I just tested for the throttle body noise, and I also have that on my G37, but it's really of no consequence compared to the noise I'm hearing from the ECU which is many times louder.

What's an ECU?
 

Can someone please tell someone new to the forum what an ECU is?

Thanks

Electronic Control Unit (ECU). Your cars brain / main computer.

I was very surprised when I heard this so called high-pitched noise while my car was completely turned off. I had it up on ramps yesterday and I could easily hear a high-pitched tone coming from somewhere in the engine bay. Really annoying and should be fixed by Nissan.

Weird thing though, I have been under the car before and never noticed it, so maybe it only comes on under certain conditions?

I don't know the specifics of this particular engine. But my best guess without actually seeing the problem in real life; I guess it could be the fuel pump. Maybe it's the sound of the fuel under pressure passing through the fuel pressure regulator. I have had cars the made similar noises.

The problem with warranty's is that it says in the terms and conditions that it doesn't cover out of place noises, sounds, or vibrations. So unless the car isn't running smoothly, there isn't much that can be done about it legally.

I just don't understand how an ECU could make much noise. All it is, is an integrated circuit with small amounts of electrons flowing through printed microscopic circuits and transistors. Electricity at this tiny level doesn't make much noise but lightning does. for example. If your desktop computer were switched ON but your had removed every single cooling fan and electric motor, the computer would be virtually silent. It wouldn't run for long before overheating though and I wouldn't recommend it.

I have seen many engines in my life. The relationship between humans and reciprocating engines is illogical sometimes. People start to expect too much out of them. They are complicated pieces of machinery and stuff is bound to go wrong. Considering how complicated they are, they are a whole labyrinth of moving parts and systems that are all operating independently of one another. Great is their complexity. At any moment certain parts of the engine are activated seamlessly without the driver ever knowing about it. A little noise is normal. You've got all kinds of fluids operating under pressure and at different temperatures.

Considering the great complexity of these engines. It's only natural that there would be some unexplained noises. And in some ways engines are no different than computers. Where the unit is programed to operate a certain way under certain conditions etc. Although I enjoy working with engines more then computers since it just seems more rewarding. I can't stand offices and cubicles and all the stale air inside to contend with.

A bad engine is almost like bad computer programing.

I plan on keeping up with this technical problem. I'd like to find out what it is.

No car company is perfect. Even BMW makes engineering mistakes at times. They once made a BMW motorcycle that had the fuel tank located close the the engine in such a way the the fuel inside the tank would start to boil from the high heat!

I'm still not convinced that it's just the ECU. My noise has been off and on for the last several days, and I can't seem to find the smoking gun of what triggers the event. It can be there from the first second after the first start of the day, or not at all, making me think there are other components involved. Very strange.

It was confirmed that some throttle bodies also make a high pitched noise and this is coming from the engine compartment. Not as loud as the noise coming from the ecu.

Yeah I'm pretty sure a throttle body can make noise if it had some electrical stuff in it.

Another item to look for is the ABS brake system. Those make noise too at start up. Especially during start up since the system has the reset itself. For lack of a better word for it.

My 2009 6MT has this issue, loud high pitched sound from back of engine. It does sound like a cheap distorted speaker... Weird.

The '09 G guys have this issue too.

They have gotten their ECUs replaced, and that has solved the issue.

*FIX for high-pitch frequency noise* - MyG37

It is the ECU. I am 100% positive.

Yup!

It's only happening to the '09 guys as well. I'm surprised Nissan hasn't owned up to this with the Z though.

I think they're still trying to find the most cost-effective fix.

They are pulling a Toyota... except this isn't a safety issue. lol