Cold start exhaust rattle

ccdre · 07-25-2015, 12:31 PM

My 135i developed this somewhat annoying cold start rattle. It's a short burst of noise that goes away quickly but it's loud enough to turn one's head for the wrong reasons.

Any idea what this is? (hopefully you can access the clip.. if not, i'll re-upload to youtube or elsewhere)

Thanks!

https://clyp.it/search?type=hashtag&query=ExhaustRattle

BigRussia · 07-25-2015, 12:36 PM

I was going to post without even listening to the clip that I know that sound and its from the CAN flap in the muffler closing on cold start. When I did the gold tee mod to keep it open I never heard the rattle again. I heard your clip and yep I was right lol.

If you want to do the golf tee mod I suggest going to your local Advance or Autozone buy some vacuum caps, pulling off the vacuum hose from the flap actuator and placing a too tight cap over the flap nipple to where the cap will act as a nipple, then you can put the hose back onto it, and viola! vacuum hose plugged and without it being noticeable or having to deal with jamming golf tees and screws into the hose or going into the trunk.

ccdre · 07-25-2015, 12:39 PM

Quote:

Originally Posted by BigRussia

I was going to post without even listening to the clip that I know that sound and its from the CAN flap in the muffler closing on cold start. When I did the gold tee mod to keep it open I never heard the rattle again. I heard your clip and yep I was right lol.

Thanks BR! I guess it's time for the golf tee... lol

ccdre · 07-25-2015, 01:11 PM

For those of you that had the BMW PE installed by dealer, what did they do with the vacuum line? My understanding is that the PE does not have this flap.

Esteban · 07-25-2015, 02:04 PM

Quote:

Originally Posted by ccdre

For those of you that had the BMW PE installed by dealer, what did they do with the vacuum line? My understanding is that the PE does not have this flap.

My exhaust shop folded the vacuum line once and then tied it with two small zip ties. Very neat. Rogers Exhaust Shop in Fontana. Does great work and I recommend him to everybody. Will only go to Rogers for exhaust work.

Andrewcoja · 07-26-2015, 07:48 AM

You don't want to dig around with the vacuum line, pull off the cover behind your left tail light then pull back the trunk liner a bit on the side of the trunk. There's a wiring harness in there with a connector you can take apart. That powers the flap. When you unplug it, the flap stays open. Some people say it throws a hidden code but I've never seen anything when checking with BMWhat and the dealership has never said anything. I know it's not really your problem as you probably don't have a warranty anymore. But for anyone who does, it's easier to explain a way a wiring harness that came unplugged than a disconnected and sealed up vacuum line. Some dealerships will look at that and try to claim it caused some other issue.

ccdre · 07-26-2015, 04:05 PM

I think I'm slowly trying to justify getting a performance exhaust or at least a performance muffler which will undoubtedly resolve the flapper problem as well.

ccdre · 07-29-2015, 08:05 PM

Alright everybody, thanks for the tips - the cold start rattle is now gone! I opted to just unplug the connector in the trunk - took about 2 minutes and that's including the time trying to figure out how to hold my iphone flashlight with one hand while getting behind the carpet with the other.

mr.fabulous · 08-02-2015, 08:52 AM

Quote:

Originally Posted by Andrewcoja

You don't want to dig around with the vacuum line, pull off the cover behind your left tail light then pull back the trunk liner a bit on the side of the trunk. There's a wiring harness in there with a connector you can take apart. That powers the flap. When you unplug it, the flap stays open.

Sorry, confused. The trunk liner is a molded piece. Did you remove the fasteners and pull the whole side?

07-25-2015, 12:31 PM	#1
ccdre Lieutenant 337 Rep 404 Posts Drives: '10 AW 135i, '13 Frozen M3 Join Date: Jun 2015 Location: NorCal iTrader: (1)	Cold start exhaust rattle My 135i developed this somewhat annoying cold start rattle. It's a short burst of noise that goes away quickly but it's loud enough to turn one's head for the wrong reasons. Any idea what this is? (hopefully you can access the clip.. if not, i'll re-upload to youtube or elsewhere) Thanks! https://clyp.it/search?type=hashtag&query=ExhaustRattle
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07-25-2015, 12:36 PM	#2
BigRussia Captain 152 Rep 984 Posts Drives: 04 M3 Join Date: Nov 2014 Location: SFL iTrader: (5)	I was going to post without even listening to the clip that I know that sound and its from the CAN flap in the muffler closing on cold start. When I did the gold tee mod to keep it open I never heard the rattle again. I heard your clip and yep I was right lol. If you want to do the golf tee mod I suggest going to your local Advance or Autozone buy some vacuum caps, pulling off the vacuum hose from the flap actuator and placing a too tight cap over the flap nipple to where the cap will act as a nipple, then you can put the hose back onto it, and viola! vacuum hose plugged and without it being noticeable or having to deal with jamming golf tees and screws into the hose or going into the trunk. __________________ 2004E46M36MTCBCinn 'Clubsport'
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07-25-2015, 01:11 PM	#4
ccdre Lieutenant 337 Rep 404 Posts Drives: '10 AW 135i, '13 Frozen M3 Join Date: Jun 2015 Location: NorCal iTrader: (1)	For those of you that had the BMW PE installed by dealer, what did they do with the vacuum line? My understanding is that the PE does not have this flap.
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07-26-2015, 07:48 AM	#6
Andrewcoja First Lieutenant 9 Rep 385 Posts Drives: 2011 135i MSport Join Date: Aug 2013 Location: Texas iTrader: (0)	You don't want to dig around with the vacuum line, pull off the cover behind your left tail light then pull back the trunk liner a bit on the side of the trunk. There's a wiring harness in there with a connector you can take apart. That powers the flap. When you unplug it, the flap stays open. Some people say it throws a hidden code but I've never seen anything when checking with BMWhat and the dealership has never said anything. I know it's not really your problem as you probably don't have a warranty anymore. But for anyone who does, it's easier to explain a way a wiring harness that came unplugged than a disconnected and sealed up vacuum line. Some dealerships will look at that and try to claim it caused some other issue.
	Appreciate 0 Quote

07-26-2015, 04:05 PM	#7
ccdre Lieutenant 337 Rep 404 Posts Drives: '10 AW 135i, '13 Frozen M3 Join Date: Jun 2015 Location: NorCal iTrader: (1)	I think I'm slowly trying to justify getting a performance exhaust or at least a performance muffler which will undoubtedly resolve the flapper problem as well.
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07-29-2015, 08:05 PM	#8
ccdre Lieutenant 337 Rep 404 Posts Drives: '10 AW 135i, '13 Frozen M3 Join Date: Jun 2015 Location: NorCal iTrader: (1)	Alright everybody, thanks for the tips - the cold start rattle is now gone! I opted to just unplug the connector in the trunk - took about 2 minutes and that's including the time trying to figure out how to hold my iphone flashlight with one hand while getting behind the carpet with the other.
	Appreciate 0 Quote