Pontiac Repair: 1990 Pontiac Grand Prix, air control valve, electric cooling fan

Question
When I start the car, it idles at 1800 rpm and stays there and the electric cooling fan runs.  I have changed the Idle Air Control Valve, Throttle Pos Sensor, O2 Sensor, Coolant Temp Sensor, and the MAP Sensor.  No change and can't get any codes from Computer, none, not even that pins A and B are in test mode.
Any ideas...
Thanks,
Adam

Answer
Hi Adam:

if you cross a and b with the key on it should flash at least a code 12. if not there could be an issue with the engine computer. the computers in those cars were noted for having issues and that perticular engine in that car ALWAYS had idel surge complaints. ther is a long drawn out proceedure to learn the idle on that car when the battery is disconnected to may steps to list on here do a google search for Idle lean/speed density conversion idle learn for 2.8 and or 3.1 liter engines on that vinatge. That may be your issue. You could also have an enegine sensor that is giving an incorrect readin to the engien computer. someone may have messed with the idle stop screw with out a true scan tool you going to be out of luck you need to see what is going on with the data sesnors to know why the idle is racin on the car. Good luck :)