase HC and CO emissions by an
average of 475% and 425%, respectively2. For vehicles equipped with three-way con-
verters, substantial increases in NOx emissions would also be expected. In addition,
converter tampering on trucks was found to be slightly greater than on automobiles (4%
vs. 5%).
Fuel switching, defined as the presence of any of three specific indicators3, was found
in 4% of the unleaded vehicles not covered by I/M and/or ATPs in the 1990 survey. Fuel
switching among vehicles in I/M + ATP, ATP-only, and I/M-only areas was 1%, 1% and
4%, respectively. The very low incidence of positive plumbtesmo can be attributed to low
availability of leaded gasoline. The pattern of overlap among the three misfueling in-
dicators is discussed in detail later in this report. While the emissions impact of fuel
switching depends upon its duration and certain vehicle characteristics, emission increases
of 475% for HC and 425% for CO can easily occur.
Component
Catalytic Converter
Inlet Restrictor
Positive Phonbtesmo
0%
0%
0%
0%
non-I/M
I/M-only
ATP-only
I/M + ATP
Tampering (%)
Figure 1. Tampering rates for selected components by program
The emissions increases mentioned in this report are from a study of three-way catalyst-equipped vehicles
presented in Anti-Tampgrinpand Anti-Misfuelinp Propams tn Reduce In-Use Rmissinns from Motor Vehicle
EPA-AA-TTS-83-10, December 31,1983.
The three fuel switching indicators are: a tampered fuel filler inlet restrictor, a positive Plumbtesmo tailpipe test,
or a gasoline lead concentration of more than 0.05 gram per gallon.
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Motor Vehicle Tampering Survey • 1990
Page 4
Catalvst Thnmerin£ and Vehicle Ac
The probability that a vehicle has been tampered with is clearly related to its age,
as has been shown in previous surveys. This is evident in Figure 2(a), which depicts
vehicles not covered by I/M and/or antitampering programs. Figure 2(b) compares the
impact of vehicle age on catalyst tampering among vehicles covered and not covered by
converter inspection programs. Overall, converter tampering is much lower on vehicles
covered by converter inspection programs than on vehicles not covered by such programs
(2% vs. 5%), and the effectiveness of inspection programs is particularly noticeable
among the oldest vehicles surveyed (vehicles that are most likely to be tampered with).
Overall Tampering (%)
70
60
50
40
30
20
10
0
1
Catalyst Tampering (%)
70
6 7 8 9 10
Vehicle Age (years)
to)
11 12
60
50
40
30
20
10
0
6 7 8 9 10
Vehicle Age (years)
(b)
Figure 2(a). Overall tampering by vehicle age for vehicles not covered
by I/M and/or antitampering programs.
2(bi. Comparison of catalyst tampering by vehicle age between
vehicles covered and not covered by a catalyst inspection
program.
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Motor Vehicle Tampering Survey -1990 Page 5
BACKGROUND
EPA estimates that highway motor vehicle emissions nationwide account for 50%
of the total carbon monoxide (CO), 28% of the airborne lead, 27% of the non-methane
volatile organic compounds, and 29% of the oxides of nitrogen (NOx) emitted into the
atmosphere4. As a result, a major focus of the nation's efforts to achieve compliance with
clean air standards has been the control of emissions from mobile sources. The first
pollution control devices were installed on vehicles in 1962, and most light-duty vehicles
manufactured since 1968 have been equipped with a variety of emission control devices
to meet required emissions standards.
The 1977 amendments to the Clean Air Act (sections 203(a)(3)(A) and (B), found
in Appendix A) make it illegal for automobile dealers, repair and service facilities, and
fleet operators to disconnect or render inoperative emission control devices or elements
of design. Regulations issued under section 211(c) of the Act (40 CFR Part 80) prohibit
retailers and wholesale purchaser-consumers from introducing or allowing the introduc-
tion of leaded gasoline into vehicles labeled "unleaded gasoline only". The 1990 amend-
ments to the Clean Air Act, effective November IS, 1990, prohibit any person from
tampering with emission control devices and from introducing leaded gasoline into
unleaded vehicles. The EPA's Field Operations and Support Division (FOSD), part of
the Office of Mobile Sources (OMS), is responsible for enforcing the tampering and
misfueling provisions of the Act.
Before 1978, the EPA had data suggesting that tampering with emission control
devices and misfueling of "unleaded only" vehicles with leaded gasoline were occurring.
Variability in the inspection procedures, however, prevented an accurate assessment of
fee nature and extent of the tampering. As a result, the Agency began conducting
'., ionwide tampering surveys of light-duty motor vehicles in 1978 to determine the rates
;: a types of tampering and fuel switching. These annual surveys have been conducted
• Afaer by FOSD directly or by EPA's National Enforcement Investigations Center
(NEIC) under the direction of FOSD. Consistent inspection procedures were used
throughout these surveys to permit comparisons and identification of trends.
The uses for the tampering surveys have evolved since the first survey was con-
ducted in 1978. Since 1983, the tampering survey results for some locations have been
used to calculate credits for State Implementation Plans (SIPs), the measures taken by
State and local governments to achieve ambient air quality standards by reducing mobile
source emissions. Data from the surveys is also used in the default data base for the
Agency's mobile source computer model (MOBDLE4.1) to estimate both the emissions
loading impact and the reductions that may be achieved by various control programs.
Comparing survey results before and after implementation of a control program is an
excellent method for evaluating program effectiveness. Sites for the surveys are chosen
in light of the need for data on specific areas either currently operating or considering
programs, as well as the continuing need to monitor the types and extent of tampering
and fuel switching nationwide.
National Air Pollutant Emission Estimates. 194Q.199Q. EPA-450/4-91-026, November, 1991.
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Motor Vehicle Tampering Survey -1990 Page 6
SURVEY METHODS
The 1990 tampering survey was conducted for FOSD by the National Center for
Vehicle Emissions Control and Safety at Colorado State University (CSU). Ap-
proximately 400 to 600 vehicles were inspected in each of 14 cities between March and
August, 1990. The entire survey included 8,210 vehicles. The mix of vehicles inspected
was assumed to be a self-weighting sample, and no attempt was made to force the sample
into matching the national vehicle mix.
Each inspection team consisted of at least four members: three CSU personnel,
one or two EPA representatives, and frequently a State or local agency representative.
The CSU personnel, assisted by the State or local person, performed the actual inspec-
tions, while the EPA representative(s) monitored the survey. Each vehicle inspection
included the following:
1. Basic vehicle identification data recorded (year, make, model);
2. All emission control systems checked;
3. Idle HC, CO, COj, and Ch emissions measured;
4. Fuel sample collected for lead analysis at selected sites;
5. Tailpipe tested for lead deposits using Plumbtesmo test paper; and
6. Integrity of fuel inlet restrictor checked.
A four-gas analyzer is used to record idle CCh and Ch emissions in addition to
the HC and CO emissions. Heavy-duty gasoline-powered vehicles were inspected in
addition to the light-duty cars and trucks. The results from the heavy-duty trucks will be
discussed separately in this report, and, except where noted, were not used to calculate
any tampering or fuel switching rates. The inspections and recording procedures are
fully detailed in Appendix B.
The survey data base has been reviewed by CSU and EPA to ensure its accuracy,
and has been offered to the major automotive manufacturers to review the classification
and reporting of their respective vehicles.
The tampering survey included only 1975 and newer light-duty cars and trucks
fueled with gasoline, as well as gasoline powered heavy-duty trucks at selected sites. For
the purposes of the tampering surveys, a vehicle is considered to be "unleaded" if a dash
label, tank label, or filler inlet restrictor is observed at the time of the inspection, or if
the emission control label indicates an unleaded fuel requirement (i.e., catalyst-
equipped). A vehicle's designation as "unleaded" or "leaded" may be changed upon
subsequent review of the data. Fuel switching rates are thus based only on the population
of unleaded vehicles surveyed. Similarly, tampering rates for specific components are
based only on the vehicles originally equipped with the component.
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Motor Vehicle Tampering Survey -1990 Page 7
The inspections were performed with the consent of the vehicle owners at either
roadside pullovers or inspection stations. The survey was designed to minimize the
refusal rate of potential survey participants. A high refusal rate increases the uncertainty
in analyzing the data gathered, since individuals who have tampered with or misfueled
their vehicles are less likely to allow their vehicles to be surveyed. The overall refusal
rate was very low (1%), however, and none of the survey sites had a refusal rate over 3%.
A brief description of each survey site follows. Unless otherwise noted, the survey
locations within a given city were changed daily.
Site Descriptions
Santa Barbara, CA
Non-I/M
Dates: March 19-23,1990
Vehicles Surveyed: 543
Fuel Samples: none
Refusal Rate: < 1%
Roadside pullovers in Santa Barbara were conducted with the assistance of the
California Highway Patrol, California Air Resources Board, and the Bureau of Automo-
tive Repair.
