I have very sensitive hearing and I noticed this about my Z. I know you Z owners hear hissing sounds when idle. When I drive easy and go to a stop and idle,open the door to hear the hissing. Hardly any hissing. But when driven hard,hissing sound is constant. Now I still havent figured out where this is coming from. Maybe the exhaust?

 

maybe you have a snake in your glove compartment

 

Here is the only thing I could think of as long as everything is normal with the car. My Dodge intrepid's injectors were decently loud and would make a kinda wooosh when accelerating. Kinda like a hiss and pssss type sound. As long as nothing is leaking on your car exhaust wise that could be it. I have really good hearing also and no one else in the car hears it that i have found.

 

Maybe you have the A/C on, but one of the vents closed. Sounds too simple to be true, but worth a check.

 

do you have an aftermarket Intake by any chance?

I have AEM and at about 3k rpm you can hear a hiss

 

I second this.

 

damn, my car started doing the same thing today!!! it was like 20 degrees outside...i don't remember if my AC was on, but i'm pretty sure it was off (i always turn it off before shutting off the car)...it doesn't sound like a hissing sound from a intake but like a sucking sound coming from underneath/toward the front of the car.....i didn't think much of it, maybe it's because of the weather i hope it's nothin serious...

p.s. i wasn't driving, i had just turned the car on for the first time today and noticed it right away as it was warming up...

 

OT, but I get a hissing sound from my Injen intake at aroung 4K rpm and it sounds really nice

 

Fuel pump, many of us have it. Varies by driving sometimes... but sometimes without rationale as there have been a few times at idle that the hissing was very audible from outside the car (esp. the passenger side) as well as in. Either it typically softens/goes away after awhile of driving, or I simply get used to it and not hear it anymore.

 

the hissing sound i hear on my car comes from (i think) the exhaust pipes. rev it hard once and leave the engine on and get out. then go around your car to the passenger side and look under your car. i dunno if you guys are talking about the same sound or not. but im gonna go check it out this monday

and yes my injen makes that turboish sound too... i love it

 

I get the hissing sound in the back as well at idle.

Bat™

 

I have noticed it about 3 times, none of which was after hard driving. Seems to come from underneath the car at about 3/4ths back (just in front of the rear wheel). It doesn't happen consitently, so I can't take it to the dealer...

 

the hissing sound that i get, which is more pronounced with the addition of a k&n cai, occurs around 3k-5k rpm, and the sound is responsive to the throttle. i noticed it on the last z i had, and even more on my new one. whereas with the last one the hissing sound started after about 5-10k miles, but with the z i have now, it started right after the break-in. due to the responsiveness (sp?) of the sound to the throttle, i first thought it was air passing over the edges of the throttle body when opened at certain angles, hence the sound only occuring between 3k-5k rpm, and its increased volume with the addition of a cai. the sound is definetly coming from the front of the car, and at times can be kinda irritating. whether i'm driving aggresively or not, from the turn of the key to shutdown, the sound is always there. the fuel pump is the only other thing i've heard that could cause this noise.

 

My Z is bone stock except for the tires. I'm talking about the hissing when idle. I had this sound from day one. I guess its no problem. Oh the A/C is off when this occurs. Does anyone have this sound with an aftermarket exhaust?

 

i first thought it was a hole in the exhaust pipes. but i guess its normal. im gonna go get my oil changed tomorrow at the dealers so ill go ask the dealer.

 

Let us know what he says.

Bat™

 

lmao, I second this statement.

 

i would describe my problem the same as
cinciZ. It doesn't happen consistly, so i could not show the dealer.
I just learned to deal with it.

 

I noticed this sound when i hit about 3 to 3.5K RPM. This started as soon as I installed Injen CAI. I verified this by a local mechanic, 300z enthousist. VERY NORMAL... If you don't have CAI and is still hearing this, i wouldn't worry. He said it has all to do with the 350Z air box setup.

 

we were not talking about cai hissing