I am using a 96' obd II ECM from a Camaro with my LT1 engine swap in my 89 camaro. I had the ECM programed for the engine conbination I am running. The motor starts and runs fine, excet for a crank sensor code.

The problem I am having is that I can pull codes and read pending codes with a scan tool with the engine off / key on. No problems, I even fixed some codes based on the data I retrieved........But when I start the engine to view live datastream I loose communication. It will start to read for just a second and then looses communication. I have re-checked all the wiring I could think of any sugestions???

 

I was having something simular to me on my car. I used to run a 165MAF ecm then I converted the car to a 7730 Speed Density. The ECM and Snap-on 2500 worked flawlessly. Then I converted the ecm to a 7749 GMC Typhoon turbo ECM.. Then my scantool wouldn't read, or even pickup any signal. I had to get Vin from any Turbo Car like Grand National, Typhoon, Turbo Sunbird and put that data in the Scan-tool, then everything worked fine. Apparently different Ecm's send out different signals.