A/T - Bucking On Acceleration at 10-50% Throttle
Bucking When Accelerating from a Standstill
38 06 02 Oct. 12, 2006, 2012003/6. Supersedes Technical Service Bulletin Group 38 number 06-01 dated Oct. 5, 2006 due to updated information.
Condition
Vehicle bucking when accelerating at 10 to 50% throttle from a stand still, sometimes with fluctuating engine speed.
Technical Background
Not Applicable
Production Solution
Not Applicable
Service
It is not necessary to receive an authorization number from the Technicians Helpline for the repairs described in this bulletin.
Attach 5051 printouts to repair order. Warranty requested documents received without 5051 printouts will be denied payment.
1. Perform the following steps to confirm that the ATF temperature is a minimum of 65 degrees C:
a. In VAS 5051/5052 Select Vehicle Self Diagnosis >> 02 - Gearbox electronics >> 08 - Read measuring value block
b. Input MVB 10 on keypad, select "Q" to confirm and observe display position 3
c. ATF must be minimum of 65 degrees C
2. With the ATF at minimum of 65 degrees C, carefully operate vehicle in an open space (clear of traffic and obstacles) as follows:
a. Accelerate from a stop on a light upgrade with 10 to 30% acceleration displayed in MVB 9, position 1
b. Drive with the hand brake pulled up two notches
c. After a few yards, the shudder should occur shortly before the clutch engages
d. After the clutch engages, the shudder goes away
- At a constant speed in Tiptronic 4th gear below 2000 RPM, the shudder may occur every 5 seconds due to clutch control.
- At a constant speed in Tiptronic 3rd gear above 2000 RPM, the shudder should not occur.
Stop the vehicle:
a. Ensure that the transmission gear oil is at a minimum of 65 degrees C
b. Read MVB 12 and calculate the difference between position 1 and position 2 (make a note of this value)
c. Read MVB 10, position 1 (make a note of this value)
d. If MVB 10, position 1 is below 220mA (2005 and later model years - below 250 mA) the ATF cooling system may be plugged
e. Clean the cooling pipes and thoroughly flush out the ATF components
f. Replace the external ATF filter. Refer to Group 37, Automatic Transmission - Controls, Housing in the Repair Manual for complete external ATF filter replacement instructions
If the condition is resolved: No additional work is required.
If the difference between MVB 12 position 1 and MVB 12 position 2 is below 65mA, or to a negative value, and if MVB 10, position 1 is below 300mA (2005 and later model years - below 350mA):
- Replace the 6 plate clutch pack with a new 6 plate clutch pack, refer to Group 38: Input shaft servicing with 6 lining discs, for complete instructions.
- Parts must be ordered individually. A parts kit is not available for the 6 clutch plate application.
All necessary parts and tools to complete clutch plate repair are listed in the "Required Parts and Tool" section of this publication.
If MVB 10, position 1 is above 300mA (2005 and later model years = 350mA)
- Replace the transmission.
If the clutch plates are replaced, the ATF must be flushed by performing the following steps:
1. Drive the vehicle onto a lift and ensure that the vehicle is secure to the lift
2. Raise the vehicle until all 4 wheels are approximately 8 inches OFF the ground and ensure that all 4 wheels rotate freely
WARNING: observe all workplace and vehicle lift safety guidelines in order to reduce the risk of serious personal injury or death.
Note: Never operate the vehicle without ATF. DO NOT exceed 35 MPH while operating the vehicle on the lift.
4. In Tiptronic mode, shift from first to top gear and accelerate moderately after each shift
5. Shift the transmission back down into first gear
6. Carefully apply the brake pedal in order to stop the wheels from rotating 6.With the brake pedal firmly applied, shift the transmission into "R"
7. Release the brake pedal and moderately accelerate to approximately 12 MPH
8. Carefully apply the brake pedal in order to stop the wheels from rotating
9. Return the gear lever to "D" and repeat steps 1 through 8 five times
10. Place the gearshift lever into "P" and turn OFF the engine
11. Change the ATF according to the instructions in Group 37, Automatic Transmission Controls, Housing in the Repair Manual
12. Repeat steps 3 through 11 a second time.
Now adapt the Transmission Control Module (TCM).
1. First perform step 1 from the beginning of this bulletin in order to confirm that the ATF is at a minimum 65 degrees C.
2. With the ATF at a minimum 65 degrees C, carefully operate the vehicle in an open space (clear of traffic and obstacles)
3. Shift vehicle into "D"
4. Drive forward at part load approximately 10 meters (33 feet), then apply brake pedal to a stop and continue to apply brake pedal for approximately 10 seconds
5. Shift vehicle into "R"
6. Release brake pedal
7. Drive backwards at part load approximately 10 meters (33 feet), then apply brake pedal to a stop and continue to apply brake pedal for approximately 10 seconds
8. Repeat steps 1 - 7 (alternating between "D" and "R" ) five times
9. Completed adaptions can be viewed in MVB 10 and 11, position 2
Warranty
Required Parts and Tools
Additional Information
The following repair procedures will be necessary to complete this procedure:
- Change ATF: Group 37, Automatic Transmission Controls, Housing in the Repair Manual
All part and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Dept. and service manuals for the latest information.