Sport Mode Issue- Engine revving when letting off gas

In sport mode, the regenerative braking is increased. You will slow down faster than in NORMAL or ECO modes.

 

Don't assume it's a problem just because it isn't what you'd expect.

The Prius hybrid ECU has complete control of that engine. You are allowed to offer it suggestions.

Sometimes a Prius decides that the battery is a little too full for optimal long-life conditions and deliberately burns off some battery charge by spinning the gas engine for half a minute or so. It isn't burning fuel, but it sounds about the same.

You don't get a lot of input on this procedure. The car does it whenever it feels necessary. Generally speaking, it only happens in situations that put more stress and heat on the battery.

Worth digging deeper to verify that this is really is what you are seeing, but don't assume it's broken because your report sounds a lot like behavior that has been built into the Prius for decades now.

 

It may also simply be high idling because the engine just started and is in the warm-up phase.

 

Is that true? For previous gen's all it did was revise gas pedal travel. Plus some air conditioning aggressiveness changes.

 

The pedal always traveled the same distance, but the curve mapping pedal position to car-oomph-wanted would be changed by the setting. Both ends of the curve were unchanged, but PWR was concave down and ECO was concave up.



The car being programmed to apply some resistance to motion when the pedal is near released, like a conventional car, means the steeper PWR curve in that region is also noticeable as you're backing off the pedal. (Really, they should have drawn that graph with the x axis intersecting the curve a little ways up.)

 

Well yes, that is true...

 

What was the battery temperature at that moment?

What I'm getting at is that at some temperatures, even that 70% might be judged as "too much." We don't know the full criteria the system uses to trigger that activity, it may be even more involved than state-of-charge + temperature.

 

There might even be two distinct kinds of 'activity' that could be involved.

I've heard it said that sometimes, if the battery state of charge is high, the car will twirl the engine even when otherwise unoccupied, just as a way of blowing off some excess charge. I haven't experienced that particular activity, but others here have reported it.

It also happens that when the car is actively slowing, it can choose to do less battery charging, in favor of more engine twirling, as a way to avoid putting excessive charge into the battery in the first place. I've experienced that activity routinely.

 

I'm not sure it's a problem; I think Toyota has been tweaking the sound profile to make the car sound more sporty.

 

I think I heard somebody on here say it. On the instrument display, when you let off the gas, Sport mode does seem to provide more regenerative braking. The downside is that it also increases braking force, so the amount you regenerate could be less than that gained from Eco or Normal modes.