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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Sound in exhaust



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      10-26-2011, 11:50 AM   #1
T335iQ
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Sound in exhaust

Hey guys,

I have a concern with my 08 335i coupe 6sp, every time I start her up with my windows down, 20seconds into the start up and I hear some sort of sound around my exhaust tips. It feels like some sort of backfire or like a piece of metal is crackling around. Is this normal? The BMW dealership told me that\'s how all cold starts sound on 335i.
What do you think? Also a small concern with hearing a light noise with my clutch when I\'m braking, they said its normal as well.
Some insight is much appreciated.thanks
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      10-26-2011, 11:54 AM   #2
flip4335
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Quote:
Originally Posted by T335iQ View Post
Hey guys,

I have a concern with my 08 335i coupe 6sp, every time I start her up with my windows down, 20seconds into the start up and I hear some sort of sound around my exhaust tips. It feels like some sort of backfire or like a piece of metal is crackling around. Is this normal? The BMW dealership told me that\'s how all cold starts sound on 335i.
What do you think? Also a small concern with hearing a light noise with my clutch when I\'m braking, they said its normal as well.
Some insight is much appreciated.thanks
On a cold start, flap on driver side is closed. After warmup, flap opens to provide exhaust at both tips. The sound you hear is the flap opening = Normal.
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      10-26-2011, 12:04 PM   #3
Beemw335
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Go to the back of your car, bend down and look at the left exhaust pipe. Youll notice a flap, now have a budyy of your start the car, youll then see this flap close.
Incase youre wondering what it is there for, it is there to reduce exhaust sound during cruise, over 3500 rpm the flap opens up to make the exhaust louder.
If you want this flap to remain open all the time and make your car louder during cruise then search up golf tee mod.
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      10-26-2011, 01:38 PM   #4
JO3
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Sounds like the exhaust flap.

Try doing the diy here (it only takes 2 minutes): http://www.e90post.com/forums/showthread.php?t=80661

and see if that gets rid of your rattle. If it does, and you don't mind the extra sound, you're good to go. If you don't like the sound, people have taken their cars back to the dealer and have successfully gotten their exhaust replaced under warranty.
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      10-26-2011, 06:54 PM   #5
T335iQ
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appreciate it guys!
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      10-26-2011, 06:59 PM   #6
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Quote:
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appreciate it guys!
Give it a shot and report back if you perceive any gain or loss of performance. No doubt it sounds louder, the growl on cold starts is to die for especially if garaged.
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