-7 psi at idle - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 12-19-2006, 11:48 PM   #1
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Default -7 psi at idle

At idle for the last few months, my boost gauge shows around -7 and not -10. I've done exhaustive vacuum leak searces and can't find any. Idle quality is fine. IAC counts or position is active when it is doing this. It will sit at -10 when coasting. Is this an IAC problem?
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Old 12-20-2006, 01:18 AM   #2
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No, this is a colder denser air issue with a small pulley. When it warms up, the problem will magically fix itself.
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Old 12-20-2006, 01:50 AM   #3
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same issue when it gets cold....
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Old 12-20-2006, 07:49 AM   #4
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Originally Posted by Hans
same issue when it gets cold....
Read above post...not an issue.

We all notice it, exhaust ourselves searching for it and then accept the fact that with a smaller pulley and denser air.. you are simply pushing a little positive pressure toward the intake and reducing the overall vacuum from -10+ to ~-7psi.
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Old 12-20-2006, 09:23 AM   #5
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My 2" pulley outflows my bypass at idle in the heat of summer now. Not just winter. Same effect in the long run though.

John, you have the 2.5" on the car right now, right?
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Old 12-20-2006, 10:34 AM   #6
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It was still warm out when this started, and it does not go away when it'* warmed up.

2.5"
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Old 12-20-2006, 10:42 AM   #7
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Get on the highway..let off the gas. What'* it at?
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Old 12-20-2006, 10:48 AM   #8
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Default Re: -7 psi at idle

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It will sit at -10 when coasting.
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Old 12-20-2006, 10:49 AM   #9
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Default Re: -7 psi at idle

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Originally Posted by J Wikoff
Quote:
Originally Posted by J Wikoff
It will sit at -10 when coasting.
There you go..it'* fine. John..you described what I see everyday. The only other thing we can tell you is .. "vacuum leak" and you've exhausted that possibility.
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