Exhaust/Butterfly Valve Rattle?

pdjafari · 09-17-2008, 10:00 AM

So I've noticed the last couple days (colder mornings 60-65F) that upon starting my car that the exhaust (drivers side) rattles/buzzes and after a couple minutes (once the butterfly valve opens) the rattle is gone.

Just wondering if this is normal and if anybody else has this problem? I thought at first it was my wastegates, however Ive noticed almost all the sound is gone once my butterfly valve opens....

BTW I am stock except for GP thunders, OEM SSK, HR Sport Springs and painted reflectors (oh and 30% tint lol)

hun77777 · 09-17-2008, 10:04 AM

does it rattle on D and goes away on N ?

Brianbmwboy · 09-17-2008, 10:13 AM

I have same issue, dealer told me pretty common on these cars and nothing to worry about. I have noticed for about the last 3 months and has not gotten worse.

Zeph · 09-17-2008, 10:47 AM

pretty sure the driver's side exhaust valve only opens when WOT and revving it up. Not sure why warming the car up would matter... as far as the valvle goes. You are at higher RPM's when cold idling, which could be causing something loose to rattle on your exhaust somewhere. Pretty weird.

zsapphire7 · 09-17-2008, 11:05 AM

Actually i just had this fixed. I brought it into the dealer thinking that i had the waste gate rattle but most of the sound came from the rear. At the beginning of summer it was just during cold starts but I took a drive out in the mountains and under moderate acceleration, fully warmed up, I can hear it tick from 1.5k to 3k rpm. It got worse over time and when i took it in, they said that i had a faulty muffler and replaced just the left side. So far 1 week driving and no more ticking noises

pdjafari · 09-17-2008, 11:34 AM

Quote:

Originally Posted by Zeph

pretty sure the driver's side exhaust valve only opens when WOT and revving it up. Not sure why warming the car up would matter... as far as the valvle goes. You are at higher RPM's when cold idling, which could be causing something loose to rattle on your exhaust somewhere. Pretty weird.

ummm, the butterfly valve closes one of the 2 chambers and opens once the car has warmed up. Many ppl speculate why this is, (warm up cats) etc but in case you've never noticed, on a cold morning go outside and start. Notice how the condensation/steam only exits one of the 2 muffler tips...

Blue Streak · 09-18-2008, 12:40 AM

Yeah... Why is that? What's the purpose of that butterfly valve in the left muffler? I disconnected that plug in the left side in the trunk to keep the valve open at all times. I heard that it's only purpose was to keep the car quieter at idle and low RPM's - for more of a "luxury sound" or something.

pdjafari · 09-18-2008, 12:44 AM

^^thats possible, I read some threads on here about it. Some ppl said the same thing, its for sound purposes, but others believe it serves a purpose (like to warm up your cats) not sure what purpose that serves...

AV9 · 09-18-2008, 04:25 PM

ya i hear something to...ever since i unplugged that thing in the trunk ("golf tee")...

how does it get fixed?

TiAg335i · 09-18-2008, 04:35 PM

Mine rattles when I can hear it open and close, but other than that I do not hear anything buzzing or rattling coming from the exhaust.

StarrDlux · 09-19-2008, 06:05 AM

probably sourced the wastegate from the same folks. ditto the rattle made me look for a few days. definitely something that has developed

