re tested it after replacement and air wouldn't flow to "engine side" so I think it was bad. Replaces it and no problems thus far.
ford damaged the clip on the plug going to the solenoid. Any idea on how to fix that?

 

I had the same issue on my drivers side. Check the line for vacuum because my problem was actually super simple and annoying. The local dealer had mine for warranty work and it started when I got the truck back. The solenoid was brand new too so I knew it wasn't that.

what it ended up being was the jag off tech didn't reconnect the vacuum line on the passenger hub, so the passenger side was always engaged and the grinding was coming from my drivers side because it was getting a vacuum leak, and couldn't fully disengage. Same thing, it would go away when I put on 4x4 and grind in 2x4 when I'd give it throttle. I never thought to check the passenger side because the issue I was hearing was on my drivers side. Really simple but annoying.

 

You might want to go back to your dealer and talk to them about it. The grinding you were hearing was the IWE having itself for lunch. That damage doesn't heal itself and since their technician caused it, they should agree to fix or at least inspect it.

 

I actually just replaced the IWE on that side last week bacause I've had issues for a while now. The dealer screwed up just prior to that. I am going to ask for my money back that I paid them for labor because it's a little ridiculous hat a certified tech doesn't check the system for vacuum after doing work like that.

 

Hey guys, new to the thread, which Ive read thoroughly. I cant seem to find the Vacuum reservoir on my 2010 F150 FX4 5.4L. Ive replaced both IWE's, Solenoid, and check valve. Ive also hooked up my hand held vacuum pump to the line heading down to the IWE's from the solenoid and have good pressure. I do have a drop in vacuum from the line which seems like its coming off the manifold. Its the one that runs off the bottom of the solenoid and across the brake booster. It hooks up at a "t" intersection which one goes to the booster and another which goes back behind the engine larger diameter black hose. Everything I've read on line says that the Vacuum reservoir is behind the battery battery box. But I don't see any lines coming from behind....After replacing all that stuff and purchasing the hand pump I still have the same problem...loss of vacuum, (cant keep the 4x4 locked in, it slips out when accelerating)...

 

(2006, 5.4L, 4x4) I wrecked my truck against a curb last month and had the 4x4 dif., shafts, and ball joint arms replaced by a DIY. when I got it back, after a few miles of driving I started getting loud grinding, like wheel bearings going out. I removed the right wheel bearing & hub & it was packed with grease w/metal shavings so I replaced it (don't know why old hub was pact w/grease, bearing are sealed).
I still have the same grinding noise but only during acceleration.
I did find a vacuum line disconnected, I re-connected.
I still have one vacuum line that comes up from left side that doesn't connect to anything (I put a cap on it) & don't know where it would connect to.
Up to now I thought that the vacuum & grinding were two separate issues.
does anyone know where the left vacuum line goes to?