Revving Noise

[fxrider]

My 2006 Infiniti FX 35 seems to have a loud revving sound when i am driving. It is more apparent when i am slowing down(coasting) and when I traveling over 60MPH. It is a loud revving sound, but my RPM are not high and the car is not slowing down. Also, my gas milege is not effected at all. I've been getting better gas milege.
It has new engine oil
Clean Air Filter
Milege: 67,500

 

[Dracula]

from the front or the rear?

 

[PJ28]

Check your air intake!
Hopefully your filter didn't disconnect

 

[fxrider]

Up front.
Checked air intake, all connected..

 

[Dracula]

check your exhaust for leaks, also reinstall ur air filter. Air filter is oe or aftermarket?

 

[fxrider]

I do hear a hissing sound coming from under the middle of the car along the exhaust piping. The sound reoccurs every 15+ secs and last only a few seconds. I can't feel where the hissing noise is coming from and no visual holes found.
Air filter has been checked and reinstalled with no results. I use a K&N filter.

 

[Dracula]

oh o, sounds like u got a crack maybe by the flange, one of ur bolts might be broken, missing a gasket. How to check: in the morning, cold start, start ur car wait 5 mins and go under ur car and lookfor any water leak on the ground.