I installed a create engine lt4 in my car, which is stock. I previously had it running with 17 and newer ECM AND TCM. But my transmission is a 16? so I had to get and ECM AND TCM, from a 16?. When I had the 17 computers engine ran fine. Now that I have the 16? computers in it, my headers are glowing red now.
Fuel pressure is good, Fuel trims and MAF seem to be reading correct.
Any ideas to check?