I'm having a problem with my 98 Camaro race car and hoping someone can help me with it. It has a LS7 427, GMPP carb style intake, running mafless OLSD making 650-700 hp at the crank. Transmission is a powerglide and the only accessorie on the engine is the alternator. I tuned it with EFIlive intergrated with a FJO wideband. It cranks and idles good, revs great and pulls strong. Problem is everytime I go WOT somewhere in the 4000 to 6500 rpm range it will backfire thru the intake or exhaust and shut off. My theory is the PCM drivers are turning the coils off. I have replaced all sensors, coilpacks and a different PCM. Fuel pressure never varies from 60psi. Wideband always shows <12.8 afr. I have done a full reflash, checked and double checked wiring and grounds and also crankshaft relearn. I also cut the VE table 25% and the IFR 25% to see if it was a torgue limit problem. Logs with my interpretation say the injectors keep firing hence the backfiring. Any help will be greatly appreciated because I have been battling this for 4 weeks now. My next move will be to change over to a 2002 pcm and wiring harness. I really hate to do that because of work and cost.
Attached is my current tune and a short log showing the pop. Actual pop is at frame 17.