Everytime my car turns left and i let off the gas, i get this loud deep rumbling noise under the car. I had a mugen exhaust put in 2 months ago but nothing seems to be hitting it when i checked. Is it possible that there's a defect inside the muffler or resonator? If not my exhaust, what else can it be? This is a really weird problem because the noise is on left turns only.

 

Get under your car and check your axles. Look for cv boot rips and grease! Sounds like your cv joints are going out! Common problem sound when turning! Hope that helps?

 

Either axles or your struts?

 

Or wheel bearing. Jack up the front and shake the wheel back and forth, if you have play....time for new bearings.

 

not a wheel bearing problem, i already checked. i thought CV joint makes clicking sounds? this is more like a rattling, rumbling and buzzing. i can feel the car vibrates when it happens. Seems to have an increase in road noise too

 

try checking your engine mounts and exhaust hanger mounts?

 

Sounds like wheel bearings to me. How did you test the bearings?

 

jacked the wheel up and grabbed it on the top & bottom & shoke it. This rattle noise is louder after letting off the gas and more apparent above 30mph

 

took it to acura, they think one of the motor mounts needs to be replaced....i'm still waiting on parts. Can a bad motor mount makes a knocking sound too? i think i'm starting to hear a bit of knockings sometimes when i shift and also turning left.

 

Absolutely it can knock.