Slow idle upon cold start

[Gelbster]

Do you touch the gas pedal before you turn the key when you start from cold ?
If you cycle the ignition switch twice before trying to start, does that make a difference ?
Stalling when you hit the gas suggests it is getting insufficient fuel/too much air. Dirty MAF ?
But why speculate? What does Herr Durametric say? Any MIL or code?

[lkchris]

Any gasoline engine requires a bit richer mixture to run when first started cold. Along with this it requires a little more throttle than is normal for warm idle.

A vacuum leak will undo this.

But, most cars of this era feature something called the idle control valve, whose purpose is to bypass some air around the maf to create extra idle speed. Mixture is richened electronically based on a temperature sensor.

So ...
Vacuum leak
Idle control valve
Temperature sensor

Fwiw but not applicable here, the advent of direct gasoline injection may eliminate the need for these components. Problem is mixture adhering to cold intake manifold and not making it to combustion chamber ... that's why engines require "choke." Mixture obviously doesn't pass through intake manifold with direct injection. "Intake manifold" describes anything behind the intake valve ... including spraying on to it from the back side.

[Porsche9]

Originally Posted by lkchris

Any gasoline engine requires a bit richer mixture to run when first started cold. Along with this it requires a little more throttle than is normal for warm idle.

A vacuum leak will undo this.

But, most cars of this era feature something called the idle control valve, whose purpose is to bypass some air around the maf to create extra idle speed. Mixture is richened electronically based on a temperature sensor.

So ...
Vacuum leak
Idle control valve
Temperature sensor

My guess is that it's one of the later two. The engine stalling and then upon restart running fine to me would rule out a vacuum leak as that would not go away upon restart. It didn't do it at all tonight some it looks to be intermittent.

[Porsche9]

Originally Posted by Gelbster

Do you touch the gas pedal before you turn the key when you start from cold ?
If you cycle the ignition switch twice before trying to start, does that make a difference ?
Stalling when you hit the gas suggests it is getting insufficient fuel/too much air. Dirty MAF ?
But why speculate? What does Herr Durametric say? Any MIL or code?

Never touch the gas pedal before turning the key. Tonight when I gave it a start the engine fired right up and idle at about 1000 rpm. Odd that it didn't do the usual slow idle. I don't have a durametric so I can't check. It means a trip to the shop.