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Odd instantaneous MPG readings

Discussion in 'Gen 2 Prius Fuel Economy' started by jstraw20, Aug 24, 2010.

  1. jstraw20

    jstraw20 Member

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    I've noticed some unusual instantaneous MPG readings towards the end of my morning commute for the last couple of days...

    My commute is about 20 miles, the car is completely warmed up. The drive ends with me exiting a highway onto a fairly level road with a speed limit of 15 mph, I'm on that for approx 1 mile until I turn onto an access path with a speed limit of 5 mph. By the time I reach the end of the highway's exit ramp the battery's SOC is just into the green bars.

    Typically I'm able to use a combination of gliding with the occasional pulse from just the battery to make the run from the highway to the parking lot with the instantaneous mpg reading 99.9 mpg all the way. However, for the last couple of days I've been getting lower readings during both gliding and pulsing (the ICE is definitely not running) which drop with the speed of the car.

    The only variable is that it has been raining, so the lights and wipers are on. Any thoughts as to what could be causing this? Could it be something with the 12 volt battery?
     
    #1 jstraw20, Aug 24, 2010
  2. uart

    uart Senior Member

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    If you're moving and the ICE isn't running then you cant get anything other than 99.9 MPG (or 0L/100k in the metric world). I know you said the ICE isn't running but the symptoms sure sound like it is.
     
    #2 uart, Aug 24, 2010
  3. jstraw20

    jstraw20 Member

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    That's what is worrying me, unless I'm suddenly going deaf I'm positive that the ICE isn't running.
     
    #3 jstraw20, Aug 24, 2010
  4. Colonel Ronson

    Colonel Ronson New Member

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    the ICE is hard to hear. But even then, if its on, you'll see it on the energy monitor. But when the consumption reads 99.9 MPG that just means your ICE is off while you're moving.
     
    #4 Colonel Ronson, Aug 24, 2010
  5. jstraw20

    jstraw20 Member

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    Well, I was going to double check myself this morning just to make sure that the stereo wasn't drowning out the sound of the ICE, but I got stuck in a traffic jam and it threw the battery's "typical" SOC off.

    I'll try again tomorrow. I swear I'm not crazy (well, not about this anyway)!
     
    #5 jstraw20, Aug 25, 2010
  6. ken1784

    ken1784 SuperMID designer

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    My bet is you're in S3 of warming up stages.

    Ken@Japan
     
    #6 ken1784, Aug 25, 2010
  7. jstraw20

    jstraw20 Member

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    Of course! I'll bet you're right.
     
    #7 jstraw20, Aug 25, 2010
  8. tumbleweed

    tumbleweed Senior Member

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    The ICE is fairly hard to hear sometimes. Consider getting a Scan Gauge available through thePriusChat Shop, you sound like someone who would appreciate one. It has a lot of functions one of which is a Tach. It plugs into the ODB port by the steering wheel and you can mount it with velcro in a few minutes.
     
    #8 tumbleweed, Aug 25, 2010
  9. uart

    uart Senior Member

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    Actually with the gen2 you don't always see the ICE running on the energy monitor. On my 2005 gen2 the energy monitor absolutely does not show the ICE running if it's doing either regen (green arrows) or glide (no arrows). If however any power is going to the wheels (yellow/orange arrows) then the energy monitor always correctly indicates the state of the ICE.

    I don't know if later year models are any different but that's definitely how it works on mine. If I'm in hybrid stage 3 and I start a glide or regen down a hill, at less than 55km/hr, then the ICE stays running but the energy monitor doesn't show it. That mode 3 silliness is the one of the most annoying things about the gen 2 IMHO.
     
    #9 uart, Aug 26, 2010
  10. jstraw20

    jstraw20 Member

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    Confirmed on all fronts. During this morning's drive I realized that if I time all the traffic lights perfectly I don't stop long enough for the car to go thru the idling check and get into stage 4. The probability of doing this three days in a row is just astounding!:eek:

    I've been thinking about getting a Scangauge since the day I discovered Priuschat, I think the time has come.
     
    #10 jstraw20, Aug 26, 2010
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