Weird ABS behavior in my AWD/FX4 first time driving it in the snow and using Slippery mode

[HappyCat]

I've only had my XLT AWD / 4k tow / FX4 for a few days and today was my first chance to drive in the snow and use something other than Normal mode. I have just over 200 miles on the Mav.

I was driving a mix of snow-covered (2-3 inches) country roads, gravel and paved. Max speed 50mph. After a few miles of using the Slippery mode, the ABS braking was suddenly on a hair trigger and severely compromised braking. I had one serious scare coming into a curve as the brakes hyperactively (and uselessly) pulsed with barely a touch of the pedal, but thankfully kept it on the road. It was really bad, even at low speeds and then creeping through the final turn as I pulled into my destination. The ABS pulsed so fast and consistently that there was no stopping power, with the slightest pressure on the pedal.

On the way home, I tried several different settings:

• Slippery with traction control off helped a little with the ABS sensitivity but of course made the handling not as good (so the computer allowed some wheel slippage and didn't trigger ABS as quickly?)
• Minor ABS sensitivity in Mud setting, and it ran at really high RPM over 35mph. Is it a setting intended for lower speeds?
• Driving in Normal had minor ABS sensitivity. In the 2-3 inches of fluffy, driven-on snow it handled well with just FWD.

After a few miles on the drive home, a message popped up on the console screen that said something about turning on performance data collection. I was focused on the road, so I don't know what it said exactly. After that message displayed, the handling improved significantly. The ABS sensitivity went away, and braking/handling was much improved and predictable in all modes.

When I drove it a second time later in the day handling and braking were very good again. That trip was in Normal mode, as the roads were mostly clear. ABS is only activating when I really stomp on the pedal, as expected, with a moderate, effective pulse rate.

Thoughts? Enough of a concern that I should have it looked at?
I just would attribute it to ABS sensors getting clogged with snow if not for the console message and improved performance after.

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[The Weatherman]

Ford had said that the vehicle may drive differently for the first few hundred miles. You may have just experienced that.

 

[TooManyVehicles]

Have it checked out.

Also, from the Bronco Sport forum:
The manual says SLIPPERY mode is good for hard surfaces covered with snow or ice. It also cautions against using it on dry pavement. The caution is related to the way the clutches in the system transfer power to the front and rear wheels. In normal mode the system is on-demand 4wd; power goes to the rear wheels only when they slip. In SLIPPERY mode the system goes into full-time 4wd, which means a clutch-based system connects the rear wheels to the engine at all times. Much like other full-time 4wd systems, the full-time 4wd system in the Bronco Sport is not meant for dry pavement because of the stress placed on the transfer system. You can experiment yourself. Select SLIPPERY and drive slowly around a parking lot. You'll hear the clutch making a stuttering noise as it slips to allow for the different rotation speeds between and across the axles. It won't cause anything to break, but the clutch slipping causes unnecessary wear. Do it enough and components will wear out prematurely.

 

[HappyCat]

I was using Slippery on unplowed roads, 2-3 inches of powdery snow, when the ABS did its weird thing.

It hasn't done it since I got the message on the console display about performance/diagnostic data monitoring being turned on. Since that message it has been handling very well. Better even than when I drove it off the lot.
I wish I had been able to read the whole message. I didn't find any way to pull it up after the fact, once I was parked.

I'm thinking this may be part of the "breaking in" that Ford warned about. But that's very concerning. I was alone on the road when the ABS misbehaved going into a curve, so I had plenty of room to sort it out safely. But what if that wasn't the case?

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