Offduty

I am just wondering if anyone else has this going on with their truck!

My 07 4.6 engine has a whisle coming from the intake at about 2K rpm. It will not make the sound when there is no load on the truck, only while driving. Took me a while to figure out exactly where it was coming from! What a pain in the *** that was!!!

So my next question is if someone else had the same thingand fixed it, what did you do to get rid of it, or should I just switch to an aftermarket intake system?

bdrey14

I put a series 57 K&N on my 05 FX4 with the 5.4L and i have the same whistle around 1700 rpm

Offduty

You got the whisle after you replaced the intake? Mine is still stock

bdrey14

Ya i never heard it before i replaced it, now around 1700-2000 rpms i hear a slight whistle...no clue why.

R2nailer

My K&N doesn't do it above 38 F.

CTRAHAN18

do u have a throttle body spacer. i got a whistle after i put a throttle body spacer on it

Offduty

my intake is all stock except for a K&N filter in place of the cheap paper filters. Had the noise even before replacing the filter.

cody ryan

i put/have a k&n filter on mine but the rest is stock i heard it an looked at the filter and it didnt have a gasket so it was sucking air in from around the filter i put http://www.toptoppershop.co.uk/ekmps...s/foamtape.jpg this on the plastic surface and its been fine since, its the single sided sticky foam tape stuff you put on your bed rails before the topper

crazykarl

one of the connections is not tight. What I mean is that the parts are plastic and under the hood so they get hot and cold, (expand and contract) mine does it and i have a 4.6 2008 XL screw. Mine mainly does it because i tried the gotts mod and decided i didnt like it... put it back to factory and the mileage got alot better. but anyway... there is just a leak in the plastic assembly..

Mod (Ret.)

If you could get it to whistle Dixie, it would not be so bad...try adjusting your speeds to see if you can accomplish this!

Have you checked for any intake obstruction? In a stock arrangement intake, leaves and other junk could perhaps produce a blockage and noise. I'd think that whistling could only happen when there's a restriction (kind of like when we whistle, we have to contract our lips and blow air through the small hole; I'd guess this is the same in your air intake). Something is diverting the air intake, making this noise. On my 4.2 V6, it is equipped with an air temp sensor, and is located in the air tube that connects the air cleaner box (a K&N semi CAI) to the throttle body. I'd guess that if this temp sensor were turned, it might make a "tune" as the air flows through it (it has a left and right plastic wall, with a hairline wire bridged accross these two walls to detect the amount of air flow). I think the 5.4's do not use an air temp switch, but perhaps the 4.6's do?

Check for these types of devices that might cause the intake air to be diverted slightly, causing the noise (whistle) you are describing.

Other potential whistle or noise producing things to check for are cracks, leaks, or loose clamp(s) in the air intake, or a vacumn leak in one or more of the engine vacumn lines. These too would create a whistle sound, as well as a possible engine stumble if the vacumn leak was severe. It would be drawing air IN through a small crack or leak in a line, producing a whistle. A bad or leaking intake plentum gasket could do this. Carefully spray some engine start fluid around the intake to head area while the engine is running; if the idle increases, you found a leak. Be carefull not to spray around any open spark areas though!