I have a 91 Z28 with a 305 TPI and when you start the car it idles up and down.You can even hear a clicking sound when it idles down and not sure what it could be. The car has sat for the last couple of years until I could walk again but ran fine before I pulled it out of the garage.


Any help would be appreciated.


Thanks.

 

a/c clutch and its normal....I wouldn't worry about it.

 

I have an 85 305 tpi, The car sat 5 years before I ran it, and it done the same thing, after nickel and diming me to death, we figured it needed a new MAF....so far so good, it seemed to remedy that up and down in idle! Once in a while it will try to surge, but calms down.

 

Thanks for the input.

 

Those might be possibilities, but a '91 does not HAVE a MAF sensor. Further, if the ECM is working the target idle is increased when the AC compressor is cycled on. If the RPMs are fluctuating while idling with no accessories turned on, the primary susect the the IAC stepper motor. Try cleaning the throttle body, remove and clean/lubricate the IAC, and check/set the throttle minimum air position.

Just for grins, you may want to diable the EGR solenoid for diagnostic purposes.

 

usually vacuum hoses would cause your car to do that at idle. When i pressed the brakes or the clutch in to shift, my rpm's would jump up to 2500 then down to 500 then bounce around awhile. I replaced some vacuum hoses and it went away.