Hanging rpm

Jbarker83

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So I'm noticing every now and then my rpm hang at 1500 while at a red light or in neutral etc does it off and on I don't drive the car much so not sure how much it happens only had the car 3 weeks
 

g36 monkey

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Vacuum leak is the biggest cause for this issue in any car.

Next is the IAC and TPS sensors.
 

g36 monkey

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Do a smoke test.

Light a cigar. Pull the vacuum line off the brake booster. Take a big puff of smoke. Exhale into the booster hose, look for smoke. If smoke is escaping, there is a vacuum leak.
 

SnakeBit!

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^^^what he said. most common I have found is the IAC. what year model, etc car?
 
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Jbarker83

Jbarker83

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i ain't doing that shit lol. its a 2001 gt 5 speed 73k it doesn't do it constantly it does every now and then when im out cruising
 
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Jbarker83

Jbarker83

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whats involved with changing the iac? i'm not throwing any codes either
 

g36 monkey

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The IAC is a pretty easy change.

But that vac test is about the best diagnosis tool. The actual machine that shops use to do it does literally the same thing, but costs thousands. The cigar could cost as little as a dollar.

When I do it, I have a huge leak between my lower and the block lol. But I will deal with that eventually. On a motor with no leaks smoke should just come out of the throttle body.
 

SnakeBit!

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you can try pulling the IAC and cleaning it and put it back. did it several times on cars and it worked.
 
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Jbarker83

Jbarker83

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the car has a aftermarket 75mm tb brand says rpm on it. so i don't know if its installed right etc if i rev the engine the rpm stops hanging
 

SnakeBit!

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that could be your problem. can't beat oem for mostly stock applications.
 

07GtS197

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Hanging rpms is a common complaint after swapping throttle bodies. My 02 gt does it too. In my case nothing Ive done has cured it but I know others have cured it with an iac restrictor plate. Its worth a try, otherwise just live with it.
 
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Jbarker83

Jbarker83

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previous owner replaced the tb and manifold with a bigger edelbrock manifold i don't have stock parts
 

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