Repair Sequence for Failed I/M Vehicles- Repair Industry Background

New York State Enhanced Motor Vehicle Inspection/Maintenance Program Final Report

An inspection/maintenance (I/M) program will achieve its goals only through effective motor vehicle repairs. For any new I/M program area, or an area such as the New York Metropolitan Area (NYMA) which is upgrading its program, a key issue is whether the repair industry is prepared for the challenge of cost effectively diagnosing and repairing emissions-related problems.

An early element of this Project required TESTCOM to obtain a general understanding of the capabilities of the industry, both nationally and in the NYMA. During this part of the Project, TESTCOM gathered information on previous repair effectiveness investigations, in part, to avoid duplicating work performed elsewhere.

TESTCOM established a meaningful dialogue with the repair industry in the NYMA in order to better understand their status and needs. This status/capability/needs information influenced the selection of topics identified for further investigation during the Project, and clearly influenced the development and refinement of the recommended diagnostic/repair sequences.

2.2. Repair Industry Assessment

2.2.1 Colorado Program

As part of its IM240 program, Colorado has established a system to generate repair effectiveness indices (REIs). Colorado also has initiated a program to certify repair technicians. The State of Colorado, dKC Consulting and Radian analyzed IM240 data from the Colorado program to characterize trends in repairing vehicles. The following topics were investigated:

The ability of repair effectiveness indices (REIs) to predict the performance of repair facilities.
The impact of technician training on repair performance.
The repairability of specific makes, model years and vehicle technologies.

Assessment of Repair Effectiveness Indices (REIs)

Using data from Colorado's IM240 program, Radian calculated repair effectiveness indices (REIs) for different repair facilities. For this analysis, the REI was defined as being the retest pass rate. The IM240 database contained a field for repair facility identification number. Based upon the results of the first retest of the vehicle, Radian calculated the retest pass rate for each repair facility for each quarter of 1996. Radian then analyzed trends from quarter to quarter. The goal was to determine if a repair facility would have a consistent REI from quarter to quarter.

The REIs were plotted from quarter to quarter. If the REI were a perfect indicator of repair consistency, a plot of the first quarter versus fourth quarter REI would be a straight line. No relationship was found between the first and fourth quarter REIs. For example, there was a wide range in fourth quarter REIs among vehicles that received a 100% rating in the first quarter and vice versa.

The coefficient of determination (R²) was calculated between the first quarter results and the second quarter results and the first quarter results and the fourth quarter results. In both cases, the R² values were low. For the correlation between the first and second quarter, the R² was 0.25; for the correlation between the first and fourth, the R² was 0.18.

It was concluded that REIs might be an effective way of providing feedback to individual stations on repair performance, but they do not provide an effective means of projecting future repair performance.

Impact of Technician Training on Repair Performance

In Colorado's IM240 program, both registered and non-registered technicians can perform repairs. Registered technicians have demonstrated compliance with minimum training requirements, whereas non-registered technicians have unknown training background. Colorado's database contains information on whether repairs were performed by registered or unregistered technicians. If the owner repaired the vehicle, a third category was used, "owner repair."

Radian tabulated the fail rate on the first retest as a function of who repaired the vehicle, i.e. registered technicians, non-registered technicians, and owners. This calculation was performed by first tabulating the fail rate by "repair technician category" for specific combinations of make, model, model year and fuel metering system type (carbureted versus fuel injected). The fail rate by "repair technician category" was then tabulated for groups of vehicles with similar characteristics, for example, carbureted cars.

The non-registered category had the lowest fail rate on retests, while the owner repair had the highest fail rate on retests. This data indicates that registered technicians, on the average, show worse repair performance than non-registered technicians. However, there are many other factors that influence the retest failure rate, such as the types of vehicles being repaired; so the results are not conclusive. For example, many dealership mechanics are non-registered and yet they are extensively trained on the types of vehicles that they repair and, therefore, exhibit better repair performance.

