1997 5.7 vortec idles too fast

firemanbob

1997 5.7 vortec idles too fast

Unread post by firemanbob » Fri Jul 30, 2010 3:18 am

My 1997 Silverado 1500 FWD idles too fast. It seems to jump up to about 1200 and then will slow settle down to about 800-900. If I slow and go through a stop, I take off like a rabbit. The truck wants to push me through the stop. If i sit for 10 seconds or so, then I can start off slowly and the idle comes down. The only computer code I am getting is "a rich/lean situation in cylinder 8".

I have had it in and the best guess anyone can give is I have a intake manifold gasket leak, but they don't sound positive about that.

Looking to see if this could be the case before I commit to such and extensive repair.

Any help?

Meccboy

5.7 Vortec idles too fast

Unread post by Meccboy » Mon Aug 09, 2010 7:29 pm

Yes, intake manifold gaskets leaking vacuum can give the problems you are having. Spraying a little carb cleaner around the base of the manifold would show a vacuum leak by changing the idle when you spray. Any other source of a vacuum leak will also do this.
Make sure the throttle is not full of carbon as this can contribute to idle problems.

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