Join Date: Mar 2002
Location: Austin, TX, USA
Re: Iroc rough idle
I *think* on the 3rd-gen ECMs you can short two pins on the diagnostic connector, turn the ignition on and count check-engine light flashes to get the codes. But I'm not sure which terminals, so I'll let another member verify my facts.
I recommend getting the codes first and then troubleshooting the problem from there. What's more, those earlier ECMs would tend to trip all sorts of codes for a simple issue. So you've got to take all the codes, and apply some deductive reasoning to figure out what the problem may be. For example, the ECM may say the O2 sensor is too lean, but the root cause may be a vacuum leak instead of an expensive O2 sensor.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI