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      07-06-2019, 05:27 PM   #1
toshiw
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Drives: e90 330xi
Join Date: Apr 2019
Location: Brooklyn, ny

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SOLVED E90 335xi Shudder on Acceleration ó Totally Stumped!

Hi everyone ó I have a 2007 e90 335xi acceleration shudder issue that I have been trying to solve for a couple months. Iíve done extensive research, many repairs and am totally stumped! Iím hoping that an expert out there can point me in the right direction.

SYMPTOMS:
The car shows classic symptoms of a bad transfer case ó very noticeable vibration / shudder / shake in high torque situations at all speeds and RPMs. When the transfer case actuator is disconnected and the car is RWD only, the problem completely disappears. Following the SI B27 04 15 bulletin, this seemed to point directly to the transfer case. However, I have now replaced the transfer case twice and the issue remains. OEM transfer case fluid was used and the actuator was re-initialized after replacement. There is no MIL light and no codes present.


REPAIRS:
I have a skilled independent mechanic working on the car. He started by diagnosing the driveline and in the process replaced the following: rear differential, rear drive shaft, center support bearing, gumbo, front driveshaft. This eliminated some driveline noise I was experiencing but did not resolve the shuddering issue.

I purchased the car with the shudder issue present and the previous owner made some repairs in an attempt to find a solution. His repairs included: motor mounts, front cv axles (non-oem), factory spec tires. In addition the motor was completely rebuilt in the last 30k miles with all new accessories.

The car has KW V1 coil overs and a mechanic told the previous owner that he should revert back to OEM suspension and OEM front axles.

CONCLUSION:
Given that the issue goes away when the actuator is disconnected, it seems to me that the engine can be totally ruled out of the equation. I have a 2006 330xi in addition to the 335xi so if you have any diagnostic suggestions that involves a comparison, that option is available.

I was going to start looking into the carís software to see if at some point a tuner tweaked the AWD power distribution ó this seems like a stretch but Iím getting a bit desperate and it seems like something worth ruling out. I am considering purchasing the xDelete software that can flash the ECU between AWD and RWD.

I really love this car and am set on fixing it, Iíve seen a lot of posts on this issue but nothing quite describing my situation. Iím happy to document and provide any info that comes to light as a result of my efforts and I hope that this might help others in the future.

Thanks kindly in advance!

Last edited by toshiw; 09-22-2019 at 06:37 PM..