Strange noise under heavy load?!

weebles · 07-11-2012, 05:57 AM

Howdy everyone.

I recently installed my agency power resonated mid-pipes and decided to try out a 3rd gear pull and log it for virtual dyno.

The car pulls good and the log didn't show any knock or timing correction but near the end of the 3rd gear pull I could hear a weird grinding or some strange noise coming from the front of the car... Not sure what it was and it only happened briefly.

Second gear does not make the sound happen, but when I tried full throttle in 3rd it did. I can't for the life of me figure out what it would be, anyone have any ideas?! The car seems to be running fine, no codes, no knock, no timing correction....

My mods are: VRSF downpipes, Agency power resonated midpipes, ETS intercooler, and K&N drop in air filter with Cobb stage 2+FMIC map. I never heard this noise at all previous to installing midpipes but I'm certain the noise is not coming from the pipes, they are installed perfectly.

I am overboosting a little bit with the cobb map (briefly hits 18.3 psi)..

Any help is appreciated.

weebles · 07-11-2012, 03:25 PM

Could this behavior be caused by the "rattling wastegate" I've read about?

Venom · 07-11-2012, 03:49 PM

My experience with rattling wastegate was this:
-a tick tick tick/pronounced knocking noise that isn't quite consistent and that is prominently different from the other engine noises
-occurs under mild load (1.5-2.5k rpm)
-boost feels off, feels like there's much more prominent lag than usual, takes 2-3 seconds for the power to come on under that rev range in any gear

Venom · 07-11-2012, 03:51 PM

6mt or 6at? I dont have any experience past stage 1, but this could be a symptom of the CDV messing up your shift.

weebles · 07-11-2012, 06:38 PM

6MT..

It doesn't happen near the shift point. If I put it in third gear and use plenty of throttle it will accelerate like normal through the RPM range and around 4-5k rpm it will suddenly make like a scraping type noise. First time it happened I thought one of the midpipes came unhooked and started scraping on the ground but that was obviously not what happened.

There doesn't seem to be a loss in power, second gear does not make the noise and it pulls like an animal.

Venom · 07-11-2012, 06:46 PM

Definitely not the wastegates then and also not the CDV

07-11-2012, 05:57 AM	#1
weebles Enlisted Member 4 Rep 34 Posts Drives: 135i Join Date: May 2012 Location: Alberta iTrader: (0)	Strange noise under heavy load?! Howdy everyone. I recently installed my agency power resonated mid-pipes and decided to try out a 3rd gear pull and log it for virtual dyno. The car pulls good and the log didn't show any knock or timing correction but near the end of the 3rd gear pull I could hear a weird grinding or some strange noise coming from the front of the car... Not sure what it was and it only happened briefly. Second gear does not make the sound happen, but when I tried full throttle in 3rd it did. I can't for the life of me figure out what it would be, anyone have any ideas?! The car seems to be running fine, no codes, no knock, no timing correction.... My mods are: VRSF downpipes, Agency power resonated midpipes, ETS intercooler, and K&N drop in air filter with Cobb stage 2+FMIC map. I never heard this noise at all previous to installing midpipes but I'm certain the noise is not coming from the pipes, they are installed perfectly. I am overboosting a little bit with the cobb map (briefly hits 18.3 psi).. Any help is appreciated.
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07-11-2012, 03:25 PM	#2
weebles Enlisted Member 4 Rep 34 Posts Drives: 135i Join Date: May 2012 Location: Alberta iTrader: (0)	Could this behavior be caused by the "rattling wastegate" I've read about?
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07-11-2012, 03:49 PM	#3
Venom Colonel 375 Rep 2,388 Posts Drives: M2 Competition Join Date: May 2011 Location: East Bay, CA iTrader: (5) Garage List 2008 BMW 135i [8.50]	My experience with rattling wastegate was this: -a tick tick tick/pronounced knocking noise that isn't quite consistent and that is prominently different from the other engine noises -occurs under mild load (1.5-2.5k rpm) -boost feels off, feels like there's much more prominent lag than usual, takes 2-3 seconds for the power to come on under that rev range in any gear
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07-11-2012, 03:51 PM	#4
Venom Colonel 375 Rep 2,388 Posts Drives: M2 Competition Join Date: May 2011 Location: East Bay, CA iTrader: (5) Garage List 2008 BMW 135i [8.50]	6mt or 6at? I dont have any experience past stage 1, but this could be a symptom of the CDV messing up your shift.
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07-11-2012, 06:38 PM	#5
weebles Enlisted Member 4 Rep 34 Posts Drives: 135i Join Date: May 2012 Location: Alberta iTrader: (0)	6MT.. It doesn't happen near the shift point. If I put it in third gear and use plenty of throttle it will accelerate like normal through the RPM range and around 4-5k rpm it will suddenly make like a scraping type noise. First time it happened I thought one of the midpipes came unhooked and started scraping on the ground but that was obviously not what happened. There doesn't seem to be a loss in power, second gear does not make the noise and it pulls like an animal.
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07-11-2012, 06:46 PM	#6
Venom Colonel 375 Rep 2,388 Posts Drives: M2 Competition Join Date: May 2011 Location: East Bay, CA iTrader: (5) Garage List 2008 BMW 135i [8.50]	Definitely not the wastegates then and also not the CDV
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