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High Altitude Study
Part 2

Methodology

This project was divided into five phases:

Data analysis
Interview
Recruitment
Validation
Course development

Each of these phases is outlined as follows:

1. Data Analysis:  The data received from the Colorado Department of Public Health and Environment (CDPHE) originated from the vehicle test record (VTR). This data did not include all the data needed to complete proposed analysis, but did include appropriate data to successfully complete the primary focus of this study. Data was received in a basic ASCII text format that was easily imported to Excel. The data was sorted by model year and then several filters were applied to find clean vehicles, marginal vehicles and gross emitters. The specifics of each filter is discussed in the report of each individual vehicle/engine family.
    
2. Interview:  The data was filtered to identify vehicles that failed the initial test, were repaired successfully and passed the second test with results within final emissions standards. The owners of these vehicles were contacted and interviewed about the type of repairs made, cost of those repairs, and quality of the repairs needed to successfully pass the I/M 240 test. If applicable, the technician performing the repairs was interviewed to determine the diagnostic strategy used in the repair of the interview vehicle.
    
3. Recruitment:  The data was filtered to identify vehicles that failed the initial test, were repaired multiple times and eventually passed with results outside of the current emissions standards implemented in 1997. The owners of these vehicles were contacted and interviewed about the repairs made to their vehicles. If applicable, the technician was interviewed to determine the strategy used in the attempted diagnosis and repair of these I/M 240 failures. Owners were then offered free repairs by Diagnostic Technician Education Consultants (DTEC) to validate the proper diagnostic strategy determined through data analysis and interviews. Study candidate vehicles were also acquired through the CDPHE Technical Centers.
    
4. Validation:  Study candidates were acquired from the owners for an average period of 3 days Each vehicle was delivered to Automotive Laboratory Sciences (ALS) for refueling with indolene.. The candidates were then driven to an Air Care Colorado test station and five before-repair tests were purchased. After initial testing, the vehicles were returned to the DTEC repair facility. The appropriate diagnostic strategy was performed. The vehicles were returned to the test station for five after-repair tests. If modifications were made, the vehicle was delivered to ALS for Federal Test Procedure (FTP) verification.
    
5. Course Development:  Data from the validation phase, coupled with existing information, was used to develop a course template for technician training seminars. The template was used to develop courses for each vehicle/engine family selected for this study.

A series of templates was developed as a guide to complete the process of data analysis, interview, recruitment, validation, and course development. It should be noted that the templates are flexible in nature and meant only as a guide. Templates can be added or deleted as necessary to fit the needs of the particular study candidate or situation. For example, the templates used for feedback systems are the same as those for non-feedback systems even though the data input and end use is quite different.
 

Data Analysis

The data for this study were acquired through the CDPHE. The VTRs for all vehicles from the beginning of the current program through the date of the data download was supplied on 3.5" floppy disks in ASCII format. The data was received in three deliveries. The first delivery contained Honda, Toyota and Mitsubishi / Hyundai / Chrysler import vehicles. The second delivery contained Ford light duty trucks and GM 2.8L light duty trucks. The last delivery contained the GM 5.0/5.7L light duty trucks. The ASCII format was received in a back-up format that allowed the easiest method of transferring data from CDPHE to DTEC without losing data. The data was recovered at DTEC and analysis began with the following sorts and filters applied.

1. Data was sorted by model year, vehicle identification number (VIN) and test date / time. This allowed the filters to be applied to vehicles with like standards. Several of the identified vehicles had model years with different standards.
    
2. Automatic filters were applied to separate the data by emissions standards and/or model year. This allowed the data to be filtered and vehicles identified as clean or dirty within the emissions standard applied to that model year vehicle.
    
3. Data was next filtered to identify vehicles that passed their initial test within final standards. The final standards used are EPA-recommended final standards, not standards currently in use in the Air Care Colorado Program. The first filter applied identified those vehicles that passed their initial test. Second Chance tests were filtered out as were Fast Pass tests. Next these vehicles were filtered by carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and minimum carbon dioxide (CO₂ ) standards. A minimum CO₂ filter was applied to eliminate any potential dilution influences. ECS (underhood visual inspection) failures were eliminated as well. This left a core sample of vehicles that were considered clean. These vehicles were then filtered by VIN to eliminate the influence of potential equipment changes for the selected model year. This exercise was used to determine if the model type being studied had the ability to pass the I/M 240 emissions test at final standards (see note at bottom of page for final standards info) or if modifications would need to be made.
    
