I just installed the K&N Intake on my 5.4L Supercrew and would like to get some feedback from those that have the same mod. Overall, I like it but what is bothering me is whenever I let off the gas I hear a whining sound coming from the K&N. It almost sounds like it is releasing air pressure. I have checked for air leaks and found none. Is this normal? Sounds great when accelerating.

Thanks in advance.

 

if it is a loud whistle noise, you need to put the little hose back on instead of the round hose they provided, (your install insructions should tell you) I will have to do the same on my now that the weather is tuning colder. Mine only done it at idle, or letting of the gas, while cold, the K&N said something aboud the shape and to much air causing this. The Ford OEM part should rid the problem, Hope this helps.

 

The only noise I get is a sucking noise when I step on it. I have not noticed any other noise than that. I don't worry to much about cold weather here, cold weather to me is in the 40s-50s (San Diego) Also I had the filter installed by the shop that did my Cat-Back at the same time as I am a whimp when it comes to doing anything under the hood.

 

Like Ross Perot said....

Listen for that giant sucking sound!

 

My K&N does the same thing. I just guessed it was more air flowing through the intake. I only notice this sound for a few minutes until the engine has had a chance to warm up a bit. I can only hear it when letting off the gas at low speed or shifting from park to a gear. (Also, the drivers window needs to be down or I don't hear any sucking.)

 

I did notice this morning that when my engine is cold it will make that hissing sound for about 30 seconds to a minute. It dosen't bother me, but if that was like that all the time, I can see where it would be really annoying.

 

No matter if the engine is cold or warm the hissing is constant, especially at 55mph. The only time the hissing stops is when I am accelerating. Last night I disassembled the damn thing and reinstalled it, but to no avail. I guess I don't need to listen to the radio anymore becase my K&N is whistling Dixie to me all the way to work.

 

I would email K&N and see what they say.

tech@knfilters.com

Also you may want to look on there site to see if there are any tech articals or not.

http://www.knfilters.com

Sorry I can't help more, I am not the techie type when it comes to engines. (Don't like getting my hands dirty)

 

I took your advice and contacted K&N. This is what they had to say...

The stock air bypass hose (upper one on tube) has flexible
fittings at the engine and at the intake tube, but is hard
plastic in the middle. Remove the entire unit and replace it
with a 26" piece of 3/4" heater hose and it cures the
"hissing" noise of the air vibrating as it waits to enter the
engine. It may be the section of hard plastic tubing that
causes the noise. I'm not sure, but by replacing it with one
piece of flexible hose makes it totally quiet under normal
driving conditions.

Believe it or not, by removing the entire top tube and replacing it with a 23" (26" was too long) 3/4 heater hose did the trick. No more hissing, not even when I first started the engine this morning.

 

Wow cool, good job getting that info! Now anyone with this issue will be thanking you...