92 firebird 3.1liter idle problem

Asked by Jul 31, 2016 at 05:16 PM about the 1992 Pontiac Firebird Base

Question type: Maintenance & Repair

I bought a 92' firebird the car has a hard time staying at an idle.My dad is a
past mechanic and we've done everything we can to fix it. So heres what
happens....It will turn on at a higher RPM (2-3k) then when it goes
anywhere lower than 1k, maybe 800rpm it will shoot back up to 2-3k then it
will repeat that over and over. Till it will die.Sometimes it will start up at the
high RPM and then just die.   We've replaced the Idle Air, MAP, Throttle
Position Sensors, New Fuel tank, Injectors, fuel filter, distributor, fuel pump
computer, timing chain, compression tests, new plugs and wires, and some
other things that I forgot. In other-words, we've replaced almost everything.
Someone asked if the catalytic converter has been taken off (in case
something was blocking the exhaust to breath) and it never had a cat when
we bought it, so we dropped the muffler and still.....shitty idle. I hope this
helps you guys out to give options available to us to figure out, but of
course taking it to an actual mechanic shop could do the trip....if it could

2 Answers


When you replaced the IAC (Idle Air Control) valve, did you set the pintle length? GM OBD I is not "plug and play" like the newer OBD II systems. You'll need a shop manual or perhaps a repair manual for the pintle length specification. HTH. -Jim


Vacuum leaks tend to be a constant high idle or rough idle. You seem to be having a surging idle. That may be related to a bad idle control circuit (not just the IAC). After that you need to start trouble shooting as there are a lot of candidates for a hunting idle. Do you have any DTCs being set? It may inform you of any faulty sensors like a bad knock sensor, crank sensor, or head temp sensor that can cause a hunting idle. Even though you replaced fuel pump and filter it wouldn't hurt to test fuel pressure and fuel pump control circuit. If you feel certain the surging idle is not caused by any of the control circuits look for cracks in the exhaust or intake manifolds, or even trapped air in the cooling system.

1 out of 1 people think this is helpful.

Your Answer

Add photo

Related Questions

  • 92 Pontiac firebird v6 9 answers

    I have a 92 Pontiac firebird v6. Driving it one day and slammed it in park while barley moving. Turned it off and and it hasn't really started since. Replaced timing chain, distributor cap and ro...

    1992 Pontiac Firebird Base


    Maintenance & Repair

  • Problems with my 92 firebied 5.0 3 answers

    I want to know more about the throttle body. I am thinking of putting on a carb but I don't know if it will work because of the computer and sensor. Any id.eas or help

    1992 Pontiac Firebird


    Maintenance & Repair

  • 1992 Firebird, NEED HELP!!! 1 answer

    I have a 1992 Pontiac Firebird 3.1L V6 that is difficult to start and when it starts it wont hold the idle. The ignition control module was tested and is good. Replaced fuel filter, ignition rotor, di...

    1992 Pontiac Firebird Convertible


    Maintenance & Repair

  • 2000 pontiac firebird Question 5 answers

    when im going 30 or more my car is idling up and down....what do you think the problem could be?

    2000 Pontiac Firebird


    Maintenance & Repair

  • 1991 firebird will not idle 14 answers

    Ok so I bought this 1991 firebird that was sitting for 3 years I brought it home got a new fuel pump in it because it was bad then I started my firebird it ran smooth for about 15 to 20 minutes an...



    Maintenance & Repair

Search Pontiac Firebird Questions

Pontiac Firebird Experts

#1 Samuel Moore
Samuel Moore
Reputation 930
#2 dandyoun
Reputation 780
#3 John Saffrahn
John Saffrahn
Reputation 700
View All

Related Models For Sale

Used Chevrolet Camaro
147 Great Deals out of 32,614 listings starting at $1,729
Used Ford Mustang
388 Great Deals out of 47,511 listings starting at $1,800
Used Chevrolet Corvette
99 Great Deals out of 20,456 listings starting at $3,495
Used Ford Mustang SVT Cobra
267 listings starting at $6,335
Used Pontiac Grand Prix
18 Great Deals out of 2,919 listings starting at $1,995
Used Ford F-150
2,247 Great Deals out of 209,704 listings starting at $1,499
Used Jeep Wrangler
275 Great Deals out of 18,613 listings starting at $2,995