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Elec mode to ICE transition is not smooth

Discussion in 'Newbie Forum' started by Bill1, Mar 12, 2009.

  1. Bill1

    Bill1 New Member

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    There is a slight lull and then lurch when driving in all elec mode and the ICE kicks in. When I go from ICE/ele combo mode to all elec the transition seems very smooth. Is this normal or should I get it checked out? I have only had it a few months and driven about 1300 miles. Any thoughts or advice would be appreciated.
     
    #1 Bill1, Mar 12, 2009
  2. firepa63

    firepa63 Former Prius Owner

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    It's normal if the ICE is not fully warmed.
     
    #2 firepa63, Mar 13, 2009
  3. richard schumacher

    richard schumacher shortbus driver

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    It is also noticeable (and normal) while in Park if the parking brake is not set. Not to worry.
     
    #3 richard schumacher, Mar 13, 2009
  4. danl

    danl New Member

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    Oh I got about around the same 1300 miles on mine. I feel the engine kick on when transitioning from all-electric to combo mode, but I don't think I've noticed a lurch. You mean a lurch forward?
     
    #4 danl, Mar 13, 2009
  5. Bill1

    Bill1 New Member

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    danl - Perhaps lurch was not the correct word. It seems like the elec motor drops out and then there is fraction of a second delay before the ICE kicks in. The car slows (ever so briefly and slightly) between when the elec motor stops and the ICE takes over and resumes speed. I notice it more at higher speed. When did you get your Prius pkg 2. I got mine in late Jan.

    richard and firepa63 - thanks for the comforting words. I plan on keeping this car a very long time and wanted to make sure all was well.
     
    #5 Bill1, Mar 13, 2009
  6. qbee42

    qbee42 My other car is a boat

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    When driving in EV mode, MG1 spins backward to keep the ICE from turning. When you step on the gas and cause the ICE to come on line, MG1 has to stop spinning backward and start spinning forward to start the ICE. MG1 is pretty quick, but the process isn't instantaneous.

    Tom
     
    #6 qbee42, Mar 13, 2009
  7. Bill1

    Bill1 New Member

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    Tom - Great explanation. I did not realize one of the elec motors had to run to keep the ICE from spinning, but that makes sense after looking at a diagram of the Power Split Device.
    You are right, it is very quick process, but since everything about the Prius is so darn smooth, I wondered if that short delay was normal.
     
    #7 Bill1, Mar 13, 2009
  8. qbee42

    qbee42 My other car is a boat

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    Right, and the faster you are going in EV, the bigger the transition to getting the ICE running. If you mash the gas from a standstill, MG1 simply starts the ICE while MG2 accelerates the car. If you pull away in EV mode, then mash the gas, you have to wait for MG1 to reverse before the ICE can start.

    Tom
     
    #8 qbee42, Mar 13, 2009
  9. danl

    danl New Member

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    Bill1, actually now that you mention it, I do notice that slight "lurch" as you describe it. Its like a split second of an absence of power. Thanks qbee42 for taking the time to explain it. So in general, from a standstill, is it better to mash the gas and kick in the ICE right away, or pull away in EV mode as long as you can until the ICE kicks in (while staying with the flow of traffic of course). I suppose the real question is: is spinning the MG1 that way good for the life of the vehicle.

    Btw, Bill I picked up my mettalic gray in the last week of Jan.
     
    #9 danl, Mar 14, 2009
  10. Mjolinor

    Mjolinor New Member

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    That can't be right. The transition to start the engine is from (MG1 current revs) to (MG1 current revs + 1000). Doesn't matter if it is stationary or negative revs when you decide to start he engine.

    From there it's a matter of adding more positive revs to the engine and MG1 until MG1 is stationary or where it needs to be.

    The lurch is caused by the need to turn the engine against the compression at an unknown time. If you always knew where the engine was when it stopped and if gases didn't escape from the cylinders then the software would know exactly how much power was needed to turn it. As it is the software cannot possibly know how much power is needed or how quickly the engine will begin to produce power, too many variables so you will always end up with a redirection of power one way or the other that you feel as a lurch.
     
    #10 Mjolinor, Mar 14, 2009
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