Tom84

Hi all, I'm new here so I'll start with a short introduction. I'm Tom, I live in Belgium, Europe. I bought my first BMW about 2 months ago, an '08 E61 520d Steptronic. Frankly I hate diesels. But with gas prices and taxes the way they are where I live, it would be ridiculous for me to do my 100+ mile/day commute with anything else :thumbsdown:

http://dl.dropbox.com/u/679898/BMW/P...0%28HDR%29.jpg
http://dl.dropbox.com/u/679898/BMW/P...%2044%2006.jpg


Anyhow, in an effort to get some more mileage and driving pleasure out of my 163hp (The Belgian version is downtuned from 177hp for tax purposes...) diesel, I got the ECU remapped. So now my car puts out 206hp and 310lbs/ft of torque on the dyno, which is quite an improvement. However this improvement came with an inconvenience (the company that did the remap is still working with me on this so I'm not -yet- getting ripped off ) :

In 3rd and in 5th gear, with the throttle 50-100% down (no kickdown) and only at 2300-2700rpm I often get a droning noise coming from the back of the car. Passengers can feel the backseat vibrating so I presume it's coming from the diff. The harder I accelerate, the lesser this occurs. It never happens during kickdown as the rpm is kept above 3000.

It doesn't show on the dyno curve, and while driving I only hear and feel the vibration. The torque peaks at just below 2000rpm, so if this was a problem of too much torque you would expect it to be earlier, and in all the gears.


Can anyone tell me how the gearbox/diff/driveshaft are fitted to the body, are there rubber mounts that could be worn so they can't absorb the increased vibrations? Enlighten me

Thanks in advance!

turboawd

i'm going to guess the problem is your exhaust drone.

a differential vibration would be more uniform and consistent with road speed...regardless of which gear you are in.