Nader Fotouhi

Having a bit of issues with my wife's 93 C2 that I hope someone knows the cause. Last week the check engine light started coming on (it was a hot day) after start up, but dose not stay on for long. It happened to her after she had driven the car for about 45 minutes and stopped for a few minutes to pick up something. She said that she noticed the CEL when she staretd the car, but then went out. I do not know if the AC was on.

I drove it for one day to check it out. No issues in the morning 40 mile stop and go commute, but in the afternoon, the CEL came on when I first started the car with the AC switch in the on position and fan on 3. Again the CEL did not stay on long. Also, the engine died a couple of times when I came to a stop sign and took a few seconds of cranking to start the car again. The car ran fine for the rest of the commute home. BTW, all this happened after we returned from a DE.

The car seems to run fine and the mechanic says that he has driven the car a couple of times and could not replicate the CEL and there are no fault codes, although one time the car did not start quickly.

Has anyone else had similar experience?

TIA

jimq

Where are you located. Maybe one of us if local with a scantool could read the code for you.

user 783003

This happened to me the other day at my AX event. Went out shortly after starting up while on the paddock. A/C was not on at the time (as not on as it can be). Spoiler light stayed on a bit longer than usual too.

psiegel

Reset the DME ( disconnect for 30 seconds or so) and see if the problem repeats although if you checked for fault codes, hopefully they did a hard reset but who knows.

Shamus964

I doubt this is the case, but have you adjusted the cruise-control cable lately?

I took the slack out of mine when I first bought the car, thinking it was the throttle cable, and made it a little too tight which brought on the CEL. With the car running, I loosened it until the light went out and stayed out.

Nader Fotouhi

I am in Central NJ. If the problem continues, I will look into finding Scantool or maybe finally give in and buy a Duramatic (sp).

I do not know if they ther reseet the DME. I doubt it since no codes were found.

garrett376

If you start a 964 with your foot on the gas pedal, it will produce a check engine light that will stay on for a temporary period of time and then go out after a minute or so, leaving no code stored in the DME. That means either the idle contact switch at start is a potential issue causing this (easily tested by barely pressing the gas pedal and starting the car - pretty sure this isn't the problem) or the O2 sensor is a potential issue (ruled out by pressing the gas pedal further at startup - 3/4 of the way). That's where I'd be searching... things like O2 sensors do wear out.

dfinnegan

I am in Warwick, NY and have a Hammer.

You are welcome to drive up, if you care to, and we can run the hammer to read any codes.

Cheers,
Dave

Nader Fotouhi

Thanks for the offer. I'll let you know if I can get the time. A busy weekend is coming up and we are heading for VIR next Thursday.

The car is still at the shop where the tech is also trying to do some reserach on the symptoms. I will ask him to try Garrett's suggestion and check the O2 sensor.

Nader Fotouhi

dfinnegan, I'll sent you a PM.

Nader Fotouhi

Garrett,

I am back at trying a few things. What do I look for with testing the O2 sensor as you describe? No CEL or CEL?

Thanks

garrett376

Hi Nader - I'd check your idle switch first by moving the throttle with your hand and listen for the click of the switch (first way to check it) - best way is to confirm with the Hammer which will tell you when the switch is on and off and working properly. I know a Hammer will also tell you the working voltage of the 02 sensor while the engine runs - I've found bad sensors that way a couple times.

Streetfighter

Do you have an aftermarket chip in the DME?

dfinnegan

Here's a pic of the idle speed switch; courtesy Jason, I believe.

Nader Fotouhi

Thanks to Dave, it was very clear to see using the hammer that the idle switch stays open if the pedal is let out slowly, but works fine when there is a hard enough blip. I may start by spraying some brake cleaner on the spring before getting my nerves up to try to adjust the cable from under the car (agin thanks to Dave) for telling me about that.