Cometflash

Sounds like you could use a mechanics stethescope. Pretty cheap at the local parts store. Does the truck have to be in motion to get the noise, or just above idle someplace ? If having the RPMS up does it, should be pretty simple to have a friend work the gas, and you handle the stethescope. Probably find the issue in 10-15 minutes ?

Your problem almost for sure sounds mechanical in nature, so I'd check all the pumps first, then the A/C ( even though it may not be on, it's still being turned by the belt, just not engaged.

If no success, next test might be removing the belt/s, if the noise is still there, that would eliminate all the belt driven things, including idler pulleys.

Hope this helps.

Dave

 

Dave,

In my particular case it's only when in motion. And the previous poster was correct in that when you lift off the accelerator then get back on, it goes away, but just momentarily it seems. It also seems to only rear it's head when the outside temps are very cold as in 5 degrees or below, and when the temps are down around -10 it seems almost constant varying with on and off throttle response till things get good and warmed up. I've been hearing it alot lately as we have been down right polar up here in Mn for the past couple of weeks.

When I mentioned it to the service people at the dealership, they quickly acknowledged that there was such an issue, and that it was the throttle body that causes the whistle. When I asked if it could cause a problem, he said no. Sounds like others are getting a different story from their dealership.

Not even pretending to be a mechanic, why do you feel it is not the throttle body?

Either way I have heard the whistle ever since I've had the truck, (2.5 years), it's just that we've had such balmy winters up until this year that I had not heard it much til this year.

P.S had a completely different whine in the front of the engine that turned out to be an idler pulley and tensioner. Had them replaced, but the whistle continues......

 

birdshooter

I guess my train of thought is based on the size and shape of an orifice, crack, or leak that usually is required to produce a whistle. Thats not ruling out vaccum fittings/lines that may be attached.

Is it possible to use a length of rubber hose with a guage and see if engine vaccum affects the noise, or lack of noise.

Sounds like something vaccum controlled is sticking, more so in cold weather, and the increase in engine vaccum on decelleration is countering that.

Since your issue is with the truck in motion, that complicates some of the tests that could be done, for instance, quickly disconnecting each line in proximity to the intake, one at a time. That would stop the whistle when you find the right line, or at least alter the pitch a bunch. Another possibility would be a solenoid controlled vaccum valvem maybe sticking, more so when cold.

It's really hard to tell without hearing/checking it myself. Kind of like narrating a vacation instead of taking pic's.

I did fix a Gremlin once with the exact same problem as yours, 6 cyl., it was an intake gasket to head air leak. Took a whole weekend to pinpoint.

Dave

 

My 04 w/5.4 has done this every winter since I bought it when the temps get down to say 10 degrees or lower. I'm pretty sure it's in the TB. I took off the stock intake and it still made the noise. But,,as soon as you change the TB position is goes away. Either up or down and RPM's are not changing that much if any. Give the go pedal a little push quickly and let go and the noise goes away, same as lifting and it goes away. But the noise goes away before there's any major change in RPM's. Why? Damn if I know. There must be some sort of harmonic noise as the air passes through the TB at certain temps.

 

thats what i was thinking... this happens on my 04 also but it has to be pretty damn cold.

 

I just got an 06 5.4L and I've noticed this a couple of times, same as wrench007 describes. It seems to only happen when really cold -20*C or so.

 

Same here. -19 seems to be the magic number for the whistle, but it goes away after a few seconds and that's it after it does it the first time. I also heard my truck scream (as many have put it) for my first time one morning when I started it up on -20 degree morning. I was actually laughing because I knew then what many of you were talking about. It only screamed when I first started the engine for about 2 seconds, but it did indeed scream

 

my 03 supercrew with a 5.4 does the same. the whistling starts when the outside temperature is -10C or colder. The whistling starts at cold start then goes away once the idle starts to drop. The whisling starts again at between 1500 and 2000 rpm and little or no engine load while cruising. It is almost as if the engine is venting too high of a vacuum. My Ford dealer service advisor tells me that they repaired a customers vehicle with the same problem 2 years ago. The fix involved replacing a bypass hose. The dealer wants to verify first that mine has the same problem. I have to wait until it gets cold again, maybe later this week. I will let you know if the fix works or not.

