I have a 2004 f 350 with a 5.4 v8 I have noticed that when i get on the throttle (mostly on the highway) that at a certain point i develop a high pitch whistle when i am on the throttle,but only for a moment and I can control it with the gas pedal,kind of sounds like a turbo on a diesel, one problem its not a diesel. Any Ideas? This is my first post just signed up. Thanks

 

Look for the dreaded PCV valve elbow, or any other vacuum leaks from the air-box to the throttle body.

 

Thanks, so it sounds like a vacuum leak?

 

Could be anything leaking BEFORE the throttle body, as in, somewhere between the air box and the throttle body. Doesn't sound like a "vacuum leak" per se, but check that elbow where the PCV valve plumbs into the throttle body.

 

Man. It almost sounds like you have one of those "tornado" or other types of throttle body spacers in there. Any chance of that?

 

Do you by chance have an open air exposed air filter, like a K&N FIPK? I used to have one on my V10 and would get a noise similar to what you are describing. If you do, that would be my guess as to the culprit of your noise. If not, back to the drawing board.

 

This is my bet. Whoever decided to install that little piece of junk should have their tongue shaved...

 

Mine does the same thing. I have an 04 SD with the 5.4 and in third gear it starts to sound almost like it has a turbo or blower or something. Its weird sounding but it when it happens its definately at the point the motor really starts to pull. Could be that we just need a better airfilter or that its just sucking that much air.

 

There is a 2002 TSB on the subject. Maybe that's the problem, maybe it isn't. The TSB has nothing to do with the PCV system, however, but with the IAC hose routing:

Article No. 02-10-8
DRIVEABILITY - 5.4L 2V - IDLE-AIR BYPASS FLOW INDUCED WHISTLE
ENGINE - 5.4L 2V - IDLE-AIR BYPASS FLOW INDUCED WHISTLE
NOISE - IDLE-AIR BYPASS FLOW INDUCED WHISTLE - VEHICLES EQUIPPED WITH 5.4L 2V ENGINE ONLY

ISSUE:
Some vehicles equipped with the 5.4L 2V engine may exhibit a "whistling" noise from the formed nylon tube in the idle-air bypass flow circuit. This may be caused by air flow passing through the sharp bend radius of the original tube assembly.

ACTION:
Remove and replace formed nylon tube with the Nipple And Hose Assembly 2L1Z-9W548-AA. This action will correct the sharp bend in the tube. Refer to the following Service Procedure for details.

SERVICE PROCEDURE
Remove the formed tube as shown ( Figure 1 ).
Replace with Nipple And Hose Assembly with part 2L1Z-9W548-AA.
Connect nipple to the air-inlet zip tube and the free end connects to resonator as shown ( Figure 2 ).
Ensure that there are no kinks in the rubber hose which could restrict air flow.


PART NUMBER PART NAME
2L1Z-9W548-AA Nipple And Hose Assembly

My truck is a 2003 but still has the old bent hose. It doesn't really bother me, when it makes a whistling sound, I just make a diesel sound with my mouth and the problem takes care of itself.

 

n578md-

That is very valuable info...Thanks!


biz

 

Excellent info guys, thanks

 

i have a simular weird noise, 2000 excursion v10, sounds more like a whistling buzzing , dont do all the time, does it on med/hard acceleration , more often or easier to make do it when its cold, on the interstate it can be gone completly and then its there , can make change tone by changing throttle position , off throttle its gone harder u push louder it gets, its as loud as a sqweeling belt , dealership changed pcv valve, but didnt help, any ideas

one thing i didnt mention , i pulled the pvc tube off , no cracks , it does have a plastic 90 degree insert on throttle body end, i also tried plugging hose , eliminating pcv valve and it still makes noise but a lot hard to get to do it

 

Someone didn't put a throttle body spacer on it, did they?

 

I had the same noise in my truck, it sounded like a turbo when I got on the throttle. It ended up being a bad alternator, I replaced it and the noise is gone. The guy at the shop tested it and said that the diodes were shot and that would make that sound. He even put it under load on a machine while I was there and showed me. Anyways, new alternator no more noise.

 

my 06 SuperDuty with the 5.4 does it and has done it since I bought it brand new last year. Its especially noticable now that I cut holes in the headlight mounting panel in front of the intake duct. Sounds cool! Have to see if the noise changes when I put a K&N filter in the truck. my cousin's 2500 HD with te 6.0 sounded like it had an intake on it when all he has was a K&N drop in filter.