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State of Engine in Prius 2004-2009

Discussion in 'Gen 2 Prius Technical Discussion' started by AllenZ, Sep 1, 2011.

  1. AllenZ

    AllenZ Active Member

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    If I use Neutral N, does engine still run? On N, when I push the gas peddle, I feel like slight brake applied to the car. What's the reason?

    If I "Stealth" driving, that is, no orange arrows appear on screen, does the engine run?

    When coasting, that is, release the gas peddle, and no break, in Drive gear, does engine run?

    Assuming in those cases, the 12V battery is good, and no need extra battery power for lights, a/c...

    Thanks!
     
    #1 AllenZ, Sep 1, 2011
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    If the engine was running before you switched to N it keeps running, you can't start it in N.

    N exists largely because some jurisdictions require such a position in the transmission. Never let your car 'coast in N from less than 40 MPH to more than 45 MPH, as in N. MG1 can't start the engine. This makes it possible to over Rev some of the motors.

    In N the engine is still connected to MG1 and MG2, but MG1 is 'freewheeling', not generating any electricity. You still get a tiny resistance due to momentum.


    If you are travelling more than 41 MPH (gen 2, but gen 3 is also in the low 40s) the engine HAS to rotate, even if no gas is being burned.

    (You sound like an ideal candidate for a scangauge II, you want to see inside the computers' decisions)
     
    #2 JimboPalmer, Sep 1, 2011
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  3. qbee42

    qbee42 My other car is a boat

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    Furthermore, the engine will run as needed to keep itself and the catalytic converter hot, so it is impossible to state with certainty that the engine will not run in a glide. Likewise, the trigger parameters will change depending on a variety of factors, including HV battery SoC.

    Tom
     
    #3 qbee42, Sep 1, 2011
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  4. AllenZ

    AllenZ Active Member

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    That's interesting! Guess it will run at idling speed on N, if it runs?

    Since you guys are so knowledgeable, I would like to ask more questions:

    2. What's the difference between stealth driving and N gear gliding? I most of time use N, because stealth is hard to keep the balance. Is that a good way to get high mpg? Right now my mpg is about 50, when T= 80F, 40psi, flat road, mild driving style.

    3. When you break, does CVT change "gear" to fit your breaking force, in order to re-gen max amount of electricity? (I guess the amount of electricity generated per second depends on the car speed and CVT's ratio. If you break harder, CVT should change to lower gear, until it reaches limit, then the physical break kicks in.)

    4. I Still can not understand why in N, when I push the gas peddle, I feel a slight breaking force to slow the car a little bit. Or is it my illusion?
     
    #4 AllenZ, Sep 2, 2011
  5. cwerdna

    cwerdna Senior Member

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    If you want to monitor the state of the ICE, you should get a proper tool such as a http://www.scangauge.com/ (II, not the E). It will also allow you to monitor the # of amps going into/out of the HV battery, ICE RPMs, etc.

    BTW, please use the correct words. It's a pet peeve of mine. You're referring to the gas pedal and braking, not peddle and breaking.
     
    #5 cwerdna, Sep 2, 2011
  6. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Since the motors and engine are ALWAYS 'in gear', N is just a software emulation of Neutral in 'normal' cars. When you rev the engine, the electric motors all spin at different speeds to 'cancel' the revving of the engine. You may be feeling delays in perfectly balancing the engine RPM.

    (I do not think I have used N twice since I owned a Prius. It is only there as it is required by law in some jurisdictions)
     
    #6 JimboPalmer, Sep 2, 2011
  7. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    MG2 (used for regeneration) is geared directly to the drive wheels at a constant ratio. There is no CVT in a Prius, it emulates one via software. (and 2 electric motors and a engine in a planetary gearset) The Prius has no clutch you can engage or gearing that can change, just software (there is a clutch you can't engage to protect from abnormal stresses) The only 'mechanical' change you can make to the transmission is in P, when a physical pawl locks the gearing, everything else is software. Even R is just software.
     
    #7 JimboPalmer, Sep 3, 2011
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  8. mikewithaprius

    mikewithaprius New Member

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    When you're in neutral and depress the pedal, yes, it's just an illusion that you're braking, the gas pedal has no effect in neutral in the Prius, engine running or not. It must just have something to do with our expected outcome for a given action (press pedal, go faster), and when it doesn't happen, it feels like the opposite is happening.
     
    #8 mikewithaprius, Sep 3, 2011
  9. V8Cobrakid

    V8Cobrakid Green Handyman

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    here.. play with This
     
    #9 V8Cobrakid, Sep 3, 2011
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  10. AllenZ

    AllenZ Active Member

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    Thanks! This really helps me to understand how Ring Gear works. I looked at John's documents before but could not get the idea at all.
     
    #10 AllenZ, Sep 3, 2011
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