2008 Honda Fit Sport.

A couple years ago, I had a broken engine mount which caused a "clunking" when accelerating hard from stop. That's been fixed, but....

As of the last several days, I've noticed a *different* sound when accelerating hard or moderately hard from a stop -- more of a loud hum which seems to come from the driver's side front area. It seems like if I keep hard-accelerating the sound persists, until I back off the accelerator, and then the sound disappears.

I took the vehicle to a transmission shop today and had them listen to this sound -- they said it did NOT sound like a transmission issue (whew!)

Any thoughts on what could be causing this?

 

I had a similar issue between 2.5 to 3k RPM. The issue was a loose exhaust manifold heat shield. There is a tiny stud or bold which holds the exhaust manifold heat shield to the car and this part usually rusts out causing a rattle.