[MonacoTT]

Has anyone noticed a rattle/buzz coming from the undercarriage upon engine RPM deceleration. I.E you are up to some high RPM level, and as soon as you decelerate, you hear a buzzing noise that persists as the RPMs drop.

I did some testing tonight, and it persists until exactly 1100 RPM, then stops.

By leaving it in gear and letting go of the gas it will persist longer (as it takes longer to get to 1100 RPM).

The buzz is something akin to putting a baseball card in your bicycles spokes as a kid, but with a more tin-like note to it.

My guess is it is coming from the exhaust piping somewhere, but this is just speculation...

Took it to the dealer today, and they said they could reproduce it but had no idea what was causing it. They opened a ticket with BMWNA, but don't expect to hear back till next Thursday...

Any ideas?

[johnnymu]

Not sure it's the same noise but I also started getting a rattling noise after I installed my full exhaust, it only comes on at certain RPM. I found out the noise is coming from the slider of my seat to the braket. At certain precise RPM that certain location will start rattling. I applied some dynamat around it and try to realign it. It help a little but unfortunately it started rattling just so slightly just recently, will try to work on it again. Hope you find your solution soon.

[Potty_Pants]

my car is stock.
i noticed a rattling sound around 1500 to 2200 or so.
the noise appeared to be comming from the engine compartment.

noise duplicated on another car in the shop, puma case opened and not addressed.

returned to dealer 4 months or so later and they couldnt duplicate the noise ??? WOW the technician also had a manual 335i with the rattle... when i picked up my car the rattle was gone ???? hasnt returned.

only thing that has changed is the cold North east weather.

fwiw shop stated it was a harmonic problem with the transmission and wouldnt affect anything.

no further action taken at this point.

ppp

[MonacoTT]

For for the replies guys.

Yeah I'm hoping its something harmless.

Still annoying nonetheless. I'm taking it in to a different dealership tomorrow. Will let you know if they find anything.

[wantmye90]

Could it be a heat shield on the exhaust?

[MonacoTT]

Originally Posted by wantmye90

Could it be a heat shield on the exhaust?

Sounds likely... hard to say. Wish I had a hydralic lift of my own so I could check it out.

Didn't get to to into the dealer just yet, but I will ask them to check the heat shields as well, maybe add some of that felt tape they use to stop rattles.

[csupernova]

I can heard rattle noise when my engine is idling. Damn annoying!

[FNV]

I had the same noise...and after numerous attempts by the dealer to fix it, they were unsuccessful. They said it was the heat shield...anyway long story short I took the car to a different dealer and they said it was the exhaust brackets that was making the rattling noise....I'm still waiting for them to come in...and yes once the cold weather hit the noise was gone.
It seemed it only happened when it was really hot or driving through the drive-thru...rattling noise was audible from the noise bouncing off the wall.

[doba_s]

Originally Posted by johnnymu

Not sure it's the same noise but I also started getting a rattling noise after I installed my full exhaust, it only comes on at certain RPM. I found out the noise is coming from the slider of my seat to the braket. At certain precise RPM that certain location will start rattling. I applied some dynamat around it and try to realign it. It help a little but unfortunately it started rattling just so slightly just recently, will try to work on it again. Hope you find your solution soon.

+1 on that ... the same problem here

[MonacoTT]

Went to the dealer today. They told me the problem is the wastegate on one of the turbos.

They are waiting for a response from engineering on the east coast, and may or may not replace both wastegates (he said even a possibility of replacing the turbos? Sounds like overkill to me, but hey, free new turbos sounds great).

Will let you know how this went.

[3thirty5]

I have a rattling issue was well, but mine seem to be coming from inside the cabin, and it only happens between 2000-3000rpm under moderate to hard acceleration.

[dth656]

guys, any update on the 1100-2200 RPM rattle? i have an e90 330i, so i know it cant be a wastegate; i was thinking that perhaps its exhaust related. its very intermittent, and sounds somehwat like a ratchet being spun quickly...

[mtn335xi]

I think I have the same rattle. It seems to come from right under the i-drive area. Rattles at idle and acceleration. Is it exhaust? How did you guys fix this? Dealer?

[fuzzy123]

at a certain rpm i get rattle/vibration here::

[down boy]

I heard a metallic rattling/spinning today from the undercarriage. It was loud and lasted for several seconds. I had only been driving for a few minutes at low speeds. It sounded like a metal trashcan lid spinning to a stop, or like a metal wire being dragged underneath the car. I was on a quiet road so I pulled over and quickly looked underneath to see if I was dragging something and didn't see anything, but I might have missed it because I just gave it a quick look. Then, when I got back in and drove again, it sounded as if whatever was dragging dropped away and the car stopped rattling. I even looked behind me to see if anything was left on the road but didn't see anything, so I assume it was internal, and not actually something being dragged underneath. Kinda freaky, and I hope I don't hear it again.

[two30i]

I have the same rattling sound and I took it to the Fremont dealership. The head mechanic did a road test with me and luckily the rattling sound was very audible. Today I received a call from my service advisor and told me that it was my catalytic converter that was making the sound. They're replacing it and I should be getting my car back tomorrow.

[clspruiell]

Originally Posted by fuzzy123

at a certain rpm i get rattle/vibration here::

I get the same rattle here. It's very annoying and im not sure how to fix it.

The loud rattle that the OP is talking about might be part of the factory exhaust tune.

I often times get a rattle that sounds like something is loose when i crank the car. I think its a loose pipe fitting somewhere but it generally goes away after start up.

[Chriztofor]

Originally Posted by MonacoTT

Has anyone noticed a rattle/buzz coming from the undercarriage upon engine RPM deceleration. I.E you are up to some high RPM level, and as soon as you decelerate, you hear a buzzing noise that persists as the RPMs drop.

I did some testing tonight, and it persists until exactly 1100 RPM, then stops.

By leaving it in gear and letting go of the gas it will persist longer (as it takes longer to get to 1100 RPM).

The buzz is something akin to putting a baseball card in your bicycles spokes as a kid, but with a more tin-like note to it.

My guess is it is coming from the exhaust piping somewhere, but this is just speculation...

Took it to the dealer today, and they said they could reproduce it but had no idea what was causing it. They opened a ticket with BMWNA, but don't expect to hear back till next Thursday...

Any ideas?

Maybe this is your problem, check out this link http://www.e90post.com/forums/showth...ht=exhaust+fix

[Brian_TII]

Originally Posted by Chriztofor

Maybe this is your problem, check out this link http://www.e90post.com/forums/showth...ht=exhaust+fix

I had this same exact problem... I actually believe it's the bolt that stretches cause mine didn't seem bent at all. I just replaced the bolt and nut at the top and haven't had any issues since.

[clspruiell]

Update: SA called to tell me about my injectors blowing. He investigated the rattle. Its not an undercarriage flap. Guess who needs a new tranny... Me.