89 Carrera Idle Stumble

[Mike Kunz]

Hey....new to the 911 world here...big change from my 914!

Was wondering if anyone could give me a quick tip on what could be causing a slight stumble when the motor is warm. Car has 120K on it...totally stock except for Andial chip and sport exhaust. Runs otherwise excellent, starts right up, etc., but has stumble at idle, barely noticeable on tach, but annoying when waiting for a light to turn green.

Any advice?

Thanks!

Mike

[stlrj]

Ignition wires.

Joe

[ianc]

Do your basic tune up stuff first if the car is new to you. Valve adjust, plugs, air filter, oil change, fuel filter, blah blah blah. Cap, rotor and wires if you're feeling expansive. That may take care of itl If not you'll have a solid base to work from. Good luck and congrats. Also, don't bother asking for help again until you post a pic.

ianc

[GeorgeM]

Good luck. I've had the same problem for 8 years and have been unable to fix it. I've tried all the mentioned items with no success. New injectors, O2 sensor, etc. didn't make any difference either. I swapped back to the stock chip and even tried a different one (have a Wong chip with SSIs now) without success.

After a while, I just got used to it so I haven't tried anything new in a long time. It idles like a V8 with a big cam.

I think this is a common issue with 3.2s. If anyone has any good ideas, please pass them on.

[mjmoran]

Check the idle control valve. They need cleaning once in a while

[ZOA NOM]

CO mixture.

[stlrj]

Loose intake manifolds with sucked in manifold gaskets.

Pretty common on 3.2's.

Joe

[stlrj]

There's an easy way to find out if your stock Beru ignition wires are any good. Just spray some windex on your distributor cap wires at idle and see if it misses.

Joe

[ZOA NOM]

Also, you can turn off all the lights in the garage and peek under the hood. If the wires are arcing, you see it. Have someone rev it.

[911finally]

In my 84 carrera I had more of a revving at idle (up/down) 200 rpm which might be different from your issue, but after doing all the usual tune ups (especially fuel filter) I found that it seemed to be triggered by use of the Cruise control.... Even if I flicked it on by accident or actually used it on the highway, once I was back in the city it would rev (not hunt) at idle...

I didn't do anything to the cruise control other than not use it since, no problem with revving since...

Maybe unrelated but I thought I'd share it. Gremlins are everywhere in these cars.

[mjmoran]

Originally posted by 911finally
Gremlins are everywhere in these cars.

There really should not be too many "gremlins" a properly maintained 3,2 should have very little to no problems.

[stlrj]

If my mixture is set too rich it will definitly stumble off idle.


Joe
86 3.2

[911finally]

Originally posted by mjmoran
There really should not be too many "gremlins" a properly maintained 3,2 should have very little to no problems.

'Should' being the operative word in your statement, there's a half million or so posts on this board that might argue against your proposition

[Nine9six]

Originally posted by ZOANAS
Also, you can turn off all the lights in the garage and peek under the hood. If the wires are arcing, you see it. Have someone rev it.

I'm no professional, but while you're back there, it may very well be possible that you can rev it yourself. Now if only I could find the throttle linkage...:-)

[scottb]

Mixture often causes idle problems. Have your wrench check it and adjust, if necessary.

[ZOA NOM]

I said mixture. I said it first.