So, I've got a noise I'm kind of curious about. It's hard to describe precisely, sort of a hiss with some irregularities in it, maybe like a ski going over packed snow or something, or maybe a teakettle just before it boils. It's not present, or at least not audible, with the hood up at idle, and if I'm behind the wheel revving the engine when parked I can't hear it, even if I'm halfway out of the car. It's most obvious on colder mornings. It changes in volume with throttle, but it doesn't change in pitch, and can be heard mainly from about 2500-3000 rpm. Above that, I can't hear it anymore (maybe because the engine is louder, maybe because it goes away).

I've been keeping my eye on oil level, and as far as I can tell on the stock dipstick, it's okay. Coolant is okay, too, or at least it's in the reservoir and probably between the min and max lines (I can't see the level on the side, but it's definitely not too far down on the inside).

Any thoughts?

 

Sounds like a vacuum leek ,

 

Following up: I'm pretty sure it was just that I'd forgotten to snap the line going to the fuel tank vent valve back into its channel. It was either that or my half-broken dipstick rattling with engine vibration. Either way, one of those two things fixed it, and I'm back to my usual set of inexplicable noises.

 

Good stuff glad u found the problem. Keep 4 wheels on the ground . Lol