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Old 11-14-2012, 03:58 PM   #4
Scooby Newbie
Member#: 333798
Join Date: Sep 2012
Chapter/Region: BAIC
Location: Bay Area, CA
2005 WRX


Thanks for the good info, much appreciated. It cleared a few things up for me but I still have a few questions...

To clear things up on my end I understand that tapering boost is normal, what I meant by under boosting was boost levels under target at specific rpms/throttle.

Originally Posted by IA Performance View Post
Vacuum at idle should be close to 16-20 inHg (inches of mercury). Keep in mind, boost cannot be a negative value, hence inHg. 8 psi = 16 inHG.
The AP boost monitor reads in psi, at idle it reads -8 and says target should be -1. Under light throttle it could read (for example) -5 and says target should be -1. What should I make of this? Are you saying the reading is wrong? The WG is closed in both examples so changing it's duty wouldn't affect boost (or vacuum) at this level.

Also, what I've gathered from your post is that my car is experiencing symptoms of both over boosting and under boosting. As you can imagine this is mighty confusing haha. I will try first shortening the WG arm by the amount you said then running the HWG map. But... wouldn't either of these induce over boosting and thus induce the fluctuating boost problem?
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