Center Diff Issues Anyone?

[Oldfart]

My '20 has 11,000 miles on it now. I noticed the last several weeks that sometimes when I was backing out of a parking space where I was nose in, that the wheels felt like they were crabbing a little bit. This was always with having arrived at the spot in 2HI. Today I went into a big empty, flat parking lot to see if I could figure out a little more of what was happening so I could tell the dealer a little more info. It was consistently crabbing if I shut it off, restarted, and backed up while turning the wheels. I then made sure the wheels were straight and I put it in 4LO, very slow speed, straight driving on level ground. After about 50 feet at 5mph it made a noise like 2 gears were losing contact and slipping past each other, and then a fairly harsh bang! Obviously, I put it in neutral right away and stopped. Put it back in 2HI and drove home, it drove fine again.

The dealer can't get me in for 3 weeks. Any ideas what the hell might be going on? I'm assuming something with the center diff is screwed up. Once I'm driving forward the truck is fine in 4 AUTO or 4 HI. Maybe @FordTechOne has heard of something like this? I've definitely never ran into something like this with a truck. Thanks for any input.

 

[JohnyPython]

If your truck is “crabbing” then your Raptor must have crabs. Truck must be sleeping around.

Have you tried replacing the IWE check valve? Only thing I can think of besides naughty things.

 

[CoronaRaptor]

I've got nothing, might need to do a vacuum test on the iwe lines, something along those lines.

 

[smurfslayer]

So it’s only in reverse?
did you ever have IWE issues? It’s possible if you don’t catch it fast enough you can cause some hard (plastic) part damage.

if it’s ok in 4h or 4a that is suspiciously like IWE but maybe something more.

 

[Oldfart]

I'll have to try the IWE hose, I bought a spare to keep in the truck. I didn't think this sounded like IWE, but I don't know much about these systems. It's fine in 2HI to drive around, it just seems off when you back up.

 

[Muchmore]

IWE somehow. Now just to find out where....

 

[fordfreek]

It seems to me when I was having IWE issues that when the truck was first started and I drove away, there wasn't vacuum applied to disengage the IWE's right away. Not sure if this was the case every time or after a cold start. If this is the case, maybe you're feeling the front torsen diff ? Just a thought. There isn't a center differential in these trucks is there?

 

[smgilles]

It seems to me when I was having IWE issues that when the truck was first started and I drove away, there wasn't vacuum applied to disengage the IWE's right away. Not sure if this was the case every time or after a cold start. If this is the case, maybe you're feeling the front torsen diff ? Just a thought. There isn't a center differential in these trucks is there?

This was a done on 2013 - 2018 F150/expeditions, but I don’t think it included Raptors.

• Note: The new TCCM calibration changes IWE operation at start up. When ambient temperature is above 0°C (32°F) the IWEs stay engaged regardless of a 4WD mode selection for approximately 0.8 km (0.5 miles). IWE engagement only occurs once per key cycle and is not reset when shifting between PARK and DRIVE. The TCCM uses this strategy to delay vacuum use until vacuum-intensive engine startup has completed and sufficient vacuum is available to fully disengage IWEs.

 

[fordfreek]

When I had a vacuum gage plumbed into the IWE side, that's what my truck did. I was gonna say the first quarter or half mile there was no vacuum applied to the iwe's. Mine's a 2020 model.

 

[mashtastic]

Had something similar on wife’s truck and ended up being rear electric locker was engaged. The switch went bad internally and sent the signal to engage