Engine stalls during warm up

Horneck · 08-26-2025, 01:42 PM

I own a 1987 Turbo Convertible (56k miles) and just had the engine out to seal some oil leaks.
Now my car stalls during the warm up.
Initially the car fires up fine and idles around 1100RPM. If I continue to let the car idle the RPM drop over the next few minutes below 600 rpm and the car stalls. When I drive the car I have to keep it alive with the throttle and after 2-3 mile (5-10 min) the idles start to climb to 600 rpm increasing further to 900RPM. No issue after the warm up.
I have rebuild my distributor and have installed a rebuild warm up regulator.

Where do you suspect the culprit of this annoying problem and what test would you perform to find the issue?
Thanks

908/930 · 908/930's Garage

A couple things to look at, you mentioned Increases to 900RPM but what is the final idle when hot? If 900RPM turn up the idle to 1000RPM. Rebuilt fuel distributer or ignition? Have you checked the actual WUR pressures? Can try adjusting the air fuel mixture at idle. The AAR could also be the problem, it is possible to adjust them to let more air in.

Bucketlist · Bucketlist's Garage

Check for vacuum leaks, air leak at the up pipe from the turbo, the O-rings there and at the throttle body. May need to run a smoke test. Check fuel control pressures and post them.

mark houghton · 08-27-2025, 05:35 AM

On top of the suggestions, it would appear that your AAR is working correctly since you do get a higher idle when cold and it drops when warm after a couple minutes. You may just have your base idle mixture not set correctly. A simple diagnostic would be to insert an allen wrench into the mix adjusting post and push it down gently until it just barely starts to deflect the airflow metering arm. When so doing, if your rpms go up then you're too lean - or vice versa you're too rich if the rpms drop. You can then adjust the mix accordingly.
Just a simple test and remedy but it won't identify where the problem is...such as an air leak somewhere or perhaps control pressure issues.

Horneck · 08-29-2025, 01:39 PM

Thanks for your feedback. I will work through your recommendations and report back.