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Boost bleeding/staying constant

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Old Feb 12, 2007 | 10:58 PM
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Default Boost bleeding/staying constant

Okay, I have a very strange problem. STS kit with GT67 and built motor.
Boost is ref'd off the manifold.

The other day I wastegated it to 9# spring and it showed 9.5 solid for a little while. Then all of a sudden it dropped back to 8#, no more, no less. It spikes to 8 and stays there. So I put an 11# spring in....same thing, 8psi.

High boost with both springs goes to 15psi then quickly drops back to 12psi and stays there.

Do I just have a leak somewhere? I checked most of the pipes and they all seem tight. I will probably get it up on the lift tomorrow and check over everything. Any way it could be my BOV? I wonder... ?
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Old Feb 12, 2007 | 11:09 PM
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Originally Posted by SSkeet
Okay, I have a very strange problem. STS kit with GT67 and built motor.
Boost is ref'd off the manifold.

The other day I wastegated it to 9# spring and it showed 9.5 solid for a little while. Then all of a sudden it dropped back to 8#, no more, no less. It spikes to 8 and stays there. So I put an 11# spring in....same thing, 8psi.

High boost with both springs goes to 15psi then quickly drops back to 12psi and stays there.

Do I just have a leak somewhere? I checked most of the pipes and they all seem tight. I will probably get it up on the lift tomorrow and check over everything. Any way it could be my BOV? I wonder... ?
I had a similar issue and found out it was just an exhaust leak at the collector. You might want to do a pressure test on the system. How is your vacum? What PSI is it at.
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Old Feb 13, 2007 | 06:50 AM
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Originally Posted by JD_Z28
I had a similar issue and found out it was just an exhaust leak at the collector. You might want to do a pressure test on the system. How is your vacum? What PSI is it at.
I'll check it out, but vac is about 18
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