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Old 11-14-2012, 04:53 AM   #1
Scooby Newbie
Member#: 333798
Join Date: Sep 2012
Chapter/Region: BAIC
Location: Bay Area, CA
2005 WRX

Question Underboost/fluctuating boost (datalogs incl.)

Hey guys,

So first of all I have an 05 WRX with the following:
-Invidia V2 catless DP
-HKS midpipe/flowmaster axelback
-Catless UP (from 06 WRX)
-Cobb AP flashed to stage 2 ACN91
-Large ebay intercooler
-Cosworth high flow air filter in otherwise stock intake

According to AP monitors boost levels are significantly under target; at idle boost hovers around -8 (target is -1) and is usually 3 psi + under target at highway speeds. Under acceleration it's not as significant but still outside the ideal range. The following datalog shows a pull in 3rd gear:

I've also had an intermittent problem where the boost will fluctuate under throttle. For whatever reason the above datalog was during a period when the car decided not to have the issue I only have a datalog of the fluctuating boost from when the car was stage 1 but I think it will show necessary info. The following is in 4th gear under moderate throttle:

I've had a boost leak test done and nothing was found, but since the fluctuating boost is intermittent I can't say for sure that that's not the problem...

I know I could use a HWG map to counter underboosting but I want to know what's causing it. I was expecting to have to use a LWG map to counter boost creep from the catless DP!

So... what's causing these problems? Could they be related? Any help is appreciated
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Last edited by WRBlueJ; 11-21-2012 at 12:25 AM.
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