Attachment Bulletin # 010207
Group: 01Number: 02-07
Date: Sept. 30, 2002
Subject:
Diagnosis of Driveability Complaints on Turbo Charged Engines
Model(s):
TT, S4 A6, Turbo (Drive by wire) 2000 --> 2003
A4 with 1.8T (Drive by wire) 2000 --> 2003
Condition
Mass Air Flow (MAF) sensor incorrectly replaced due to rough idling, vehicle hesitation, car lacks power, multiple misfires or the following DTCs stored in DTC memory:
P0103, P1111, P1112, P1128, P1130, P1144, P1145, P1146, P1147, P1148 or P1557
All of the listed DTCs except P1144, P1145 and P1146 may be caused by air leaks in the pressure side air duct.
Service
Before replacing the (MAF) sensor, on turbocharged vehicles with Electronic Throttle Control (Drive by Wire), check the table shown according to DTC.
To help determine if an air leak exists on vehicles with Electronic Throttle Control (Drive by Wire only):
- Check Measuring Value Block Display groups 032 (for 2.7L BiTurbo and 1.8L Turbo) and Display group 204 (Biturbo only) with the VAS 5051 or VAS 5052 Diagnostic tool as follows:
For 2.7L BiTurbo and 1.8L Turbo
- From VAS 5051 Start-up screen, select "Vehicle self diagnosis".
- Select Diagnosis function "01-Engine electronics".
- Select Diagnosis function "04-Basic settings".
- Input 032 on keypad to select "Display group 032"
- Select "Q" button to confirm.
For 2.7L BiTurbo
- Channels 2/4 (adaptation values) are normally between -7% and +7%.
If channels 2/4 are below -7% (e.g. -10%):
These values indicate system is richer than normal (due to the engine getting less air than measured by the MAF sensor)
For 1.8L Turbo
- Channel 2 (adaptation value) is normally between -10% and +10%.
If channel 2 is below -10% (e.g. -15%):
These values indicate system is richer than normal (due to the engine getting less air than measured by the MAF sensor)
- Check for air leaks in pressure side air duct using VAG 1687 Diagnostic Tool as outlined in Technical Bulletin Group 01 Number 01-01 dated Oct. 26, 2001.
For 2.7L BiTurbo only
- Select Diagnosis function "04-Basic settings".
CAUTION!
Use a second Technician when performing the following road test!
- Input 204 on keypad to select "Display group 204".
^ Road test vehicle at full load between 2500 and 4000RPM in 3rd or 4th gear.
- Select "Q" button to confirm.
- If channel 2 (black arrow) is more than 70mbar higher than channel 4 (white arrow):
- Check for air leaks in pressure side air duct using VAG 1687 Diagnostic Tool as outlined in Technical Bulletin Group 01 Number 01-01 dated Oct. 26, 2001.
If no leaks are found:
- Check fuel quality, drain fuel and replace with a quality Premium fuel as necessary (only with engine running rough).
- Check connection and condition of vacuum hose to fuel pressure regulator (located in fuel rail).
- Check fuel pressure regulator and replace if necessary (see Repair Manual, Repair group 24).
- Check coolant temperature sensor -G62- and replace if necessary (see Repair Manual Fuel Injection & Ignition Repair Group 01).
- Inspect air filter for proper installation and replace if damaged.
- Check flange connection between turbo charger and exhaust pipe for leaks.
- Check for sufficient fuel supply (consider DTC P1250).
If No leaks are found in the pressure side air duct and additional checks have been performed with No cause found and:
- In Display group 032:
^ If channels 2/4 (arrows) are over +7%
^ Symptom indicates the MAF sensor requires replacement:
If No leaks are found in the pressure side air duct and additional checks have been performed with No cause found and:
In Display group 204 (Biturbo only!):
If Channel 2 (black arrow) is more than 70mbar less than channel 4 (white arrow).
- If channel 2 (black arrow) is over 70mbar less than channel 4 (white arrow):
^ Symptom indicates the MAF sensor requires replacement:
If No leaks are found in the pressure side air duct and additional checks have been performed with No cause found and:
If the DTCs shown still exist.