[E90_boostjunky]

Ive been noticing since the weather is getting colder a lot of people are complaining about rough idles etc. Well right when the weather started getting around 40 degrees I noticed my exhaust on the drivers side is rattling non stop when I'm in drive thrus or just waiting at a light but when I put it in park it stops. Any ideas?

[Red_Bean_Bun]

Subscribed ......

[fun2drive]

Driver's side? There is no exhaust over there unless you mean toward the rear.
Suspect you have waste gate rattling or exhaust heat shield failing...

[unrealii]

Check the flap on your left muffler. My car always rattles on cold start (dealer has replaced the muffler twice).

[isteeze]

Its usually the wastegate, or turbos..

[Meeni]

Turbo issue if its at the front, otherwise there is a stupid little flap in the muffler itself for noise management that maybe has failed.

[E90_boostjunky]

Originally Posted by fun2drive

Driver's side? There is no exhaust over there unless you mean toward the rear.
Suspect you have waste gate rattling or exhaust heat shield failing...

Yeah thats what i meant, Drivers side (rear). Its weird, when it rattles i wrap my hand tight around the exhaust tip and it stops rattling then when i release it it rattles again. This rattling only occurs around a cold start, its not everytime.

[E90_boostjunky]

Originally Posted by Meeni

Turbo issue if its at the front, otherwise there is a stupid little flap in the muffler itself for noise management that maybe has failed.

the flap stays open i believe with JB4 it has an option built in, so i dont know why it'd be doing it if the Jb4 is supposed to keep the flap open.

[Meeni]

A flashlight will tell you quickly.

[914kidd]

Its the left muffler flapper valve. BMW replaced mine under warranty.

[Miller335]

Originally Posted by E90_boostjunky

the flap stays open i believe with JB4 it has an option built in, so i dont know why it'd be doing it if the Jb4 is supposed to keep the flap open.

I have the same problem and I have a Jb4 and it's because the JB4 doesn't seem to kick that option in until about 5 seconds or so.

So you get the rattle from it closing, then opening back up with the JB4 on a cold start.

For me, at least it doesn't rattle between shifts when cold with the JB4 option flap turned on cause it did when stock.

I'm quickly learning the only real fix is after market exhaust cause if they put the same one back on it's going to happen again. My 07 E92 only has 25k miles.

[jeffro535]

mine was doing the same, the dealer tightened it up, been fine ever since

[E90_boostjunky]

Originally Posted by jeffro535

mine was doing the same, the dealer tightened it up, been fine ever since

Thanks for the info everyone.