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Old 04-21-2020, 07:33 PM   #1
Scooby Newbie
Member#: 461463
Join Date: Jan 2017
Chapter/Region: BAIC
Location: San Francisco, CA
2004 WRX wagon

Default Boost will not exceed 8 PSI on 2004 WRX; need help!

I have a 2004 WRX and my boost pressure will not go above 8 PSI, even with WOT, and was hoping someone could help me figure out why. I recently made the following upgrades:
Cobb high-flow cat downpipe
Grimmspeed catless up-pipe
Samco silicone intercooler hoses
XPT stage 2 tune (target boost of 18.5 PSI)
Stock intake and filter

After reading this forums endlessly, I have ruled out the two most likely culprits (I think):
- WG actuator/valve: I have confirmed that I cannot blow air through the WG actuator valve when car is off. I connected 12V to the valve, I heard a click, and I can blow air. I have also pulled the vacumm hose off the turbo outlet, connected compressed air to this hose, and watched the WG actuator arm move up to about 1/2". I then connected 12V to the WG valve, and the compressed air was released and the WG closed again. This all appears to be normal.
- Boost leaks: I have boost leak tested my entire intake from the intake elbow and found no leaks. I tested up to 15 PSI, and it takes about 10 seconds to drop to 10 PSI, and another 40 seconds to drop to 0 PSI. The only place I can hear air escaping is from my oil filler cap.

The maximum boost I can make is always between 7.9 and 8.9 PSI, which sounds suspiciously like wastegate spring pressure. However, I don't know what could be causing this, per my above test. I have also tried pulling the vacuum hose off the WG actuator nipple, and cautiously driving around, but boost still will not exceed 8 PSI. My IAM is at 16 (the highest value for this generation WRX).

I have attached a log of a recent 3rd gear pull. It includes AFR data from my AEM UEGO wideband. I am new at this, so hopefully there are some useful clues in the logs that I missed.

Link to logs:
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