I have a LS3 in a 33 ford with a spear tech harness and GM computer. I have not been happy with some running issues with this setup so I ordered a GM performance pre flashed PCM part number 19258271. After installation, the engine starts runs 4-5 seconds then dies, no spark. Sets codes P2138, P0512. It will not restart until the computer is disconnected and reconnected.

I`m told the VATS system in this preflashed PCM is disabled. Will this system (HP tunners) give me the ability to not only read but change this if need be. Has anyone run into this sort of problem? any guidance would be helpful.

Dennis