Maintaining revs after cold start
 

Currently have an inconvenient issue where the revs will drop and stall the car after a cold start.


The car starts first time no problem in the morning and the revs idle around 700-800 rpm quite happily, I then reverse off the drive and go to put it in 1st but the revs will drop before I have a chance to move away and the car stalls. I then start the car again and drive away and the problem goes away until I do a cold start in the evening or the next day.

There is a component in the fuel injection system designed to prevent this problem, the ICV or idle control valve. A few things can cause ICV problems.

1. ICV missing, unplugged, or non-functional.
2. Idle air bypass screw out of adjustment.

You can consult Clark's Garage for idle adjustment procedure.

If all that checks out, I would next suspect the coolant temperature sensor.

I got the exact same thing happening.
Definitely the ICV. Did not want to open or close when applying voltage to it, until I cycled it a few times. It was slow to operate..... I need a new one.

Adjusted the idle via the screw when I resealed the throttle body last weekend. Now it idles great when it's warm.

The ICV sometimes decides to start working again but usually I need to keep the throttle depressed so it won't stall out while idling till it warms up.

Early 944 doesn't have an ICV, it has an Auxilary Air Regulator and an Electric air Valve

Guess I should check my own blog posts more often944 Foot To The Floor: Erratic Idle Problem Porsche 944 (Square Dash Model)