What should the RPM's be when my 4.3 liter engine is at idle? on 2000 GMC Jimmy

Tune-up idle speed

by in Muskogee, OK on June 23, 2012
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1 answer 5 comments
ANSWER by , June 23, 2012
Idle speed is controlled by PCM. What problem are you having?
COMMENT by , June 23, 2012
Knocking at 600 rpm
COMMENT by , June 23, 2012
When you say knocking, do you mean an actual bootom end knock. If so that has nothing to do with idle speed.
COMMENT by , June 24, 2012
My 2000 GMC Jimmy makes a knocking noise after it warms up. There doesn't seem to be anything else wrong with it, it runs fine otherwise. I have asked several mechanics and they are stumped. I was told it could be a wrist pin? It idles at 700 rpm, is that too low? What else could cause a bottom knock?
COMMENT by , June 25, 2012
It is 12 years old. Not knowing how many miles are on the engine it could be an oiling problem.
COMMENT by , July 31, 2012
The idle speed is usually onthe underhood sticker with the engine/emissions info.Most are between 650-750 at idle in drive.If it's just one or two wrist pins as suggested while it's running kill one cyl at a time and see which cyl. the noise goes away at.