4. Next the filters were removed and the data was re-filtered to identify those vehicles that failed their first test, had multiple repair and test attempts, and passed the I/M 240 test but would not have passed final standards. The first filter applied identifies the vehicles that had multiple tests. Fast Passes were filtered out. Second Chance tests were also filtered out. The CO, HC and NOx filters were set for vehicles that passed the phase-in standards but would not have passed the new standards. The VIN was also filtered to eliminate equipment change influences. The owners of these vehicles were identified by the Colorado Department of Revenue (DOR) using data supplied by DTEC through CDPHE.
    
5. The list of marginal vehicle owners was delivered to DTEC on floppy disk. This information was used to send a letter to the owners asking for information about the repair history of their vehicle. When possible, the technician was identified and interviewed to determine the strategy used to repair the vehicle. Vehicle owners were offered the opportunity to have free repairs made to their vehicles to identify and validate repair strategies. These vehicles were to be used in the validation process.
    
6. Next the filters were removed and the data was re-filtered to identify those vehicles that failed their first test, were repaired and passed their second test with output within final standards. The same basic filters as used in step 4 are applied to identify vehicles that had multiple tests, without Fast Passes or Second Chance tests, with CO, HC and NOx outputs within final standards. The VIN was also filtered to eliminate equipment change influences. The owners of these vehicles were identified by the Colorado Department of Revenue (CDOR) using data supplied by DTEC through CDPHE.
    
7. The list of clean vehicle owners was delivered to DTEC on floppy disk. This information was used to send a letter to the owners asking for information about the repair history of their vehicle. When possible the technician was contacted to determine the strategy used to repair the vehicle.

Specific data is listed in the chapter for each engine family. The template for data analysis can be found in the Template chapter. This includes a step by step procedure to sort and filter data. All other analysis such as average mileage or average CO output are basic Excel functions and will not be outlined.
 

Interviews

The interview process was used to identify the diagnostic strategies that result in the proper repair of the vehicle. The interview process also identifies the strategies that result in improper diagnosis and repair of I/M 240 failures. Although this process identified many ineffective strategies, no attempt was made to identify or categorize these strategies. Only strategies that proved to be effective are discussed in this report.

The interview process was divided into two distinct subjects. The first interview was used to identify those diagnostic strategies that were effective in repairing I/M 240 failures on the first attempt. The second interview was used to identify those diagnostic strategies that were ineffective in repairing I/M 240 failures on the first or subsequent attempts. The questions asked in the interview are listed below.

Questions asked during interviews used to identify successful diagnostic strategies:

How many times did you attempt to repair the vehicle after it failed the initial emissions test?

Did you do the repairs yourself or did you take your vehicle to a technician?

Can we contact your technician to discuss the repairs made to your vehicle?

What repairs did you make to the vehicle yourself?

How did you determine what the problem was?

How much money did you spend on the repairs made to enable your vehicle to pass the emissions test?

Questions asked during interviews with technicians who repaired the vehicles successfully:

What repairs did you make to the vehicle in question?

How did you determine what the problem was?

How many repair attempts were made to successfully repair the vehicle?

What equipment was used to find the problem?

What kind of training have you had to help you make effective repairs?

How much time was spent on the repair?

Questions asked during interviews with vehicle owners who had multiple repairs and failures:

How many times did you have your vehicle repaired and re-tested before it passed the emissions test?

Who made each repair?

Can we contact your technician to determine what he/she did to get the vehicle to pass?

If you made the repair, what repairs did you make to get the vehicle to pass the emissions test?

How much money did you spend to get the vehicle to pass the emissions test?

Questions asked during interviews with technicians who made multiple repair attempts on a vehicle before it passed the emissions test:

How many repair attempts were made before the vehicle passed the emissions test?

What repairs were made that were not successful in getting the vehicle to pass the emissions test?

What repair was made that successfully repaired the vehicle to pass the emissions test?

How much money was spent to repair the vehicle to pass the emissions test?

The answers to each question are compiled in each engine family report. The results were used to determine what strategy was the most effective in repairing I/M 240 failures on the first attempt.
 

Recruitment

The recruitment phase resulted in a change in direction because of the lack of response from the study and interview candidates. Initially the vehicle owner data received from CDOR via CDPHE was used to send a letter to each identified vehicle owner. Out of over 700 letters sent, only 18 interview candidates and 2 study candidates responded. As a result, the interview process involved contacting shops in the metro area to identify a successful diagnostic strategy. Also, a different method of recruiting study candidates was formed. Of the 18 study candidates, only 2 came from the initial recruitment process while 16 were accessed through efforts made by the technical assist personnel of Envirotest Systems Corp. as well as the technical assist personnel of CDPHE. This proved to be a favorable method of recruitment as these vehicles were current failures, not history failures.

