I recently bought a used F-150 4x4 with the 5.4 L. engine with 50,000 miles. It already has a K&N Air filter system installed. I am a newbie, so I do not know what model it is. I do know that the whole stock air filter assembly from the throttle body outward is replaced with K&N parts. My question is, what would cause a whistling noise from inside the airfliter by the mass air flow sensor? At first I thought it was the belt squeaking, that is what it sounded like. The place I bought the truck replaced the belt, but no help. They said to come back during the week and they would look into it. The noise only comes when you first get on the gas. It is fine once you let up on the throttle. Any help is greatly appreciated!!

 

No worries man, it's normal. That's what they all sound like. Just sit back and enjoy!

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2001 Bright Red Supercrew
4X4
5.4 V8

Mods:
Superchip
BFGoodrich TA KO 285/75/16
Airforce One intake kit
Exhaust: Hooker AeroChamber Muffler, SI/DO
SurePull Class III Hitch
Rhino Liner (Planned)
Catch-All Floor Mats (Planned)

Go Buckeyes!
&
Go Bluejackets!

 

wingnut33
Thank you for the answer. This message board is the greatest thing for us newbies!!