Idoling problem vn

[Thebiglomos]

Hey guys first time posting, just recently bought a 1991 vn commodore.
When I turn the car on it idles high and then really low almost as if it's about to stall.
I've changed iac, tps, cleaned the throttle body, new leads, new spark plugs, put l67 coilpack in, new fuel filter and oil filter and oil, and ran injector cleaner through it.
Started it up today and thought it was running fine until it started this again.
Stalled on me twice, can anyone help with this problem it's driving me insane.

 

[strgas]

sounds like base idle is out and set to low .

 

[Thebiglomos]

sounds like base idle is out and set to low .

How do i fix that? Don't really know much about cars.

 

[strgas]

havent done a base idle reset in many years 20+ myself and abit foggy on the etails myself try doing a search on here someone may have posted a how to .

 

[delcowizzid]

If it starts fine cold and idles and then turns to **** as it warms up the ecu could be toast.they had issues with the coolant sensor circuit traces on the circuit board

 

[JBAV6Tony]

My guess is a intake manifold leak or pcv valve needs replacement.

The pcv you wont find. I found a used one at a wrecker. The air leak? Well not an expert so cant tell you how to find it. Replace intake to heads gaskets suppose.

At fast idle the vacuim is less of an issue but at idle air will seep through the hole in the gasket and reduce vacuum causing rough low idle

As suggested adjust idle screw first where the accelerater moves the throttle but best to get correct diagnosis of you could adjust wrong items and make the situation wirse!
Listen to mama! Lol

 

[Indrid cold]

Hey I've go the same sort of problem. Won't idle without my foot on the peddle. Replaced spark plgs,coils,leads,air filter now won't idle can any one help?????

 

[HSVBMW]

When you changed the iac sensor or disconnected the battery did you reset the idle with the 'hold revs at 3000rpm for 10 secs' procedure? That must be done anytime computer gets reset as soon as you start the car.Do it if you have not....but disiconnect battery or remove engine management fuse first to again reset computer prior to performing idle procedure.

Is car temp correct? Thermostat functioning?
If yes to above it will more than likely be your 'coolant temp sensor' failing. The ecu controls fueling from this and it only plays a part in fueling after the car gets to temperature and enters 'closed loop' setting. If your cars seems ok at start up then once warm coughs n struggles look there.

Try resetting idle first n go from there.

 

[Indrid cold]

Hey thanks for your reply, no I didn't rest my idle, I don't have a rpm taco. Should I put a gauge in to reset the idol? The radiatior fan comes on strait away as well when I try to start it, or just after when its on aceseries. ??

 

[delcowizzid]

Check coolant sensor is plugged in test its resistance if you have a multimeter if its fine find a spare ecu or borrow a mates one to test