I hope there are some LT1 experts here!!!!!

I have a 1993 Z28 LT1. The "service engine soon" light comes on when I drive it. In the AM on my way to work when it is cold it is fine, light is off for about 10-15 miles of driving then the service engine soon light comes on. If I park for 4-5 hours and start it up it will come on right away. The car runs and drives fine and has no problems that I can see. The code indicates the problem is with quad driver #1 in the PCM. Quad driver #1 controls EGR sol., evap. sol. and the AIR pump relay. I have changed the EGR sol., Evap. sol. and the AIR pump relay and had the PCM gone through by A1 Cardon and I still have the same problem. Cat converter is about 1 1/2 years old.

Any ideas guys??????????????????????????

Thanks
Dennis

 

Look for a wire going to one of the components listed that is rubbed through some where getting grounded out intermitently.

 

Thanks for the suggestion, but I have pretty much done that while I was working on it the last dozen times. I will take another look because I am completely baffled on this electronics crap! I really need to get this light turned out so I can sell this car.

Thanks again for the help!
Dennis

 

It is possible that the pcm is still bad. Could be heat/vibration induced failure which cardone really can't account for.

 

I checked the wiring as you suggested and didn't see anything. This car has not been butchered up and the OE wiring seems to be in perfect condition. I guess the next step is to try (again) to find an ECM from someone (that knows it is as good one) that is parting out a 1993.

Thank you again for the help!
Dennis