The data from CDOR via CDPHE were received on floppy disk. The vehicle owner information was organized and a form letter was developed to send to the owners of both groups of vehicles. Two mailings were made to 720 vehicle owners. The split was divided with 276 letters sent to owners of successfully repaired vehicles and the balance of 444 letters sent to owners of vehicles with multiple failures. Within five days, 20 vehicle owners had contacted DTEC offering information about their vehicles. As is normal in a study of this type, the people who were most concerned were those who had successful repairs made to their vehicles. Of the 20 responses, the only study candidates acquired were a Mitsubishi Precis and a Chevrolet S10 Blazer. These vehicles were used during the validation phase. The remaining 16 study candidates were acquired through the CDPHE Emissions Technical Centers.

For future studies, it should be noted that DTEC advises CDPHE use the Emission Technical Centers for recruiting study candidates. The candidates acquired with this method can be easily tracked for repair and test information. This method is also less costly than the previously discussed method.
 

Validation

Each study candidate was received from the vehicle owner at the AutoPort @ DIA (at Denver International Airport) repair facility. The customer was advised that the process would take approximately three to five days depending on parts, delays at the test stations, or modifications made to the vehicle, which would require FTP testing. Each customer was advised of the process and ensured that there would be no cost to them for the repairs or testing performed to their vehicle. The following process was carried out on each vehicle.

1. Each vehicle was safety inspected and a determination was made as to the test worthiness of the vehicle. The safety inspection included a fluid check, visible smoke check, tire inspection, suspension inspection, and test drive for noise and alignment quality. If the vehicle passed the safety inspection, it was accepted as a study candidate.
    
2. The vehicle was delivered to Automotive Laboratory Sciences (ALS) for refueling with indolene fuel. Approximately 8 to 10 gallons of indolene was installed to take care of the drive from ALS to the nearest stations (Commerce City or Stapleton), 10 initial tests (Second Chance doubled the test mileage), the return trip to DIA, test drives before and after repair, the return trip to the test station and five after-repair tests. The total mileage for a typical study vehicle averaged 90 miles.
    
3. After re-fueling, the vehicle was driven to either the Stapleton or Commerce City test stations for baseline I/M 240 testing. The vehicles were tested in the same manner as any regular customer. The only concession made was the ability to write one check for each vehicle after all five tests were completed. Over 80 percent of the 90 baseline tests required a Second Chance test. This proved these vehicles to be gross emitters. Each Vehicle Inspection Report (VIR) was kept in Position Three at the test center until payment was made for the five baseline tests.
    
4. The vehicle was returned to DIA for diagnosis and repair. The EDGE diagnostic strategy was used for all vehicles. This procedure was chosen because of the consistent application of OE type procedures. EDGE is also the strategy used in the Air Care Colorado ATTP provided by Envirotest as a part of the contract with the state. Other strategy-based diagnostic systems would more than likely have resulted in similar success. The Diagnostic Trace Report (DTR) was analyzed to determine how the vehicle should be driven to gather baseline information. During a test drive, the oxygen sensor and fuel control device was monitored to determine the exhaust condition and computer command in a loaded situation. The non-feedback vehicles were test-driven but no data was recorded. The exhaust gases were baselined in the shop with a five-gas analyzer. Readings were taken with and without secondary air injection operation at both idle and 3000 rpm. A visual inspection was performed to check vacuum line routing, base timing, idle speed, and general condition. The basics were adjusted before continuing. The EDGE charts were used to determine the diagnostic path. For feedback vehicles, Chart 1 was used while Chart 3 was used for the non-feedback vehicles. After repairs, the exhaust readings were compared with the baseline readings. A final test drive was made comparing baseline data with the results. If results were favorable, the vehicle was returned to the test center for after- repair testing.
    
5. The vehicle was returned to the same test center for after repairs testing. The five after-repair tests were purchased in the same manner as the baseline tests. It was not possible to turn off Fast Pass because of the extremely busy nature of the stations during the summer months. This does not affect the results of this study because the initial retest is always a full test and the subsequent re-tests, if Fast Pass, reflect real world situations. If the vehicle passed, a certificate of emissions compliance (CEC) was issued and a sticker was applied to the windshield.
    
6. After the verification tests, the vehicle was returned to DIA. If the vehicle required Federal Test Procedure (FTP) testing, the vehicle was delivered to ALS for pre-conditioning and FTP testing. ALS required the vehicle for approximately 24 hours. When the FTP testing was completed the vehicle was delivered to DIA. Upon arrival at DIA, the vehicle was cleaned and the fuel tank filled with regular unleaded fuel. The vehicle owner was contacted and advised of the results of the study. Arrangements are made to deliver the vehicle and paperwork to the customer.
    
