CalebMeyers11

Hey guys, my dad has a 6 speed manual transmission ‘02 Pontiac Firehawk and it recently had some idle issues. I figured it was the IAC (Idle Air Control Valve) so I replaced that and relearned the system after replacing it. The Idle was fixed and it no longer surges or stalls out. On the other hand, when one of us drives it the RPM holds in gear at what ever RPM it was at before letting off the gas until you force it to go down by braking, and even increase up to about 3500-4500rpm when going into neutral and releasing the clutch at highway speeds.

Best way I can explain it is almost as if cruise control is on (which it isn’t because the CC doesn’t work as that just stopped working recently as well.). I’m stuck at this point, I’ve cleaned the throttle body and the front of the intake manifold (Throttle Body was pretty clean but the Intake had a bunch of carbon build up at the IAC), inspected both of them and they seem to be perfectly fine.

I’ve watched just about every video on installing the IAC to see if I did anything wrong, which I didn’t. So what’s the next step? It never did this before the new IAC so maybe it’s a faulty one, but I doubt it? I just relearned the IAC again and the first drive everything went great, stopped rev hanging and everything but the second I shut it off at a gas station and turned it back on, it went back to its old ways.

Any opinions will help!

Thanks,
Caleb

2002 Pontiac Firebird Trans Am Firehawk

G Atsma

I'm wondering if cruise control just quit working NORMALLY and is malfunctioning since braking still affects it.

CalebMeyers11

Braking doesn’t really affect it though, the RPM just drops with braking because the car isn’t forcing itself to keep moving at say “55 mph” when you’re slowing down to 35 mph if you get what I’m saying. And the cruise control went out about 3 weeks before the IAC started having problems, so you’d think we would’ve had this problem before installing the new IAC.

G Atsma

New IACs CAN be faulty. is it genuine GM?

CalebMeyers11

It’s Delphi which I believe is a GM brand right?

G Atsma

Should be, though AC Delco might be a better bet.

CalebMeyers11

That’s what I figured, everything I’ve replaced on my truck has been AC Delco except my knock sensors and those keep going out. I figured Delphi would work as it was the only brand AutoZone had in stock. You think it’d be best to swap it out again for AC Delco or should I wait for more responses and see if anyone had similar problems?

G Atsma

If you can get AC Delco easily enough, just do it.

the_merv

iTrader: (88)

Check the Clutch Anticipation Switch, might be sticking. Something to look at.

Slick26

Caleb’s dad here, and owner of the car. We replaced the IAC (again) and TPS for good measure with AC Delco gold parts from Rock Auto. Idle is perfect now but the rev hang is still there. Clutch anticipation switch seems like an interesting idea. Might have to look into that one. The clutch IS starting to go out and I had wondered before if it might be related.

Slick26

*UPDATE*

At the advice of my brother, we sprayed the throttle cables with WD-40 and wiped them down really good, pressed the gas pedal a bunch of times and then greased them up with a light layer or lithium grease and now no rev hang or sticking RPM’s. It is possible that over time the throttle cables got gunky inside the cable sleeves and needed to be cleaned and greased. Either way, it drives like brand new now.