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Old 01-08-2013, 05:37 PM   #1
dead_eye
Scooby Newbie
 
Member#: 308265
Join Date: Jan 2012
Location: PHL
Vehicle:
2008 WRX

Default diagnose TGV leak

Is there a way to test if the TGV valve is leaking?

2008 wrx, STOCK EVERYTHING. On a few cold mornings, upon starting the car and letting it warm up for a few minutes it would throw the dreaded 0171 "bank to lean" code.

I have read a lot of the good threads here and it appears that cars with extensive mods seem to be plagued by this code. But I am totally stock...

Then I read in one of these threads where someone described the TGV valves can get stuck or leak, drawing more air than is metered, and truly runs lean. They also described it would cause a slightly rough or varying idle speed, which occasionally happens to me when it's cold, even when it doesn't generate a code.

I also checked under the hood and made sure all my intake parts were secure. I found the bypass valve was not secured and fixed that right quick.

I do not have a boost gauge (yet) so I can't tell you if I am making target boost due to a leak. I do have a nice scan tool at my disposal but I am still trying to make sense of what I am looking FOR.

Otherwise the car runs great and I have no complaints.

Any ideas on how to test would be appreciated!
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Old 01-08-2013, 06:06 PM   #2
Uncle Scotty
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Join Date: Mar 2002
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OK Houston
we have an Uncle

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bet the airbox lid isnt on properly
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Old 01-08-2013, 06:17 PM   #3
dead_eye
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Join Date: Jan 2012
Location: PHL
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2008 WRX

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Quote:
Originally Posted by Uncle Scotty View Post
bet the airbox lid isnt on properly
I'll double check it.
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Old 01-08-2013, 09:38 PM   #4
Leafy
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Member#: 330625
Join Date: Aug 2012
Chapter/Region: NESIC
Location: MA
Vehicle:
2006 WRX
WRB

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Yes, because that matters.

Op, you have a vac/post maf leak most likely. Your ecu wouldnt even know the difference if air was just leaking past the butterflys on your TGVs. Or the maf is dirty or the o2 is on its way out. Having a pre-maf leak aka loose airbox lid wont amount to ****.
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