Houston, TX
ATP-only
Dates: April 2-6,1990
Vehicles Surveyed: 580
Fuel Samples: none
Refusal Rate: 1%
The decentralized annual tampering inspection program covers vehicle model
years 1968 and newer. The tampering inspection includes a check of PCV, evaporative
canister, EGR, and air system. 1980 and newer vehicles are also checked for catalyst,
inlet restrictor and plumbtesmo.
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Motor Vehicle Tampering Survey -1990 Page 8
Beaumont, TX
Non-I/M
Dates: April 9-13,1990
Vehicles Surveyed: 500
Fuel Samples: 378
Refusal Rate: 3%
The Texas Department of Public Safety provided assistance with the roadside
pullovers.
Tampa, FL
Non-I/M
Dates: April 16-20,1990
Vehicles Surveyed: 500
Fuel Samples: 331
Refusal Rate: 0%
While not classified as an ATP area, the state performs a 1% roadside/fleet
tampering check of all components plus Plumbtesmo test on 1975 and newer vehicles.
The Florida State Police assisted with the roadside pullovers.
Miami, FL
Non-I/M
Dates: April 23-27,1990
Vehicles Surveyed: 500
Fuel Samples: 324
Refusal Rate: 1%
While not classified as an ATP area, the state performs a 1% roadside/fleet
tampering check of all components plus Plumbtesmo test on the last 10 model years.
The Florida State Police assisted with the roadside pullovers.
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Motor Vehicle Tampering Survey -1990 Page 9
Raleigh, NC
I/M + ATP
Dates: May 7-11,1990
Vehicles Surveyed: 525
Fuel Samples: none
Refusal Rate: < 1%
Roadside pullovers were conducted with the assistance of local law enforcement
officials. Raleigh has a decentralized annual I/M inspection of the last 12 model years.
Program includes a tampering check for EGR, PCV, air system, catalyst, and inlet
restrictor.
Greensboro, NC
Non-I/M
Dates: May 14-18,1990
Vehicles Surveyed: 570
Fuel Samples: 362
Refusal Rate: 3%
Roadside pullovers were conducted with the assistance of local law enforcement
officials.
Knoxville,TN
Non-I/M
Dates: May 22-25,1990
Vehicles Surveyed: 575
Fuel Samples: 44
Refusal Rate: < 1%
Roadside pullovers were conducted with the assistance of local law enforcement
officials.
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Motor Vehicle Tampering Survey -1990 Page 10
Huntington,WV
Non-I/M
Dates: June 4-8,1990
Vehicles Surveyed: 600
Fuel Samples: none
Refusal Rate: < 1%
Roadside pullovers were conducted with the assistance of local law enforcement
officials.
Lexington, KY
Non-I/M
Dates: June 11-15,1990
Vehicles Surveyed: 610
Fuel Samples: none
Refusal Rate: 2%
Roadside pullovers were conducted with the assistance of local law enforcement
officials.
Louisville, KY
I/M-only
Dates: July 10-13,17-20,1990
Vehicles Surveyed: 951
Fuel Samples: none
Refusal Rate: 1%
Jefferson County has a centralized annual I/M inspection of all model years with
vehicle weight up to 10,000 Ibs. The Louisville survey was conducted at the city's
centralized inspection stations.
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Motor Vehicle Tampering Survey -1990 Page 11
Covington, KY
ATP-only
Dates: July 23-27,1990
Vehicles Surveyed: 610
Fuel Samples: none
Refusal Rate: < 1%
For the counties of Boone, Campbell and Kenton, the decentralized annual
program inspects 1980 and newer vehicles up to 8,500 Ibs. for tampering of all com-
ponents. Roadside pullovers were conducted with the assistance of local police officials.
Gary, IN
I/M + ATP
Dates: June 18-22,1990
Vehicles Surveyed: 536
Fuel Samples: none
Refusal Rate: < 1%
Roadside pullovers were conducted with the assistance of local law enforcement
officials. Gary's program is a part of the Chicago Suburb area and the program is a
centralized, biennial, registration enforced inspection. A tampering check is made for
catalyst, inlet restrictor and gas cap.
Boston, MA
I/M + ATP
Dates: August 6-9,1990
Vehicles Surveyed: 611
Fuel Samples: none
Refusal Rate: 1%
Roadside pullovers were conducted with the assistance of local law enforcement
officials. There is a statewide decentralized program with a visual tampering inspection
for catalysts and inlet restrictors on 1980 and newer vehicles. A catalyst refit is required
only if the catalyst is missing.
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Motor Vehicle Tampering Survey -1990
Page 12
RESULTS
A. VEHICLE TAMPERING
1. Site and Aggregate Thtak
The vehicles surveyed have been classified into four categories established by
previous surveys: tampered, arguably tampered, malfunctioning, and okay. Each vehicle
was classified by the worst state of any component in the vehicle. For example, a vehicle
would be classified as "tampered" if any one component had been tampered, even if all
other components were functioning properly. A vehicle classified as "okay" must have
all observed components functioning properly5. The criteria used for component clas-
sification are presented in Appendix B. This overall tampering rate is useful only as a
rough indicator of the emissions impact of a tampering problem, since the different
components making up the rate may have widely varying emissions implications.
The proportion of inspected vehicles with at least one tampered component was
17%. Approximately a third of the surveyed vehicles displayed some form of malfunc-
tion, arguable tampering, or clear tampering of emission control components. The
specific distribution of surveyed vehicles among these categories is depicted in Figure
3.
The frequency distribution of tampering instances for those vehicles classified as
"tampered" is also shown in Figure 3. Forty-three percent of the tampered vehicles had
multiple components tampered, and 13% had four or more instances of tampering.
Malfunctioning (456)
MH J
lamperoa
i« * • ^
Okty (70%)
Tampered (17%)
Four or more (13%)
Three (12%)
Two (18%)
One (57%)
Condition of
Surveyed Vehicles
Number of Tampered
Components
Figure 3. Breakdown of ffuri"Tfil vehicles by fffnJMnn »nA extent of tamp*™^,
5 An "okay" vehicle, however, may still be classified as fuel switched (see section B.I., Fuel Switchin
and Overlap of this report).
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Motor Vehicle Tampering Survey-1990
Page 13
TABLE 1
1990 Tampering Survey Summary - Light-Duty Vehicles
Number of Tampering Misfueling Survey
Survey Location Vehicles Rate(%) Rate(%) Type*
Santa Barbara, CA
Houston, TX
Beaumont, TX
Tampa, FL
Miami, FL
Raleigh, NC
Greensboro, NC
Knoxville, TN
Huntington, WV
Gary, IN
Lexington, KY
Louisville, KY
Covington, KY
Boston, MA
OVERALL
*R = roadside pullovers,
542
580
500
500
500
525
570
575
600
536
610
951
610
611
8210
C =
11
24
16
19
17
15
16
18
22
19
20
16
16
12
17
centralized
3
5
4
6
3
3
4
6
5
2
4
4
5
1
4
inspection stations,
R
R
R
R
R
R
R
R
R
R
R
C
R
R
only
Refusal
Rate (%)
<1
1
3
0
1
<1
3
<1
<1
<1
2
1
<1
1
1
Table 1 summarizes the 1990 survey data by site for the light-duty vehicles surveyed.
As in previous surveys, the overall tampering in 1990 varied considerably from site to
site. This can be attributed to the variety of program configurations among the cities
surveyed and to geographic differences.
Table 1 also contains the refusal rate at each survey site. The overall refusal rate
for the survey was very low (1%), and none of the survey sites had a refusal rate exceeding
3%.
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Motor Vehicle Tampering Survey -1990
Page 14
2. TVnesof Tiunneriiu?
The tampering rates for all emission control components and systems surveyed in
1990 are presented in Table 2. The component-specific tampering rates for the 1990
survey are presented by survey site in lable 3. Only those vehicles originally equipped
with a particular component are considered when computing the tampering rate for that
component. The site-specific tampering rates listed in Tables 1 and 3 are for all light-duty
vehicles surveyed at each location, including out-of-state vehicles and other vehicles
possibly not covered by any local inspection program. The tampering rates for only
vehicles covered by local control programs will be examined later in this report.
TABLE2
Prevalence of Tampering by Component
Component/System Tampering Rate (%)
Catalytic Converter 4
Inlet Restrictor 4
Air Pump System 12
Air Pump Belt 10
Air Pump/Valve 8
Aspirator* 3
PCV System 5
Evaporative System 6
EGR System 8
Heated Air Intake 2
Oxygen Sensor and 1
Computer System
* Vehicles with aspirated air systems are not equipped with
other listed air-injection components, nor do conventional
systems include aspirators.
