pcm testing

[shipp13u]

1996 saturn sl2 1.9 liter........runs rough at idle, used scanner discovered no codes, rebuilt heads, new piston rings, and bearings, gotten rid of the smoking but car still runs rough at idle. how do you test the integrity of the pcm? and the cat muffler?

[peppermrj]

Originally Posted by shipp13u

1996 saturn sl2 1.9 liter........runs rough at idle, used scanner discovered no codes, rebuilt heads, new piston rings, and bearings, gotten rid of the smoking but car still runs rough at idle. how do you test the integrity of the pcm? and the cat muffler?

Welcome. Not sure on a PCM test. I would try a few easy things for the rough running. Assuming you have good plugs, wires, and spark, try checking ECTS sensor and it's pigtail. Clean the throttle body, AIC valve and port, EGR valve and port, and check the PCV system.
A clean fuel filter, injectors and good fuel pressure.

A simple test for a plugged cat is let the car idle till the cooling fan comes on and just look at it. If it is glowing orange don't park in tall grass. You can also check with a vacuum gauge.

Good luck and let us know how you make out.