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Old 04-04-2010, 02:09 AM   #1
BrianMR2
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Member#: 238679
Join Date: Feb 2010
Location: Longmont, Colorado
Vehicle:
2007 WRX TR
WRB

Default Not hitting peak boost with Accessport V2 and extreme taper.

I have been having trouble hitting peak boost with my WRX, it's a 2007 2.5 and Cobb says peak boost should be around 15 PSI with 91 Octane and taper to around 10 PSI. I have not been getting quite that, I have been getting a highest peak of around 13.5 and Tapering to around 7-8 PSI. It seems to be holding stable around 12 PSI which seems low. I am at High Altitude (Colorado) so this may play a factor but a buddy of mine with an 02 WRX hits just above peak up here. I have been noticing a light noise if I floor it at about 2-2.5k of a fluttering noise (sounds very much like a exhaust leak or as if the wastegate is fluttering). I have tried adjusting the wastegate arm several times and each time I saw no difference whatsoever in boost or stability of boost. I have posted a datalog hoping someone would have a similar one to compare, of if you could tell me if you see anything strange that might be causing the issue. I know online diags are hard but unfortunatly I have to buy license plates this month and do not have the extra money to see a subaru specialist at the moment.
Mods :
Cobb Bellmouth DP
HKS Carbon TI Catback
Accessport V2 running Stage 2 91 Oct Map
Forge Blow Off Valve non recirc.

Appriciate any insight on this issue.

Brian Melton

Datalog in Excel format :
http://www.brianmelton-pc.com/DatalogBoost.xls
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Old 04-04-2010, 02:17 AM   #2
BrianMR2
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WRB

Default

Additional information : The run was a 2nd Gear pull also have a 3rd Gear Pull Datalog of same peak boost level.
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Old 04-04-2010, 01:01 PM   #3
arghx7
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pressure test for boost leaks
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Old 04-04-2010, 02:41 PM   #4
BrianMR2
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40 Views 1 reply, anyone have a datalog of a 2nd or 3rd gear pull of a 06-07 stage 2 wrx I could at least compare with?
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Old 04-04-2010, 02:57 PM   #5
Uncle Scotty
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sounds like elevation to me

those cobb numbers arent applicible for cars at 5000 foot altitude

call cobb and ask THEM
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Old 04-04-2010, 03:19 PM   #6
Erik F
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Yes, altitude and or temp. If you look at your Turbo Dynamics...at least in the middle of the run...you are pretty close to what the ECU is requesting. In the area where the turbo is working best...you never really seem to be more than a PSI off what the computer is asking for. There are compensations in the mapping to lower waste gate duty cycles for intake air temps, altitude, and on the newer cars this even effects the target boost numbers. Looks like you are running ok. If you were to run the same boost as someone at sea level your intercooler would not be able to effectively cool the charge.
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Old 04-04-2010, 04:36 PM   #7
scby rex
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do you have a exhaust leak pre turbo? Or a leak between the turbo and i/c/?
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Old 04-04-2010, 08:52 PM   #8
BrianMR2
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Quote:
Originally Posted by scby rex View Post
do you have a exhaust leak pre turbo? Or a leak between the turbo and i/c/?
This is what I am trying to figure out, I do start to hear a small fluttering when I hear the turbo about to spool and while under boost, which could deff be either of these options. The noise is not a whistle which is making me want to kind of eliminate the pre-turbo leak, and push more towards a leak between innercooler. I do feel the cars performance is good, but the sound is my biggest concern as it really does sound like an exhaust leak of some kind, the fact that you mentioned the innercooler to turbo portion, that is something I have not checked. Is is plausible to upgrade to an 05 STI Innercooler on an 07 or will it not fit as I have noticed the innercooler size is significantly different from the 02-05 wrx on the 06-07.
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Old 04-05-2010, 12:00 AM   #9
scby rex
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aw, MPS 2.34 breaking in

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to find a leak take a hose with the engine running and put it to your ear, then move it around to exhaust joints to hear it leaking.
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