Ok got a newly rebuilt CC qjet and the car runs great. However if I am at highway speeds the check engine light comes on. It will go off when the car is shut off and only come back on at highway speeds. Only thing disconnected is smog pump and the other misc smog equipment (hoses were all dry rotted and cracked). Previous owner plugged the port on the EGR valve. Does not seem to be a change in the way the car runs with the engine light on.

 

Pull the codes from the computer (can be done with a paperclip if you don't have a scan tool). But don't be surprised if the code is for the EGR system. They won't usually pop up driving around town on and off the gas a lot. Out on the highway in a steady-state cruise is when the ECM figures out the EGR isn't working. This is because it has no way of directly knowing if the valve is there, but it can INFER if it's working by how the engine runs in a steady cruise state after a while. And no, it won't run any different if that is the cause of the light.

 

I'll check it out, thanks!