ok so i noticed this problem with my rpms dropping and shutting the car off and a thumping sound. I have z tube, and nismo axelback, and megan Y pipe. 64K miles.

This only happens after a drive. After driving and turning the car off, right when i try to turn it back on again, it cranks, but the rpms drop down under 0 and the battery light comes on for a split second and then it catches itself and they go back up to normal. (Somes times it just stalls out) I also here like a thumping sound, (Sounds like an exhaust rumble from an idle.) The thumping/rumble sound also happens after a drive. (I changed the battery and it still does this) At an idle the car is fine and steady.

Whats wierd is that from a cold start, the car starts up and there fine. and there is no thumping sound. But right after a drive around for 30 seconds, (driving normaly) the rumbling comes, and if i shut the car off and try to turn it back on it will almost try to stall out.....

here is a video, for some reason the sound quality is really low but if you used headphones you can here the thumping.


Please help Thanks.

 

Try cleaning your MAF and throttle body. I had similar start up issues, and think it was because I recently oiled my filter and didn't let it completely dry, so my TB and MAF got a bit gummed up.

 

I already tried those but it still refuses to get back to normal rpm after a warm start up

 

and i also disconnected the battery for ,more than 6 hours. still a no go =[ im going to bring it in soon though