Engine Controls - Evaluating Fuel Mixture DTC's
01 07 49May 18, 2007
2010558 Supersedes T.B. Group 01 number 07-19 dated Feb. 9, 2007 due to update of illustrations and addition of City Golf, City Jetta Models.
Affected Vehicles
Condition
Evaluating Fuel Mixture DTCs - How to Perform Effective Diagnosis Related to Fuel System Adaptation - System Too Rich/Too Lean
This technical bulletin applies to fuel mixture related DTCs only (i.e. system too lean or system too rich). All other engine management DTCs should be diagnosed and eliminated before proceeding.
Technical Background
This technical bulletin guides the technician through a procedure to establish a "before-repair" mixture adaption baseline. You will repeat this procedure "after-repair" and compare mixture values results to determine whether the repair was successful.
Production Solution
No production change required.
Service
Requirements
^ Oxygen sensor control catalyst is functioning properly. Refer to ElsaWeb or Guided Fault Finding for correct component or function check.
^ Engine operating temperature of minimum 80°C (176°F).
^ Clean vehicle snow screen, if installed.
Before-Repair Diagnosis
Part 1 - Evaluating fuel system condition at idle:
^ Connect the VAS 5051/5052 Diagnostic tool.
^ Switch ignition ON.
^ Select "Vehicle Self Diagnosis".
^ Interrogate and erase fault memory.
^ Select Diagnosis Function "006 - Basic settings".
^ Input "32" on keypad to select "Display group 32".
^ Select "Q" button to confirm.
^ If required, Press the "Activating" button to initiate testing -arrow-.
^ Allow motor to idle for 5 minutes.
^ Print Display group 32 values after 5 minutes.
This is the value used to evaluate the fuel system at idle.
Part 2 - Evaluating fuel system condition at part load:
Tip:
The following part of the procedure requires driving. During driving channel 1 values may change further, these changes are to be ignored.
NOTE:
For safety reasons, a second person should sit in the back seat and operate the scan tool.
^ Select Diagnosis Function "006 - Basic settings".
^ Input "32" on keypad to select "Display group 32".
^ Select "Q" button to confirm.
^ If required, Press the "Activating" button to initiate testing -arrow-.
^ Reset instrument cluster trip meter.
^ Drive vehicle for approx. 10 minutes.
^ Speed should be a minimum of 35 MPH and an appropriate gear should be selected to maintain at least 2000 RPMs.
^ After 10 minutes, the minimum distance driven should be at least 4 miles.
^ If necessary, continue driving until 4 miles are indicated on the trip meter.
^ Print Display group 32 values.
^ "Before-repair" baseline is complete.
Troubleshooting tips for mixture related DTCs based on MVB 032 results
NOTES:
Values in the table shown correspond only after performing procedures outlined in this technical bulletin. Utilize Guided Fault Finding or the Repair Manual for details to the suggested checks.
Perform checks in order listed, until cause is determined.
NOTE:
Do not replace Mass Air Flow connector terminals unless visible signs of damage are present.
After-Repair Diagnosis
^ Erase DTC memory to reset values to 0.
^ Repeat "Part 1 - Evaluating fuel system condition at idle".
^ Repeat "Part 2 - Evaluating fuel system condition at part load".
NOTE:
It is important to perform the driving portion exactly the same using the same route initially used.
Evaluating Repair
1. Correct Display group 32 values:
Channel 1 -black arrow- = 0 3% (evaluated after Part 1 completed).
Channel 2 -white arrow- = 0 10%.
2. Required improvement values:
Channel 1 improvement from before-repair reading must be at least 1.5%.
Channel 2 improvement from before-repair reading must be at least 5%.
A repair should bring Channel 1 and Channel 2 values into correct range and improve values by the amount indicated.
Examples:
Improvement values OK. Displayed value not OK.
Before-repair, Channel 2 value = 16.0%.
After-repair, Channel 2 value = 11.0%.
The repair has improved the value by 5.0%, but the 11.0% displayed value is still not within the correct range of 10%.
Displayed values OK. Improvement value not OK.
Before-repair, channel 2 value = 11.0%.
After-repair, channel 2 value = 8.0%.
The repair brought the displayed value of 8.0% into the correct range but has not achieved the required 5.0% improvement.
Displayed values OK. Improvement value also OK.
Before-repair, channel 2 value = 13.0%.
After-repair, channel 2 value = 6%.
The repair brought the displayed value of 6% into the correct range and has improved the value by at least 5%.
Above examples are for Channel 2 only. Channel 1 range is 3% and required improvement is 1.5%.
Warranty
Claim allowable A-Time per Warranty Policies and Procedures Manual and applicable Service Circulars.
Required Parts and Tools
No Special Parts required. Always see ETKA for the latest parts(s) information.
No Special Tools required.
Additional Information
All part and service references provided in this Technical Bulletin are subject to change and/or removal. Always check with your Parts Dept. and Repair Manuals for the latest information.