81SC Diagnostic Help- Keeps cutting out

[SP2]

Hello,
My SC had some new problems after work today. It was hot here today and my car was outside. It was about 90 deg on the blacktop pavement. Usually when the car is cold, it will start briefly, then cut out, then I restart it again and it is fine to drive, getting better as the car warms up.

But today the car kept cutting out. I would start it and keep my foot on the gas to keep the rpms, but then it would die. I had to restart it about 15 times. Once or twice the car would try to stall, then a big rush of power as if the engine had more time to get fuel into the cylinders. I was driving a small side street, sputtering and trying to get her going, then I realized there was no way I could drive it on the main street like this.

So I pulled over and put it in neutral and just gave it gas and tried to keep it at 4-5000 rpm. It wasn't smooth like it usually is. Then after about 5 min of this you could hear the car smooth out, so I let off the gas and was pleased that the engine settled down to about 800 rpm, smooth. I did notice that the idle was slower than usual. It usually is 1100 rpm at idle. But I had to get home so I took it on the road, then the highway and it was fine. I had to stop for a 2 hour meeting before going home and was worried this would start all over again, but it didn't. This time the car was parked in a covered parking garage out of the sun.

My first inclination was to bring it to John Walker, but after the car settled down I am thinking of trying to figure this out. Last year I pulled the engine, rebuilt the 915 (with JW help), put in new 964 cams in to the stock 3.0 Euro engine, set the chain timing, etc. so I have a little mechanical ability. But my diagnostic skills could use your help.

Thanks!

[john walker's workshop]

O2 sensor relay?

[SP2]

Thanks John. It's weird, I drove the car last night when the engine was stone cold and it was back to normal. Is that still consistent with an O2 sensor problem?

I don't know much about the O2 sensor relay, or even where it is....

[TTinCT]

maybe a bad load of gas or a partially fouled plug??.....drive it some more and see if it re-occurs....probably had nothing to do with the heat/blacktop.....

[john walker's workshop]

unplug the relay and see if it duplicates the problem. small, square with a mounting tab, under the right seat, in front, close to the tunnel.

[SP2]

Will do. I will try this today when I get home from work.