Ok, so Thursday my 90 Cavalier was running no problems. I park it for a while and then next time I start it the service engine soon light stays on, and the idle is kind of rough. Also it is running rich, carbon on the plugs, some black smoke from the exhaust. And the cooling fan starts running as soon as I turn the key, and runs all the time. I tried to pull codes with a jumper wire but the ses light never would flash. I have no idea what it could be, and why I can't pull any codes unless the ECM is malfunctioning. Anyway, if anybody has a clue I need one.

Anyway, hooked it up to diagnostic computer and read no data, so I take it the computer is done. Oh well, I'll just get another one.