09-17-2008, 10:00 AM	#1
pdjafari Colonel 153 Rep 2,468 Posts Drives: G80 M3C Join Date: Oct 2007 Location: Earth iTrader: (5)	So I've noticed the last couple days (colder mornings 60-65F) that upon starting my car that the exhaust (drivers side) rattles/buzzes and after a couple minutes (once the butterfly valve opens) the rattle is gone. Just wondering if this is normal and if anybody else has this problem? I thought at first it was my wastegates, however Ive noticed almost all the sound is gone once my butterfly valve opens.... BTW I am stock except for GP thunders, OEM SSK, HR Sport Springs and painted reflectors (oh and 30% tint lol)
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09-17-2008, 10:04 AM	#2
hun77777 Brigadier General 198 Rep 4,647 Posts Drives: SG E92 Join Date: Nov 2007 Location: Seattle WA iTrader: (58)	does it rattle on D and goes away on N ?
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09-17-2008, 10:13 AM	#3
Brianbmwboy Private 5 Rep 81 Posts Drives: 2022 M3 Comp X-drive Join Date: Mar 2008 Location: Spokane Washington iTrader: (0)	I have same issue, dealer told me pretty common on these cars and nothing to worry about. I have noticed for about the last 3 months and has not gotten worse.
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09-17-2008, 10:47 AM	#4
Zeph Major 27 Rep 1,410 Posts Drives: 2008 E92 335i 6MT SGM CR/BD Join Date: Jul 2008 Location: Southeast USA iTrader: (0)	pretty sure the driver's side exhaust valve only opens when WOT and revving it up. Not sure why warming the car up would matter... as far as the valvle goes. You are at higher RPM's when cold idling, which could be causing something loose to rattle on your exhaust somewhere. Pretty weird.
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09-17-2008, 11:05 AM	#5
zsapphire7 Colonel 104 Rep 2,368 Posts Drives: 08 e92 M3 Join Date: Oct 2007 Location: SF Bay Area iTrader: (21)	Actually i just had this fixed. I brought it into the dealer thinking that i had the waste gate rattle but most of the sound came from the rear. At the beginning of summer it was just during cold starts but I took a drive out in the mountains and under moderate acceleration, fully warmed up, I can hear it tick from 1.5k to 3k rpm. It got worse over time and when i took it in, they said that i had a faulty muffler and replaced just the left side. So far 1 week driving and no more ticking noises
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09-18-2008, 12:40 AM	#7
Blue Streak Gunny 30 Rep 623 Posts Drives: '07 E90 335i 6MT, 2016 F10 535 Join Date: Sep 2007 Location: San Diego, CA iTrader: (0) Garage List 2007 E90 335i [9.00]	Yeah... Why is that? What's the purpose of that butterfly valve in the left muffler? I disconnected that plug in the left side in the trunk to keep the valve open at all times. I heard that it's only purpose was to keep the car quieter at idle and low RPM's - for more of a "luxury sound" or something. __________________ 2007 E90 335i 6MT, ZSP, Nav, PDC, CA, Montego Blue, Terra Dakota leather, CDV, clutch-stop, E46 M Shift Knob, Logic HVI, JB4 PnP, MS 3" downpipes, Koni Yellow adjustable sport shocks, RE 12mm(f)/BMS 15mm(r) spacers, Blacklines, LUX 5.0 LED halo ring lights, DAEOS (Vista) harness, GP Thunder 7500k fogs, 35% sides-20% rear tint, matt black kidney grill, matt black 335i trunk badge
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09-18-2008, 12:44 AM	#8
pdjafari Colonel 153 Rep 2,468 Posts Drives: G80 M3C Join Date: Oct 2007 Location: Earth iTrader: (5)	^^thats possible, I read some threads on here about it. Some ppl said the same thing, its for sound purposes, but others believe it serves a purpose (like to warm up your cats) not sure what purpose that serves...
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09-18-2008, 04:25 PM	#9
AV9 Brigadier General 137 Rep 4,314 Posts Drives: 2009 e92 m3 Join Date: Jun 2008 Location: OC/SD iTrader: (7)	ya i hear something to...ever since i unplugged that thing in the trunk ("golf tee")... how does it get fixed?
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09-18-2008, 04:35 PM	#10
TiAg335i Trance Life 315 Rep 4,706 Posts Drives: 2007 E92 335i Join Date: Jan 2007 Location: Long Island, NY iTrader: (4)	Mine rattles when I can hear it open and close, but other than that I do not hear anything buzzing or rattling coming from the exhaust.
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09-19-2008, 06:05 AM	#11
StarrDlux Pussycat's Meow 9 Rep 682 Posts Drives: '08 335i montego \| Stock Join Date: May 2008 Location: Midtown (Altanta) iTrader: (0)	probably sourced the wastegate from the same folks. ditto the rattle made me look for a few days. definitely something that has developed __________________ 2008 335i montego \| stock 2002 A4 1.8TQS \| APR 1+ 1990 VW Corrado \| Stage 4 by SNS
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