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Vacuum reads 25~30 psi during driving

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Old 03-06-03, 02:13 PM
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90s riceboy

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Vacuum reads 25~30 psi during driving

I searched but couldn't find anything directly related to what I am about to post.

Anyways, I've been noticing that my vacuum when driving will often go as high as 30 psi at times. When my car idles at a stop, the vacuum will sit at 19-20 psi. Do I have a loose vacuum hose or something?

I also did the boost test and from what I saw, I think I may have something loose. I was boosting 10-5-6 from what I remember.

Any ideas, guys? Thanks!
Old 03-06-03, 02:41 PM
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Is this when you let off the gas but are still in gear?

If so, thats about right... the engine isn't "working" but the crank is still producing power so your vacuum is higher.

I've never heard of a vacuum problem causing TOO much hg, only too little....
Old 03-06-03, 02:55 PM
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vaccum is not measured in pounds per square inch (psi)

it's measured in mmHg
Old 03-06-03, 03:21 PM
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yep, typical idle vacuum for a stock-ported engine is 15-19 in. I normally see my coasting vacuum get as low as 25 in. Your boost is a little low, however. Check all your couplings. Also could mean a potentially clogged cat.
Old 03-06-03, 03:23 PM
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In inches of mercury for you. As opposed to millimeters. So that would mean at idle your car's vacuum is pulling 19 to 20 inches of mercury.

garrett
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