Here's the deal, car has a rough idle, it seems to want to idle higher. It almost pushes against you when you're at a stop sign and its choppy and the car trembles.

I can describe it almost as though the car has a cam that wants to idle higher.

Cap and rotor, and spark plugs are new. Wires are in good condition. IAC was cleaned. A shop went over everthing and they decided it was the transmissions fault. The tranny is kinda messed up. However, I had a transmission shop go over it yesterday and they said the tranny needed a rebuild, but it was NOT the cause of the rough idle.

Could it be EGR? 127,000 miles and still the original one. How difficult is that to change?

I just got an ALDL cable and I have a laptop and Datamaster software. What can I look at to get more info?

Thanks.

 

Does the idle stay rough all the time....or mostly after the car is warmed up? If its rough as soon as you start it, could be EGR, or maybe something fuel related. If it runs ok when cold, but gets rough after it warms up, its your fuel injectors most likely. I just had the same problem....nobody could find ANYthing wrong, no codes, etc. Check the resistance on your injectors, both cold and hot....should be between 11-14ohms. Might also check to see if your Canister Purge Valve is stuck open.....And finally, did you check the TPS voltage(s)??? Might be broke, making the computer think the throttle's moving....

 

It happens when its warm. Seems to get really bad when its nice and hot.

I'll check that stuff, thanks.

Maybe I can have an excuse to get me the SLP 25lb injectors out of this :-)

 

I just got the SLP's finally. They are on backorder there now though. They work fine in my car without the PROM tuning. That's probably whats wrong. Let me know what you find out.

 

Sorry to drag this one up, but as I'm searching for rough idle problems, I found this. Mine is the opposite though, when hot and idling, it starts stumbling and has actually died 3 times either at a stop light or in the drive through. If I can give it more gas, it's alright. If it turns out to be the injectors, will the 24lb injectors work in a 350-L98/700R4 without any tuning? This is a stock 1992 B4C Camaro with about 200k miles.

I've replaced the following with the help of some friends over the past year and a half:

AC Delco plugs (twice) and just added MSD wires
Cap, rotor and electronic module, which left me for dead one night
Fuel filter
EGR valve
most vacuum lines
Canister purge valve and charcoal canister
Cleaned TB and IAC
T-stat swapped for 180*F
Fan switch replaced for cooler temp
Radiator
O2 sensor
Coolant temp switch
I'm sure I'm leaving some stuff out.

I had Magnaflow universal cats installed where the old ones were removed by the previous owner. Now, the rough idle has gotten bad enough that one of the new cats is vibrating.

Could all this be due to the injectors? The car had a wet nitrous system on it that I sold on here. Would anything have been done to the car as far as the fuel pump or injectors in prep for the nitrous? The idle and timing were adjusted the other day by a friend - we found that out of spec for stock and fixed it.

Thanks for your comments.