24 XLT Hybrid trans issue

[DelSil]

Recently on my 2024 XLT hybrid, as I'm slowing down the transmission seems to rev almost as if it is not getting into gear. Seems it is doing most when going downhill. When I come to almost a stop it jumps forward a little bit. Has anyone had an issue like this? I had the same issue in my 18 F-150 got worse and needed a new transmission. My Maverick only has 24,000 miles on it

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[Hoagus]

It would be very odd if it had the same issue as your f150, unless it had an eCVT.

 

[Darnon]

Likely symptoms due to it being the winter and cold.

Cabin heat demand keeps the engine running when at a stop. Because the generator rotor can't perfectly neutral balance the engine's power through the planetary gearset some torque wants to apply to the wheels and the variation in this results in the "rocking/lurching" when stopped.

And because the ICE is running more the HV battery is likely to hit full charge on regen downhill and therefore hands over to engine braking; letting the engine be turned to use the compression to slow.

 

[Matso]

This happened all the time with my previous '22 XLT hybrid on downhill grades. It seemed to me to be some kind of aggressive regen braking. The rev went away immediately when I lightly pressed the accelerator. The service techs could not duplicate nor explain the behavior and nothing else became of it.

 

[HeyBales]

As stated, totally different trannies.

Down a hill huh.
If it's cold and the HVB can't be regen recharged, or it's already at max 70% SOC - the engine is brought in for engine braking, no fuel, and the generator motor changes the eCVT gearing to whatever is needed for whatever level of assist is needed from the engine.

That's the sound probably.

Sometimes the switch to physical brakes at the end is different than normal, depending on the gearing, and grabby or jerky as the engine is disengaged could indicate it's still cold and the damper to lessen that effect is having an issue.

Watch for when cruising in electric mode (not accelerating), and it switches to hybrid, is it very smooth catch or you can feel it?

 

[DelSil]

Thanks. I just thought it was interesting that my F150 did the same thing and knowing it is not the same trans. That was a coyote V8 with it's own set of problems. This is my fist hybrid so need a little getting used to. I being trying to see when it happens most and when cruising in electric does not seem to do it.

 

[vandeda2024]

if coasting down the hill, is your high voltage battery full? In my prius, when the battery is full, it will aggressively engine brake down hills to avoid damaging the battery.

 

[Master Blaster]

Recently on my 2024 XLT hybrid, as I'm slowing down the transmission seems to rev almost as if it is not getting into gear. Seems it is doing most when going downhill. When I come to almost a stop it jumps forward a little bit. Has anyone had an issue like this? I had the same issue in my 18 F-150 got worse and needed a new transmission. My Maverick only has 24,000 miles on it

Braking while going downhill and the battery already at optimum charge will cause the drivetrain to flip into the backup braking mode where it turns off the ignition and fuel on the gas engine and runs it as an airpump to loudly blow off the unrecoverable energy. Its a jake brake in big truck terms.

 

[HeyBales]

Thanks. I just thought it was interesting that my F150 did the same thing and knowing it is not the same trans. That was a coyote V8 with it's own set of problems. This is my fist hybrid so need a little getting used to. I being trying to see when it happens most and when cruising in electric does not seem to do it.

The test is cruising in electric and then it switches to hybrid, in other words brings on the engine for slight extra power, like slight incline or battery ran low.

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