Another annoying noise question

[dartgts]

OK, I am a little confused by this. When reving the engine up past 4k RPM I get a noise out of the engine compartment that can only be described as a farting bumble bee... Actually if you have ever heard a (cough) Honda with the farting bumble bee exaust this is what it sounds like. There is an extreme power drop off when the noise hits also caused by the knock sensor viewing it as knock and the ECU retarding the timing..

Could cam timing do something like this?
Balance shaft jumping time?(I know remove it..
Turbo? (not sure because it does it under boost or not)

Sounds like it is coming from the intake believe it or not.. (doesn't matter if a load is on the motor either)

Any ideas???????

 

[Defiant]

Leaking BOV. Are you free-revving? Don't.

 

[dartgts]

Actually I am not free revving to 4k.. But the noise is still there regardless of hard load or not. I will check the BOV. Actually I have 1g BOV sitting in my basement. I will hook it up to see if that might be the issue.

I appreciate the help some things I just can't figure out and this is one of them.. I will let you know (if you are interested) as to what the problem is once I find it... Just a side note this is probably one of the best resources for diagnosis that I have found kudo's to all...