Whistling noise

[1991KOTH]

Hey guys, my Z just recently started to get a whistling noise. It only really happens when the car is warmed up and gets louder when I hit the gas. Any ideas?


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[A26B]

Vacuum leak.

[1991KOTH]

Vacuum leak.



Yep, just checked the MAP sensor lines and all was good. I fear I may have to pull the plenum again. Will most likely get rid of the secondaries and do the coolant bypass once Im in there. Sounds like its coming from this general area. Will have to investigate further.
9267




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[Jagdpanzer]

Ive had mis-aligned air horn bellows hose clamp come in contact with the AC pulley make a similar high pitch noise to a vacuum leak.


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[Ccmano]

The alternator can make a whine or whistle (I guess). Hard to say without hearing it.
H
:cheers:

[ZWILD1]

This is interesting. Not long after Carlisle this year my car started to make a whiny kind of noise. My car has no secondary as Marc H did one of his 510 packages. It's not a vacuum leak as the idle has been checked and Marc said it's ok. I checked the bellows clamp and that is ok also. Not sure what else it could be though. I think the idle was around 770 but Haibeck said that wasn't all that out of line. To me it sounds like the driver side area of the plenum but it's hard to tell really.

[XfireZ51]

A vacuum leak would very likely cause an oscillating idle. And it would idle higher.

[1991KOTH]

A vacuum leak would very likely cause an oscillating idle. And it would idle higher.



Idles at about ~800 when cold but “searches” for a bit when Im coming to a stop and put the clutch in. When it warms up the idle can be quite erratic. Check engine light also comes on and off at times. Gonna have to put a piece of cardboard up to the airhorn and see if the engine stalls out tomorrow.


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[XfireZ51]

Idles at about ~800 when cold but “searches” for a bit when Im coming to a stop and put the clutch in. When it warms up the idle can be quite erratic. Check engine light also comes on and off at times. Gonna have to put a piece of cardboard up to the airhorn and see if the engine stalls out tomorrow.


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Yes I would block the airhorn. Idle hunt when coming to a stop w clutch disengaged is not unusual and not necessarily indicative of a vacuum leak. See if SES has a code to it.
What are the conditions that have SES come on?
If idle oscillates w warm engine, could be vacuum leak.

[ZWILD1]

My noise is there cold when you first start the car and it remains when hot. About a month before Carlisle I did a service on the K&N air filter and it was fine. The car sat three or four weeks after Carlisle and then I went to start it and the noise was present. Marc Suggested I try and put a towel over the air box on top of the filter and see if the noise changes. It has the replacement PCV hose assembly ( non factory style ) and Marc put small plastic ties around them to make sure they are sealed and don't come loose.