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jolting and juddering while at standstill

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by harveygp, Dec 27, 2006.

  1. harveygp

    harveygp New Member

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    I have a 2005 T-Spirit.

    If in cold weather, I drive off from cold (for example returning form work in the evening) the ICE immediatley starts and continues to run for a few minutes, irrespective of whether I am moving or not.

    The stange thing is that in this state, usually at the first junction, foot hard on brake, the engine runs accompied by some fairly disturbing shaking, lurching and jolting.

    The effect is similar to an beat-up old car way overdue for a service, with severe misfire.

    I know it's not a misfire though because the car has only covered 7k miles and as soon I take-off everything is once more silky smooth.

    It does however feel similar to the occasional jolt I get when the engine switches off at a junction in normal operation - except repeatedly for at least up to a minute.

    It makes me wonder if the system cannot decide whether the engine should be running or not - and is continuoulsy switching it on and off.

    Has anybody else experienced this or does anyone know what is causing the effect?

    Thanks,

    Geoff
     
    #1 harveygp, Dec 27, 2006
  2. DaveG

    DaveG Member

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    <div class='quotetop'>QUOTE(harveygp @ Dec 27 2006, 08:17 AM) [snapback]367158[/snapback]</div>
    The engine has to heat-up the catalytic converter for proper emissions control, so it will always run the engine for a few minutes when cold to get the element up to temperature. Once it's hit that temperature, the engine will cycle on/off as needed.

    The engine cycling on/off/on may be the system attemping to reduce excess charge in the HV battery pack by repeatedly spinning the engine up/down. If the battery pack is showing fully green in the MFD, that's what's going on.

    Occasionally when stopping, I get the feeling that my car is surging a bit (applying power even though the brake pedal is pressed). I find that rolling the car a couple of inches forward then stopping again seems to eliminate this (though I'm not sure what causes it).

    Dave
     
    #2 DaveG, Dec 27, 2006
  3. tumbleweed

    tumbleweed Senior Member

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    What is the state of the battery when this occurs? If it is completely charged, green bars clear to the top, it may be turning the engine over with MG1 to reduce the charge on the battery. This is more likely to happen during cold weather because the battery accumulates more charge due to the ICE running more. In some cases when the battery has to much charge the computer will bleed some of it off by using MG1 to turn over the ICE with the fuel and ignition turned off, just to protect the battery.

    If this isn't the case you may have a problem. Perhaps you could take it in and see if there are any codes and what they are.
     
    #3 tumbleweed, Dec 27, 2006
  4. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I'm going with Dave on this one.

    The way I have explained it in the past is like this:
    The car knows it's at a stand-still. The engine wants to stop.
    The temperature's still low. The engine needs to run.
    But the car's not moving. The engine should shut off.
    But the engine's still cold. We'll keep the engine on a little longer.

    (and as tumbleweed mentioned, if the battery's low we can throw that in the mix)

    It seems as though the Prius is stuck in this loop until the engine temperature is eventually warm enough to allow proper shut-off. Even then, the first time is usually a little rough and often short-lived.

    Yes it's awkward sometimes but I consider it normal. Mind you, sometimes new passengers find it disturbing.
     
    #4 TonyPSchaefer, Dec 27, 2006
  5. PA

    PA Member

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    <div class='quotetop'>QUOTE(harveygp @ Dec 27 2006, 12:17 PM) [snapback]367158[/snapback]</div>
    I believe I have experienced the same thing, it's like the ICE can't decide if it should be on or off and turns itself on but then turns itself off before it's finished turning itself on. Since it's so quick, nothing displays on the MFD, but the car shudders and shakes while it's doing this. I have experienced this occasionally, but I don't recall battery state or temp. at the time.
     
    #5 PA, Dec 27, 2006
  6. harveygp

    harveygp New Member

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    <div class='quotetop'>QUOTE(DaveG @ Dec 27 2006, 04:34 PM) [snapback]367170[/snapback]</div>
    Many thanks to everyone for the reassurance that I'm not the only one, though I will try to get this checked out at the next service.

    I don't believe the battery has been showing green when this happens - but I will make sure on that next time I experience it.

    One might think if the problem were catalytic converter under temperature, that it would make sense for it to be electrically preheated:-

    http://auto.howstuffworks.com/catalytic-converter3.htm

    But maybe this is just one of many refinements that Toyota have in mind for the next version!

    Geoff
     
    #6 harveygp, Dec 28, 2006
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