While driving, at a certain range of throttle% vs. MAP, I get a "whistle" from the throttle. It's easiest to make happen while at highway speeds and flat areas. I very slowly start to creep the throttle open more and the "whistle" will come on. It's only there for a few % then goes away above that. I can back off a bit and it comes back in. Depending on load (hills), it may move up or down a few % but always around the same general range.

I have had this issue for years and smoothed the TB to try solving the issue, but this didn't seem to change anything. Since then it has just "been there" and I ignored it.

Now that I put the LS1 intake on, the whistle seems more pronounced and louder. I'm sure it has something to do with turbulence around the throttle blade but not sure how to go about attacking the problem.

 

I had this same thing. I noticed it after I first removed my OEM TB for a ported one. I later put the OEM tb back on and still had it. Same exact thing you are describing. Today I put a brand new intake and TB on and the sound is gone.

 

So your ported TB didn't whistle but the OE did?

What intake and TB did you convert to?

 

stock again.

 

I noticed at after I installed my "Cold" air intake kit.

 

 

any idea what was "wrong"?

 

I dont think anything is wrong, just a noise lol, though it could be a small leak maybe.

 

well if it's "whistling" then it certainly isn't "right" in my book.....

not right = wrong

 

I had a nasty whistle with the fixed orifice PCV and catch can...the PCV by itself didn't whistle, but once I installed a catch can it whistled like crazy. I installed a spring and plunger PCV and the noise went away...probably not your problem though...