ok so ive been hearing this noise coming from my car at first i thought it was the new exhaust system i had fabricated flexing and contracting for it being new, but it persists after 3 weeks. i can only hear it at idle its very noticeable from the inside not so much from the outside. u can also feel the "bubbling/rumbling" from inside the car. im pretty sure its not a knock because it doesnt seem to be coming from the motor and it doesnt make nose in rhythm with the motor nor does it do it consistently. it comes in and out with relatively no pattern. any help would be appreciated. other than that the car seems to be happy and run fine.

 

Mystery sounds are not fun to troubleshoot. It could be a loose bolt somewhere or a part is rubbing on something new. Inspect all the connections, bolts, and anywhere where something is close to touching.

 

ive tried shaking the exhaust but cant replicate the sound

 

video please, cant diag a noise without hearing it. did you change size of exhaust? is there a wideband in the car? is it tuned ???? more information would be helpful

 

Any cooling issues?

What are you using for coolant?

 

ill try to get a viseo up when i get home.
yes: it has a 2.5 DP to a 3inch "catback" no cat
its street tuned in s300 AEM wideband
the car does get hot when the a/c is on and not moving, no ac is fine. and im using water for now cause i just changed the radiator hose.

 

Water has a lower boiling point then a mix of antifreeze and water. Not saying its the issue but I would consider correcting it. Did you get all the air out of the system?

 

http://www.youtube.com/watch?v=dVfHJ...ature=youtu.be

the sound first appears at around 8sec and happens every now and then. its dar cause i was holding the phone down by the floor.

 

bump for the vid