boost problem - Subaru WRX Forum
 
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post #1 of 9 Old 11-30-2011, 11:26 PM Thread Starter
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boost problem

HI all

I have a forester xt 04 with tbe, walbro fuel pump, catless up-pipe and td05 18g and has been tuned. When i got car back from tuners it was awesome. Boost was coming on nice in all gears around 3k and by 3.5k it was at full boost (17psi) all the way to redline. Even under light throttle she would be taking off at 3k and boosting nicely. Then after 3 or 4 days i was holding back in traffic in 2nd gear and put my foot down and i didn't feel my boost coming on. Looked at the revs and they where up around 5k. When i took off from a set of lights on wot it boosted fine. I installed a guage to see what was happening. When i'm in 1st, 2nd or third the boost guage doesn't get out of vacuum it rises and falls unless i'm on wot. I can redline without getting any boost at all under moderate throttle. However when i'm cruising in 5th the boost pressure builds and i take my foot off the accelerator the guage will drop to 20 vacuum and if i touch the gas again the guage will jump up to the pressure it was before i took my foot of the gas. So its not building boost pressure in lower gears unless on wot but builds boost ok in higher gears while light on the throttle. I checked all hoses, exhaust, restrictor pill, bpv, fuel filter. Took it back to the tuners and data logged and they couldn't find out what's causing this either. Has this happened to anyone else or does anyone know what might be causing this to happen. Any help would be greatly appreciated.
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post #2 of 9 Old 12-01-2011, 07:31 AM
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3port BCS or stock BCS?

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
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2007 MS3
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post #3 of 9 Old 12-01-2011, 10:17 AM
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This "just" started happening? Sounds like the boost table is tuned kinda funky. Maybe crazy cold temp wastegate compensation? Or cold temp boost compensation? Doesn't make sense it's hitting "target" boost at wot though...I assume "hitting boost fine" means you are hitting target at wot? I would think if it was truly the boost controller it would be a bit off in all gears "especially" wot as that is the toughest to tune spikes out of.
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post #4 of 9 Old 12-01-2011, 11:08 AM
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Post a datalog for these fools. I still think it could be the bcs.

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
2007 Foz XT sold
2007 MS3
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post #5 of 9 Old 12-05-2011, 09:23 AM
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my 09 wrx is doing the same exact thing. it's stock at the moment and my good friend just bought a 2012 wrx hatch and his cars pulls twice as hard as mine does and they're the exact same car and both have the vf52... and my car only has 30k on it. no idea what the problem is.
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post #6 of 9 Old 12-05-2011, 10:54 AM
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^start your own thread and post a datalog and whatever you have recently done to it.

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
2007 Foz XT sold
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post #7 of 9 Old 12-05-2011, 01:32 PM
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Quote:
Originally Posted by tommelleo22 View Post
my 09 wrx is doing the same exact thing. it's stock at the moment and my good friend just bought a 2012 wrx hatch and his cars pulls twice as hard as mine does and they're the exact same car and both have the vf52... and my car only has 30k on it. no idea what the problem is.
Also, if his car feels faster than yours and you are the passneger, that makes a huge difference.... I know my car feels slow because I get used to it, but put somebody else in the drivers seat and it feels fast as hell.

-Chris
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post #8 of 9 Old 12-15-2011, 04:40 AM Thread Starter
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i did a boost leak test. Found a few small leaks and one on the intake manifold gasket. Replaced the gasket and re-checked for leaks. All good in that department. However the problem still persists. I checked the exhaust for leaks and that came back fine so...
Maybe a wastegate problem its internal 15psi. I cant hear any fluttering just a slight whistle sometimes when it should be building boost but isn't. The whistle sounds a bit like my bpv when i change gears. checked the bpv its not the cause.
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post #9 of 9 Old 12-15-2011, 06:45 AM
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You checked all vacuum hoses ?

What are you monitoring with ?

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
2007 Foz XT sold
2007 MS3
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