Table 2 shows that air pump system tampering remains the single most tampered
component (12% of equipped vehicles). Tampering with evaporative systems also shows
no evidence of subsiding. Also of interest is die slight but measurable tampering found
with the oxygen sensor and computer control system. Because of the difficulty in
inspecting the oxygen sensors (no determination could be made on 93 vehicles), the one
percent rate reported is a conservative estimate. Oxygen sensor tampering is of consid-
erable interest because of the dramatic emissions increases which result from its disable-
ment - an average increase of 445% for HC and 1,242% for CO.6
Antitampertng ai}d Anti-Misfueling Progra^ns to
EPA-AA-TTS-83-10, December 31, 1983.
I-Use PmJssiQflgfrppi Mnr Vehicle
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Motor Vehicle Tampering Survey -1990
Page 15
Table 3 shows the wide variation in tampering from site to site for any given
component. Air pump system tampering, for example, ranged from 6% in Beaumont to
21% in Huntington. This range is partly due to the effectiveness of I/M and antitamper-
ing programs (as will be discussed later in this report), geographic location, age of
vehicle population, and socioeconomic differences between these areas.
TABLE 3
Component-Specific Tampering Rates (%) by Survey Location*
Survey Catalytic
Location Converter
Santa Barbara, CA
Houston, TX
Beaumont, TX
Tampa, FL
Miami, FL
Raleigh, NC
Greensboro, NC
Knoxville, TN
Huntington, WV
Gary, IN
Lexington, KY
Louisville, KY
Covington,KY
Boston, MA
OVERALL
1
5
4
5
4
2
3
6
8
3
6
3
5
1
4
Inlet
Restricter
3
5
4
6
2
3
4
6
5
2
4
4
4
1
4
Air Pump
System
10
18
6
8
14
9
15
17
21
12
15
9
11
10
12
PCV
System
2
7
4
4
5
3
3
4
6
6
6
4
5
3
5
EGR
System
4
13
7
7
8
5
6
10
10
7
10
8
7
5
8
Evap. Any
System Component
3
11
6
7
6
8
5
6
7
7
7
5
6
4
6
11
24
16
19
17
15
16
18
22
19
20
16
16
12
17
* Includes any out-of-state vehicles or non-covered light-duty vehicles surveyed within the program area (if
applicable).
-------
Motor Vehicle Tampering Survey -1990
Page 16
Table 4 shows the condition of the gas tank cap among surveyed light-duty vehicles
by survey location. Although -a missing or malfunctioning tank cap is not classified as
tampering, the emissions impact of a missing cap nonetheless is substantial. A missing
or malfunctioning gas cap can completely negate an otherwise properly functioning
evaporative system, causing large increases in evaporative HC emissions. The mal-
functioning rate among non-stock gas tank caps was considerably higher than among
stock gas tank caps (3% vs. 0%).
TABLE 4
Condition of Gasoline Tank Cap by Survey Site
Malfunctioning
Survey Location lank Cap (%)
Santa Barbara, CA
Houston, TX
Beaumont, TX
Tampa, FL
Miami, FL
Raleigh, NC
Greensboro, NC
Knoxville, TN
Huntington, WV
Gary, IN
Lexington, KY
Louisville, KY
Covington, KY
Boston, MA
OVERALL
1
1
1
0
1
1
1
1
1
1
0
1
0
0
1
Missing Tank Missing or
Cap(%) Malfunctioning (%)
1
3
1
1
1
1
1
0
1
2
1
1
0
0
1
2
4
2
1
2
2
2
1
2
2
2
1
1
0
2
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Motor Vehicle Tampering Survey -1990
Page 17
3. ^fehide Chararteristi'** «nd Thmnprino
The next section of this report investigates the interrelationship between tamper-
ing and three vehicle characteristics: manufacturer, vehicle type (car or truck), and age.
Manufacturer. Figure 4 presents the 1990 tampering rates for each major
manufacturer. The smaller foreign manufacturers have been combined into two groups,
European and Other Asian. Vehicle tampering was higher among vehicles of domestic
manufacture than among those of foreign manufacture. Overall, tampering with domes-
tically manufactured vehicles was three times that found for the foreign manufactured
vehicles (21% vs. 7%).
Honda
Figure 4. Vehicle Manufacturers and Tampering
-------
Motor Vehicle Tampering Survey • 1990 Page 18
A number of factors might explain the difference in tampering prevalence among
manufacturers. Differences in design may make some vehicles more tamper-prone than
others. Changing market share history results in different age distributions for vehicles
of different makes, and vehicle age is clearly related to tampering prevalence. Tampering
rates seem to vary with geographic location and socioeconomic background, so the
owner demographics for different makes may affect the likelihood of tampering.
Vehicle Type. The overall tampering prevalence for light-duty trucks (LDTs)
was 16%, compared to 18% for automobiles (LDVs). Since the 1986 tampering survey,
the tampering rates for cars and trucks have basically been the same, and the discrepancy
between car and truck tampering decreased steadily in surveys prior to 1986. While the
overall tampering rate is less meaningful than the rates for individual components, even
the component-specific truck rates tend to be similiar to the automobile rates. Catalytic
converter tampering, for example, was only slightly higher for trucks than for cars (5%
vs. 4%).
Heavy-duty gasoline-powered trucks (HDTs) were also surveyed at selected sites
in the 1990 survey. Of the 102 HDTs surveyed, nearly one-third (30%) had one or more
components tampered. This high tampering rate is largely attributable to the skewed
model year distribution of the HDTs surveyed, since 42% of the HDTs surveyed were
manufactured in 1979 or earlier. By comparison, the overall tampering rate for 1979 and
older light-duty trucks was even higher (78%). This suggests that vehicle age has a much
greater effect on tampering prevalence than vehicle type. Heavy-duty tampering may
increase in significance as the prevalence of catalyst-equipped HDTs increases.
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Motor Vehicle Tampering Survey -1990
Page 19
TableS _••
Tampering Percentage (and Sample Size) by Model Year and Vehicle Age at Time of Survey
Model
Year 1st
1990 0(528)
1989 0(444)
1988 1(524)
1987 1(627)
1986 1(757)
1985 2(816)
1984 1(462)
1983 7(182)
1982 1(250)
1981 2(57)
1980
1979 6(371)
1978 7(298)
1977
1976
1975
1974
1973
1(1023)
1(794)
1(832)
2(1058)
3(1130)
2(1001)
4(471)
4(226)
7(448)
5(63)
14(502)
10(457)
Year of Vehicle Life
2nd3id4th5jh6ih2thSUi2th Ifth nth 12th 13th 14th 15th
2(996)
3(741)
3(915)
3(972)
5(1018)
6(710)
7(466)
13(206)
9(454)
9(59)
15(476)
18(395)
2(867)
4(758)
6(855)
7(908)
7(706)
9(621)
15(458)
15(211)
18(477)
15(79)
19(374)
22(274)
8(859)
7(779)
8(765)
10(633)
11(574)
11(607)
18(516)
31(288)
21(430)
21(66)
22(271)
33(276)
11(801)
13(681)
15(532)
19(525)
19(560)
25(564)
28(503)
39(238)
26(316)
29(52)
27(242)
32(253)
17(689)
12(414) 24(442)
21(506) 25(414) 35(375)
26(501) 34(479) 28(384) 41(337)
25(556) 28(472) 32(419) 37(351) 53(299)
37(673) 36(699) 42(555) 44(464) 46(416) 58(317)
34(559) 37(562) 50(548) 49(443) 55(404) 54(318) 60(249)
44(190) 41(408) 48(452) 48(465) 49(356) 54(265) 57(250) 65(190)
26(317) 40(171) 39(385) 49(369) 53(318) 60(219) 61(179) 56(162) 62(85)
32(22) 37(183) 55(89) 46(197) 54(194) 60(198) 65(103) 62(113) 66(83)
36(251)
Table 6
Percentage of Catalyst Removal (and Sample Size) among Catalyst-Equipped Vehicles by Model Year
and Vehicle Age at Time of Survey
Year of Vehicle Life
Model
Year 1st
1990 0(524)
1989 0(444)
1988 0(521)
1987 0(627)
1986 0(757)
1985 0(808)
1984 0(462)
1983 1(179)
1982 0(250)
1981 0(57)
1980
1979 0(326)
1978 0(291)
1977
1976
1975
loth nth 12th 13th 14th 15th
0(1005)
0(794)
0(810)
0(1058)
1(1128)
0(978)
2(471)
1(225)
2(441)
2(61)
0(445)
1(417)
0(960)
0(741)
0(887)
0(972)
1(1018)
0(686)
2(465)
5(204)
2(428)
4(55)
1(417)
2(377)
0(824)
0(758) 0(822)
1(818) 1(779)
1(908) 1(726)
1(706) 1(633)
2(597) 1(574)
6(457) 3(567)
3(200) 6(487)
6(429) 12(252)
0(71) 4(362)
2(59)
2(305)
2(242) 2(204)
1(743)
1(680)
2(505)
3(525)
5(552)
6(522)
10(455)
8(213)
2(271)
10(48)
2(644)
2(414) 5(409)
3(466) 5(414) 9(340)
7(499) 9(421) 7(378) 12(302)
7(528) 8(440) 9(346) 9(332) 15(266)
12(572) 12(638) 13(505) 13(376) 13(383) 20(275)
8(486) 10(472) 10(466) 15(394) 13(312) 17(277) 23(211)
11(166) 14(357) 17(379) 19(409) 11(320) 19(212) 17(221) 28(159)
6(257) 12(139) 12(314) 15(291) 20(276) 19(184) 15(137) 24(135) 31(67)
26(19) 12(139) 23(75) 16(174) 21(130) 23(167) 25(77) 14(72) 30(63)
-------
Motor Vehicle Tampering Survey -1990 Page 20
Vehicle Age. Table 5 relates vehicle age and model year with tampering
prevalence for the 1978-1990 surveys. Catalytic converter removal rates are similarly
related to vehicle age and model year in Table 6. The results from any given survey are
entered diagonally in each table.
