Advice on torque converter / diff
I have a 2012 120d E82 (Coupe) Auto 174BHP (Remapped to 219BHP) with 20,000 miles.
- mapped and dyno tested (before and after) by a very reputable tuner 2 months ago. He came recommended by many users on this forum.

The car is developing a very deep rumble/vibration under fairly heavy load in high gears. Most evident when increasing from around 65mph to 70mph in top gear (D mode - sixth). Only lasts for a few seconds and goes away suddenly as the revs increase.
Best way of describing it is if you were to hit a short patch of rumble strip at speed.
There's no drop in power, and lock up clutch appears to be absolutely fine.

The tuner, who has mapped 100's if not 1000's of 2litre diesel BMW engines without problem has pointed to a potential torque converter fault?
An independent BMW specialist garage has road tested and checked out the underneath of the car and can't see anything obvious, except for the rumble..
Another independent specialist (who was an ex-bmw technician) has advised has never heard of torque converter failing on car with 20,000 miles! And has mapped 120d autos to more power without any issues. Has said that it could be a problem with the diff.

Has anyone heard of this before? I'm stuck at the moment between blaming the remap, or blaming an existing fault on the car!?



- I don't know how relevant this is, but if the gearbox is switched over to manual, I can't recreate the issue in 6th gear at all.
And when it starts vibrating in D, if I flick the right paddle to engage manual 6th gear, it stops.
It still shows up in 3rd to 4th gear under heavy accelleration.


Thanks,
Jamie