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Old 03-14-2011, 02:51 PM   #1
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Default Whistling noise while accelerating '04 5.4l Triton

Hi,

I recently installed a new K&N cold air intake and for the first week or so, it sounded fantastic. At higher RPMs, my truck sounds beastly now. However, ever since, I've been noticing this annoying metallic whistling noise coming from the front end of my truck. It only seems to occur at lower RPMs. If I let off the gas pedal, the sound goes away. Alternatively, if I gun it, the sound goes away.

I've read other forum threads about similar issues but some people say it's supposed to be like that, or turn up your radio. Not really constructive advice on how to get rid of this annoyance...

So after doing a bit of research, I found it could either be:
- Throttle Body Spacer
- Air leak
- Idle Air Control Valve
- Rear Bearing issue in the Alternator

I don't have a Throttle Body Spacer installed so that's not it.

So far, I've checked all electrical connections and hoses that connect to the intake and everything looks as it should. I also verified the clamps are all tightened and there don't seem to be any visible inconsistencies or leaks. How would I go about diagnosing an air leak?

Here's the link for the intake I bought for reference:
http://www.autoanything.com/air-inta...0A2606089.aspx

Any ideas what could be causing this? The sound is very annoying and does not sound in any way to how a supercharger sounds so living with this problem is not an option for me.

Any help would be greatly appreciated.
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Old 03-14-2011, 03:21 PM   #2
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somebody says that to test for an air leak, you can use a lighter, open it, but no fire it, and go around all posible places... if the engine revs up, then you had found your air leak.
i had not tried that, but sounds good.
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Old 03-14-2011, 05:07 PM   #3
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It could be an air leak, the air intake you just installed or could be the bearing on the alternator. The 04 trucks don't have an IAC. If your not getting a CEL (yet - 04 run lean from the factory and your new intake will make it worse over time.) then most likely not an air leak. My money would be on the alternator or intake.
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Old 03-14-2011, 06:29 PM   #4
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It could also be the bearings in your alternator, I just had this same problem. My truck did it most frequently when the engine was cold, but my problem ended up being a broken vacuum line for my 4x4. i had to have over 800 dollars worth of work done b/c it destroyed my hubs when they remained engaged even after I took it out of 4x4 high so if you think that could possibly be a problem check it out asap.
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Old 03-14-2011, 07:02 PM   #5
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I have an 08 XLT SCREW and have the same thing happen. It has only done this since I installed the K&N CAI. This leads me to believe that it is not the alternator or any bearings. I have tightened that clamp for the filter as much as possible and called and spoke to someone at K&N. They said it is just the air going through the filter. Makes sense to me and I have no codes or anything else unusual. I actually think it sounds sort of cool. I listened to my wife drive off in the truck yesterday and it sounded cool...IMO of course. Sounded sort of like the turbo deisels, just not quite as bada** of course. In short, I personally am not worried about it.
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Old 03-14-2011, 08:12 PM   #6
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the filter will make some noise at lower rpm from its high flow design, but i think the problem you talk about is the alternator my truck does the same thing even befor my CAI, i dont have any charging issues so im not changing it
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Old 03-15-2011, 01:13 PM   #7
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Quote:
Originally Posted by JohnnyRed View Post
I have an 08 XLT SCREW and have the same thing happen. It has only done this since I installed the K&N CAI. This leads me to believe that it is not the alternator or any bearings. I have tightened that clamp for the filter as much as possible and called and spoke to someone at K&N. They said it is just the air going through the filter. Makes sense to me and I have no codes or anything else unusual. I actually think it sounds sort of cool. I listened to my wife drive off in the truck yesterday and it sounded cool...IMO of course. Sounded sort of like the turbo deisels, just not quite as bada** of course. In short, I personally am not worried about it.
Then I don't think we have the same issue cause the sound it makes is pretty much unbearable. I'll try to get a video clip of the noise.

Also, it wouldn't make any sense that this sound would be normal considering it worked fine for about a week without any whistling sound.
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Old 03-15-2011, 02:39 PM   #8
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Anyone have a picture of the engine compartment that would show me where the throttle lever is so I can try to rev up the engine while I have the hood open?

Or is that only for vehicles with a carburator?

Last edited by HelloMoto; 03-15-2011 at 02:43 PM.
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Old 03-15-2011, 02:59 PM   #9
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my truck does this too, its an 07 with a gotts mod style intake, and it does it up to 1500rpm or so when im lightly on the throttle. i think it started doing it more when i cleaned my MAF
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Old 03-15-2011, 04:26 PM   #10
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There is no throttle cable. Fly by wire controls. There is a servo motor in the TB that controls the throttle.
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Old 03-15-2011, 04:26 PM
 
 
 
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