Evaluating Vehicle Emissions Inspection and Maintenance Programs (2001) / Chapter Skim
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4 Emerging Emissions Testing Technologies
4 Emerging Emissions Testing Technologies
Pages 90-117
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From page 90... ...
systems and remote-sensing technologies may eliminate traditional I/M testing for some vehicles. These emerging emissions technologies are descnbed below.
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From page 91... ...
reported the failure rates and initial emissions test results for HEP versus non-HEP vehicles. As shown in Table 4- I, the HEP made only a small improvement in identifying vehicles likely to fail, and the improvement was only for post-1986 model-year vehicles.
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From page 92... ...
The U.S. Environmental Protection Agency (EPA 200 ~ ~ has recently finalized an OBD rule that requires states to begin implementing OBD testing in I/M programs for ~ 996 and newer OBD-equipped vehicles.
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From page 93... ...
will illuminate and diagnostic trouble codes issued for a potentially significant number of vehicles despite vehicle emissions being below the state's I/M emissions cutpoints and even the vehicle's certification standards. Furthermore, OBDIT's strict malfunction criterion (the MTE illuminates if a problem is detected that could cause emissions to exceed ~ .5 times the vehicle's emissions certification standards)
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From page 94... ...
If more then two readiness codes are found unset, then the vehicle would be tested by an emissions tailpipe test or rejected from OBD testing. EPA (2000c, 200 ~ ~ estimates that the frequency of finding more than two readiness codes unset will be small.
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If the MIL is illuminated or there are unset readiness codes, the vehicle will not fail, but the vehicle owner will be
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The federal emissions control warranty is 96 months/80,000 miles for major emissions control components (such as the catalyst) , and 24 months/24,000 miles for other components (such as sensors, PCV valve, EGR valve)
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or no MIL illuminated but suspected of having high emissions (eight vehicles) .2 Once recruited, each vehicle was iThe Clean Air Act Amendments of 1990 and later regulations mandated that OBD checks be incorporated into I/M programs by January 1, 2001.
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Evaporative emissions effectiveness of OBDII (EPA 2000c) CE-CERT Rental car fleet 75 vehicles Tailpipe comparison of (University of and newspaper IM240 with OBDII MIL on California, ads (Durbin et al.2001)
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From page 99... ...
That study found that 63°/O of vehicles with MILs illuminated had emissions below their certification standards, and 79°/O had emissions below 1.5 times their certification standards. The eight vehicles in Table 4-3 with no MIL illuminated were recruited because of either high IM240 test lane results or other characteristics such as high mileage or driveability problems that suggest high emissions.
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From page 100... ...
The third EPA study used data gathered in Wisconsin to assess failure rates and other issues associated with implementing an OBDI/M program. This study examined the relative failure rates for OBDI/M versus lane IM240 testing.
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From page 101... ...
or more readiness codes unset lowered the percentage of vehicles that would be rejected from 3.2% to I.4°/O. At the time ofthis report, the Colorado Depa~l~entofPublic Health and Environment(CDPHE)
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From page 102... ...
This result is not surprising since the OBDTT system will cause MTE illumination for a number of problems that do not cause high emissions in the short term but could lead to higher emissions or the nondetection of an emissions problem in the future Summary of Technical Issues Regarding OBD I/M Tests The combination of much higher failure rate, Tower emissions reductions, and comparable cost of repair for OBDIl-failed vehicles is likely to lead to higher repair costs and lower cost efficiency associated with an OBD I/M program. It should be noted, however, that the failure rate and repair cost information currently available come from first-generation OBDll systems and young vehicles with low overall failure rates.
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From page 103... ...
Ratios of individualpollutants to CO2 presentin vehicle exhaust are determined by analysis of a series of sensor scans of the exhaust plume made after a vehicle has driven by. Background corrections are made by using readings taken just before the sensor beam is blocked by each passing vehicle.
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Fuel economy (not measured by remote sensors) must be estimated to obtain mass emissions rates per distance traveled.
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From page 105... ...
c' 0 ~ ~ `~ 40u) 0 ct CD a, ,,, 6020O0.0250.020O 0.015z - a ° 0.01 00.005O— Emerging Emissions Testing Technologies ~ 05 (a)
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From page 106... ...
Therefore, remote sensors (as well as infrared analyzers typically used in idle and acceleration-simulation-mode (ASM) tests)
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. By modifying the UV absorption technique used in earlier DU remote sensors, Popp et al.
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Quantitative measurement of mass emissions rates for PM will be more difficult to achieve because the scattering and absorption of light by airborne particles are complex functions of particle size and chemical composition. Site Selection and Effects of Engine Load An important consideration when measuring vehicle emissions by remote sensing is careful selection of roadside monitoring sites.
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From page 109... ...
Note that remote sensors provided measurements for unregistered and out-of-county vehicles operating within Sacramento County; some ofthese vehicles would not be covered by traditional I/M programs. Need for Quality Assurance and Quality Control As with any emissions testing program, a critical element is data quality.
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Paso. For the most recent 10-15 vehicle model years, HC emissions measured by one of the two remote sensors used in Houston were systematically lower by factors of 2-3 than those measured with the other.
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(The actual CO concentration required to pass the roadside test ranged from 2.5% to 7°/O for pre-1975 vehicles, in contrast to levels of approximately ~ % CO required for ~ 980 and newer cars.) Of ~ 0 additional vehicles that were measured by remote sensing to have Tow CO emissions, all passed the CO portion ofthe roadside inspection (2 of these ~ O vehicles failed for reasons other than high CO emissions)
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From page 112... ...
Of 307 vehicles that had both remote-sensor and roadside inspection data available, ~ 5°/0 failed the exhaust emissions (idle test) portion of the roadside inspection, and the overall failure rate (including vehicles with tampered or noncomplying emissions-control systems identified during an underhood inspection)
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From page 113... ...
This study showed that remote-sensing identifications of high CO- and/or HC-emitting vehicles were confirmed in 86% to 96% of IM240 and BAR90 emissions tests administered on the same or the next day. Arizona High-Emitter Program The state of Arizona implemented a remote-sensing program to identify high-emitting vehicles in the Phoenix area, starting in ~ 995.
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Fail UH only ~ Pass FIGURE 4-3 Results from Orange County study showing percentage of vehicles identified by remote-sensing device (RSD) that failed IM240 and BAR90 emissions tests.
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From page 115... ...
These and the methods described earlier in this chapter could be used to control lifetime emissions from vehicles and reduce or eliminate the need for traditional I/M testing. SUMMARY Traditionally, I/M programs have used tailpipe emissions tests, often accompanied by visual underhood inspections, to assess vehicles registered in the
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From page 116... ...
A variety oftechnologies that matured during the ~ 990s will affect emissions testing regimes in the future. These approaches include developing profiles of vehicles likely to have high or Tow emissions, use of OBD systems to detect and help guide repairs of emissions-related malfunctions, and the use of remote sensing to identify vehicles most likely to fail traditional tai1nine emissions tests.
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From page 117... ...
Emerging Emissions Testing Technologies 117 quality control, and achieving adequate coverage of the in-use vehicle fleet. Studies in which vehicles suspected to have high emissions based on remotesensing measurements are pulled over for further roadside testing have confirmed that remote sensing can identify vehicles likely to fail emissions tests with a success rate of 80-96%.
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