1996 Geo Prism Idles High

09-30-2006, 11:32 AM
I have a 1996 Geo Prism which idles very very high (rpm) when engine is cold. After running for about 15-20 mins, the idle rpm reduces, but is still a little above the lowest idle I was used to.

Last time I gave my car for a tune up, the mechanic said he had to take down the "manifold" to check for a leaking gasket, and he replaced it. I have been having this idle problem sincec then.

I checked Air filter - its clean, put in injector cleaner, ran one complete gas tank but still no effect.

I dont want to take it back to him..any suggestions?

Thanks a bunch,

- Shrey

07-02-2007, 12:49 AM
Looks like an old post, just wondering if you ever got this fixed or gave up?... If you're still driving it and haven't fixed it yet, I might be able to help you out.

Is the MIL flashing or illuminated? Several things can cause high idle issues:
Idle control Valve
disconnected vacuum lines throughing the idle off by pulling in air without the MAF sensor reading it.

Unless you are familiar with the vacuum routing on the car or have a routing chart to follow, you are going to need to find a shop to look it over.

I am looking at buying a '96 model tommorow afternoon, if I do, I'll be more able to help you when I get back to my shop and look things over. PM me if you don't find help elsewhere, I'll be happy to help if I have something more to go by from you on it.

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