DCT Vibration in certain gear at certain rpm during decel?

[jbraslins]

2010 E90 M3 M-DCT

I've noticed something odd happening to my car. When I decelerate, downshift to 4th and let the car engine brake from ~4300 rpm to ~3900prm range, sometimes I get vibration/noise from what I think is transmission that resembles tire noise/vibration as if you were going over rippled pavement.

It seems to be doing it only in 4th gear, only in that rpm range and only during engine braking. It's definitely not subtle/faint, but not crazy/grinding either.

It happened maybe 3 or 4 times during last 4 month. But this week it happened twice. Makes me a little worried.

I feel it's definitely coming from the driveline though, not suspension/tires.

I hate to go to the dealer with "my car is making this weird noise/vibration" type question, and not being able to reproduce it consistently. Hence asking here first.

Any thoughts?

Thank you.

[jbraslins]

Anyone? Bueller?

[328iSC]

I have a similar noise, that I could not duplicate when I took it to dealer. I hear mine when decelerating\engine braking in any gear. The noise disappeared when I took it into dealer. That was last month while it was still under warranty. Now a month later the noise has returned, but out-of-warranty!

I had a tech ride with me, It sounded like to me it was coming from the rear diff, drive shaft area. When they couldn't duplicate the problem he told me sometimes the AC fan (squirrel cage) in blower is known for getting out-of-alignment and it can cause a noise to come out of the rear AC vents near the back seat, which is where I heard the noise.

I'm not sure if this is my problem, but it looks like another trip back to the dealer is in order, now what do I do if its a transmission problem discovered under warranty and now its out of warranty?

[funan]

op +1, mine start to make similar noise when deceleration, it happens in higher gear mostly 5th at lower rpm ( 1500-2500). The noise sounds similar when you driver over rippled pavement, low pitched rumble. When I shift to neutral the noises goes away, so must be the gearbox that is having issue. Mine's E92 2010, DCT.

[IL8Apex]

Originally Posted by funan

op +1, mine start to make similar noise when deceleration, it happens in higher gear mostly 5th at lower rpm ( 1500-2500). The noise sounds similar when you driver over rippled pavement, low pitched rumble. When I shift to neutral the noises goes away, so must be the gearbox that is having issue. Mine's E92 2010, DCT.

This is exactly what my car started doing, except that it only happens in
D mode. I use D mode only when in stop and go traffic, so i notice it more in the lower gears. In S, it goes away. Low pitch rumble is exactly the right description, like a "whomp, whomp, whomp" sound.

I took it to the dealer for inspection but they told me it was only tire noise. They wanted $ for more thorough inspection but I passed. I'm out of warranty.

Anyone have a good diagnosis?

[jbraslins]

Mine quit doing it. No idea what it was, but I am certain it was not tires.

[IL8Apex]

Originally Posted by jbraslins

Mine quit doing it. No idea what it was, but I am certain it was not tires.

Did you do anything that made it stop? Change fluids, tune, seals, etc?

[jbraslins]

Originally Posted by IL8Apex

Did you do anything that made it stop? Change fluids, tune, seals, etc?

Nope, just went away.