Background: 2005 xlt 4x4 with 5.4L. 33K miles. 2.5 AS and 285/70/17 terra graps.

Problem: I don't get to use the 4 wheel drive all that often. About 3 weekends ago I was out on a buddy's sandbar and had the 4-hi engaged all night. I was fairly easy with it not spinning any more than what was required. After about 3 hours of on and off driving I go to leave and i was running about 10 mph and there was a loud pop or clunk that came from the passenger side. I got out and looked and my buddies looked and the 4 wheel seemed to be working ok. I didn't think much about it, just passing it off as a one time deal.

Last saturday we actually go ssome rain and I put it in 4 hi coming up a hill in my hunting lease. went about 10 feet and the pop came back again. Just one time. This time i was spinning while it popping and I think i felt the passenger tire stop grabbing (just for a split second) then start again. But then again it worked fine after that.

I've also noticed since the popping began It takes longer to engage and i can hear it engage a lot louder than before. I've never been hard on it and never abused the 4 wheel drive, or truck for that matter.

I've done a search on here but couldn't exactly get a diagnosis and solution. What is the probably cause? Seems to me vacuum related but I don't know

 

I have a poping/binding sound from the right front side. 39,000 miles Fx4. It was first noted after the alignment. It ended up being the lower control arms were loose and shifting back and forth. I had them tightened and worked fine for a while. BUT, it has been a couple of weeks and I still get the clunk, sound from the right front side when turning left. That is without engaging 4 wheeldrive. I'm still annoyed and trying to find out what the heck it is. Some clunking is heard when the 4hi is engaged and the manual states that it is normal. You might have to take a look at the issue further, as long as it is not a constant noise they may not do anything at the dealer. If it's still in warranty take it for a dealer look. Or check to see if there is a TSB on the issue. If I find out more I'll let you know and post it. Good luck

 

I was gonna say sounds vacuum related but you've come to that same conculsion. Check your edge for fault codes. You might have the IWE solenoid going bad.

 

Checked with the edge and came to the conclusion that there are no DTCs.

Does anybody have a vacuum diagram to point me in the right direction?

 

I have (had) the same problem. I took it to the dealership while it was still under warranty and they replaced the IWE solenoid. Now, 3000 miles later it's doing it again. I don't use 4x4 that much, but nonetheless it's back. Anyone know a permanent solution for this?

 

Sorry about digging up an old thread, but I searched and this was the closest I could find to what happened today. I was driving in 4x4 high on the beach in fairly deep sand and got a clunk from the left front end, thought I ran over something. Went about 100 feet farther and it happened again. Stopped the truck and it sat for about 2 hours (waves were good). When I started up again it was soft sand, had to stop and back up several times, working it hard to get up and moving but never heard the clunk again. 4x4 seemed to work fine the whole time. Does anyone have any idea of what this would be and if its anything serious? Truck is a 2004 Screw with the 5.4. Thanks