97 Z28, Idles fine. Runs rough. Read codes: AIR malfunction (I removed AIR system so DUH!)

THe other code was, in effect: Alternator malfunction causing PCM problems. It charges between 13-14 volts by the guage. Anyone else had an alternator bad causing car to run like crap. P.S. New Platnium plugs and 8mm Taylor wires, cats gutted, seafoamed, throttle body cleaned.

 

need to put a voltmeter on it and find out for sure. thats a little low and if you get under voltage during high load operation it could cause all sorts of running problems. Sick

 

Possibly a bad diode. Murrays and Autozone do charging system tests.

 

Low voltage will confuse the PCM and the engine, and sometimes the gages will act weird. A shorted alternator diode, generates a lot of electrical noise in addition to low voltage, further confusing the PCM, while a blown diode will only result in low voltage under load.