I've been having this issue for a couple weeks where anytime i accelerate I get screeching/grinding noise. From what I've read here on this site I'm figuring its the IWE trying to engage. The passenger side is the one I suspect is foul.

Now here is my trouble, I've tested the vacuum at the actuators and the intake and I've gotten confused on what I'm actually supposed to be getting as far as results go.

2 hi
Vacuum is present on passenger side
Vacuum is not present on drivers side

4 hi
Vacuum is not present on passenger side
Vacuum is not present on the drivers side

Vacuum at the intake is 20 in Hg

 

I would suspect a leak in the driver side line, no vac =hub engaged. So your driver side is probably engaged all the time.

When you accelerate there is a drop in vac so there is not enough to keep the passenger side disengaged. You may be lucky and only have to replace the driver side vac line and not the IWE, (fingers crossed).

That is how I understand the IWE's to work, my truck is 2WD so I'm going on what I have read on the subject. I'm sure someone smarter will chime in soon.

Good luck, and don't forget to post the fix.

 

This thread should help you:

https://www.f150online.com/forums/20...then-some.html

Also, if you go to the 2004-2008 forum and search for IWE, you'll find a wealth of information.

 

Thanks for the advice guys, I believe I've fixed it now.

I ended up disconnecting the hose from the solenoid to both actuator's and blew compressed air (i checked to the diagram and there were no valves, just open line.)through it, doing my best to cap off the passenger side. It ended up blowing the double line on the drivers side so i got a replacement for it and installed. Noise is gone now and I guess time will tell if i need to replace any of the IWE but for now I'm happy. Again thanks for the input.

 

Glad we could help. Oh, and welcome to the site!