I am having an issue with my fathers 1994 LT1 Z28. After swapping in a 1995 LT1 using the 1994 harness the car will sometimes run fine for days the it will start up and die after 2-3 seconds. After checking for fuel and spark it has spark and loses injector pulse after a few seconds. Has anyone had this issue before or am I the only one with something crazy like this happening? Any help would be great.

 

Have you scanned it for codes?

 

The only code found was a 42.

 

That would be the code for "Ignition Control (IC) circuit (shorted or grounded circuit)", as copied from Shoebox's website. There is a fairly detailed diagnostic logic chart in the factory manual that will help you work your way through the problem. Since the engine runs most of the time, its an intermittent problem. Could be the signal from the PCM to the ICM, power supply to the IC Module, problems with the coil (since that supplies power to the IC Module), heat soak of the IC Module, faulty IC Module, short between the high and low res signal wires in the Opti harness, IC Module ground circuit, etc.

 

So far have checked and cleaned all grounds, replaced opti harness, replaced coil, and replaced ICM. Still no start. What is a website that might show other tests to preform? Thanks for the help so far Injuneer.

 

You need to find the factory manual diagnostic chart for DTC 42.