High Pitched Whine Only At Idle?

[Kanaric]

I have a R32 skyline GTS-T and at slightly above idle there is a high pitched whine coming from the engine bay that I can't find the source of. Basically it's like a high pitched tone that usually will switch to a lower pitched tone then go away, there is no gradual change of it it's high then low then nothing. The tone doesn't happen when the car it at any other RPM than slightly above regular idle. Like the car will temporarily have a high idle then will go to the normal idle rpm and it will go away.

Any ideas on what I should look for? The car otherwise is driving fine and there are no noticeable issues.

edit: i realize that the past two times i drove the car the idle has been very high at near 1500rpm and I found some threads on that like this one:

http://www.sau.com.au/forums/topic/227514-how-to-adjust-tps-and-idle-on-r32-gts-t/

Could failed TPS cause this noise as well? Don't see any mention of that.

Edited July 20, 2015 by Kanaric

[niZmO_Man]

Noise might be a belt?

[Kanaric]

I was wrong about the 1500 idle, what i get for posting from work and memory alone. It idles at 1100.

So I tested the TPS and it is fine, that is not an issue.

I borrowed a Power FC that has a stock tune and when you do the pre sets it idles fine at 700rpm. Regular ECU it idles at 1100. Weird. Anyways it seems like this is a separate issue.

  On 21/07/2015 at 2:49 AM, niZmO_Man said:

Noise might be a belt?

I can't find it right now but would it only be two different tones like that if it were? Like it's a constant consistent flat tone almost like a musical note no whirling sound or changes in pitch until it then changes to a lower pitched one for some time then goes away. I did some hard driving over the weekend and it was staying high pitched and not going away until the car cooled down. It's late here now but tomorrow i'll try to get it to be consistent like that so i can try hunting for it again.

Edited July 21, 2015 by Kanaric

[Hadouken]

So,

High idle and high pitch squeal when driving?

Boost leak?

[Kanaric]

  On 21/07/2015 at 6:50 AM, Hadouken said:

So,

High idle and high pitch squeal when driving?

Boost leak?

Maybe it is, here is a video of the sound.

The thing is though with a boost leak i should hear it get louder at higher rpms, am I right? I don't hear anything at higher rpm than idle. Even if I just use light throttle.

Edited July 21, 2015 by Kanaric

[breaker1845]

Auxiliary belt pulley bearings maybe. Sometimes when they are on their way out they will whine a bit while at idle but usually won't hear anything at higher revs. Put your ear up to the pulley as close as you can and you might be able to pin point if its coming from there or not.

[Kanaric]

  On 21/07/2015 at 3:25 PM, breaker1845 said:

Auxiliary belt pulley bearings maybe. Sometimes when they are on their way out they will whine a bit while at idle but usually won't hear anything at higher revs. Put your ear up to the pulley as close as you can and you might be able to pin point if its coming from there or not.

Ok, i'll check that out

[Kanaric]

Found the source of the sound, it's the alternator. Just have to figure out if it's the belt, pulley, or whatever.

I think the pulley is causing problems because since i've had the car it has a pulley that is wider than it should be i'm guessing previous owner put one from another car on it for whatever reason. Only problem is I can't find one that isn't part of some expensive underdrive pulley kit. Anyone know where I can get one?

Edited July 27, 2015 by Kanaric

[tridentt150v]

Usually when alternator makes that sound its the bearings in it.........needs a rebuild.

Get it checked but if it needs rebuilding best do it before armature is damaged.

[hardsteppa]

I went to a bosch alternator that has the fan on the front of it rather than in the casing. Has a similar whine but sounds sexier, like a jet engine idling, i like it. Once the revs go up you can't hear it anymore, i just put it down to the fan audibly moving air through thr alternator now. So anyway your alt's not a new bosch one is it?

[hardsteppa]

Mine's probably more a whistle sound that a whine actually. They're cheap enough, if yours does need replaceage

[Kanaric]

  On 27/07/2015 at 10:14 PM, tridentt150v said:

Usually when alternator makes that sound its the bearings in it.........needs a rebuild.

Get it checked but if it needs rebuilding best do it before armature is damaged.

The alternator seems like a new item but I bet it was overrevved or something by this non-stock pulley when I was at autocross....

  On 28/07/2015 at 9:14 PM, hardsteppa said:

Mine's probably more a whistle sound that a whine actually. They're cheap enough, if yours does need replaceage

I'll have to see how to wire this. I am not very electrically inclined.

[tridentt150v]

Replacing alternators is pretty much plug and play. You remove the old one, install the new one and plug in the wires. If the plug pack doesn't fit then you may need a plug supplied with the new alternator or cut the wires and crimp on spade terminals. Just take note of how it comes apart and do the same when putting it back together.

Or take it to an auto electrician.