Engine mystery

[pontus]

Hello:

My 89' 3.2 Carrera starts normally runs fine while warming (2-3 min.) then surges until the engine dies. If I step on the gas it will die. I am baffled. Before I take it to the shop($$) does anyone have some experience with this that I can check and address myself.
Before this problem the motor ran strong. It had been given a service 3 months ago.

Thank you.

[steely]

Cylinder Head Temperature sensor? Just a guess because I really should offer a proper list of troubleshooting steps.
Is it cold where you live?
Seasonal problem? Did it just start doing this?
Do you have a Bentley workshop manual?

[pontus]

Warm here in Florida. Just started doing it. I have the Bentley Manual.

[jimtweet]

I had this problem on my 944. Turned out to be bad O2 sensor

[steely]

That's it - rub it in :-)
There's a troubleshooting table in section 200, but I don't think it mentions the CHT - but I think the DME ignores the CHT until the engine warms up some, then switches to using it as a dedicated input. There is a test for shorting it I think to fake out the DME, but I don't know it offhand. Maybe search here for some symptoms - hate to pawn you off like that, but it's a start.

on edit:
engine cuts out.

[larrym]

doubt it's the 02 sensor - i run my 3.2 without one

Originally Posted by jimtweet

I had this problem on my 944. Turned out to be bad O2 sensor

[Porsche 935]

My '84 Carrera turned out to be a vacuum leak.

[Targa Me]

my guess is that its the CHT sensor.

[Mick_D]

Sounds like it could be a fuel delivery problem.

[GaryR]

To eliminate it as an issue and to not waste time chasing 20 different things, I would send the Motronic box to Ingo for a checkup. A cracked trace in there can cause all kinds of odd things to happen. Once you KNOW it's good, then move on to mechanical items. Just MHO..

[bigel]

Originally Posted by larrym

doubt it's the 02 sensor - i run my 3.2 without one

Easy to eliminate the O2 sensor...just unplug it and see if it changes.

[pontus]

Thanks for the replies. I'll try the CHT check. Not the O2 sensor. Disconnected it with no change.