Hello everybody. I am new to this forum and need some help. I have an 07 screw with the 5.4 and a KN air intake that I installed myself. I quadruple checked everything, but there is this annoying as hell whistle that occurs under light throttle and goes away when I punch it. Any ideas and how to fix would be GREATLY appreciated! Thanks!

 

Did this just start to occur when you installed the K&N filter?

 

I would say it started within a couple of days yes. But when I punch it, the whistle goes away. It's just at lower rpm's or when cruising

 

Welcome to FTE. Its coming from the K&N. The stock intake system has baffles and other measures built in to cut down on these whistles, and other intake sounds (NVH). You have removed these features (that Ford spent a lot of time and R&D $$ on), and there is nothing you can do about it sadly unless you go back to the stock intake.

 

Thanks, I'm really glad I found this forum! And thank you for the information. I am almost to that point of putting the stock airbox on because I'm tired of driving around with what sounds like a squeaky belt....but with the money invested I didn't want to go that route. Do you know if the roush air intake would have the same issues since it's a ford performance product? Thanks again!

 

In reality... you aren't going to gain anything by doing the intake swap (its a hotly contesting thing in these forums.. I am very against, some others are very for). If you take a very simplistic look at the stock job... it is a cold air intake from the factory!

All of these performance manufacturers claim they outflow and everything else compared to stock... they are correct. They do.. they can sufficiently flow enough to power an F16 turbine in some instances. What most folks fail to realize is that you dont NEED all of this flow. The engine is an air pump, and will only *use* as much as it can. You cannot 'force' more down its throat under normal circumstanes. The stock assembly flows more than the engine will ever need, and does so in a quiet manner.

 

I absolutely agree with WheelMa1!

If you do an online search for “air filter test” there is a lot of very good information. IMHO, the CAI units are NOT WORTH THE $$! Unless you are talking about a system that was specifically designed for a specific application there are very little hp/tq gains actually achieved in a street use vehicle and there are very few docs that these mfg’s can produce that actually show an increase in hp/tq in the power-band range of a relatively stock street vehicle- especially if you take into account that they typically list the HP/TQ gain at around 5% and that is the same % most dyno's state is the variance.

I would also avoid oil impregnated filters. While they have their purpose in off-road applications, Ford/GM/Dodge all have “watch-out” bulletins where the oil has contaminated intake sensors. - they even have a training video for the tech's on this (flatratetech.com) .

If you look at the flow data, WIX HP filters flow 98+% of K&N and have a much smoother flow post filter plus excellent filtering, for a fraction of the price! The OE’s have an excellent air intake system. You can use a WIX OEM HP replacement filter in the OEM plastic manifold box and either remove the plastic tube and replace it with a piece of pipe/hose, etc or remove the tube completely and replace the tube by building an air ram type intake into the air box manifold (where the pipe use to attach)- make sure ti terminates above the fan shroud to avoid water intake or fan induced pulsations.

 

Wheelma1 and beechkid.....THANK you for the info! I think I will reinstall the factory box (which already had kn air filter) and compare the two. Thanks also for the idea about the cold air tube into the box. I just thought that with my superchips programmer a cold air intake would be the next logical step.