Downhill accelerator surge?

[Hamerhead]

We were driving in the bluffs near La Crosse, WI and on 3 separate occasions, while coasting down a somewhat long, steep grade (8%), the truck ('24 Hybrid) acted like it was in neutral with somebody's foot on the gas. I wasn't using the cruise control and hadn't touched or changed anything. It just started doing it, and at a pretty high RPM.

I stomped the accelerator trying to 'unstick' it, which did nothing. I hit the brakes, also nothing. When we reached to bottom of the hill, everything was normal again.

It was like having the cruise set at 80 and shifting into neutral.

Any ideas?

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[Clarkdonbran]

It’s a feature. Downhill causes too much regen so the engine needs to expel the energy.

 

[Darnon]

Engine braking because the HVB reached full charge. Normal behavior.

 

[El Kabong]

while coasting down a somewhat long, steep grade (8%), the truck ('24 Hybrid) acted like it was in neutral with somebody's foot on the gas.

"Grade Assist"
The owners manual describes it:
https://www.fordservicecontent.com/...ingEnabled=False&userMarket=usa&buildtype=web

 

[Hamerhead]

Thanks, guys! Had the dealer said, "It's supposed to do that." , I probably wouldn't have believed it.

 

[HeyBales]

Add in the fact that just like a normal tranny with resistance in lower gear may not be enough to maintain speed depending on incline.
The need to change from regen that could have been a decent amount and held the desired speed, to ICE air braking because the HVB is full - could result in much less resistance and increasing speed.

So you'll need to go into the brake pads.
And even while doing that - the ICE RPM could be max and very loud, because when the pads are engaged the max regen rate is still being applied - with the generator motor wasting that electrical.

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