Infiniti told my dealer that it was the ECU. According to my dealer.

And actually, there is a spectrum analyzer for the iPhone that is, believe it or not, used by a lot of recording engineers because it is an extremely high quality pice of code, and the mic in the iPhone is apparently extremely sensitive, yielding an extremely usable tool for audio troubleshooting. But it costs, I think, about 1k, so forget that!

 

Yikes...yeah, the real audio meters are even more than that. It's good to hear that your dealer says it's the ECU. There's a post on "the370z.com" site that says they are replacing them, but some on that site are thinking the poster may be gaming them. We'll see. This is going to be an expensive and embarrassing fix if it's the ECU.

 

Last night I was moving a bunch of stuff from one house to another and had a stack of sheets and comforters in the front passanger seat floorboard. It was enough to hide the noise completely! I've been thinking about leaving the comforters there and asking passengers to ride in back

My dash wasn't covered, only the floorboard and passenger footwell area. If the noise was emanating from the ECU behind the dash, wouldn't I still hear it? Seems like the noise is coming from somewhere lower to me. Honestly it still seems like it is coming from the passenger speaker, even if the ECU is the cause, the noise seems to be produced by the speaker in my humble opinion. If I were more mechanically inclined, I would try removing it to see if the noise went away.

 

I'm like you - just a little skeptical that it's the ECU. The problem I have pinning it down is that my ears are so sensitive that they start ringing at the same frequency when it happens, so I can't make out the direction at that point. The weird thing lately is that the noise has been coming and going and very unpredictable. It didn't make the noise at all on a 30 minute drive on Saturday, but was super loud for half the trip back a few hours later. Very aggravating.

 

Mine seems like its coming from the trunk/gas tank, but as many have said it is hard to pinpoint b/c it bounces. When I lean my head between the front headrests and turn my head sideways it seems to be coming from the rear. I can put my head by the rear tire and hear it too. VERY ANNOYING.

The noise comes and goes for me, but is much more commonly heard in warmer weather. A/C, radio and heater do not affect the noise. The hearing test noise is a good description of the noise, but it also sort of sounds like a faint vacuum cleaner off in the distance or something.

 

Mine is intermittent...was fine yesterday, but super loud today. Can't seem to find what sets it off. The 370z forum guys are reporting an ECU capacitor fix, but no one can confirm the claims of the originator of that post. Has anyone had this issue escalated to a factory rep via their service manager?

 

I wish there was someway for Infiniti corpoate to see this thread and the 370z forum threads. If they knew how widespread this issue was, Im sure it would put some pressure on them

 

What about sending an e-mail to edmunds.com or another automotive publication? They might appreciate the scandalous nature of the sound.

 

What about sending an e-mail to edmunds.com or another automotive publication? They might appreciate the scandalous nature of the sound cover-up.

 

It would be interesting to find out if all the cars have this problem, but only some of the people can hear it... or if this problem really affects only some cars. In my car, the noise is pretty much constant. It used stop whenever I would let off the accelerator, but now the noise remains while I'm coasting too. I started to get a glimmer of hope that there was a fix on the way when I went to the 370Z forum, but I guess no one can verify it's true. It's ridiculous to think that I will have to wear earplugs on any extended trip in my "luxury" $40K car.

 

If yours is as loud as mine, earplugs would be a good idea until they get a fix for the problem.

 

Actually that's exactly where the ECU is located - under the dash on the passenger side. Everthing I've gathered on the topic, from the this forum, from 370 forums, from Fx35 drivers, from G35driver - it all points to the ecu. Some of the fx35 owners have had their ecus switched out to much success. You know, they don't cost that much money - for those of you with some extra cash, you could just buy another ecu and switch it out and see if that makes a difference? I am thinking of paying for it myself, to be honest. But I'll have to admit, I do not know the actual price of the module/unit. But I am looking around - I'll tell y'all when I find out.

Anyway, this is driving me crazy. I am going back to my dealer, and I am going to have them apply the fix that they suggested, with the insulation around the ECU. Even if the noise is cut in half, it will be a great improvement.

 

If it's really the ECU and you swap it out yourself, you may end up with another one just like it since it may have been sitting on the shelf for a while. I'm still skeptical that it's the ECU - not ruling it out, just skeptical. Everyone seems adamant that it's the ECU and that Infiniti is "working on it", but in reality, 99% of the dealers just say they can't hear/duplicate the problem and send you on your way. What we need is physical proof...rigging the car with a microphone, laptop, and spectrum analyzing software to show the frequency and loudness of the noise. If the db levels were high enough to cause hearing damage, they'd fix the problem right away.

 

No offense, there's no way that the SPL generated would be high enough to cause hearing loss!! For people with sensitive hearing, the frequency (which is somewhere near 12-15k hertz I think) is maddening and irritating, but it would be impossible for it to cause physical damage. It's a very quiet sound, for goodness sake, probably less then 50 or 60 DB, if that much. You need to get into the 80's over very long periods to begin to cause issues. Our car's interior noise level is 69 DB at 70 mph, for example.

Anyway, I agree - another ECU might be just as bad, which is why Infiniti is not doing the same, I am sure - they need to isolate the problem, make it replicable, figure the design issue, re-design the ECU, then manufacture new units. That means time and $$$.

 

And, might I add, aaarrrghhh! This is so frustrating.