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ENGINE RUNNING indicator - WE NEED THIS!!!

Discussion in 'Gen 2 Prius Audio and Electronics' started by Eisenson, Jul 22, 2004.

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  1. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i think it is disconnected from the transmission which allows the transmission to spin without the motor which is counter to the way a regular car works. i think this is where the confusion is coming in. when the car is coasting or doesnt require power input to maintain speed of the car, the engine shuts off after a certain period. then the car runs just like any car would run in neutral.

    only when there is a need for more power would the ICE start up spin up to speed then engage the transmission.

    the car makes too much noise to actually hear the ICE shut down (heck even at very low speeds, its tough to tell if the ICE is running. its easy to hear it start up on occasion, but unless im sitting at a light, i can never tell when it shuts off. when the car isnt moving i can feel the vibration of the engine stop when the ICE shuts off.)

    also i noticed especially on hilly roads, that sometimes i can feel the ICE starting up and engaging the transmission. i feel that if the ICE was turning then the "bump" wouldnt be as noticeable.
     
    #21 DaveinOlyWA, Jul 27, 2004
  2. LeVautRien

    LeVautRien Member

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    Yeah...now that I realize what I said, if the engine was disconnected, there'd be no need for it to spin, right?
     
    #22 LeVautRien, Jul 27, 2004
  3. Batavier

    Batavier Member

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    An RPM meter would be nice as well. :)
     
    #23 Batavier, Jul 27, 2004
  4. kenmac

    kenmac New Member

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    From what I remember of the theory of how the transmission works, the ICE is always connected to the "planet plate" and as such must follow the requirements of the planetry drive.
    There is no disconnect device such as a clutch - it's always in mesh.
    At a certain road speed the ICE must start to rotate - it's simply the result of the relationship between the planetry gears, sun gear and planet plate and ring gear!
    It's that clever device that makes this machine so smooth.
    There are links on this forum to sites explaining the operation of a planetry gearbox if you are interested, but it's very technical and difficult to grasp.
    Just accept that it happens and enjoy.

    kenmac
     
    #24 kenmac, Jul 27, 2004
  5. daniel

    daniel Cat Lovers Against the Bomb

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    The geometry of the planetary PSD (which, BTW, does not allow any component to be disconnected - it has no clutch) requires the ICE to spin if the car is moving over 42 (?) mph in order to prevent MG1 from spinning faster than its maximum rpm. The same geometry and MG1 spin limit is what limits the car to a maximum speed of 106 (?) mph.

    Strictly speaking, the Prius does not have a transmission, though, in a sense, the PSD might be regarded as a totally revolutionary new kind of transmission.
     
    #25 daniel, Jul 27, 2004
  6. Eisenson

    Eisenson New Member

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    Here's an interesting situation resulting from the combination of the EV control and the ENGINE RUN indicator...

    Coasting down an off-ramp at, say, 50mph, the engine turns off. If I hit the EV button, it stays off until the conditions are met for engine start (SOC, throttle, speed under acceleration).

    That is, I can come to a stop at the bottom of the ramp, wait, and accelerate from zero - all with ICE off. At 30-35mph, ICE comes on as usual. Zero fuel consumption from the time my foot leaves the accelerator pedal on the freeway until a quarter mile past the stoplight on the surface street past the exit ramp.

    I WANT A TACH!!!
     
    #26 Eisenson, Jul 27, 2004
  7. efusco

    efusco Moderator Emeritus
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    Interesting observation, and against my sense of what the EVb does and how it works. Have you repeated that test? I'll check it out today...I have times it would be useful to have that.

    Has Dave given you any indication when the production version of the engine/brake indicator will be available? If you see him see if you can press him for an approximation for us.

    Finally, the tach is a very self-doable install. Tom Stangle at VFAQ installed one. He made a cut out on the vent cover on the right side of the radio stack (symetrical and same size as the shifter knob 'hole'). A green digital display to match the HUD of the speedometer would be pretty cool there and it would be easy to power it up by tapping the nearby cigarette lighter power supply. See the diagram below for where the tach sensor wire goes.
     
    #27 efusco, Jul 27, 2004
  8. Eisenson

    Eisenson New Member

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    I suspect the combination of that ENGINE RUN indicator and a tach will be yet another revelation.

    Well, I don't have a handy tach - but I do have a DVM with a so-called frequency counter. On the off-chance that it might read that low, I wired that black lead and ground to a pair of test terminals bored through the dash, and tried it, but got nothing. Drat!

    The local Pep Boys had Sun only - nothing right for the car, so it's off to JCW mail order, I guess.
     
    #28 Eisenson, Jul 27, 2004
  9. LeVautRien

    LeVautRien Member

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    Would a tach really give any useful information? I would simply first assume that with how complex the HSD is, there's much much more going on than a tach would show. That's just my initial reaction, so please, do tell me how useful a tach might be for the Prius. :mrgreen:
     
    #29 LeVautRien, Jul 27, 2004
  10. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    a tach would tell me if the engine is running
     
    #30 DaveinOlyWA, Jul 27, 2004
  11. FredWB

    FredWB New Member

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    Assuming Wayne's 10,000 RPM limit (in his THSII program) for the MG1 is correct, then the ICE could be zero RPM up to about 69 MPH, after which the ICE must run to prevent MG1 from over speeding. So the MG1 or MG2 speed limit doesn't appear to be what would force the ICE to run at 42 mph if that is in fact the case.
     
    #31 FredWB, Jul 27, 2004
  12. LeVautRien

    LeVautRien Member

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    Oh lordy, to simple for me to imagine! :mrgreen:
     
    #32 LeVautRien, Jul 28, 2004
  13. Eisenson

    Eisenson New Member

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    Well, a tach will tell me the degree to which the engine's disengaged when the fuel pump is OFF. I'd like to know if the engine's spinning when it's not driving.

    There's math to show that above 70 or so the ICE *must* spin, but I suspect that when the throttle is closed below that point, ICE RPM drops to zero.

    I just ordered an unobtrusive 2" tach by mail, which will tell the whole story.

    ....uh, no shift light.
     
    #33 Eisenson, Jul 28, 2004
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