Before the search police say anything, I tried it already. I haven't found any real explanations or solutions.

When cruising at or about "0" boost, I've got this whistle coming from the engine. It goes away at 2lbs. of boost or at Vac. It's not the radio. The whistle changes pitch slightly within that small range of boost - NOT with RPM. This whistle is not audible the stock airbox. It's only heard with the cold air kit. There no other mods on the truck. Any suggestions would be greatly appreciated.

-Edward

 

With the cold air kit on your truck the whistling noise your hearing is the air going past the throttle body blades, its a normal sound that you hear once you change from the stock air box to an open air filter kit.

 

Are you running a single blade T/B?

 

This sound is with the stock TB. I pulled off the rubber elbow; and inspected it. It seems that there's a mismatch between the TB and the plenum. There's a little wiggle room if I loosen the TB; but not enough to compensate for the mismatch. I think the sound is coming from the air hitting the "lip" of the plenum.

 

I have the same noise too, but i have the stock air box with a K&N and the air box mod. It will start to whistle right between vac and 0. It never did it before the filter and the mod. So i guess it only happens with a less restrictive box and filter.

 

My guess is that the paper filter dampens the noise better than the K&N.

 

Edward,
You hit the nail on the head. Typically the noise comes from the mismatched single blade T/B and upper intake just as you decribed. You can align the two to improve it but to make it completely go away you will need to do a little dremel work. The upper intake needs to be opened up to match the T/B (port match). Very easy to do with a dremel type tool. After you port match install the T/B and align it on the upper intake before reinstalling the upper intake. This makes aligning it much easier. As a side benefit it's free H/P.

 

Thx so very much for this info, gents. This was the problem that I was having as well. I noticed it more during the winter in the colder weather. I'm going to check it out and dremmel down any excess that doesn't match up.

Paul G.

 

A lot of us running the SBTB's have had the "whistling" sounds and as previously noted, it's usually because of a mis-match between the throttle body and plenum. Fortunatley my Accufab lines up quite well and I've had minimal whistling sounds.

 

 

Tim... we need to sit down and have a LONG talk!