89 pathy stalls now that the weather is cold at idle

[Scaramoche]

Well not sure where to look, Now that the weather has taken a turn towards winter, im having an issue where i occasionally stall when pulling up to a light.

 

Basically when i start the car it idles hight(1200rpm), ie cause its cold and warming up. it doesnt stall at this point

 

Once i get on the road, and say hit, a stop light, the rpms, drop really low(100rpms or so) for a few seconds(1-3) this is when it stalls. if it doesnt stall durring this 1-3 sec, it goes back up to it's 900rpm range.

 

after about 30minutes of running(basically getting to operating temp) it runs fine and stops stalling.

 

What can i adjust?

 

Im not sure i want to crank out the idleadjustment screw, im kina of happy with the 900rpm range, and not really sure if this would clear up the problem. am i missing a sensor somewhere?

 

I rebuilt the engine last year, including heads, and it ran fine all summer, passed immisions etc , the only problem i have is this silly idle issue when it cold, and slowing down.

[adamzan]

I would check the maf, o2 and coolant temp sensors.

[Kingman]

If it does it when it's cold, check the Cylinder Head Temperature Sensor (ECU Coolant Temperature Sensor). MAF and O2 wouldn't be an issue with temperature or the engine being cold. Those two only adjust things when the engine is in closed loop mode (above 150F).

 

The idle screw won't do you any good adjusting it, it'll only idle where you set it when the engine is actually running correctly. Any other time it'll still act the same regardless.

[GrimGreg]

It is probably this +\(wd21&cPath=5572_5573_5590_5591"]part , it controls cold idle. If you look at the throttle lever, there is a little bump that this pushes against if it is cold, once it warms up the part retracts allowing a lower idle.

[MY1PATH]

X2 on the cold Idle settings and coolant sensors

 

+ check your "stove pipe" its a intake heater hose that draws hot air from arround your exhaust manifold.

 

 

[Kingman]

I think there's a real electrical component problem, I ran my TBI for a while without any cold start systems, and without the hot pipe, and it never had an issue with stalling or a low idle like that.

 

Check for vacuum leaks anywhere as well.

[Scaramoche]

I think there's a real electrical component problem, I ran my TBI for a while without any cold start systems, and without the hot pipe, and it never had an issue with stalling or a low idle like that.

 

Check for vacuum leaks anywhere as well.

humm, i dont have the stove pipe installed, so im currious if that may be an issue, id forgotten about that(i need to see if i still have the cover that goes over the manifold), but if you ran ok, im currious any one else have feedback?

[Perris]

I had a problem that sounds the same. Turned out to be a vacuum leak. A hose popped off underneath the air box back towards the firewall. I also found a cracked hose under the air box closer to the front. If you have some brake cleaner you can generally find a vacuum leak fairly easy. Do you know that trick? Also if it was smoged recently i have had problems with those smog guys knocking off hoses or whatever else.

[ahardb0dy]

It is probably this +\(wd21&cPath=5572_5573_5590_5591"]part , it controls cold idle. If you look at the throttle lever, there is a little bump that this pushes against if it is cold, once it warms up the part retracts allowing a lower idle.

 

 

Thermo element, wax filled, when hard wax pushes against the idle cam causing idle to be high, as coolant flows thru it metls the wax causing he idle to drop