The results in Tables 5 and 6 indicate that vehicle tampering increases directly with
vehicle age. Examining Table 5 diagonally (by survey) shows that tampering increases
consistently with vehicle age in each survey conducted. In the 1990 survey, for example,
the tampering rate increases from 0% for first year (1990) vehicles to 62% among the
1976 model year vehicles surveyed.
Table 6 shows a similar, though less pronounced, increase in catalyst removal. The
catalyst tampering rate remains negligible for the first six years of a vehicle's life, and
then increases thereafter. This delay in catalyst tampering is understandable, since the
emission control components on all new vehicles are warranted for 5 years/50,000 miles
by the manufacturer, providing an incentive to maintain the catalysts on vehicles still
under warranty. A similar delay in overall tampering is less apparent in Table 5, but
becomes more evident when only non-I/M vehicles are examined (Figure 2(a)). Examin-
ing these tables in this manner has the advantage of comparing data collected during one
survey in one set of locations, but ignores the possible effects of model year differences
(i.e., technology), geography, or program coverage on tampering.
Two additional ways of analyzing Tables 5 and 6 address the impact of model year
on tampering rates. Analyzing these Tables horizontally (holding the model year con-
stant) provides a look at the tampering rates over time for the vehicles of a particular
model year. This approach shows the same distinct increase in tampering with vehicle
age for all model years since 1975. (The 1974 and 1973 data sets are too small to permit
any conclusions.)
Tables 5 and 6 can also be examined vertically (holding vehicle age constant),
which provides a look at the tampering rates for different model year vehicles of the same
age. This approach permits a crude examination of trends in tampering adjusted for
vehicle age. Examining Table 5 vertically, for example, shows a decrease in overall
tampering from the 1978 survey to the 1990 survey for vehicles in each of their first seven
years of use. This decrease in overall tampering appears to lessen in the later years of a
vehicle's life. A similar, though less pronounced, trend is apparent in the age-specific
catalyst tampering data (Table 6).
-------
Motor Vehicle Tampering Survey -1990 Page 21
The comparisons made in the two preceding paragraphs involve observations
made in different survey locations during different years, and are affected by the site
selection in each survey. An increasing percentage of the 1981 and newer vehicles in
recent surveys have been covered by antitampering programs, which could contribute to
the lower tampering found among newer vehicles. The impact of improved technology
on tampering can be more accurately assessed by examining only vehicles from non-I/M
areas (Flgure2(a)). The data in Figure 2 (a) suggest that tampering with new technology
vehicles that are no longer covered by new car or emissions warranties (Le., post-1980
vehicles that are six to ten years old) is consistent with tampering among older technology
vehicles (pre-1981 - over ten years old).
4. Tmnact of T/M and Antitamnering Programs
Inspection and maintenance (I/M) programs require vehicles to meet specific
emission standards. Vehicles registered in areas with these programs are required to be
periodically tested to assure that they comply with the specific emission outpoints
established by these jurisdictions. In addition to reducing emission levels by stimulating
better owner maintenance, I/M programs may deter some tampering with emission
control components. Data from previous surveys has tended to support this proposition,
since tampering in I/M areas has historically been lower than in non-I/M areas.
Many local areas have also instituted antitampering programs (ATPs), which
involve periodic vehicle inspections to check the integrity of specific emission control
components. Antitampering programs vary greatly in the components inspected and the
vehicle model years covered, so that a vehicle or component which would be inspected
in one program area might not be inspected in a different program area. Successful
antitampering programs should reduce existing tampering and deter future tampering.
Classifying the survey areas into program types is made difficult by the consider-
able variation in control programs. For example, Covington's antitampering program
includes inspection of all emission control devices, but only on 1980 and newer vehicles.
In contrast, Boston's inspection program covers only the catalytic converter and the inlet
restrictor on 1980 and newer vehicles.
In order to minimize the impact of these variations in program types and model
year coverages, the vehicles in the 1990 survey can be classified by the model year
restrictions applicable in the program areas surveyed. These classifications, and the
resulting tampering rates for each program type, are shown in Figure 5. Since
Covington's antitampering program only covers 1980 and newer vehicles, for example,
only those model year vehicles are classified as "ATP-only"; the 1975-1979 vehicles
surveyed in Covington are classified as "non-I/M". This method of classification does
not take into consideration the components inspected by each program, a program's
effectiveness, or the frequency of inspection. Any comparisons between program types
(e.g.» I/M + ATP vs. non-I/M) should thus be made carefully. For example, the high
overall tampering rates in ATP-only areas inspected in 1990 can be attributed to the high
underhood tampering rates found in Houston. For a more detailed breakdown of
component tampering rates in ATP areas, see Tables 8 and 9 in this report.
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Motor Vehicle Tampering Survey -1990
Page 22
Non-I/M
Gieeosboro, NC
Huntingtan, WV
KnoxviOe, TN
Lexington, KY
Miami, PL
Tampa, PL
Santa Batfaan, CA
Raleigh, NC (1975-78)
Covingtao, KY (1975-79)
I/M + ATP
Barton, MA (1980+)
Gary, IN (1976+)
Raleigh, NC (1979+)
ATP-only
Covington, KY (1980+)
Hourtoo, TX (1968+)
I/M-onlv
Louuvilk, KY
Beaton, MA
Note: Program ooven aU model yean furvcyed union otberwiie indicated.
Ptogran Type
18%
17%
15%
Noo-I/M
I/M-ooly
ATP-only
I/M +A'
2%
Tampering (%)
Pud Switching (%)
Figure 5 Classification of 1990 survey sites by program type (and model
year coverage), with the resulting tampering and fuel switching
rates for each program type. (The fuel switching rates are
derived from a slightly different classification scheme - see the
text of this report for details.)
-------
Motor Vehicle Tampering Survey -1990
Page 23
Table 7 compares the proportion of the 1990 survey sample and the national vehicle
fleet under control programs.-While approximately 22% of the national vehicle fleet
were covered by I/M + ATP, only 17% of the survey sample represents vehicles covered
by such a program. Non-I/M vehicles are slightly overrepresented in the survey sample.
Otherwise, the 1990 survey closely approximates the portion of the national vehicle fleet
under control programs.
TABLET
Comparison of 1990 Survey Sample
to Actual Nationwide Vehicle Fleet
Percentage within Approximate Percentage
Program Type Survey Sample (%) of Nationwide Fleet (%) *
non-I/M
I/M-only
ATP-only
1/M + ATP
60
12
11
17
55
12
11
22
* From County Population Estimates! July 1, 1988.1987, and 1986, U.S.
Department of Commerce - Bureau of the Census, August, 1989.
5. Ikmoerine TVends for Selected Sites
The impact of I/M and antitampering programs in specific locations can be
examined by comparing the 1990 survey data with that from earlier surveys. Com-
parisons made between surveys widely spaced in time, however, must take into con-
sideration the differences in average vehicle age in each survey. The average odometer
reading per vehicle surveyed in 1990, for example, is over 18% greater than it was in 1984.
Since vehicle mileage correlates with vehicle age, which is directly related to tampering
prevalence, a significant increase in tampering might be expected to have occurred
between 1984 and 1990, even if all other factors remained constant (car/truck distribu-
tion, owner demographics, etc.). Inferences regarding program effects should thus be
made with this in mind.
Tables 8 and 9 present tampering data for the two ATP-only and three I/M + ATP
sites surveyed, respectively. Because of the large number of programs represented in
Tables 8 and 9, only a few representative comparisons will be discussed in this report.
Detailed analysis of each program's effectiveness is beyond the scope of this report. The
comparisons made in these lables have been limited to the specific components and
vehicle model years covered by each antitampering program actually in operation during
the 1990 survey. In some instances this reduces the sample size substantially. The
tampering data listed in Tables 8 and 9 were compiled only for surveyed vehicles included
within the local program jurisdiction.
