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Old 08-09-2015, 04:21 AM   #1
FRESHPRINCEoLC
Scooby Newbie
 
Member#: 427630
Join Date: Aug 2015
Location: Denver, Co
Vehicle:
2003 Subaru Wrx
WRB

Default Recent stage 2 Cobb AP cant boost over 10psi..

Recently got a Cobb Ap and installed a custom turbo back with stage 2 tune. I immediately noticed that it wasn't boosting more than about 8 psi and then 10psi the next day. The exhaust was custom made for another subie and had some clearance issues where it was touching/ almost touching parts of the undercarriage. Also modified the turbo heat shield to fit around bellmouth. So far ive tested:

- BCS actuated normally on car battery and was not clogged
- All vac hoses are newish and pill was inserted as specified
- Reset ECU 2x and was not able to make stock boost
- Shortened wastegate arm and no improvement

Should also mention i live in Denver so idk if that could be affecting my boost that much. Also its a 2003 wrx wagon with 13k on rebuild and 200k on chasis.

Here is my datalog before reseting the ECU the last time. noticed the knocking correction but didnt know if these are acceptable values

https://docs.google.com/spreadsheets...it?usp=sharing

Datalog after reseting the ECU. 3rd gear pull is the first part then just normal driving

https://docs.google.com/spreadsheets...it?usp=sharing

I would really appreciate any help here as i want my boost back

Also can provide any other dynamics requested.
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Last edited by FRESHPRINCEoLC; 08-09-2015 at 04:24 AM. Reason: forgot to mention what car i have
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Old 08-09-2015, 04:14 PM   #2
crosswound
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Member#: 317629
Join Date: Apr 2012
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check the whole exhaust system to make sure its not loose up pipe/down pipe/header if air is coming out anywhere in the exhaust system before the turbo also if there is black carbon any where in the engine bay under the engine.
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Old 08-09-2015, 09:23 PM   #3
svltrack
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Member#: 391110
Join Date: May 2014
Location: Pennsylvania
Vehicle:
15' STI

Default

Quote:
Originally Posted by FRESHPRINCEoLC View Post
Recently got a Cobb Ap and installed a custom turbo back with stage 2 tune. I immediately noticed that it wasn't boosting more than about 8 psi and then 10psi the next day. The exhaust was custom made for another subie and had some clearance issues where it was touching/ almost touching parts of the undercarriage. Also modified the turbo heat shield to fit around bellmouth. So far ive tested:

- BCS actuated normally on car battery and was not clogged
- All vac hoses are newish and pill was inserted as specified
- Reset ECU 2x and was not able to make stock boost
- Shortened wastegate arm and no improvement

Should also mention i live in Denver so idk if that could be affecting my boost that much. Also its a 2003 wrx wagon with 13k on rebuild and 200k on chasis.

Here is my datalog before reseting the ECU the last time. noticed the knocking correction but didnt know if these are acceptable values

https://docs.google.com/spreadsheets...it?usp=sharing

Datalog after reseting the ECU. 3rd gear pull is the first part then just normal driving

https://docs.google.com/spreadsheets...it?usp=sharing

I would really appreciate any help here as i want my boost back

Also can provide any other dynamics requested.
The car is commanding boost shown by the wgdc being increased. 10psi is spring pressure so the turbo is operating. You have an issue with your bcs (not likely without a code), with the wastegate actuator, or with the actual wastegate (blocked from closing for example). Try testing the actuator first and go from there

Quote:
Originally Posted by crosswound View Post
check the whole exhaust system to make sure its not loose up pipe/down pipe/header if air is coming out anywhere in the exhaust system before the turbo also if there is black carbon any where in the engine bay under the engine.
Only a disconnected header or up pipe would really cause this issue and ANY part of the exhaust being disconnected would be incredibly obvious to the ear on startup/run. (Ever run a car with open headers around the block?)
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Old 08-09-2015, 09:29 PM   #4
svltrack
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Join Date: May 2014
Location: Pennsylvania
Vehicle:
15' STI

Default

Also make sure that you are running a map designed for your bcs
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Old 08-10-2015, 12:10 AM   #5
crosswound
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my header once fell off on one side lol i know what it sounds like but one time when i had worn up pipe studs that didn't make obviously air leak noise only would rock back and forth while trying to build boost i was only hitting wastegate pressure. this was like 3 years ago though.

only trying to give easy suggestion to help doesn't cost much to check if bolts are still torque good and everything connect.
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Old 08-10-2015, 03:04 AM   #6
FRESHPRINCEoLC
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Member#: 427630
Join Date: Aug 2015
Location: Denver, Co
Vehicle:
2003 Subaru Wrx
WRB

Default

So i checked all the vacuum lines going through the T fitting and bcs and found the pill was in the wrong hose . Making 14-16psi easily now but spiking to 20psi at wot signaling boost creep. Any ideas how to help resolve this until i can get P&P? Thanks for the replies!
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Old 08-10-2015, 10:46 AM   #7
svltrack
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Member#: 391110
Join Date: May 2014
Location: Pennsylvania
Vehicle:
15' STI

Default

Quote:
Originally Posted by FRESHPRINCEoLC View Post
So i checked all the vacuum lines going through the T fitting and bcs and found the pill was in the wrong hose . Making 14-16psi easily now but spiking to 20psi at wot signaling boost creep. Any ideas how to help resolve this until i can get P&P? Thanks for the replies!
Spiking is bad bad bad.. If it is creeping up to 20 then you could try a lower boost map but really it is a mechanical issue and needs to be solved as such
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