I remember a post a while back regarding this and was able to locate it in the search function. I thought i would throw it out there to see if there was any newer information regarding this.

My 06 5.4l tends to "whistle" during throttle up and seems to be most prevelant in the upper rpm as i go thru the gears (manual 6 spd). It sounds similar to a small turbo spooling up but not quite as loud. The original post comments on a possible air leak in the intake system and maybe the PCV system as well. I don't have an aftermarket CAI or throttle body spacer. The motor is currently stock except for a K&N filter element. This was not noticed after replacement of the filter and has seemed to get a little louder since i first noticed it. I have also not noticed any decrease in performance or mileage.

Have any of you had this issue and if so have you cured or found any problem?

Thanks
Dave

 

Strange, I too have a similar issue. When I mat the pedal to the floor, my truck whistles as it approaches 5-6K RPM. It's real loud and it is most audible through the exhaust.

 

It's the K&N...

 

You really think so? Like, I had a cold air intake on my Jeep and that thing would wistle, but it was nice and kinda sounded like turbo. This is more like a hum-ish whistle.

 

Mine sounds like a loud whistle any time you apply 1/2 throttle or more. You can hear it in the cab with the windows shut. Yours may be something different.

 

I know the whistle you are talking about. This is different, I think I will make a video of it this weekend.

 

Mine did the same thing but, it turns out it wasn't a whistle it was a squeal... EZ fix, turns out it was the pulley nut on the Altenator. Quick snug up and it was all better!!

 

This is clearly not a squeal, not my K&N and isin't coming from the exhaust.

 

So what have you done so far to troubleshoot it?

 

I've noticed that I too have that "turbo" sound coming from my 5.4L 3V engine. It's more noticeable at the lower RPM range (0-3,000 RPM's). I personally like the sound but that's just me. I have the K&N CAI kit.

 

I thought there was a TSB for an intake whistle on certain year 5.4's?

 

There is a related TSB for the diesel engines.

https://www.ford-trucks.com/tsb/full...hp?tsb=05-21-9

 

I believe the CAI kits generaly make a note in their instructions that the "whistle" indicates normal function. I have no actual problem necessarily with the noise other than making the assumption (which i typically don't like to do) that it is something that may cause a future problem or failure of a specific item "or" the indication that something that may need to be serviced/cleaned etc..

I have not done anything as of yet other than a physical inspection. I plan on checking and or removing the AI system and inspecting and cleaning it if need be. I cleaned the K&N last week.

 

my 06 does it and has done it since I bought it new, Its more noticeable since I put a K&N drop in and cut a hole in the headlight mounting panel in front of the intake tube, basically made my own Zoodad. so im chalking it upto intake noise. I think it sounds badass.

 

Last night I changed my exhaust tip from a 3" to a 4" and the whistle in the upper RPM's disappeared.