I have replaced the distributor and the coil. Code 42 never went away. The strange thing is if i started it cold let it warm up the code wouldnt come on for a few minutes. The motor runs like crap when its cold started but after its warm if i restart it the code will still set but it runs like it should. I'm so confused about this thing. My next step is to replace the ecm. I'm just wondering what you guys think?

 

Have you done the troubleshooting steps for code 42 using an ohm meter and a test light? http://chevythunder.com/est_code_42.htm Follow this chart, it will help determine your problem. HTH!

 

Wiring on these cars is over 25 years old so don't overlook the points about open or shorted wiring in the circuit!

 

I have checked all the wiring I can and it all looks good. No broken casings or ends. I'm gonna pull the ecm and check somw of thw harnesses ground on ckt 423 i believe is the correct one.