Repairability of Specific Vehicle Types

Again, using data from Colorado's IM240 program, Radian characterized retest performance according to specific combinations of vehicle type, model year, make, engine displacement and fuel metering system. It also tabulated repair performance for broader groupings including vehicle type, model year and fuel metering systems. In certain cases, vehicles with similar model years, makes, displacements and fuel metering systems have similar retest fail rates.

For example, four of the top five vehicles were '85 to '88 model Chrysler Corporation vehicles with a 5.2 V8 and a carbureted fuel metering system. The '85 to '87 Ford 3.8 V6 with a fuel injection system are clustered together with similar retest fail rates. Some of the carbureted GM engine models with a 5 or 5.7 liter engine show similar retest failure rates. The results indicate that the IM240 database can provide an indication of how difficult it is to repair certain specific types of vehicles.

Radian analyzed overall trends in the repairability of different types of vehicles. Carbureted vehicles historically are much more difficult to repair than fuel injected vehicles for a given model year. The retest fail rate for fuel injected vehicles appears to be about half of the retest fail rate for carbureted vehicles. Given the increased complexity of a carburetor versus a fuel injection system, these results are not surprising. The results raise the question as to whether or not repair strategies should focus on carbureted vehicles, which appear to be more difficult to repair than fuel injected vehicles. Few vehicles built since 1990 are equipped with carbureted fuel metering systems.

2.2.2 Repair Effectiveness Experiences of Other I/M States

Appendix E of this report contains a report prepared for TESTCOM by de la Torre Klausmeier Consulting entitled: "REPAIRS TO VEHICLES FAILING I/M TESTS." The following subsections identify some of the more relevant studies associated with state programs.

California

The California Fuel-injected Vehicle Study was conducted by Radian, under contract to the California Air Resources Board (CARB), in 1987. The purpose of the study was to identify causes of excess emissions from fuel-injected vehicles with three-way catalysts. In this project, 55 fuel-injected vehicles were procured that received cost waivers in California's Smog Check program. An expert diagnostician conducted a step-by-step repair procedure on each vehicle and mass emissions were determined by the Federal Test Procedure (FTP) in the as-received condition and after each step in the repair procedure.

Michigan

The USEPA/MVMA Cooperative Test Program, conducted in 1990, was a joint effort between the USEPA and domestic as well as foreign automakers. Vehicles initially failing Michigan's two-speed idle I/M program were selected for participation in the program. The testing and repair procedures are very similar to the California Fuel-injected Vehicle Study with the exception that the CTP only targeted HC and CO, not NOx. The CTP included 110 fuel injected and 88 carbureted vehicles.

Arizona

The USEPA, in 1993, repaired fuel-injected vehicles identified as high emitters during IM240 tests. The project repaired 31 vehicles failing pilot IM240 tests in Arizona and 22 vehicles that were identified as having high emissions during routine emission factor tests. The purpose of the program was to verify different diagnostic techniques aimed at identifying problems causing high emissions during the IM240 tests. Additionally, the USEPA had a goal of only using readily available data such as the emissions versus time trace from the IM240 test to guide the technician through repairs.

Michigan Roadside

The Michigan Roadside Study was performed in 1993 by domestic automakers and the State of Michigan. Using remote sensing test results, vehicles were identified as high emitters and repaired by expert technicians in the employ of the automakers until the vehicle met FTP standards. In this project, groups of repairs were performed, rather than a step-wise progression, as seen in other projects.

El Monte

The El Monte Pilot Program was conducted over a six month period starting in July 1994 as part of the overall California I/M Pilot Program evaluation. The goal of the project was to evaluate alternative loaded mode tests, in particular the Acceleration Simulation Mode (ASM) test, and to assess the effectiveness of methods to target high polluters in a test-only environment. Expert technicians, employed by the California Bureau of Automotive Repair (BAR), repaired vehicles that failed ASM and IM240 tests. The vehicles in the study were broken into two groups when received by the California Air Resource Board for testing. There were 106 vehicles that received the ASM test first followed by an IM240 and 114 vehicles that received the IM240 first.

2.2.3 Conclusions From These Studies

The purpose of these studies was to determine which components must be replaced to correct high emissions problems. These studies and the diagnostic/repair techniques inherent in them could be characterized as a component replacement approach to diagnostics/repairs.

The Project Team concluded that correctly repairing vehicles failing I/M tests requires addressing several different components and systems. In addition, many vehicles had more than one problem that needed to be corrected.

All of these studies found that replacing bad oxygen sensors along with worn-out catalytic converters reduces HC and NO_x emissions cost-effectively. However, a wide variety of problems were found in addition to bad oxygen sensors and catalytic converters.

In many cases, repairing the EGR system results in large NO_x reductions. Traditional tune-ups of the ignition system can be effective, in some cases, but often result in no emission reductions. In general, fuel-injected vehicles appeared to be easier to repair than carbureted vehicles.

2.3. Orientation of This Project

These above referenced studies have provided valuable information on the causes of high emissions. However, the goal of this Project was to identify a diagnostic/repair sequence that would lead technicians through a logical and orderly set of procedures that would produce cost effective, emissions-reducing repairs.

In other words, this Project approached the diagnostic/repair challenge from the process/procedural perspective using the results of exhaust readings and other information. It was not a component-oriented process, but naturally component replacements were eventually made to achieve emission reduction objectives. It is believed that this process approach to diagnostics and repairs, verses the component replacement approach, is a significant departure from other studies and the classical repair industry strategies.

2.4. New York State Industry Resources

Shop Survey

TESTCOM conducted a repair industry survey targeting existing inspection stations in the NYMA. Although the survey was mailed to approximately 1,000 shops, the response to the survey was poor (87 responses), causing TESTCOM to then interview personnel from industry trade associations, a variety of diagnostic/repair equipment providers, individual shop owners and State personnel routinely engaged in functions requiring visits to repair shops.

The results identified a lack of training related to emissions diagnosis and repair, even though almost 80% of the shops sponsor some form of technician training. Of the shops surveyed, only 39.9% had technicians involved in emissions training over the past two years.

An important concern identified is the lack of diagnostic and repair equipment available to shops. The survey indicated that the industry doesn't generally view the emissions inspection analyzer as a diagnostic tool. Only 45% of the survey respondents indicated that their shops had a 4-gas analyzer, when all of the respondents were, in fact, inspection shops.

Repair Advisory Information Sources

Technical support, in the form of repair advisory service, is available to the industry. In addition to Hotline services, technical support is available in hard copy form such as via service and repair manuals and computer based information systems. Such computer based information systems can be used on an engine analyzer PC or on most office computers.

These information systems also supply the user with Technical Service Bulletins (TSBs), as do some of the Hotline services. The TSBs often relate to excessive exhaust gases as well as recall and repair information.

No specific assessment of the frequency of use in the NYMA and type of use of repair advisory resources was conducted during this Project, but the consensus among associations is that use is modest, with dealerships having access to and using more such resources as compared to independents.

Training

There are typically a wide variety of seminars and some training programs available to the NYMA repair industry. These are listed in other reports available from the New York Department of Motor Vehicles (NYSDMV). Manufacturers of tools, automotive diagnostic and repair equipment and automotive parts are among those that provide training.

The NYSDMV recognizes the value of and supports the Automotive Technician Training Program, known as ATTP. This program is designed for the mid-career technician rather than an entry-level individual and contains four core programs, starting with electronics and proceeding on with emissions systems, automotive computer systems and fuel injection. These modules are twenty-four hours in length, with the exception of the electronics course, which is thirty hours. The NYSDMV ATTP also makes available to students who successfully complete the four core courses an advanced computer emissions systems course (ACES) that requires approximately thirty hours of training.

The training requires a commitment on the part of the technician to devote the hours required to complete all four courses. These courses are offered by independent training agencies that must meet certain criteria established and monitored by NYSDMV. These training agencies normally offer evening classes in order to accommodate the working hours of technicians.