Weird noise under very light throttle/boost.

wooden · 06-13-2018, 12:25 AM

Ok, I’ve done a lot of searching for this issues and can’t find anything that seems related to my issue.

It happens under very light load/throttle, Sounds like it’s coming from the exhaust side. The best way form me to discripe the noise is a grass sprinkler, when it goes, shhhh-tik-tik-tik. Like a fluttering/pulsing noise.

I know what compressor surge is and it don’t think it is that because it doesn’t really make the noise when I let off the throttle more so when I’m on the throttle

Unfortunately I can’t do WOT right now, bedding in my clutch.

The only thing I might think it is maybe a boost leak, idk.

Thanks guys

upshift_downshift · 06-28-2018, 10:17 PM

Sounds like it's the wastegates on the turbos, but can't be very sure without a video. The bushings that hold the flapper wear down (mine were loose with new turbos), and rattle when the wastegate isn't fully closed. When closed, the tension on the actuator arm keeps them from rattling.

Just monitor for any boosting issues. You will need new turbos once the car struggles to make boost, as the wastegates will wear down so far, that they will no longer properly seal on the turbine housings.

If it is the wastegates, don't worry too much right now. They probably still have plenty of life left.

06-13-2018, 12:25 AM	#1
wooden New Member 0 Rep 26 Posts Drives: e90 335i Join Date: Apr 2009 Location: ca, Riverside iTrader: (0)	Weird noise under very light throttle/boost. Ok, I’ve done a lot of searching for this issues and can’t find anything that seems related to my issue. It happens under very light load/throttle, Sounds like it’s coming from the exhaust side. The best way form me to discripe the noise is a grass sprinkler, when it goes, shhhh-tik-tik-tik. Like a fluttering/pulsing noise. I know what compressor surge is and it don’t think it is that because it doesn’t really make the noise when I let off the throttle more so when I’m on the throttle Unfortunately I can’t do WOT right now, bedding in my clutch. The only thing I might think it is maybe a boost leak, idk. Thanks guys
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06-28-2018, 10:17 PM	#2
upshift_downshift Private First Class 41 Rep 116 Posts Drives: BSM 07 E90 335i Join Date: May 2016 Location: Ann Arbor, MI iTrader: (0) Garage List 2007 BMW E90 335i [0.00]	Sounds like it's the wastegates on the turbos, but can't be very sure without a video. The bushings that hold the flapper wear down (mine were loose with new turbos), and rattle when the wastegate isn't fully closed. When closed, the tension on the actuator arm keeps them from rattling. Just monitor for any boosting issues. You will need new turbos once the car struggles to make boost, as the wastegates will wear down so far, that they will no longer properly seal on the turbine housings. If it is the wastegates, don't worry too much right now. They probably still have plenty of life left.
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