1991 Eagle GTX DOHC revving problems

[Jasens]

Additional info. See below: Hoping there is a guru out there that can help me. While the vehicle is idling or even in gear sitting at a light the engine rpm's rev up and down (just like a little kid sitting in the car quickly stepping on & releasing the gas pedal). Mechanic has not been able to identify. One mechanic says it is a little "v" valve and caused by moisture & should quit when engine warms up; not so. Another mechanic says he doesn't think this engine has the "v" valve and he is stumpled. Anyone every experienced this or know the problem?
Got further info from mechanic. Normally if you unplugged the idle control motor the problem would stop BUT not so. He says he can't identify what is telling the computer there is a problem.

[A790]

Originally posted by Jasens
Hoping there is a guru out there that can help me. While the vehicle is idling or even in gear sitting at a light the engine rpm's rev up and down (just like a little kid sitting in the car quickly stepping on & releasing the gas pedal). Mechanic has not been able to identify. One mechanic says it is a little "v" valve and caused by moisture & should quit when engine warms up; not so. Another mechanic says he doesn't think this engine has the "v" valve and he is stumpled. Anyone every experienced this or know the problem?

Vacuum leak?

[Jasens]

I don't know anything about cars so can you tell me why you think this or where to look so I can tell the mechanic why you think it is a vacuum leak?

[teggypimp95]

I had a vacuum leak in my sir a week or 2 ago, and when i first started it , it would rev up then drop then rev up and down constantly. still drove ok but the idle was messed.

[teggypimp95]

check engine light on at all?

[dsmturbo]

It is the BISS setting...Base Idle screw. On top of Throttle body, you should see a plastic cover with a screw inside. You need to put ECU in diagnostic mode and then adjust idle

[GTS Jeff]

Haha damn, you need to find more competent mechanics. First Google and try to fix it yourself (these problems are usually easy fixes once identified) and if not...try a dealership if all else fails.

[GTS Jeff]

Haha damn, you need to find more competent mechanics. First Google and try to fix it yourself (these problems are usually easy fixes once identified) and if not...try a dealership if all else fails.