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Stop Start Idle Technology won't work when Transmission is in B mode

Discussion in 'Gen 3 Prius Fuel Economy' started by walter Lee, Aug 7, 2012.

  1. walter Lee

    walter Lee Hypermiling Padawan

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    FYI .. This morning I was playing around with my 2010 Prius "B" mode - I realize today that when the Prius CVT is in "B" mode the Prius ICE won't turn off even when it is at a complete stop -- instead the ICE runs/idles at a 996 RPM / .20-.40 GPH while stopped in traffic. The coolant temperature (@190F ) doesn't matter, Battery State of Charge (54% soc) doesnt matter. To re-enable the stop-start idle technology - I had to switch the Prius CVT back to "D" mode. I end up burning a bit more fuel on this trip because it took me a while to realize that I was in "B" mode and that the stop start idle technology had disabled in the "B" mode ... :whistle:
     
  2. gmcneil05

    gmcneil05 Member

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    Yes I believe all Prii do that. I know my 05 does.
     
  3. macman408

    macman408 Electron Guidance Counselor

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    I'm pretty sure I've seen the engine off in B mode, but you are absolutely right - it is very reluctant to do so. B mode is not useful if your primary objective is to save gas. It's more useful for ease of driving down a steep slope, or saving wear on your brakes.
     
  4. cwerdna

    cwerdna Senior Member

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    Interesting. I didn't know that. I'll have to give it a whirl on my 06.

    That might be another reason some people get "poor" mileage when driving in B mode.
     
  5. walter Lee

    walter Lee Hypermiling Padawan

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    I was playing around with - practicing running in B mode while going down some steep slope in my commute- the Prius more aggressive goes into automatic regenerative braking mode and seems to recharge the battery faster in B mode when I do this ( or atleast it feels that way). :whistle: :p I had forgotten to switch back to D mode after the downhill segment and saw my MPG drop from my normal numbers :confused: - it took me a while to figure out what was going on. :oops: At first I thought it had something to do with the ECO, PWR button setting:unsure: - then I realize I was in B mode and I switch back to the D mode and all was back to normal. :)