Is the '93 ECM and ' ECM the same? I bought a "95" LT1 and have got it to run and drive. I have recently deveolped an ignition problem. So, I pulled the Optispark to replace it and it definaltly is not a 95. I have the Optispark that has the splined shaft(93,94?). I had the computer burned to 95 specs. Will this be a problem later or not?? The engine is in a 69 Chevy C10 and has the 4L60E. Later, FuelCellGuy

 

No, They are completely different PCM's. I don't see how they could have burned any code fromt the 93 from the 95 as they are 100% different in every way.

 

I don't know what is going on. I got the ECM with the engine and tranny when I picked them up. The guy told me they were out of a 95 Camaro. He didn't have the wiring harness so, I bought a used one of ebay for a 95. I sent the ECM and the wiring harness to Fuel Injection Specialties in San Antonio. They sent the reworked harness and reburnt ECM back to me. We put it all together and it fired right up and ran fine. I have been told that these ECM's generally take around 500 miles to "dial in". The engine and tranny ran fine until about 600 miles. The engine went to missing and backfiring when I try to start it(optispark). It also will not fully engage into overdrive. Where do I start???

 

It sounds like you meant to say 94 instead of 93 PCM. The 94 Optispark is similar to the 93 as it has a splined shaft whereas the 95 is different and has a dowel pin. As far as it dialing in generally it takes several drive cycles of more than 10 minutes each to get the LTFT's in a stabilized range. If it is missing like you are saying does the SES light flash? Do you have any data logging tools or scanners? It is very possible that the Opti has gotten wet or is dying. The older 93-94 style are very notorious for failing quickly and the symptoms you are describing sound very similar. I would check all other avenues first though. I would check the plugs, wires, and even the coil and it's grounds first.

 

I just took the Optispark apart and can see a line when a puddle of water had sat in it for a while. I am not sure how long it sat before I got it. I am going to get the coorect Optispark next week. As for the programming of my PCM, wouldn't the guy that programmed it, know what year it actually was by external markings or internal programming id?? The SES light is not flashing, just steady on. I don't know. When I get it fixed, the whole truck is going up for sale. I am ready to move on to the next project. Later, FuelCellGuy

 

Well if it was running good like you said when you first got it back you can be assured that it was programmed correctly for your year model. The symptoms you mentioned plus the water almost guarantee the problem. Once you replace your Opti you will most likely be running like new again and will not want to sell it.

 

I'll give it a try. Thanks, FuelCellGuy