3rdGenSkan

hi everyone. i have a 1990 camaro rs LO3 305 v8 and im having a small issue. my car seems to be reving itself. ill turn her on and her rpms will sit normally but soon after her rpms will drop extremely low almost to the point of cutting off and then her rpms will jump way up and start the process all over agian. i feel likes shes losing power and to get it back she over compensates causing her to rev up and down. my thought was that this could be the iac. any ideas?

safemode

iTrader: (1)

IAC may not be letting enough air in (clogged or stuck ?) or the EGR may be leaking some exhaust into the intake, when it should be closed.

I had the same problem and couldn't figure out why it was idling so low. I just upped the idle a tiny bit. I did also notice that the rpm reported by digital timing lights read ~200rpm lower than what my tachometer in the dash read.

3rdGenSkan

are these two parts hard and expensive to replace?

RBob

iTrader: (1)

The reason that the engine rev's up is from the RPM dropping. In the ECM/calibration is a stall saver routine. If the RPM drops too low this routine kicks in and opens the IAC. The opening of the IAC causes the RPM to flair.

Of course, trying to figure out why the RPM drops may not be so easy. As posted above a leaky EGR will do it. Low timing, needing a tune up, low fuel pressure, leaky injector o-rings, etc. will also cause the RPM to drop off.

RBob.

3rdGenSkan

are the egr's common to go out? not much on my car has been replaced by the original owner so i wouldnt be surprised if things needed to be replaced