Easy fix for the the early morning cold whine that goes away and really is no trouble or concern at all, and for my absolutely awful constant engine howl - trade it in for a 2009 like I'm doing. Problem solved.

Only have to listen to that horrid engine whine for another 6 weeks or so, hopefully it will arrive in early April.

Still not sure why the very short-lived whistle on cold morning start-up's that goes away fairly quickly is bothering anyone, seems extremely minor to me. Try living with a high-pitched engine howl that NEVER goes away as long as you are giving the vehicle gas, no matter speed. Total nightmare. Can't wait to say goodbye to this 2004!!!

I had the high pitch whistle noise. Only occurred at cold temperatures and the whistle pitch worsened with speed/rpms. After Ford replaced belts and tensioner, the alternator was replaced. That fixed the problem. Was told by one dealer that this is common.

The whistle happens in cold air only while the air intake is still cold. You should notice this only under light throttle and only until the air intake warms up. The reason is the air rushing through the intake and whistling across either the intake or one of the hemholtz resinators. The cold intake is slightly smaller and the dense air together cause this. As soon as the intake warms it expands the opening slightly and the air rushing across no longer set up the standing wave. Mine almost sounds like a a tug-boat whistle. This is similar to the sound from blowing across a glass soda bottle (or beer bottle). The production air intake has either 3 or 4 hemholtz resinators on it already, so there isn't any room for another which really is only needed for 2 minutes during sub-zero temps.

There is nothing wrong with the truck and there would be no fixes from a dealer. Of course you will never be able to repeat this at a dealer because it will warm up enough by the time you get there that it cannot make the noise.

Smokewagun update?
 

Mine is doing almost the exact same thing and I'm running the same tune and intakes as you. Did you ever get this fixed?

Ladies and Gentleman, pls forgive me as I did not read every post. I am new to the forum and I have an 05 f-150, 5.4l. I to have the dreaded whistle. To me it reminds me of the sound effect when the coyote falls off a cliff (which is what I would like to do to my truck right now). I have noticed that it really only makes this whistle at certian mph ranges such as 62-64ish mph and 72-75ish mph. When I let off the gas and coast it becomes louder until I coast under the mentioned mph. To me it really sounds like it is coming from the speedometer. Do we have mechanical or elect speedometers?

ive been fighting with this noise on my parents truck for the past few winters. This year I changed the belt and noise is gone.

Mine is not a belt and has nothing to do with speed. It is for sure coming from the intake.

Is there a specific brand belt you used?

This whistle is driving me nuts, really loud when the temps below 0.

Thanks

has anybody tried replacing the fan clutch yet, I swear that is what I am hearing. I am glad I am not the only person fighting this darn issue

replaced with another motrcraft belt, high pitch whistle/hooting is gone.

I guess it could be the intake. But on my NEW 2009 F150 with just 6300 miles, the whistle occurs above 45mph on cold days and stays pretty constant. It only lessens when I open the driver window presumably that changes the path and cabin pressure.

I do love my heated seats in the winter!:banana:

I got it
 

Thanks to 2stroked you were right all along, I did not think it could ever be my alternator but it was. After a fan clutch did not fix it I decided to try the alternator and that did it. Thanks

The alternator.

when you get old enough you wont be able to hear it lol :] but for now my truck always whistles and doesn't bother me at all

high pitch whine
 

I have a 05 fx4 with 5.4. I bought it used, i now have a high pitch whine at 60 to 70 mph. It did start until i checked the air filter. It is cold outside. any help on fixing it.