So after driving it, there's a LOT of crackle under the car (sounds like pop rocks). It seems like it's normal but I never heard it in my old honda accord or my moms 3 series. Also I cannot distinguish where it's coming from, it sounds like its hopping from front to back under the car.

 

When do the noises occur? Any aftermarket parts installed? Any further info you can provide will help us diagnose your problem. Only think I can think of is maybe your sway bars need some lube or. Maybe part of your splash guard is loose.

 

I get the same thing... Think it's coming from the heat shields on the catalytic converters.

 

I am pretty sure it is just metal parts contracting as they cool down. True that it never happened to this degree in most of my other cars but I have never had anything with this kind of power output before. I would not worry about it...

 

Thanks guys, I have a stock car and it happens after I shut off the car, I'll try to get a video later on.

 

Mine is same thing, it has some cracking popping sound after you shut off the car.

 

Yeah it's probably normal. I heard a bit of it when I shut off the 3 series, just not to the same degree but then again the G's got more power so maybe that comes into play.

 

I'd bet its the catalytic converters cooling down, they tend to make noises sometimes

 

My 09 FX does it too:

https://www.myg37.com/forums/g37-cou...ml#post3465282

This is not normal during idle. Yes it is normal after the car is shut off but not while running!

 

It is the cats cooling off,and the metal contracting......

 

It's only suppose to do that when the car is shut off not during idle. If it's doing it while the car is running something is wrong.

 

You didn't plastidip the underside did you?

 

Nope. Just the emblems and wheels and that fugly chrome spoiler. Not sure why everyone has the impression that my whole car is dipped.

 

It was a joke man lol. Its the expansion and contraction of metals under the car as others have said, the exhaust and cats to be specific.

 

Did you miss the point where OP stated it was after shutting down the car????