7. All data acquired from the study candidate vehicle are recorded and analyzed. The data are then analyzed and used in the development of courses for use by technicians repairing like vehicles. Templates for the development of these courses are included in the Template section of this study.
    

Course Development

After reviewing the results of the validation phase of the study, templates were developed to aid in the construction of short courses designed to inform the technician of the diagnostic strategy and modifications, if any, determined to be necessary for the successful repair of these problem vehicles. The looks of the courses are meant to stay consistent with EDGE material. Templates were designed to allow the course developer to easily build each individual page of a course manual. Templates include those for individual components, procedures, diagrams, waveforms, title pages, and diagnostic strategies.

The basic outline for each course is determined by the system in question. Listed below is an example of the course outline for feedback vehicles.

1. Introduction – identifies the basics of the specific system. Outlines the basics of the course.
2. Critical Inputs – gives detailed information on the critical inputs that influence fuel control.
3. Critical Outputs – details the fuel control device as well as systems that influence fuel control.
4. Strategies – details the fuel control strategies and any other strategy used by the system to control fuel and emissions.
5. Diagnosis – lays out the procedure the technician should follow to successfully diagnose, repair and verify the repair of the system.
6. Diagrams – schematics and wiring diagrams needed to understand the system strategy and make successful repairs.
7. Waveforms – known good waveforms used by the technician to test the critical inputs and outputs and to verify fuel control.

The templates as well as this study report are developed in Word 97. This will enable future course developers to easily modify the look and feel of the information used to inform technicians of difficult to repair I/M 240 failures. Diagrams and illustrations are designed to be accessed from the repair database used by CDPHE. These graphics can be pasted into the publication as needed. Digital camera illustrations are also used to enhance the learning experience. ShopKey information was used to develop the courses within this study.
 

Observations

During the course of the study, several observations were made. It is the opinion of DTEC that a large gap exists between those technicians who successfully repaired these vehicles in one attempt and those technicians who unsuccessfully repaired these vehicles even after several attempts. When interviewing the unsuccessful technician, the lack of basic diagnostic and repair skills was apparent. The need for the continuing education of in-service technicians is critical.

While observing the drivers of the baseline and after-repair tests, many different drivers with varying skills were used to complete the testing. It was noted that no matter how smooth the driver was during the baseline testing, the vehicles failed. It was also noted that no matter how poorly the vehicles were driven during the after-repair tests, the vehicles passed without failure.

It was also determined that a feedback vehicle operating as designed will pass an I/M 240 test. This is true even with low altitude-certified vehicles. Non-feedback vehicles that are certified for low altitude operation will most likely need to be modified. This is especially true if the non-feedback vehicle is a light duty truck.
 

Study Candidates

Refer to the reports that contain the specific data and results of each engine family as well as each study candidate. The information includes individual vehicle data, results of the baseline I/M 240 tests, results of the diagnosis and repair of the vehicle, results of the after-repair tests, results of the FTP tests if applicable, and comments on the overall experience with each vehicle.

Documentation Notes

Accompanying vehicle documentation and the technician guide for this group of vehicles are available in the printed version of this report, available from the Colorado Air Pollution Control Division, 303-692-3126. We plan to add the tech guides to this website as PDF files in the near future.

"Final standards" refers to U.S. EPA recommended final emissions standards. These can be found at the EPA website at www.epa.gov/oms/epg/techguid.htm. Click on the "6/96 Draft Revised IM240 Technical Guidance" item, and go to page 3. Note high altitude standards. You will need Acrobat Reader to view this PDF document. It is free from the Adobe website.

More Info

  Part 1: High Altitude Project Profile
  Part 2: Project Methodology
  Part 3: 1982-86 Chevrolet LDGT 5.0/5.7L; Non-Feedback Quadrajet
  Part 4: 1983-85 Ford LDGT 4.9L; EEC-IV Feedback Carburetor
  Part 5: 1984-85 GM/Jeep LDGT 2.8L; Non-Feedback Varijet
  Part 6: 1984-85 Low Altitude Honda Accord; Carburetor Feedback System
  Part 7: 1985-89 Imports: Hyundai, Mitsubishi, Plymouth; Feedback Carburetor System
  Part 8: 1983-87 Toyota Tercel; Computer Controlled Emissions

Chris Chesney is the owner of Diagnostic Technician Education Consultants (DTEC), 5497 S. Danube Way, Aurora, CO 80015. He can be reached at 720-870-6761 or via email at  chesneydtec@cs.com. Chris has trained hundreds of technicians in I/M 240 diagnosis and repair.