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shifting into neutral when driving to increase mpg

Discussion in 'Gen 2 Prius Fuel Economy' started by beckerman, May 26, 2010.

  1. TheSpoils

    TheSpoils Member

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    Maybe someone with a scangauge can verify; if you are traveling downhill and engage neutral while the ice is on, the ice rpm will increase as the speed of the vehicle increases? In my altima hybrid that is the case, the rpm will increase while in neutral to match the vehicle speed, therefore negating any fuel savings by being in neutral.
     
  2. JimboK

    JimboK One owner, low mileage

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    No, it will run at idle.

    Of course, a major part of the fuel economy benefit to using neutral in the Prius is shifting when the ICE is off so it remains off for as long as the car is in neutral.
     
  3. MJFrog

    MJFrog Active Member

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    OK, the pulse and N-glide while <= 40mph sounds pretty good, esp. if you've reached S4.

    On the other hand, all this shifting from D->N and back is going to cause additional wear and tear on the shifter. The question arises whether this will result in significant chance of failure of the shifter with subsequent need to replace it...and how much does it cost to replace the shifter (parts/labor)?
     
  4. qbee42

    qbee42 My other car is a boat

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    The shifter is just a switch assembly. It is fairly easy to replace and is inexpensive.

    Tom
     
  5. Philosophe

    Philosophe 2010 Prius owner

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    Another question:

    Does switching between D and N could cause harm/wear to the electrical system components?

    I found that when I switch “gears” at low speed, I feel a jerk in the “transmission” while doing so. Does this leads to an electrical pike in the inverter? At higher speed the jerk disappears but the phenomenon may be even more important while not visible.

    As anyone tested this with a ScanGauge to see what the inverter current/voltage are when doing this “gear” switch?
     
  6. qbee42

    qbee42 My other car is a boat

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    I haven't tested with ScanGauge, but I am reasonably certain that there are no fish in the inverter. Things can get fishy, but that's only an expression.

    As for the jerk (and no, I'm not talking about the person typing this message), it is the inverter applying a drive voltage to the MGs. These sort of electrical transitions occur thousands of times per minute and shouldn't be a concern, since this is designed function of the drive electronics. Once we get into worrying about transistor cycles we are officially over-thinking this issue.

    Tom
     
  7. nerfer

    nerfer A young senior member

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    My understanding is that the mechanical limit on the 2004-2009 Prius is 6500 RPM and the 2010 Prius is 10,000 RPM but they kept the electronic limit. Now if I can only remember where I read that, but I think I started from one of the threads on IGN 14, and maybe went to cleanmpg.com in the process.
     
  8. nerfer

    nerfer A young senior member

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    Tom, I think Philosophe misspoke, and was actually referring to the new bio-hybrid system using electrical eels. Test results show it works pretty good but you need to stop every 100 miles (150 miles for hypermilers) and feed them some minnows.

    Now a spike in the inverter, that might be a problem. Particularly a railroad spike.
     
  9. qbee42

    qbee42 My other car is a boat

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    Perhaps put a scoop in front and feed them the occasional jogger or bicyclist.

    I think you use a wooden spike on hybrids, just as you do with vampires. This is the recommended solution for SUA.

    Tom
     
  10. Philosophe

    Philosophe 2010 Prius owner

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    Thank you all for noticing my unintentional pun. :rolleyes:

    Tom,

    I understand that the system takes good care of itself but this "jerking" effect (feel free to suggest a better word!) is not usual (the HSD normally doesn't do that, it always transition softly). I was simply wondering if a driver constantly shifting between D and N could cause a slow, unintentionnal, wear to the system (mechanically to PSD or electrically to inverter).
     
  11. Bob64

    Bob64 Sapphire of the Blue Sky

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    Welp, even if you managed to break the shifter by using it excessively, there are plenty on ebay to be had for under 200$.
     
  12. MJFrog

    MJFrog Active Member

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    Noticed something interesting doing P & N-Glide this morning. Whenever I shift into Neutral, the B position on the display goes away. Then when I shift back into D, it reappears...weird.
     
  13. ItsNotAboutTheMoney

    ItsNotAboutTheMoney EditProfOptInfoCustomUser Title

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    B is only available while in D so it's not displayed until you shift to D.
     
  14. reeed

    reeed Junior Member

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    i understand that the PSD contains no detachable gears -- all the eCVT magic happens in the control logic governing RPMs of each of the 3 gears. Thus there is no mechanical Neutral, only an electronic or logic one. Am I correct ?
     
  15. Philosophe

    Philosophe 2010 Prius owner

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    Correct. The two electrical motors will simply spin freely.