speeddemon86

Hey guys i'm going to do my best to explain this problem. I put my truck in 4 high this morning at a dead stop in my driveway and waiting a little bit so it had time to engage. I gave the truck some throttle of loose gravel and heard a bang then the back tires only spinning and a few more bangs with the same result. I then put the truck in 4 lo and tried to take off and it was fine 4wd worked with no issues. I put the truck back in 2wd and drove out to the road. When I got on the road I pulled over and stopped put the truck in 4 hi and pulled out onto the road and all was fine, I started to lay into the throttle pretty hard and the popping and banging came back all the wAy up to 80kph before I took it out of 4wd. I replaced the IWe on the drivers side and the passenger side IWe seems fine to me no noise or anything. It sounds to me like the noise is either conning from the transfer case or the drivers side iwe. But what I don't understand is the problem is not there in 4lo. Does anyone have any suggestions? Thanks in advance

speeddemon86

Also, could it be that when the iwe went bad the first time it damaged the splines or teeth on the hub or cv shaft and it's not engaging all the way? 4high would put a heavier strain on it causing it to pop and bang and ultimately slip where 4lo is not as much strain and it's ok? I'm just lost on this one lol

1800Beatdown

Clean out the vacuum lines under the hood by the battery with an air compressor. I had the exact same problem until that.

speeddemon86

What am I looking for? Broken or plugged lines? Thanks fir the reply I'm heading out now to look

speeddemon86

I went and checked and found where the vacuum lines run to and I found this but can't figure out where its supposed to be hooked up to. It's the only line I see unhooked and I followed it up from the iwe. I just don't get why it works some but pops out of 4wd when a load is placed on it.

speeddemon86

Bump.. Does anyone have any thoughtful this subject? I'd really like to be able to rely on my 4wd as I need it on a daily basis

speeddemon86

Update... I just went out and got in the truck to try to replicate the problem for my old man... Could not get it to do it again.... I know things do not fix themselves though and I'm scared its going to leave me at the worst possible time hauling a load of wood through the mud on my land... I guess I'll just have to drive it till it breaks

60DRB

Two lines come off the IWE. One for vacuum and the other is a vent.

speeddemon86

Ok that's good to know. Thanks ! I went out yet again and tried to get it to jump out if 4wd again and it stayed it. I really don't get it

60DRB

I would think the issue would be the same for HI and LOW if it was the IWE[s]. Is the tranfer case fluid full? Maybe the shift motor on the transfer case only parially actuated the 4HI when you activated it that day. Here's a good trouble shooting guide for the vacuum system, but I'm not certain what the issue is at this point.

http://www.ford-trucks.com/forums/836438-everything-you-wanted-to-know-about-the-iwe-system-and-then-some.html

I would not drive in 4WD on pavement and I recommend not "pushing" the truck during a mechanical malfunction (while the "banging" is occuring).