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Old 09-28-2012, 02:15 PM   #1
cineris
Scooby Newbie
 
Member#: 263329
Join Date: Nov 2010
Chapter/Region: MWSOC
Location: Columbus, OH
Vehicle:
2011 Impreza WRX
DGM

Default Another screeching noise thread

2011 WRX sedan.
Mods:
Cobb catted downpipe (stock midpipe)
Nameless muffler-delete axleback
AEM intake
Process West TMIC
TP stage 2 tune
Basically, stage 2 setup.

The car runs fine, pulls strong, good mileage, linear acceleration, all good for the most part except:
Problem starts 3rd gear or higher between 3000-3750rpm under ~60% throttle to WOT. Sounds like a shrieking sound going in and out very rapidly. It seems to happen more when the weather is hot out or after I've been driving for a while (~20 mins). Its cooled off a bit and I haven't heard it lately. If I avoid the stated rpm range, I don't hear it at all and the car accelerates smoothly through the gears. Other symptoms are that the car hesitates a little bit under WOT, especially in 4th and 5th gear. I data logged and it showed the boost was fluctuating about .8psi higher than peak (peak = 19psi) when the sound happened, but then went back to normal as soon as it cleared 4000rpm through to redline.

Does this sound like an exhaust issue? Reading other threads with similar issues points me to thinking its an uppipe gasket failing. Thanks in advance. I want to get this fixed before I switch to E85.
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Old 09-28-2012, 02:23 PM   #2
Source,LLC
Former Vendor
 
Member#: 322524
Join Date: Jun 2012
Chapter/Region: MWSOC
Location: Chicago,IL
Vehicle:
3.5 WRX STI
WRB

Default

Going 0.8 psi above target boost in 4th gear is normal, and you really should go WOT in 5th gear because the likelyhood of overboosting is even greater. If you are only experiencing the issue at specific rpm ranges I'd say it's more likely that you are hear transmission noises, and these cars tend to have more then their fair share of them. Also 3000-3750 is the range when your turbo will be spooling, so are you sure you aren't hearing that? Send a log to eric over @ TP and see what he says.
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Old 09-28-2012, 02:26 PM   #3
cineris
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Member#: 263329
Join Date: Nov 2010
Chapter/Region: MWSOC
Location: Columbus, OH
Vehicle:
2011 Impreza WRX
DGM

Default

I forgot to add, AFR read normal (11.02@WOT). Also, this issue didn't happen when I first put the car together about 4k miles ago. Odometer = 23700.
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Old 09-28-2012, 04:52 PM   #4
cineris
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Member#: 263329
Join Date: Nov 2010
Chapter/Region: MWSOC
Location: Columbus, OH
Vehicle:
2011 Impreza WRX
DGM

Default

Quote:
Originally Posted by Source,LLC
Going 0.8 psi above target boost in 4th gear is normal, and you really should go WOT in 5th gear because the likelyhood of overboosting is even greater. If you are only experiencing the issue at specific rpm ranges I'd say it's more likely that you are hear transmission noises, and these cars tend to have more then their fair share of them. Also 3000-3750 is the range when your turbo will be spooling, so are you sure you aren't hearing that? Send a log to eric over @ TP and see what he says.
Thanks for the input. It doesn't sound very regular so I don't know if its the turbo spooling. I don't really know what the trans would sound like, but wouldnt it continue to sound all the way until the torque dropoff? 1st and 2nd gear make no noise at all. Also, it seems to be coming from around the turbo area for whatever that's worth. I'll try sending some numbers to Eric.
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Old 09-28-2012, 05:00 PM   #5
Source,LLC
Former Vendor
 
Member#: 322524
Join Date: Jun 2012
Chapter/Region: MWSOC
Location: Chicago,IL
Vehicle:
3.5 WRX STI
WRB

Default

Quote:
Originally Posted by cineris View Post
Thanks for the input. It doesn't sound very regular so I don't know if its the turbo spooling. I don't really know what the trans would sound like, but wouldnt it continue to sound all the way until the torque dropoff? 1st and 2nd gear make no noise at all. Also, it seems to be coming from around the turbo area for whatever that's worth. I'll try sending some numbers to Eric.

Are you hitting the same boost levels you were before the issue? If not then I'd say check for vacuum leaks.
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Old 09-28-2012, 05:15 PM   #6
ecbmxer
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Member#: 228059
Join Date: Oct 2009
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
2010 WRX
Spark Silver Metallic

Default

Sure you aren't just hearing the wastegate fluttering?
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Old 09-29-2012, 12:49 AM   #7
cineris
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Member#: 263329
Join Date: Nov 2010
Chapter/Region: MWSOC
Location: Columbus, OH
Vehicle:
2011 Impreza WRX
DGM

Default

I'm going to try to get a recording of the sound and post it here. The exhaust might drown it out but its worth a shot. Thanks for the input. If its just wastegate, then I will be both happy and dumb.
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Old 09-29-2012, 01:02 AM   #8
DHRDAN
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Member#: 204358
Join Date: Feb 2009
Chapter/Region: SCIC
Location: Santa Paula, CA.
Vehicle:
01 2.5RS W/ EJ257
Black

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Take It To The Dealer.
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