Engine surging rough idle 1995 Olds Cutlass

[maxwedge]

Ok when the cel is on and no codes there is an internal issue with the pcm or as I said the scanner is a basic one that cannot communicate with obd1.5, a sticking or bad egr can cause rough idle, poor low speed performance and possible stalling when slowing down, but it would be there almost all the time. Try disconnecting it and see what happens, that should set a code also, stalling intermittently can be caused by a bad crank sensor, both wiring to the sensor or a pcm, but again all this would be guess work without having the condition stay long enough to diagnose.

[scorpiowoman1025]

The egr is next and we have tested the crankshaft and cam sensors if that is what you mean. We haven't had a solid check engine light for a very long time and it didn't stay. As soon as we changed out the o2 sensor it disappeared. The shop itself is even a little stumped but they also suggested that egr because it would cause those very symptoms. To be fair in the last day or so since we did the last repairs it runs a lot better. My question is that I heard there is some sort of re learn procedure we need to do when you install those sensors, the iac valve and the throttle position sensor, is that true??

[Tech II]

No......

[scorpiowoman1025]

Originally Posted by maxwedge

Ok when the cel is on and no codes there is an internal issue with the pcm or as I said the scanner is a basic one that cannot communicate with obd1.5, a sticking or bad egr can cause rough idle, poor low speed performance and possible stalling when slowing down, but it would be there almost all the time. Try disconnecting it and see what happens, that should set a code also, stalling intermittently can be caused by a bad crank sensor, both wiring to the sensor or a pcm, but again all this would be guess work without having the condition stay long enough to diagnose.

Well now it has started up again and it has some sort of smoke/exhaust coming out the tailpipe when we start it up. It still stumbles a little at stoplights and has a rough idle. I am getting really confused and frustrated but still no cel at all

[greasyhog]

What color smoke? You mentioned several times that your on board computer isn't working correctly. If it is bad why not replace it? If the computer is bad it could be the cause of some of these problems.

[scorpiowoman1025]

I guess I am confused replace what?? The egr valve is being pulled out and replaced tonight if necessary and we are being told to check the ecm. Everything on that car is really old I am finding out and little or no maintenance was done. So its not a matter of not doing things, its just doing the things first to try and correct the driveability problems and go from there. It is super expensive but I do have good mechanics and the two shops couldn't figure it out exactly either without doing some of the same things we are. Just frustrating.. But I do appreciate the comments and the suggestions. I am looking into the egr now, sounds like it could cause a lot of what is still happening, each part seems to improve the gas mileage and running condition of the car overall