-------
Motor Vehicle Tampering Survey -1990 Page 24
The data in Table 8 suggest that the ATP in Covington has helped lower catalyst
tampering and misfueling rates (i.e., plumbtesmo, inlet restrictor), but tampering with
underhood components has not declined appreciably. In fact, underhood component
tampering has increased slightly from earlier surveys. A similar pattern is apparent in
Table 9, where I/M + ATP programs have been generally effective in reducing catalyst
tampering and misfueling, but much less so in reducing underhood tampering.
Houston is an unusual exception in Table 8. The catalyst tampering, misfueling
rates, and underhood component rates have risen since recent surveys. Only Plumbtes-
mo has decreased and this can be attributed to the low availability of leaded gasoline in
1990.
The difference in programmatic impact on catalyst and fuel-related tampering
versus the underhood components is illustrated by Figures 6(a)-(f), where tampering
rates by model year for the major components covered by inspection programs (either
ATP-only or I/M + ATP) are compared to tampering rates for the same components on
vehicles that were not covered by inspection programs. Caution is recommended in the
comparison of older vehicle tampering rates. The sample sizes of older vehicles in this
analysis are smaller than newer vehicle sample sizes. Catalyst and inlet restrictor
tampering (Figs. 6(a) and (b), respectively) were much lower on vehicles covered by
converter and inlet inspection programs than on vehicles not covered by such inspec-
tions. Air pump system tampering (Fig. 6(c)) was slightly lower in areas with inspections
than in areas without inspections, although the rates decreased with increasing vehicle
age. Areas inspecting evaporative and PCV systems (Figs. 6(d) and (e), respectively)
had only higher tampering rates. The PCV and evaporative system rates are noteworthy
because these two systems control crankcase and evaporative HC emissions, respectively
- emissions which the catalytic converter does not control. EGR system rates (Fig. 6(1))
were higher in control areas for 1980 and older model years.
The overall rates for the data presented in Figs. 6(a)-(f) are shown in Figure 7. The
difference between program and non-program areas is less acute for evaporative, PCV
and EGR systems when vehicles are compared in the aggregate.
-------
Motor Vehicle Tampering Survey -1989
Page 25
TableS
Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs in ATP-only Areas
Surveyed between 1984 - 1990
Tamnerinff Prevalence (%} bv Survev Year
Survey Location
Component and
(Prop-am Start Date) Model Years Covered 1984
Covington, KY
(8/86)
Houston, TX
(7/84)
Catalyst
Inlet Restrictor
Pos. Plumbtesmo
PCV System
Evap. System
Air Pump System
EGR System
Catalyst
Inlet Restrictor
Pos. Plumbtesmo
PCV System
Evap. System
Air Pump System
EGR System
80+
80+
80 +
80 +
80 +
80 +
80 +
80 +
80 +
80+
75 +
75 +
75 +
1985 19S6
3
2
1
0
1
3
2
1 3
0 2
2 1
4 2
4 5
7 8
1987 1988
1
1
1
1
2
5
2
1 1
1 1
1 1
7 6
8 5
6 10
1989 1990
0
1
0
3
2
3
3
3
2
0
8
12
18
14
-------
Motor Vehicle Tampering Survey -1990 Page 26
Table 9
Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs in I/M + ATP Areas
Surveyed between 1984 • 1990
Tampering Prevalence (%^ bv Survey Year
Survey Location Component and
(Program Start Date) Model Years Covered 1984 1985 1986 1987 1988 1989 1990
Boston, MA Catalyst 80+ 1 ----- 1
(4/83) Inlet Restrictor 80+ 3 ----- 0
Gary, IN Catalyst 76+ - - - - - - 4
(6/84) Inlet Restrictor 76+ ...... 2
Raleigh, NC Catalyst 79+ - 8 - - 3 - 1
(11786) Inlet Restrictor 79+ - 11 - - 5 - 2
PCVSystem 79+ - 2 - 5 - 2
Air Pump System 79+ - 4 - - 5 - 7
EGRSystem 79+ - 4 - - 4 - 3
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Motor Vehicle Tampering Survey -1990
Page 27
Tampering (%)
40
30
20
10
Cowed by Program
Not Covered by
90
89
88
87
85
84
83
81 80
Model Year
(a) Catalytic Converter
Tampering (%)
16
14
12
10
8
6
4
2
Oovcnd by Program
NotOovemlby
Program
90 89 8887 86 85 84 83 82 81 80
Model Year
(b) Inlet Restrictor
figure 6. Comparisons of component-specific tampering rates by model
(a-f) year among vehicles both covered and not covered by ATPs.
-------
Motor Vehicle Tampering Survey -1990
Page 28
Tampering (%)
35
89
88
87
86 85 84
Model Year
(c) Air Pump System
83
82
81
80
Tampering (%)
30
90
88 87 86 85 84
Model Year
82 81 80
(d) Evaporative System
-------
Motor Vehicle Tampering Survey -1990
Page 29
Tampering (%)
40
30
20
10
CovBrao by Flognoi
tCaveni
PiQgNot
89
88
87
86 85 84
Model Year
(e)PCV System
83
82
81
80
Tampering (%)
40
30
20
10
Govcttd by Pipgrani
NotCovcndbjr
90 89 88
87
86 85 84
Model Year
(f) EGR System
83
82
81
80
-------
Motor Vehicle Tampering Survey -1990
Page 30
Component/System
Catalytic Converter
13%
Component not cvnL
by ATP inspection
Component covered
by ATT* inspection
Inlet Restrictor
Air Pump System
Evaporative System
PCV System
EGR System
Tampering (%)
Figure?. ComparisoD of oampooent-specific tampering rates among
vehicles both covered and not covered by ATPs.
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Motor Vehicle Tampering Survey-1990
Page 31
6. fVnTelarinn hetween Tltinnering and Idle Emissions
As was mentioned previously, vehicles which are subject to an I/M program must
meet specific idle emissions outpoints. To assess the relationship between tampering
and fuel switching and idle failure rates, the idle emissions from unleaded vehicles have
been tested against the outpoints established by the I/M program where they were
sampled. Vehicles in non-I/M and ATP-only areas were tested against the outpoints
specified by the New Jersey I/M program. The outpoints for each I/M area are listed in
Appendix C.
The results of the idle tests are presented in Figure 8 for vehicles in the various
tampering and fuel switching categories. The failure rates for fuel switched vehicles that
were arguably tampered with or otherwise okay are based upon very small samples and
may be unreliable. The results in Figure 8 indicate that a substantially larger proportion
of tampered and fuel switched vehicles than of okay vehicles fail an idle test at I/M
outpoints. For example, only 10% of the unleaded vehicles surveyed that were free of
tampering and fuel switching failed an idle test, while 60% of the tampered and fuel
switched vehicles failed that test. It should be noted from Figure 8, however, that 40%
of the tampered and fuel switched vehicles were still able to pass an idle test.
Entire Survey
Sample
100%
Figure 8. Distribution of unleaded vehicles surveyed among
tampering1", misfueling, and idle test categories.
'excludes malfunctioning vehicles (2% of total)
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Motor Vehicle Tampering Survey -1990
Page 32
Idle Test Failure Rates
Table 10
(Percent) by Pollutant
and Vehicle Condition
Failure Rate(%) by Pollutant for Model Years Listed
Vehicle Condition
Okay
Arguably Tampered
Tampered
Catalyst Removed
or Misfueled
1975-80 1981 +
HC CO HC CO
27 20 75
32 28 15 14
43 40 27 28
51 45 40 38
Entire Survey (1975 + )
HC CO HCorCO
85 10
19 17 26
34 34 47
47 43 61
Table 10 shows the percentage of vehicles that failed the idle emissions test for
each vehicle condition. The failure rates are listed for the entire survey, as well as in two
model year groupings representing "old" technology (1975-1980) and "new" technology
(1981 + ) vehicles. "New" technology includes closed loop emissions control, which came
into widespread usage in 1981 model year vehicles.
The overall percentage of tampered vehicles exceeding I/M cutpoints for HC
emissions was over four times that for okay vehicles (34% vs. 8%). Over six times as
many tampered vehicles exceeded CO cutpoints as did okay vehicles (34% vs. 5%). The
majority (61%) of the vehicles that either had been fuel switched or had their catalysts
removed also exceeded HC or CO limits. Conversely, 39% of the vehicles with missing
catalysts or classified as fuel switched were still able to pass an idle emissions test. A
significant number of arguably tampered vehicles also produced excess idle emissions.
