I'm still having problems after my header install. I fixed all of the leaks, and tried new O2 sensors. But my car is still backfiring at a low throttle for slow acceleration, and it backfires if I go to WOT. I'm still confused as to why it is doing this. I have triple checked what seems like everything on the car. Is it time that I just breakdown and get a tune? Would this really fix the problem? I still think it shouldn't be running this bad from a header install. What should I do?

 

I'm seeing you have a loudmouth on the car, that exhaust tends to pop which could be mistaken for a backfire, my old LT1 did it every time I let off the gas.

 

If you had the spark plug wires off during the instal, then I would go over the wiring to make sure that you don't have two of them crossed. The passenger side has gotten me a couple of times and it ran poorly and backfired. Take your time and hopefuly you'll have some luck!

 

What do you mean have two of them crossed? Don't the powerpacks sit above the cylinder they are supposed to be hooked up to?