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Discussion Starter #1
I've had a whistling noise under the hood for almost two years.


It only happens under the following conditions:

  • When it's cold outside
  • When the engine temp is warmish but not yet the normal 210 running temp
  • When I shift or take it out of gear
  • But not when it's out of gear and I'm standing still
The whistle is an obvious air flow issue but I cannot detect it in the shop. (I haven't yet been able to get my ears under the hood while someone else is driving.)

Of course I have checked the K&N connections and they are all tight. The whistling started long after the K&N was installed.

Has anyone experienced something like this? Any clues you can give me are welcome.
Thanks.
 

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I had a whistling noise develop after my exhaust manifold was replaced. Turned out that the top front bolt loosened up, caused a leak at intake manifold, most noticeable right before reaching operating temp.


Seems like your situation may be due to a slight vacuum leak, temperature related. You may need to do a smoke test to check for any vacuum leaks.
 

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When was the last time you cleaned out your throttle body and IAC motor?
 

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Discussion Starter #4
Whistling Noise Under the Hood - FIXED!

Fixed! My two year teapot whistle is gone.

I checked for vacuum leaks with cleaner but found nothing.

The throttle body definitely needed cleaning so I took it out and gave it and the IAC a thorough degrease. It did NOT fix the whistle, but I noticed the whistle was different. Instead of whistling when it was out of gear between shifts, it mostly whistled while in gear just before the upshift for gears 1, 2 and 3. Weird.

When I took the throttle body off the bolts were firm but too easy to loosen. I merely made it a little more firm on the re-install. After cogitating on the whistle change, I figured I'd tighten these bolts some more. The whistling only occurs in cooler weather when the engine is warming up, so I waited until morning when it was 50 degrees and went for a drive... The teapot whistle is now completely gone.

A guy on a YouTube video said he just tightened the throttle body without worrying about the torque spec as it didn't matter. Apparently not. I didn't bother looking up the torque, for my test drive I just tightened it very firm but didn't go crazy.

The throttle body gasket was very thin but in very good shape. Next time I clean the throttle body I'm going to either put in a thicker gasket or maybe two thin gaskets. Then I'm going to torque it to spec.

Torque Matters!
 
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