The effectiveness of idle emissions testing on "new" technology vehicles can also
be seen in Table 10. The data in Table 10 actually underestimate the impact of "new"
technology because "old" technology trucks manufactured after 1980 have been included
in the "new" technology category due to the model year split. As was found in previous
surveys, idle emissions testing is more effective in identifying tampering in 1980 and older
vehicles than on 1981 and newer vehicles. For example, 40% of the tampered "old"
technology vehicles exceeded CO cutpoints compared to 28% of the tampered "new"
technology vehicles. This suggests that idle emissions testing may not be as effective a
strategy for identifying tampering and fuel switching among "new" technology vehicles,
since many vehicles with closed loop systems are able to produce low idle emissions even
with tampered emission control devices.
The mean idle emissions for tampered and okay vehicles are presented in Table
11 by program type. The classification of survey sites is the same as was described in
Figure 5, with two alterations. The data from Raleigh is listed in a separate category
(I/M (CO only)) because these programs have no HC cutpoints. The remaining I/M and
I/M + ATP sites have been combined into the "I/M" category.
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Motor Vehicle Tampering Survey -1990
Page 33
TABLE 11
Mean Idle Emissions for Tampered and Okay Vehicles Within Each
Program Type
HC emissions fnnml CO emissions (%)
Program Type
non-I/M
I/M*
I/M (CO-only)
ATP-only
Tampered Arguable
337
252
** 292
373
147
143
135
106
Okay
45
54
65
54
Tampered
2.4
1.7
L8
1.8
Arguable
1.0
0.9
12
1.1
OVERALL 323 140 49 2.1 1.0
* Includes any program where idle emissions are checked, including I/M +
areas.
••Consists of vehicles surveyed
checked.
in Raleigh, NC,
Okay
03
03
0.4
03
03
ATP
where only CO emissions are
The mean idle emissions from tampered vehicles were considerably greater than
from untampered vehicles (Table 11). Overall, HC and CO emissions from tampered
vehicles were over five times greater on average than from okay vehicles. Vehicles in
Raleigh (which doesn't have HC outpoints) had slightly higher HC and CO emissions
than the I/M and I/M + ATP areas which checked for both.
B. FUEL SWITCHING
1. Ftoel Switching Tndicatqfjt ftt^d Overlap
Fuel switching is more easily defined than measured, since no single indicator can
completely characterize its prevalence. Since 1981 the surveys have used a combination
of three indicators to measure fuel switching more accurately: a tampered fuel filler inlet
restrictor, a positive Plumbtesmo test for lead deposits in the tailpipe, and a gasoline
lead concentration of more than 0.05 gram per gallon (gpg). Of these three indicators,
only a tampered inlet restrictor is also considered tampering, and as such is used to
determine both tampering and fuel switching rates. Since false positive indications
should be extremely rare for these measures, the percentage of vehicles with at least one
positive indicator is a reasonable minimum estimate of fuel switching.
Measuring fuel switching is somewhat unusual because two of the three indicators
(positive Plumbtesmo and leaded fuel in the tank) disappear with a series of subsequent
proper fuelings. Positive Plumbtesmo results disappear slowly, while leaded gasoline is
quickly diluted with subsequent tanks of unleaded fuel A vehicle which has one or both
of these transient indicators, however, has recently used or is currently using leaded
gasoline. The presence of a tampered inlet restrictor provides no information about the
immediacy of the fuel switching. A fuel switching rate derived from the two transient
indicators would thus measure how many vehicles have recently used leaded gasoline,
while all three indicators together provide a more accurate indication of long-term fuel
switching behavior with its associated catalyst destruction and elevated emissions.
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Motor Vehicle Tampering Survey -1990 Page 34
The presence of any of these three indicators suggests that a given vehicle has been
misfueled; their absence, however, does not rule it out. For example, fuel samples were
obtained from selected sites and only comprised 18% of the all unleaded vehicles
surveyed, limiting the scope of this variable. A vehicle with an untampered fuel filler
inlet restrictor may also have been fueled at a leaded pump equipped with a smaller
nozzle, or by using a runnel or similar device. The tailpipe lead test may also fail to
identify misfueling, particularly if older vehicles have had their tailpipes replaced since
last operated on leaded fuel As the lead phasedown program has lowered lead levels
in leaded gasoline, the incidence of false negative Plumbtesmo results may be increasing.
The uncertainty in these measures, then, is always toward underestimating the number
of vehicles misfueled.
During the 1990 Survey, only five of the fourteen sites had fuel samples taken. The
sites were: Beaumont, Tampa, Miami, Greensboro and Knoxville. For specific informa-
tion concerning the number of fuel samples taken at each site, refer to the "Survey
Methods" section of this report on pages 6 through 11.
The limitations of the fuel switching indicators can be seen in their incomplete
overlap. The Venn diagram (Figure 9(a» illustrates the degree of overlap in the
misfueling indicators for all unleaded vehicles surveyed in 1990 where data for all three
indicators were recorded. Figure 9(b) shows the percentage of the misfueled vehicles
with each combination of the three misfueling indicators. For example, none of the
misfueled vehicles exhibited all three indicators.
The prevalence of two of the fuel switching indicators (Plumbtesmo and Leaded
Fuel in Tank) in this survey is greatly diminished. In past surveys they have been strong
indicators of fuel switching. But as leaded gasoline becomes scarcer, these indicators'
usefulness also decreases. Of the 1439 fuel samples taken in this survey, only one of them
showed a lead content greater than 0.05 grams of lead per gallon. This leaves tampered
inlet restrictors as the predominant fuel switching indicator. As Figure 9(b) shows, 98%
of the fuel switched vehicles had a tampered inlet restrictor.
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Motor Vehicle Tampering Survey -1990
Page 35
(0 Total)
Leaded Pud in Tank
(1 Total)
Tampered Inlet
Rcsttictor
(58 Total)
(a)
Tampered Inkt Only
(98%)
Leaded Gai Only
(2*)
(b)
Figure 9(a). Overlap of fuel switching indicators among misfuded
vehicles for which afl three indicators were inspected.
9(b). Breakdown of mkfiidgd vehicles in 9(a) by prevalence
faniirflfnr rnmhinaHnn _
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Motor Vehicle Tampering Survey -1990
Page 36
2. Fuel Switching Trends
Of the vehicles requiring unleaded fuel, 4% were identified as misfueled by at least
one of the indicators discussed above. The fuel switching incidence by survey site is listed
in Table 12. The data in lable 12 again show that inlet restrictor tampering is easily the
most prevalent indicator of misfueling. This is not surprising, since inlet tampering is
the most persistent indicator of past misfueling, even when the vehicle has been properly
fueled for some time. Figure 6(b) also shows how inlet restrictor tampering increases
with vehicle age.
TABLE 12
Fuel Switching Rates among Unleaded Vehicles by Site and Indicator
Survey
Location
OVERALL
Leaded Tampered Positive Overall Fuel
Fuel in Inlet Plumbtesmo Switching
Tank (%) Restrictor (%) (%) (%)
Santa Barbara, CA
Houston, TX
Beaumont, TX 0
Tampa, FL 0
Miami, FL 0
Raleigh, NC
Greensboro, NC 0
Knoxville.TN
Huntington, WV
Gary, IN
Lexington, KY
Louisville, KY
Covington, KY
Boston, MA
3
5
4
6
2
3
4
6
5
2
4
4
4
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
3
5
4
6
3
3
4
6
5
2
4
4
5
1
0
0
Note: The overall fuel switching rate may actually be lower than the rate for any one indicator because
of the slightly different population sizes for each indicator (i.e., not all vehicles were able to be tested
for all three indicators).
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Motor Vehicle Tampering Survey-1990
Page 37
Table 13 presents the combined tampering and fuel switching rates for all vehicles
surveyed in 1990. Covered and non-covered vehicles in cities with control programs are
included to determine the whole extent of tampering for these areas. The percentage of
unleaded vehicles that were tampered or fuel switched was 17%, and the percentage of
unleaded vehicles with missing or damaged converters was 6%. Table 13 thus suggests
that approximately 35% of all tampering and fuel switching is composed of vehicles in
the catalyst removed or fuel switched category. Since these conditions have the largest
emissions impact, this indicates the very serious nature of much tampering.
Combined
Survey
Location
Santa Barbara, CA
Houston, TX
Beaumont, TX
Tampa, FL
Miami, FL
Raleigh, NC
Greensboro, NC
Knoxville, TN
Huntington, WV
Gary, IN
Lexington, KY
Louisville, KY
Covington, KY
Boston, MA
OVERALL
TABLE 13
Tampering and Fuel Switching Rates
Catalyst-Equipped Vehicles
with Catalysts Removed or
that were Fuel Switched (%)
5
7
5
8
6
4
6
8
9
5
7
5
7
2
6
Unleaded Vehicles
either Tampered or
Fuel Switched (%)
11
24
16
19
17
15
16
17
22
19
20
16
16
13
17
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Motor Vehicle Tampering Survey -1990
Page 38
Table 14
Prevalence of Fuel Switching Indicators by Program Type
Percentage by Program Type
Fuel Switching Indicator non-I/M ATP-only I/M-only I/M+ATP
Tampered Inlet Restrictor
Positive Plumbtesmo
Leaded Fuel in Tank
Overall Fuel Switching
4
0
0
4
1
0
0
1
4
0
0
4
1
0
0
1
Table 14 presents the prevalence of each fuel switching indicator by program type.
