Gas engine turning on & off rapidly in rush hour traffic with hot weather and AC running

<div class='quotetop'>QUOTE(local_host @ Apr 29 2007, 07:50 PM) [snapback]432359[/snapback]</div>

As long as you enter B-mode above 20 MPH, it'll keeping the ICE running even when you come to a complete stop. It a weird quirk that could be useful for you here.

Off topic, why doesn't anybody use this for idle smog-testing for the Prius instead of the dance-steps?

 

Can you put the car in neutral and rev it up?

 

Not sure anyone is still following this thread, but just throwing this out there..
Is this only true for models before the 2008? I have a 2008 and am able to switch in and out of "B" mode regardless of my speed. Even at a dead stop...

 

Evan was talking about keeping the engine running. One can always shift into "B".

Note that "B" should only be used on long downgrades to avoid riding the brakes, for example when driving down from the top of Mount Hamilton. "B" reduces fuel economy and so should not be used in ordinary driving.

 

Not once have I seen the mpg meter drop below 99.9 when I switch into "B" as a way of slowing down. Obviously if you drive in "B" Mr. Schumacher's statement is true, but does it actually reduce fuel economy while coasting?

 

It reduces fuel economy because it forces more regeneration (battery charging) than would otherwise happen, and charging and discharging the battery is fairly inefficient. It's better than friction braking, but not as good as anticipating traffic and gliding (lightly touching the gas pedal so that there are no arrows on the "Energy" display). In "B" you lose the option of gliding, which would be happening at least sometimes even if you're not trying.

 

Furthermore, and more importantly, B mode causes the engine to do compression braking, which is a way to deliberately throw away energy that could otherwise be used.

Tom

 

Got it. I think. Thanks.

 

My 2006 has this problem. Did you ever determine the cause of this problem?

 

No, this is how it's designed to operate. When the HV battery is low then the slightest power demand will start the engine.

If the majority of your driving is under these conditions then I guess a PIP or EV would work better.

 

Edit: I forgot to point out there is a work around, though it's not particularly efficient and personally I'd rather just let the engine cut in and out as needed.

But if it really annoys you then here's one possible work around. When you come to a complete stop you can just hold your left foot firmly on the brake and then squeeze the accelerator enough to start and keep the engine running (transmission stays in "D"). This force charges the battery.