 

Sounds like most everyone has this noise at cold startup, for very short periods of time. Sweetness. I could deal with that. My whine is at any temp and at any speed as long as I am giving it gas. Soon as I let off gas, the noise goes away, even if vehicle is still moving. As soon as I touch the gas pedal, BAM, engine whine is back. Doesn't get louder the more I press, the whine is constant as I give gas, no matter how hard or soft I'm pushing the gas pedal. No change in tone or intensity, just a very loud annoying whine every second of every day I drive it while I am giving it gas no matter speed, temp, pedal depression, etc. I absolutely HATE it, and it's the #1 reason I want to get an '09 and get rid of this '04.

 

JohnR-61

Sounds like things might be narrowing down somewhat. 5.4L, -15 to 20 degrees, more or less at start up, gradually diminishes with either warm idle or change in TPS.

Another post mentions replacing a by-pass hose ( maybe smaller I.D. ? ) I'm not sure if the 5.4 has the same lines on the underside of the TB as a 4.6, but mine has a large ( 3/8) line on a 90 deg. fitting ( but mine doesn;t have the problem). On a 5.4, it might be interesting to play around with an inline needle valve with the correct barbs in/out. Cut this large line, install the valve and try to tune the flow ( assuming this is the line).

Just thinking out loud, but at the temp's everyone says the problem occurs, the air density has to be pretty high, calling for a corresponding adj. in the injector shot. No additional air is required because of the density of super cold air, but the increased shot of fuel brings up the rpm's. Normally the TB would be opening more, but with these criteria it is not. So you have the potential for the engine to try and suck air through a closed, or nearly closed throttle plate ( enough to whistle ?), or pulling this high speed cold air across one of those several vac lines on the TB. Starting to sound like the air bypass hose from just forward of the TB to the IAC ( mine goes thru a plastic rectangular part of some sort, not sure if it is a filter, baffle, or flow control device).

Dave

 

Just had my alternator replaced - temp dropped to -16c (3f) - Squeal is GONE!

Note Regarding my Dealer: I described the problem, they said they couldn't replicate the noise (it was above zero on the day it was in the shop). I called them back later, after printing out one of these forums (stating that in a large number of cases - it's the alternator), and they ordered one right away and had it installed (without hearing the squeal for themselves). Sad that you have to self-diagnose problems like this - my service guy said he's replaced 5 already this winter for the same reason. It's almost like they know about this issue, but don't want to make it public (FREE ALTERNATORS FOR EVERYONE!!!!)... HOWEVER, my dealer also looked up my "in-service" date, and made sure that I got in for the new alternator before the warranty ran out (in March). Guess they're not all bad!

 

was driving on the highway today it was around 27*F and I'm getting the whistle at 75mph/2000rpm if I give it gas th whistle goes away and if I let off the gas the whistle leaves by 71/72mph. Strange.

 

Sorry to ruin it but my 4.6l does it to, annoying as hell, upgrade stereo system, worked for me...lol

 

My 05 4.6l will make a high pitched noise also. Mine is due to the cool air intake.

 

I've been trying to read as many threads on this problem as I can (many different forums) and there is not any one fix. I've read for the 04/05s that there is a TSB about the fog lights making this noise. Many people have reported that a new Alternator fixed the whistle. Some say its coming from the throttle body whether its the gasket or something else? Loose plstic cowl that cover washer fluid sprayers.
In my case I'm leaning to the alternator, I think that the 2000rpm range that I'm hearing this noise has something to do with the bearings.
Eventually I'll figure this one out.