Engine dies at 90C when out of gear!

[Martyn]

Car starts fine. Runs OK at the beginning with temperature guage showing coolant temperature rising as normal.

Then, when the temp guage reaches, at what looks like, dead on 90C (194 F) and I change gear (foot off gas pedal) the engine cuts out. When it happens I can sometimes jump start if travelling fast enough or use ignition key to restart. No problem restarting the engine but will die if coolant at 90C and not in gear and foot off accelerator. If slightly below 90C after problem has happened, then car continues to drive fine until temperature rises to the critical level and it happens again.

I imagine its an electrical problem somewhere, but I dont understand what is happening or what to change.

Look forward to your guidance.

[18Fiatsandcounting]

It sounds like your engine is not idling properly. If you just warm up the engine in the garage or driveway or street without driving the car, does the engine die when the coolant temperature reaches 90 degrees? Regardless, I'd have the idle set properly when the engine is fully warmed up.

A remote possibility is that the Ignition Control Module (ICM) is failing when hot, which is pretty common. However, it usually doesn't fail as consistently as you describe, so I would start with the idle adjustment.

-Bryan

[Martyn]

Apologies Bryan. Just seen the reply.

Yep idling is erratic. It seems worse when engine gets warmer. A mechanic has tried to adjust it but still not good. He says its running too rich and he has had no success in changing mixture. His conclusion is that the air flow meter is faulty! But he cant be sure. If it is the AFM then very expensive to replace here (Spain) just for a refurbished one. And I'm reluctant to replace when mechanic is not 100% sure.

I was thinking of replacing ICM and see whether anything changes.

[18Fiatsandcounting]

It does sound like it might be an AFM issue, since the fuel injection is usually pretty accurate if it gets a good signal from the AFM (air flow and air intake temperature). Other possible causes for richness are a leaking cold start injector, and a bad coolant temperature sensor on the front coolant neck.

The tracking mechanism inside the AFM is known to get crusty over so many years, but it is possible to take the top cover off and clean it with electrical cleaner.

-Bryan

[Martyn]

Hi Bryan,

Thanks for the prompt reply.

The cold start injector is disconnected. I will test the temp sensor and investigate and clean the connections in the AFM and see whether any difference.