Ok well i finally got my dad to hear this thump sound. No back firing but maybe some unburned gas or something, he said something like that. Hes a mechanic and started talking and i just kinda dazed off after i heard unburned gas.....

 

thats a relief

 

I wonder what happened... Any news on the progression or degression of this problem?

--- Kei

 

Well once the weather started warming up, mine stopped doing it. My pops cant even answer as to why or what it may be doing. He thinks its unburned gas in the exhust igniting. Like the smog valve that controls the comptuer and it is sending a signal that is partially incorrect (he's guessing). Cuz i wasnt about to leave my car over night. But if i did that im sure that would have found the problem.

 

I hate to say it but everyone is hearing the gas tank pressurizing and depressurizing, same sound from my car , but luckily I was at a muffler shop last time it happened.
I saw and heard it first hand as they did exhaust upgrade!!
try it for yourself, as the tank warms and cools, or gains and looses pressure this will be the outcome.
kinda like popping your ears with change of elevation.

 

when you stop for gas and take off the gas cap, listen to the depressurization!!

 

Interesting.

 

does anyone with a CAI have it hit the front bumper when you start the car, or sometimes shift...that's the only noise i got, and if so how did you fix it?

 

Interesting, I've never had that sound. But of course, it never gets very cold here in south east Georgia. Sounds like it could be a faulty muffler setup Get your dealer to check it out. Good luck hope nothing is seriously wrong. Oh and by the way, mine is automatic, no mods.