The classification of survey sites is the same as was described for Figure 5.
Table 15
Prevalence of Fuel Switching Indicators by Vehicle Type
Percentage of each Indicator
Fuel Switching Indicator LDV LDT
Tampered Inlet Restrictor
Positive Plumbtesmo
Leaded Fuel in Tank
4
0
0
4
0
0
Overall Fuel Switching
3. Fuel Switching hy Vehicle Type
The prevalence of each fuel switching indicator by vehicle type is presented in Table
15. Overall fuel switching among trucks was no different from passenger cars. Fuel
switching data from the heavy-duty trucks was not included in Table 15 because of an
insufficient sample of unleaded HDTs.
4. Fuel Switching and Catalyst Tampering
Consumers and mechanics remove catalytic converters for a number of reasons, but
some of their motivation may be related to fuel switching. The vehicle owner may remove
the catalytic converter either prior to misfueling, or after some misfueling if the vehicle's
driveabitity has been adversely affected by a catalyst damaged from the repeated misfuel-
ing. With the decrease in availability of leaded fuel and its greatly reduced lead content
the connection between fuel switching and catalyst tampering is probably more tenuous.
The data from this survey cannot be used to distinguish between these two situations, but
can be used to examine the extent to which these types of abuse occur in conjunction.
Figures 10(a) and (b) examine the relationship between converter tampering and
two of the three misfueling indicators (positive Plumbtesmo and tampered inlet restrictor).
Vehicles included in Figures 10(a) and (b) had to meet two criteria. First, only those
vehicles that have not been subject to an ATP with Plumbtesmo testing were included.
Second, the sample population was further restricted to those vehicles in which all three
parameters were inspected during the survey. The three parameters examined in Figures
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Motor Vehicle Tampering Survey -1990
Page 39
10(a) and (b) have been incorporated into a number of antitampering programs to
determine if a converter is missing or damaged. A vehicle failing the Plumbtesmo test or
inlet restrictor inspection in some programs is required to have its converter replaced.
Figure 10(a) shows the value of these programmatic criteria in detecting missing or
lead-poisoned converters. A simple inspection of the converter, for example, would catch
68% of the group of vehicles which lack functional converters (converter either missing
or presumed to be disabled from lead exposure). Inspecting both the converter and inlet
restrictor, however, would detect 99% of these vehicles. The usefulness of Plumbtesmo
in detecting damaged converters appears to be limited, since only 1% of the vehicles in
Figure 10(b) failed for Plumbtesmo only. In 1984, prior to the latest phase of lead
phasedown, 17% of the vehicles failing one of these programmatic criteria failed for
Plumbtesmo only.
Positive Plumbtctmo
(7 Total)
Missing Catalytic
Converter
(291 Total)
(a)
Plumbtesmo Only (1%)
All Three Indicators (<1%)
Cat + Inlet (33%)
Tampered Inlet
Rcstrictor
(271 Total)
Catalyst Only (35%)
Inlet + Plumbtesmo (OX)
Plumbtesmo + Cat. (0%)
Tampered Ink* Only (31%)
(b)
Figure 10(a). Overlap of indicators used by ATft to
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Motor Vehicle Tampering Survey -1990 Page 40
5. Gasoline Lead Concentrations
During the 1990 Survey, gasoline samples were only taken at five sites: Beaumont,
Greensboro, Knoxville, Miami, and Tampa. Of the vehicles sampled at these sites and
identified as misfueled by any of the three misfueling indicators, 98% were using
unleaded gasoline when surveyed (Le., their gasoline lead concentration was less than
0.05 gram per gallon (gpg)). These vehicles, then, were identified as fuel switched by a
tampered inlet restrictor and/or a positive Plumbtesmo test. Figure 11 presents die
distribution of lead concentrations of 0.05 gpg or more in misfueled vehicles for the
1984-1990 surveys. The impact of lead phasedown can be clearly seen in Figure 11. Not
only has the overall prevalence of leaded gas in unleaded vehicles declined, but the
distribution of lead concentrations in the leaded gasoline has shifted dramatically. The
role of the higher concentrations sharply dropped from 1984 to 1985, and by 1990 leaded
gasoline in the tank had almost disappeared as an indicator of fuel switching. During
1990, leaded gasoline represented only 5% of the total gasoline sold in the United States.
The low availability of leaded gasoline is reflected in the low frequency of misfueling for
1990 in Figure 11.
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Motor Vehicle Tampering Survey -1990
Page 41
lead concentration
range (gpg.)
Percentage of
Mlsfueled Vehicle*
100
90 -
80 -
70 -
60 -
50 -
40 -
30 -
20 -
10 -
1984 1985 1986 1987 1988 1989 1990
Survey Year
Rgure 11. Distribution of lead concentrations In leaded fuel sampled
from fuel switched vehicles: 1984 - 90 surveys. Percentages
based on all fuel switched vehicles, Including those using
unleaded fuel (<0.05 gram per gallon (gpg.)).
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Motor Vehicle Tampering Survey -1990 Page 42
APPENDIX A
RELEVANT PORTIONS OF THE CLEAN AIR ACT
Section 203(a)(3): The following acts and the causing thereof are prohibited —
(A) for any person to remove or render inoperative any device or element of design
installed on or in a motor vehicle or motor vehicle engine in compliance with regulations
under this title prior to its sale and delivery to the ultimate purchaser, or for any
manufacturer or dealer knowingly to remove or render inoperative any such device or
element of design after such sale and delivery to the ultimate purchaser; or
(B) for any person engaged in the business of repairing, servicing, selling, leasing,
or trading motor vehicles or motor vehicle engines, or who operates a fleet of motor
vehicles, knowingly to remove or render inoperative any device or element of design
installed on or in a motor vehicle or motor vehicle engine in compliance with regulations
under this title following its sale and delivery to the ultimate purchaser.
APPENDIX B
SURVEY AND DATA RECORDING PROCEDURES
1. Explanation of Survey Forms
The forms on the following pages were used for recording the survey data in the
field. The forms were forced choice to ensure coding consistency, and were designed to
facilitate direct data entry. The following codes were used to record data for the major
system components on the data sheets:
0 - Not originally equipped 8 - Misadjusted item
1 - Functioning properly 9 - Malfunctioning
2 - Electrical disconnect A • Stock equipment
3 - Vacuum disconnect B - Non-stock
4 - Mechanical disconnect D - Add on equipment
5 - Incorrectly routed hose Y - Yes
6 - Disconnect/Modification Z - No
7 - Missing item
Additional codes were used for those components which could not be classified into
the above categories. If a determination could not be made about a given component's
condition, the variable was left blank. A brief description of each data entry follows.
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Motor Vehicle Tampering Survey -1990 Page 43
Form A - Underhood
1-4 ID Number - Vehicles are numbered sequentially as they are inspected. This
number is preceded by a site identifying letter.
5-8 Month and year of last I/M inspection (left blank if vehicle is licensed in non-I/M
area).
9-12 Manufacturer of vehicle
13-23 Engine Family - as recorded on the underhood emission label.
24-34 Non-serial number portion of YIN - as recorded on the driver's side of the dash
under the windshield or the driver's door post. The VIN is recorded only if the
engine family can not be determined.
35-38 Displacement - as recorded on the underhood emission label.
39-40 Vehicle Model Year
41 Originally Catalyst Equipped - as recorded on the underhood emission label or
the driver's door post.
42 Engine Status - is coded 'V if the engine is the one originally installed in the
vehicle; and is coded 'Z' if the vehicle: has a different gasoline engine than was
originally equipped; was originally equipped with a diesel engine and currently
has a gasoline engine; was converted to operate on a fuel other than gasoline or
diesel fuel (i.e., propane); or is a "gray market" imported vehicle.
43 Air Cleaner-is coded'A','B', or T.
44 Heated Air Intake - provides warm air to the carburetor during cold engine
operation. The heated air intake is coded '0', T, "3', '4', T (stovepipe hose), '9'
(vacuum override), or 'B' (custom air cleaner).
45 Positive Crankcase Ventilation (PCV) system - prevents crankcase emissions by
purging the crankcase of blow-by gases which leak between the piston rings and
the cylinder wall in the combustion chamber under high pressures. The PCV
system is coded T, *3', '4' (fresh air hose), T, '9', or 'B' (includes fuel economy
devices).
