Ok guys I'm new to this forum but have a question about my intake. I bought and installed a K&N 77 series cold air intake for my 07 F-150 5.4L FX2. It sounds amazing when acclerating but i've notice a high pitched whistle that happens anytime i hit the gas and even when i'm barely touching the gas. I have to let off or set the cruise to make it stop. Anyone out there know how to fix it or dial it down a little? Thanks for any info.

 

Make sure that everything is tight and snug.

 

Two truck guys

Inspect the induction tube or any other holes, double check clamp connections and fitment to the filter, and throttle body, and make sure there isn't an oversized hole that was punctured into the filter.

 

Thanks guys, I've inspected and checked tightness of clamps and hoses, etc. It all works fine it's just a loud whistle that is getting kind of annoying. Also, when leaning down and listening i can tell that it's coming from just the filter itself....

 

The filter does whistle a little bit but not as much as what you're saying. Mine does the same thing but it is by no means annoying. If it is that loud, something is loose and creating the whistle as the air is sucked past it.

 

Mine does the same thing. I can only hear it if I roll down the window.
I like it though and sometimes I just roll down the window to listen to it

 

I've had my K&N CAI on my truck for the past 2 years, and last week it started whistling between 1200-2400rpm.....

No idea why

 

Mine does the same thing. Called k&n and they said although not normal this is common. Reinstalled mine 3 times and it still does it. Just part of the deal I think. Would like to find a cure. I get asked if I changed the throttle body cause I hear that it is a very similar whistle.

 

I am haveing the exact problems with my 2008 5.4. I have been talking with K&N for possible solutions. They have asked me to video the sound and send it to them. I am suspecting a whole in the filter element of the buterfly of the throttle body. I am going to remove the element this weekend and listen to it. I have asked K&N if polishing the edges of the buterfly may help or if I should consider upgrading to an 80mm throttle body. I will post my results.

 

After rmoving the filter element and playing with the setup I have determined its not the k&n but rather the butterfly in the throttle body. Has anybody else found this to be the problem and how have you solved the whisle. I am going to try to polish the edges of the butterfly ths weekend.

 

yeah, apparently its the air hitting the butterfly valve of the throttle body at certain angles. let me know how the polish idea works

 

After "carefully" polishing up and cleaning the throttle boy and the butterfly, I only got a slight change. Their are 2 screws that hold the butterfly on to the pivot rod. I have noticed that they extend quite far to the other side and am considering grinding these down to a more rounded shape. ............MORE TO COME>>>>

 

^ Waste of time dude.

 

Mine does the same thing. It's not loud or annoying at all tho.

 

Well, I have tried to seal up the K&N heat shield to try and redirect the noise but to no avail. Im not ready to spend $300 on a larger throttle body so for now I just turn the stereo up.