aww996

I've got a weird problem with my 993 C2 stalling. It tends to do it when the engine is half warmed up from a cold start. Usually it happens when I pull up at lights or a junction and have to stop - instead of ticking over the revs just die. On a couple of occasions it has simply died on me on an open section of road. The dash warning light saying "CHECK ENGINE" comes on when the engine stalls. (Until the engine is fully warm it tends to "hunt" the revs around tickover, as though I'm continually blipping the throttle.) Once the engine has stalled I have to wait for two to five minutes, trying to restart every 20 seconds or so, until it decides it's happy to start up again. Once the car is fully warmed up it runs fine. My dealer (not OPC) has looked over the car and says he can't find anything. The car is a US spec 993 C2 (imported to the UK), and as far as I know unmodified. Does anyone have any idea what could be going on, or where we should try looking for a fault? Please?!

kkim

What year is your car? Also, if it's throwing a CEL, do you know what code is causing it?

BTW, welcome to Rennlist!!

aww996

Doh!!! It's a 1995 car (S-series?). Only other thing I can add is that it always dies somewhere very public, usually when there's loads of people about to watch me sat there stranded...

kkim

Do you know if the wiring harness update has been done to the car, if it needs it?

also, did the mechanic pull the codes from the ECU? if so, what are they? if not, you might want to change mechanics.

JasonAndreas

Has your mechanic checked the cylinder head temperature sensor? If you have a multimeter (or Bosch Hammer) you can check the resistance of the white connector in the back of the engine bay (left side). The other cold/warm-start temperature related item is the oxygen sensor. You have a US-spec MY95 so try reading the fault codes with your gas pedal.

aww996

I don't know if the wiring harness has been done or not - I'll get it checked. I'm led to believe there were no codes in the ECU, but I'll get them to check again, along with the head temperature sensor. I think it's model year 1995.

901aero

You might want to replace the DME relay. My car- also a '95- would do the same thing and it got progressively worse. It's a cheap enough part and my motto is always work from the easiest and most inexpensive to the toughest and most costly of cures.

the_buch

Another idea might be to disconnect the battery for a few minutes and then go through Steve's (@ Rennsport) ECU training sequence to relearn how to idle??

aww996

I'll get a new DME relay in there (as it's cheap!). How can I find the ECU training sequence online? Thanks by the way for all this help - I'm instantly a Rennlist fan!

Monique

Had that once. Traced to an improper cable connection onto the Idle Stabilizer Valve. (ISV)

Remove and replace the cable.. then report! Good luck.

aww996

Sorry to seem stupid, but where will I find the ISV?

By the way, I tried the gas pedal ECU code trickc a couple of times and it seems to point to the oxygen sensor, but the codes were different each time...

Monique

See arrow slightly left of center. Good luck.

TomF

I would second starting with the DME relay. As they fail, they can cause all sorts of wierd symptoms.

JasonAndreas

Do you still have the codes written down?
If you suspect the DME relay and you don't have a replacement you can jumper a wire across connectors 3 and 7 in the relay socket in the fusebox (pins 30 and 87b on the relay). If the engine starts okay than you know you have a bad relay. And if you're ever stuck somewhere you could attach another wire to connector 8 and actually drive a short distance. You can drive with only two wires but the DME will set itself to limp mode because there is no power running to the O2 sensors.

aww996

The codes seem to be either 21 (hot film mass air flow sensor) or 22 (oxygen sensor (signal)). I also tried Monique's suggestion and fiddled the wire on the ISV. Don't know if it's coinicidence, but the fault seems to have changed and now the cut-outs happen when driving (as opposed to pulling up to a stop), usually with the engine half warmed-up, and always with a good audience. I'm off to get a new DME relay (the existing one is 944.615.227.00, but I gather it's the same part..?) and see what happens. Thanks for your help chaps - fingers crossed...