46 Exhaust Gas Recirculation (EGR) System - directs a portion of the exhaust gases
back into the cylinders to reduce NOx emissions in the exhaust gas. The standard
EGR configuration consists of a vacuum line from the carburetor to a sensor
(used to detect engine operating temperature to activate the EGR valve), and
another vacuum line from the sensor to the EGR valve. The EGR system is
coded '0', T, '2', "3', '4', 'F, T, or '9'.
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Motor Vehicle Tampering Survey -1990 . Page 44
47 Evaporative Control System (ECS) • controls vapors from the fuel tank and
carburetor. Some systems have two lines: from the fuel tank to the canister, and
from the canister to the carburetor or air cleaner (for purging the canister).
Other systems have a third line connected to the carburetor. The ECS is coded
T, '3' (carburetor line), '4' (tank line), '5', '6' (air cleaner unsealed), T, or '9'
(cracked hose or canister).
Air Injection System - extends the combustion process into the engine's exhaust system
by injecting fresh air into the exhaust ports, lowering exhaust emissions while still
maintaining proper vehicle performance. Two types of air injection systems are currently
used. One type uses a belt-driven air pump to direct air through a control valve and into
the exhaust manifold. The other type is a Pulse Air Injection Reaction (PAIR) system,
which uses an aspirator commonly located in the air cleaner to supply air to the exhaust
manifold.
48 Aspirated Air Injection System (PAIR) - coded '0' (if air pump system or none), T,
'4', T, or '9'.
49 Air Pump Belt - is coded '0' (if PAIR or none), T, T, or '8' (loose belt).
SO Air Pump System - for the purposes of this variable, consists of the air pump and
control valve and is coded '0' (if a PAIR or none), T, '3', '4' (other than belt
removal), T, or '9'(frozen pump).
51 Exhaust Manifold-coded'A'or'B'.
52 Oxygen and Related Sensors - The oxygen sensor controls the air-fuel mixture
going into the engine of vehicles equipped with three-way catalytic converters. A
vehicle's computerized engine and emissions control system receives input from
various sensors for engine condition information, and constantly adjusts the
air/fuel ratio, distributor, and emissions devices for optimum economy,
driveability, and emissions. These sensors are coded '0', T, '2', '4' (unscrewed),
'6',orT.
53 Carburetor Type - is coded 'F (fuel injected), 'A' (stock carbureted), or 'B' (non-
stock carbureted).
54 Turbocharger-coded'0','A','B',or'D'.
Form B - Rear
1-4 ID Number - Same as on Form A.
5-8 Make
9-12 Model
13 Vehicle Type - coded as follows: C = car, T = light-duty truck, H = heavy-duty
truck.
14-15 License Plate - State abbreviation
16-19 Program Jurisdiction - the city or county of the vehicle's registration is entered
(if the vehicle is covered by a control program).
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Motor Vehicle Tampering Survey • 1990 Page 45
j->
20-23 Exhaust gas HC concentration (in ppm) at curb idle.
• 24-26 Exhaust gas CO concentration (in percent) at curb idle.
27-29 Exhaust gas COj - concentration (in percent) at curb idle.
30-32 Exhaust gas Oz - concentration (in percent) at curb idle.
33-35 Odometer - mileage in thousands
36 Dash Label - displays the fuel required and is coded '0' (for leaded vehicles), T, or T.
37 Catalytic Converter - oxidizes the HC and CO to water and CO2 in the exhaust gas.
Later model catalysts also reduce oxides of nitrogen. The converter is coded '0',
T, T (entire catalyst canister removed), or 'B' (aftermarket catalyst present).
38 Exhaust System - if as originally equipped an 'A' is coded. If non-stock a "B' is coded..
39 Exhaust System Integrity - the condition of the exhaust system is coded T (no
obvious leaks) or '9' (leaks evident).
40 Tank Cap - seals the fuel tank during normal operating conditions and is coded T,
T, or '9' (loose cap). A separate entry (see below) is made to indicate whether
the tank cap is stock or non-stock ('A' or 'B').
41 Tank Cap Origin - is coded 'A' if the tank cap is a stock cap. The cap is coded 'B'
if it is non-stock.
42 Tank Label - displays required fuel and is coded '0' (for leaded vehicles), T, or T.
43 Filler Neck Restrictor - The restrictor is designed to prevent the introduction of
leaded fuel into a vehicle requiring unleaded fuel. It is coded '0' (for leaded
vehicles), T, '4* (widened), '6* (nozzle adaptor present), T, or 'B' (non-stock
inlet restrictor-functioning properly).
44 Plumbtesmo - Plumbtesmo paper is used to check for the presence of lead in vehicle
exhaust pipes. A positive indication is coded as T' and a negative as 'N1.
45 Fuel Sample - indicates if inspector was able to obtain fuel sample for later lead
analysis ('V or 'Z').
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Motor Vehicle Tampering Survey -1990
Page 46
2. Classification of Component Conditions
The table below was used to classify the various system components as tampered
(T), arguably tampered (A), or malfunctioning (M). Only those codes which are
applicable to a given component are listed. Codes for 'not originally equipped' and
'functioning properly* are not included in this table. Refer to Appendix B, Part 1 for an
explanation of the codes.
Codes from forms A and B
Component/system
Dash Label
Tank Cap
Tank Label
Filler Neck Restrictor
Catalytic Converter
Oxygen and Related Sensors
PCVSystem
Heated Air Intake
Evaporative Control System
Aspirated Air Injection System
Air Pump Belt
Air Pump System
EGR System
2 3
T
T
T
T
T
T
T T
4 5
T
T
T
A
T T
T
T
T T
6 7
A
A
A
T T
T
T T
T
A
T T
T
T
T
T
8 9
M
M
M
M
M
M
M
M
B
T
T
T = Tampered
A = Arguably tampered
M = Malfunctioning
3. Fuel Sample Collection and Labeling Procedures
An attempt was made to take a fuel sample from each vehicle surveyed. These
samples were collected in two-ounce bottles with a hand-operated fuel pump. Once the
sample was drawn, the fuel was replaced with an equivalent amount of unleaded fuel if
the driver requested, and the pump was flushed with unleaded fuel.
Each bottle was identified with an adhesive label that had the vehicle identifying
survey number on it. The vehicle identifying number was the first entry on the data forms
described in Part 1 of Appendix B. The bottles were packed, labeled, and shipped to
EPA's Motor Vehicle Emissions Laboratory in Ann Arbor according to the shipper's
requirements.
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Motor Vehicle Tampering Survey -1990 Page 47
4. Plumbtesmo Application
1) Clean a portion of the inside of the tailpipe large enough for the test paper by wiping
it out with a paper towel or cloth. This may be necessary to remove soot deposits
which might mask the color change.
2) Moisten the Plumbtesmo paper with distilled water and immediately* press firmly
against the surface to be tested for approximately thirty seconds. If the tailpipe is
hot you may wish to damp the test paper in the tailpipe using a dean damp.
•Note
The Plumbtesmo paper must be applied during the time that the
paper is yellow for the reaction to occur. After approximately 15
seconds the yellow color disappears and the paper is no longer
effective. Excess water also interferes with the reaction.
Care must be taken to avoid contamination of the test paper. If a
person has recently handled a test paper with a positive reaction,
some lead or reactive chemical may have been transferred to their
fingers. Subsequently handling a clean test paper may cause con-
tamination.
3) After removing the test paper, determine whether a color change has occurred. Red
or pink coloration indicates the presence of lead.
5. Field Quality Control
Reference and calibration gases were used to ensure the accuracy of the emissions
analyzer. Horiba gases certified by RTF were used as reference gases. Two cylinders
of reference gas were used to validate the accuracy of the calibration gases before they
were taken to the field on each survey.
Two calibration gases (Horiba) were used. These gases were a mixture of CO, HC,
and COa in nitrogen and were used to check the instrument twice a day. These
calibration gases were certified by the manufacturer and the RTF reference gases. Their
approximate compositions were:
8% CO
11%CO2
1560 ppm HC (Hexane equivalent)
1.6% CO
11% COi
320 ppm HC (Hexane equivalent)
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Motor Vehicle Tampering Survey -1990
Page 48
APPENDIX C
EMISSION CUTPOINTS FOR I/M AREAS
The table below lists the emission outpoints used by the I/M areas covered in the
1990 tampering survey. The outpoints for pre-1975 vehicles are not included, since these
vehicles were not surveyed.
Emissions Outpoints
Survey Site
Boston, MA
Gary, IN
Louisville, KY
New Jersey
Raleigh, NC
Model Year
1975-79
1980
1981 +
1976-79
1980
1981 +
1975-76
1977
1978
1979
1980
1981 +
1975-80
1981 +
1975-77
1978
1979
1980
1981 +
CO(%)
4.0
2.7
1.2
3.5
2.0
1.2
65
63
5.5
4.5
25
12
3.0
12
45
4.0
25
2.0
1.2
HC (ppm)
400
300
220
350
250
200
700
650
600
600
250
220
300
220
-
-
-
-
.
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