I feel like an idiot for not being able to figure this out, but im no mechanic. I made a video to show exactly what it sounds like. I dont know whats causing the backfiring. I thought it was the catalytic converter so I removed it and put a straight pipe in, but to no avail. Could be the muffler? its the stock one i believe.

http://www.youtube.com/watch?v=oLbIT7_r7xo

 

That sure doesn't sound like backfiring. As the engine revs down the PCM leans the mixture (IIRC), the exhaust starts making that sound. It is typical on Non stock mufflers, which you can tell you don't have a stock muffler anymore. It is fine, just annoying.

 

Agreed. I would point the finger at something you have done to the exhaust.

 

do you think it could be a rod or piston?

 

No, it sounds like a failed attempt to modify the exhaust.

 

to much air out of the engine not enough in.
it sounds like your pipes are to big for your v6 to really make good use of.
what you hear is the mixture being sucked out of the cylinders before it's finished buring so it goes boom in the pipes. contrary to popular belive modern converters don't offer much resistance. especially not to a 3.9. a 5.2 or a 5.9 doesn't really see the difference unless the old one is plugged. but they do act as a ressonator. what little resistance they have to the flow of gasses is enough to smooth out the pulses some and make that noise you hear less noticeable. im betting you have 3 inch pipes. try putting a restiction in it somewhere. like a few feet of smaller pipe.

i have 2.5 inch on my 5.2 with 3.21 gears and i can smoke one of my buddies 4.7 with 4.10 gears. he has a chip on it and the 45rfe but still once i'm out of first the lower flow keeps the power down low where it's most useable on a stock truck and with my gears that is a great thing to have. the only other thing you could do would be to advance the timeing a bit so it's all burned before the valves open. not gonna happen with the pcm our trucks have. it will just set it back to stock and turn on the light.
not to mention the power loss and chances of detonation being likely. just put smaller pipes back on it and you will be fine.


or you could v8 it

 

Just one thing to say . . . turn up the tunes and drive it.
And 9652, I don't understand what the point was going from 3.55 to 3.21 gears? We use 3.21 gears without the OD and they work slick there but was thinking of swapping the 3.55 to 3.9. But it sounds like you're having a lot of fun.

 

Well it pops like that when i accelerate too. I bought it like this. When i looked under it the only odd thing i saw was the cat converter had been welded in so it wasn't stock. And the pipe size changes. It comes from the headers to a 2 1/2 in pipe to 3 inch to the muffler and then to the small traditional tail pipe size (which is cracked).

 

There is no need for 3" pipes on a 3.9. My 4.7 has 2.5" pipes and that's just about right.

 

I think im just going to buy a full exhaust system. Thanks for all the suggestions guys.