Hello, i drive a 1990 firebird with the 3.1L v6. i am having some issues with my car surging at idle. it doesn't really occur until i hit operating temperature. it only surges at stops. it used to only happen when i had the brakes applied but now it happens in park and neutral. I had an O2 sensor rich code, and a Manifold Air Temp code. i fixed the MAT code, and replaced the o2 sensor. i also cleaned out my IAC unit (yes i did use the search function ). however, it still surges. Also, if i let it surge long enough i do get the o2 sensor rich code again. i wish i could give you guys more information but i don't have the money for a scan tool and going to a shop is out of the question due to a tight budget D: Any help would be greatly appreciated as i need to get this car through emissions before i can register it

Check your plugs wires cap and rotor coil igntion module etc. Also

I would check your collant temp sensor like 20.00 new and possible your egr valve these are vey expensive I do have a used good one that I can sell you.

I'm assuming it's an automatic... Try unplugging your TCC solenoid. You've got two plugs on your transmission, one on the tailshaft for the speedometer, and another on the side of the housing above the pan for the TCC. If the problem goes away with it disconnected, get a new solenoid at the parts store, and swap it out. If you just drive it disconnected your mileage will go to hell and eventually you'll burn up the transmission.

yes its an automatic, i forgot to mention that. i'll definitely give that a go. thanks.

sorry for the double post and border-line bump. i cleaned out my throttle body with carb cleaner, the car does seem to shift better then it did before, no more late shifts. however, it still does not like to run hot. usually around the 220 range it will have issues running, mainly at idle. also, i did notice that my oil pressure seems lower then what i think it should be at said temperature (about a couple hash marks above the red zone). at cruising speed, i would say about 40mph it seems to feel like it is back-firing. not sure if this is the case (there is no loud bang) i can feel it sputter if you will, this may be due to it burning off the gunk from the cleaning. i have yet to test the TCC solenoid theory.

the TCC won't make the engine run rich

well, i hooked it up to a scan tool. everything seemed ok except for the fact that it does not like to go into closed loop. the car has a pretty nasty misfire as well, could the rich condition be caused by the ECM trying to compensate for the cylinder that isn't firing properly? possibly a dirty injector, bad plug wire, or spark plug.

Have you check your O 2 sensor How are the plug rich full of carbon. Your O2 sensor could be telling the computer that its lean with actually its rich. I had that problem on my 3.1 Als have you check your timing chain could also be a problem. Also tming could be and issue.

Suppose you don't want a youngin' giving you information, im 18 and have been working on cars since i've been 8, changed my first tranny at age 10 =). Just some backround information on me, now to the problem.

I've had this problem with my bird, try removing the Intake Manifold, and upper plenum, and the complete throttle body including the electronic pieces IAC, TPS, yada yada, then get some engine degreaser soak'em with ALL the electronic pieces removed, bring the parts to a garden hose, or i prefer a pressure washer and give them a throughly rinsing, i bring mine to a $2.50 car wash and pressure wash all my parts there.

then reasemmble all your parts, torque them to specifications and see if the problem persist.

Mines went bye-bye after all that about an hour's work, and bout 10 bucks later (new intake gaskets)

ALSO, if you got some gunk or engine degreaser caught in the TB or plenum without a good cleaning it will cause horrible surges and codes will set.

P.S. if it surges while you drive meaning like a pull or backfire, could be your distributor unit.

any advice is worth listening to. i'm only 20 by the way :P sounds like a good idea, i'll try that out A.S.A.P. any further ideas or theories on my car's issues would be greatly appreciated

intake manifold gasket. if its bad it will suck air in. for instance the genius who previouusly owned my car used silicone instead of a gasket. the car idles high 60rpm range, and sucks gas. i got a 92 3.1. try it trust me

It seems there are tons of people who have surging idle - maybe it's time for a sticky?

Hello again, also look for any arc's (gap bridging looks like a big carbon deposit between the electrode and the metal tab) on the spark plugs.

pull all six of your plugs look for carbon deposits, etc.

gap then to specs, and make sure there in zero arcing taking place, that could cause a dead cylinder, thus stumbling.

***Found an arc on my #2 plug today wasn't even firing.***

haven't had much time to do much with the car since starting work, but i did check for arc and my plugs were surprisingly clean. i did notice some oil on the plugs on the 1-3-and 5 cylinders. i talked to a fellow tech and he mentioned that a bent push rod might cause the issues i am having. thoughts?

double post, sorry.
updates on some things i bought.
new cap and rotor
new spark plug wires
new set of plugs.
no change.
new I.A.C. unit
still surges, car seem to want to lurch forward when it does surge (TCC solenoid maybe). headlights seem to draw a lot of power for some reason and almost kill the battery during stops....kinda leads me to believe i have a short somewhere.