I need some help.
I put together a 427 L92 for my 2005 GTO. It was tuned and put down 490 rwhp unlocked through a ss3600 tc. The car ran fine for a week. I took it to the track and ran a 11.60@ 120 on the first pass. I let the car cool down a touch and on the second pass it layed down a 12.55 @105. It had a rough idle while driving back to the pits. The car left hard but layed down at 1/2 track. While looking the car over in the pits, I discovered a hanging ground wire off the drv. side head. I figured I had found the problem. Put the ground back on and no improvement. At this point the car would hardly idle, and was backfiring throught the intake. We towed it home and here we are today.
I have changed or tested all the sensors, changed plugs, plug wires, coil packs, throttle bodies, intakes, etc. At this point it's idling again, but when in gear with the traction control on, while steeping on the brake pedal, the pcm pulls timing to -3 to -5 degrees almost stalling the engine. It only does this while in gear and with te traction control on. With traction control off, the car is fine so to speak. It lacks power, but I think a retune is in order.
While driving to day, it was o.k. with the tc off, but towards the end of my 15 mionute ride, it was loading up and poppping through the intake agin. I am stumped.
Tune and log available to email. I have no clue how to attach.