raredesign

I thought I would create a new thread instead of hijacking someone else'.

Since I bought my 07 GT new off the lot, the first bit of return to idle from gas results in a loud pop...pretty much a backfire. After that, it is all better. It is so bad actually, that if I try to drive away slow without first "blipping" it, the car will buck violently.
I have taken it to the dealer, but of course they "couldn't replicate" the issue.

Since then, I have added SLP Loudmouths, a CAI and tune, and gears. Now the snap/pop is so loud that I seriously turn heads. While it sounds cool, I can't help but worry if it is hurting something. I can only compare this to things I relate to such as rejetting the carb on my bike, and obviously backfire is not something you want.

So, since it is not the tune as it did it both stock and bama-fied, what on earth could it be?

highline

no idea...subscribed

raredesign

well, if this ends up being a dead thread, I will post a video in the spring so you guys can hear it.

Simon1

I think it would be something in the PCM or in the throttle body. BUt really, I have no idea. There is really no way to know without putting it on some diagnostic equipment or getting a data log while it does it.

So baciscally there is excess or unburnt fuel that ignites, which is what I understand a backfire to be. Have you pulled all of the plugs and inspected them? Looked in the throttle body? Checked vacuum lines?

RAT281

+1 on pulling the plugs

Derf00

I'd get a live data scan on it (Code scanner with live data option) and see if you're burning a bit rich at idle.

SilverHoss

A backfire is caused by ign timing being off and fuel igniting at the wrong time-this will result in a "backfire" up through the intake manifold, and possibly a fire under the hood. I doubt you have what is actually a backfire situation. People get backfire and exhaust popping mixed up.
Most likely, you have an exhaust leak somewhere. I have seen this many times over the years, most recently I had a header leak on my previous car, and when you rev'd the car and then let off it would POP real loud. Something about the extra air getting in the and igniting unburned fuel, i suppose but i don't really know how it happens, I only know that it does and it does not take much of a leak.
Check the band-clamps that connect the mid-pipes underneath the car, they have two 15mm bolts on them. With exhaust good and cold, tighten those real good. I bet they are not tight. Also you will notice black soot around the ends of them if they are leaking. Well anywhere there is an exhaust leak for that matter...

Spdfreak

Mine does that if I rev it up cold. If I let it warm up before I rev it, it doesn't do it.

raredesign

Thanks man! Great info. I will check when I get the car out of storage.