BigMike05

Ok a bit of back story, this is a friends C3 1981 V8 vette Auto tranny with a Hypertech: 11042, Thermo Master chip(PROM), the problem is that it has a check engine light, does not miss or splutter, and when i try to pull the codes the DLC does not communicate with the obd1 scanner. So I had an extra 3 pcms that are known to be good that I swapped into the car with the stock chip (PROM) and the check engine goes away but the car will not accelerate it backfires and splutters and such, so I checked the ignition timing and the recalibrate the carb with no luck so I tried a carb from another car same year and still no difference, What would cause the check engine light and no communication on the computer with the aftermarket chip? and why would the stock pcm with the stock chip cause the car to backfire and miss, any help or ideas are appreciated I need to get my buddy's car running.