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Old 12-31-2006, 09:59 AM   #1
2005wrbluesti
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Default Possible boost leak on my 05 STI?

Well I have a 05 STI with a txs fmic, header, uppipe, tbe, tune, and intake. Performance wise thats about it that would be significant to my problem. I was under hard excelleration this morning and when I went to the next gear under WOT I felt a little stutter and then after that the performance loss was horrible.


The car runs fine, but slowly builds boost up and only to 10 psi. I checked all the couplers, they look fine?


Anyone have any ideas?

Oh the bypass valve doesn't flutter anymore like is used to as well?


Thanks guys.


Brandon
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Old 12-31-2006, 10:09 AM   #2
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Are you running a different bypass/blow off valve?
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Old 12-31-2006, 10:19 AM   #3
2005wrbluesti
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Are you running a different bypass/blow off valve?

Only the one that came with the fmic.
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Old 12-31-2006, 10:22 AM   #4
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If you're handy I'd suggest you take that off first, clean it, lube it, and go for a spin. There used to be threads all over about BOVs sticking, etc. Also.. that flutter sound is not good.. you should get a nice whoosh - do a search for BOV flutter and you'll get a zillion hits.
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Old 12-31-2006, 10:25 AM   #5
2005wrbluesti
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If you're handy I'd suggest you take that off first, clean it, lube it, and go for a spin. There used to be threads all over about BOVs sticking, etc. Also.. that flutter sound is not good.. you should get a nice whoosh - do a search for BOV flutter and you'll get a zillion hits.

Well its using a larger spring for a bit high boost. It came with two spring rates, and those running higher boost recomended using it.

I'll trying lubing it.


Is it possible that the wastegat solinoid is going bad?
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Old 12-31-2006, 10:33 AM   #6
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if the solenoid goes bad you'd boost to wastegate pressure in a flash - but wouldn't build anymore past that (maybe a bit more due to boost creep).
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Old 12-31-2006, 10:35 AM   #7
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The heavy spring and flutter syndrome is common - I ditched a TiAL BOV 'cause I couldn't tune it properly and went back to the JDM STi valve. If you can run your original valve and plumb it back to the intake you may be happier. BOV flutter allegedly shortens the life of the turbo. But God damn I love that loud whoosh.
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Old 12-31-2006, 10:38 AM   #8
2005wrbluesti
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Originally Posted by PeteDucati View Post
The heavy spring and flutter syndrome is common - I ditched a TiAL BOV 'cause I couldn't tune it properly and went back to the JDM STi valve. If you can run your original valve and plumb it back to the intake you may be happier. BOV flutter allegedly shortens the life of the turbo. But God damn I love that loud whoosh.

Well its not a BOV its the bypass valve that came with the fmic.

BUT I think I found the problem. I took the piston out of the bypass valve, well lets say I tried to. The darn piston was so hard to come out, it seemed stuck. Thats whats cuasing so boost build up and less boost at WOT don't you guys think?


Should I use some type of lubricant? Like WD40?
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Old 12-31-2006, 02:36 PM   #9
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WD40 is too light.. use something heavier - I believe RedLine assembly lube is the best, or something like wheel bearing grease. A heavier white lithium grease would suffice - but nothing light like WD40.
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