QR25DE hissing noise when accelerating

[fyrcomm]

There's a new high-pitched hissing noise coming from my engine, sounds kind of like a school bus accelerating or a turbo spooling up. The noise starts at about 2000 RPM and just gets louder from there. I only hear it when I'm driving, and not when the car is stationary in neutral. Also, the sound seems to be coming from the passenger side of the engine (opposite from my intake)

I've done some searching and found some possible causes to be faulty vacuum hoses, belt tension, loose heat shield, faulty gaskets and a slew of other stuff. I haven't been able to find a solid conclusion, though. Any ideas? Should I just take it to the dealer and have them check it out?

I have a 2008 Altima Couple 2.5S CVT with a K&N intake and Nismo exhaust. It has just shy of 30K miles on it.

[fyrcomm]

update:

the noise can be heard when the car is stopped in neutral, but not in park. I had my friend rev the car for me while i listened for it from the outside, but i couldn't hear it at all

[comatoseculture]

Any change with your intake? a loose intake tube will whine. check the filter/intake and all clamps associated with it.

[fyrcomm]

i took it to the dealer the other day to ask if they had any insight.. they took it to the garage and of course said they couldn't hear anything out of the ordinary. they were nice enough to insult my intelligence and say that i probably haven't been closing the fuel cap all the way, and the noise i'm hearing is from the fuel pump sucking in air. i know i close the fuel cap every time i fill up, so even if the fuel pump is sucking in air, it's definitely not from the fuel cap.

yesterday i installed my racingline grounding kit, so i got a chance to look at most of the tubes and lines around the engine. I didn't notice any holes, and i still couldn't hear the noise from outside the cabin.

Any change with your intake? a loose intake tube will whine. check the filter/intake and all clamps associated with it.

i also removed and reinstalled the intake and made sure everything was tight. took it for a drive and the sound still persists...

[comatoseculture]

How long ago did you switch to the K&N? And did you install it? Do you still have the original air box? If it's really bothering you, and you have it, I would reinstall the oem intake and take it for a spin. Might be very suprised. Sorry. Trying to help.

[fyrcomm]

How long ago did you switch to the K&N? And did you install it? Do you still have the original air box? If it's really bothering you, and you have it, I would reinstall the oem intake and take it for a spin. Might be very suprised. Sorry. Trying to help.

I installed the K&N myself over a year ago and never had this problem until recently. I do have the the original air box, but it's at my parent's house in San Diego, and I'll be living on the east coast for at least the next year.

The sound isn't really bothering me (it actually sounds pretty cool), but I'm just concerned that it's something that isn't supposed to be there! And if it's a problem, I definitely don't want it to get any worse.

And no need to be sorry; I'm open to any advice at this point, especially since the techs at the dealer can't find a definite source of the noise

[comatoseculture]

You can only hear it from inside the cabin....inside...what about the cabin air filter? Clogged up now more then ever and making a noise? Its a stretch but there is def something to it being audible interior wise only.