Who is whistling under my hood.

[Fifty150hs]

Originally Posted by RenaissanceMan

Don't have an answer for you yet, but I am following this thread with much interest. I have the exact same high-pitched whistling noise that varies with throttle application coming from my motor. Interestingly enough, it's started immediately AFTER I replaced my cracked CVV and related hoses. I have smoke tested the motor, scanned for codes, and done other tests and cannot find any evidence of a vacuum leak. I'm not really sure what to check next. Car is running perfectly but the whistling is driving me crazy even though it's not that loud. My long-term fuel trims are also hanging out a little high between 1.6 and 3.7 on any given day, but again I can't seem to find any vacuum leaks whatsoever.

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Have you checked your tensioner pullies? They can sound like whistling when the bearings go bad. When mine went it sounded like I had a flute under the hood!