05' Fx4

When I am going 40 plus miles per hour and I really step on the gas.. I get this really weird rattling sound. As long as I keep the petal 3/4 of the way pushed in it continues. As soon as I let it off the sound stops. It is def coming from the passenger side. It sound like from under the passenger side door or possible the wheel well. It's only at the high speeds and only when I put the gas down 3/4 of the way and have the higher RPM's going.

Not sure if this could be an exhaust heat shield or something on that side. Someone mentioned something about a vaccum line being off going to the hub? and that could be causing the hub to try to insert or something? I am not sure about all that

 

If it's a 4WD vacuum issue, this should help.

w.ford-trucks.com/forums/836438-everything-you-wanted-to-know-about-the-iwe-system-and-then-shttp://wwome.html

 

We have an article right here on that. Your link is invalid.

https://www.f150online.com/forums/ar...then-some.html

 

Sounds like a bad CAT. I thought it was coming from the passenger side so the dealer replaced the passenger side CAT under warranty. I got a mile down the road and the noise was still there. I took it back and it was actually the driver's side CAT. It can be deceiving because the driver side CAT has the cross-over pipe.

As soon as I would let off the gas the rattle goes away. Mine made the noise at the same speeds as you mention. I had the dealer look at the 4wd vacuum system / solenoid / IWEs (Integrated Wheel Ends) and it was not the prob. Have them hook up a microphone system by both CATs and they should be able to pin-point which one it is if they are careful. I got two new ones on Ford because they messed up.