quick question when i first start my car i have it idle at 600-650 rpm after i drive for alittle bit [10-15 minutes] and it warms up my idle goes to 900-1000 rpm what would cause this

 

dn7 -

You sure about those numbers, just seems like a big jump? (650 to 900 might be a little different than 600 - 1000 rpm) A couple of hundred rpm is normal for older engines, as they "reach operating temperature". The oil becomes more fluid and starts doing it's job and the engine actually becomes more efficient.

Archer

 

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yep i am positive about those numbers it has only done it the last couple of days i was under the impression that once your motor warmed up the idle kicked down alittle bit not up the cold idle is suppose to be higher

 

it should go down in idle. if the idle linkage is working propery. a small vacumm leak could make it go up in idle. but it would seam to me it would run high all the time. not just when warm..unless the heat of the engine opens a vacumm leak?

 

dn7 -

Most performance engines I've been around do not use a fast idle cam or a choke. Might want to let us know what you're dealing with. Mine is set up that way and picks up a few hundred rpm.

A vacuum leak is a possibility, but you'd have other symptoms as well.

Archer