Hybrid Engine Revving When Going Downhill

[dogie rider]

I recently took a trip to the NC mountains. On my way home I was on a long downhill run, with my cruise control on, when I had a couple of episodes of my engine revving out of control. Anybody else experienced this? I have wondered if it was because I had the cruise control on.

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[Nightowl]

Eeek! (Watching thread)

 

[Snax]

How are you defining "revving out of control"? Without a tachometer?

 

[dogie rider]

How are you defining "revving out of control"? Without a tachometer?

By the sound. It sounded as if it kicked out of gear for a period of time.

 

[mamboman777]

I would bet you experienced engine braking.

 

[mamboman777]

 

[bombast]

That's the regen brake trying to control your descent. It goes absolutely nuts when you go down a steep hill for a long time. First time I heard it I was sure my transmission was about to explode.

 

[Mymaverick2021]

I would bet you experienced engine braking.

Yes I do believe that the Hybrid has grade control that keeps your truck from running away when on a downgrade

 

[dogie rider]

Thanks! I bet that's exactly what it was.

 

[dogie rider]

That's the regen brake trying to control your descent. It goes absolutely nuts when you go down a steep hill for a long time. First time I heard it I was sure my transmission was about to explode.

You're not kidding. I'm going around curves, and wondering if this may be my last one.

 

[clavicus]

You can even get this to happen with a high battery state of charge and put it in L mode on a somewhat normal hill descent.

 

[Otto B. Abear]

Toyota Prius owner here. When going down long grades, engine braking is used to prevent overcharging the battery pack. Because the engine isn't under load, rpm limits are increased a lot.

 

[BILLNOROVILLE]

My 2016 Prius with cruise control on has done the same thing many times. I either give is a little gas and that seems to help the engine noise and also in the hills I turn off cruise control. I feel in more control with my foot. I have not seen this on my Maverick hybrid yet but I probably will some day.

 

[Sykotyk]

Think of it like a Jake Brake.

 

[Egz]

Like said above, its engine braking. Thats normal.

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