2fast4u1989

found this on youtube, sounds just like what mine is doing. fast foward to 1:14 and you should hear it when he hits on the gas

2fast4u1989

my bad lol here is the link http://www.youtube.com/watch?v=0DquhbduR5U

jrockgts197

There are so many variables involved with a backfire that it would be hard to identify without an obvious problem. Exhaust leak, intake leak, wacked out A/F ratio, timing, o2 sensor, plugs, coils, etc. The fact that it only happens during WOT at 40mph could rule out most of those and would seem to be something computer related. If you're not getting a CEL then I'm stumped. Try disconnecting the battery for about 15 minutes to reset the computer and try it again. Maybe the fuel/timing maps are off a tad from the adaptive learning and that might help. I don't know, I'm really grasping at straws here without more info. It's worth a shot (free). If it was an actual backfire I would think you would be able to feel a loss of power for a split second and it would almost definitely trigger a CEL.

2fast4u1989

did that battery thing already, yet no cel lights or anything. idk lol its just like that video i posted

jrockgts197

The more I listen to that clip, the more I think it's a product of the exhaust. Can't be that much of a coincidence that he is running the same exhaust.

adairt

I know this is an old and possibly dead thread but I wanted to say that mine does the exact same thing. I also have cats only with muffler deletes. Jumping on the throttle around 30-40 miles per hour causes a firecracker type sound from the exhaust. I would think that it's normal with deleted mufflers.

JCON

I have muffler deletes and mine don't pop.

I did recently hit a failing spark plug. I was getting a low volume pop at certain engine rpms. Is it loud or quiet? Is it one pop or is it multiple pops at a seemingly irregular frequency?

Just listened to the video. my pop was very low volume. You def have a backfire. Probably the rich stock AF. Extra fuel is igniting. Is it popping constantly at 40 or just WOT? If you're shifting at 40 and it's popping, it's most likely unburnt fuel.

adairt

It only occurs at or around 40 when you drop the hammer. From a dead start it doesn't do it. I'm with you, I think it is dumping fuel and that unignited fuel is burning off past the engine. It doesn't sound like a bomb going off but it can be fairly loud. I'm not sure if there is a tune for muffler deletes. Do you know?

adairt

Oh...and this one in the video isn't mine. I'll try to see if I can get one today. I can almost always make it pop.

Shift

It's is nothing to worry about. It's a good sign your system is letting out a lot of air flow. My xpipe and corsa setup doesn't do it until I near redline revv but then it makes the loudest sound it can then pops multiple times. It's the popping that tells people "step back".