I don't know what is causing this, but its been getting a little worse on my car, I intend to go through every friggin piece on my intake system, but when driving, only with load on the engine (thus throttle bodies opening some), and with a cold engine and 70's or lower temps, I get a whistling sound coming from my engine. Today it was 50-55 MPH in 6th gear that provided the whistle. Depending on temperatures, and gear, the speed varies.

I'm just curious if anyone else has encountered it, I don't think its serious, and think its just a resonation inside the intake manifold or one of the intake tubes, but it still annoys me.

 

I've encountered some weird sounds lately on my Z. One of the sounds is, if I turn on my car in the morning and just leave without warming up the engine, then sometimes it sounds like its squealing. And I've also encountered some whistling but not sure if its coming from the intake.

 

i have the same issue, but its at certain rpms (around 2000 - 2400) It disappears after that.

 

I hear the same thing every morning too whenever I dont let it warm up and it only last maybe 5 mins tops. But I still have no idea what it is???

 

Same here, but after it warms up its fine...

 

does the whistle go "WOO-WOO" ?

 

What type of intake do you have?

 

no man thats what the exhaust tips sound like

my pop charger makes a slight whistle at certain rpm ranges, I like the way it sounds though.

 

Stock.

Since its not something only my car does I'll ask my dealership tech if its concern. Its probably just resonance in the intake and nothing to worry about, but when I hear "new" noises, I tend to worry a bit.

 

Sounds like the differential.

 

I get it too, but only in bitter cold temps (20's and below). Mine sounds like it is coming from the rear hatch though. Only lasts a minute or two though.

 

My car makes the same sound, only when the weather is cold, and when my engine is cold. It goes away when the engine warms up, I wasn't really too worried about it.

 

Take out your air filter and bang it out to get out the leaves and **** that's gathered in there. Check your intake box too.

 

yes ... same noise when it's cold ... it comes from behind and listens like wind noise ...

 

How do I get that fixed?

 

Turn up the stereo, haha

 

wow

 

we've been tracking this on a G35 forum (Gs are seeing it too). i'd love to get all the communication together on the issue, but i don't know forum rules on posting links to other forums so i won't post a link to that thread until i get some sort of info on that one way or the other.

here's what we've got so far:

this is a widespread problem. i've probably seen ~30 G-Z owners with this issue in my research.

the basic behavior we're seeing is a high pitched whistle or howl, like someone blowing over a bottle or into a flute.

the pitch changes based on SPEED (not RPM). for me it's between 30 and 55 mph.

it only occurs in relatively cold weather (i see mine under 35-40).

the sound goes away after around 5 minutes of driving at speed.

we had one guy say letting the car heat up for like 15 minutes before driving stopped the sound from happening, but several that said it didnt. in my experience, it doesnt.

once the sound has come and gone through driving, it wont come back unless the car has been sitting for several hours in the cold. significant because the engine can cool completely but the noise still not come back.

has been observed in 03-06 Gs. haven't yet seen a confirmed case in an 07 (anyone know if anything in the drivetrain changed in 07?).

it's not the airbox/filter, people with stock and aftermarket intakes all see the same behavior.

its not any sort of body structure, as we're seeing it on both the Z and the G with their different body panels.

Dealers have a tendency to blame it on the transmission, but that doesn't always bear out. one person claims that a transmission replacement seems to have fixed it, multiple have said they've gotten the transmission replaced and still have the noise.

drivers usually claim that the sound seems to be coming from in front of them, but we don't have much evidence, and in-cabin acoustics are unreliable. (to this end i'm planning on getting my car on stands and getting it to 30. from there i should be able to tell exactly where it's coming from, and whether its caused by mechanics or wind passage. just have to find a free cold weekend now.)

the growing theory on the other thread is that it's the Diff. mostly just because we're not sure what else it could be at this point.

please, if anyone has anymore real info, post it hear to keep everything together. if you see someone else start another thread about it, point them this direction. theories are welcome, but preferably ones with facts behind them.

so... what's everyone thinking?

 

**DISCLAIMER: what i did in this post was dangerous and probably exceptionally stupid. If anyone decides to attempt to recreate this, they do so entirely outside of my influence or instruction. I'm not liable for any damages that may come from attempting the following activity on your own. if you drive through someone's house, it's your own damn fault.

Just got back in from running the car to 60mph on jackstands in my apartment parking lot. (if my landlord ever finds this i'm probably going yo get evicted on the spot ) here's my findings:

Procedure: jacked up the rear of the car and put it up on jackstands. ended up with about 2 inches of clearance between the tires and the ground. got in the car, turned it on, and slowly accelerated from 0 to 60, holding speed at 20, 30, 40, 50, and 60 for about 15-30 seconds to listen for the sound. shifted 1st-2nd around 2k rpm, 2nd-3rd around 2.5k, and 3rd-4th around 3k.

Safety precautions: Parked the G with a large metal dumpster in front of it to minimize damages if the car were to fall off jackstands. Chocked the front wheels to avoid hitting the dumpster if at all possible.

Conditions: 25* F. sunny. very little wind.

Results: The whistling was present between 40mph up through 60mph. It acted as it does when driving normally, with pitch changing based on speed.

Conclusions: The noise is purely mechanical. wind from movement obviously plays no role in this issue. This eliminates every "bad seal" theory, as well as the "air intake damper" theory. The transmission and the rear diff are both still possible sources.

Notes:
*I stopped at 60mph for safety concerns, but the noise was still at that point, so i don't know where the upper range would have been. I don't think that really matters for this study though, as the point was to replicate without wind.

*VDSC must be turned off before you begin accelerating, otherwise the car will sense that it isn't moving and immediately kill any acceleration.

* Cruise control doesn't work with the rear wheels off the ground. attempting to activate cruse control with the rear up led to a quick acceleration spike followed by an immediate drop in RPMs.

*because of the cruise control not working, i was unable to get out of the car and investigate further where the sound was coming from. I did take a rubber hose with me though, and was able to wrap it around under the car and listen, and the noise was decidedly louder under the car. I was unable to get any further info from pointing the hose one way or the other, unfortunately.

*shifting without moving feels unusual. i had to go through a brief period of learning how to shift again, and burned the hell out of my clutch once.


So, there we have it. anyone have any thoughts?

 

Since my diff made a weird whining noise, the car is less responsive when cold (feels as though a brake is holding), etc. I'm in agreement on the diff being the culprit. I'm wondering if its a VLSD issue, a diff fluid issue, or a mechanical issue.

I'll ask my dealership tech, I have to go in Friday regarding some alignment adjustment, and will get some input from him then. He is a car guy at heart and won't be as reserved as most techs.