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Engine Does not Shut Off

Discussion in 'Gen 2 Prius Technical Discussion' started by ematzen, Jun 10, 2010.

  1. ematzen

    ematzen Junior Member

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    Hi Friends - I know this was covered before, but not precisely what is going on with me. First, I live in hot Houston, so engine warm-up isn't a major issue.

    When I stop at a stoplight, regardless of whether the engine is warm or not, the ICE typically takes some time to shut down. It does the sputter shimmy that people have described, which I believe is the engine trying to stop at the precise spot, and missing that spot and running through one more cycle, then one more cycle, etc...

    Although the ICE eventually stops, it can run for up to 30 seconds at a stop before it fully shuts down. Even when the battery is well charged. Sometimes it does this, and sometimes it shuts down no problem.

    Any thoughts? I've tried using an engine cleaning additive (to the gas), etc... I also used a product that removes water from the gas. I don't think either of those helped.

    Any thoughts? Is this simply normal?

    Thanks in advance!

    Evan
     
    #1 ematzen, Jun 10, 2010
  2. justlurkin

    justlurkin Señor Member

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    Are you running the air conditioning?

    If you are, the engine will spin more frequently (including when the car is stopped) to provide electrical power to the air conditioning in order to keep the HV battery from being drained. And yes, that's normal behavior.

    I wouldn't use those gas additives with the Prius.. Those octane enhancers delay combustion, which is actually not good for the Prius engine.
     
    #2 justlurkin, Jun 10, 2010
  3. Politburo

    Politburo Active Member

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    I assume you haven't seen the check engine light at all?

    And when you say the battery is well charged, you don't mean that it's completely full with 10 green bars.. just somewhere above, say, 5 bars?
     
    #3 Politburo, Jun 10, 2010
  4. ematzen

    ematzen Junior Member

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    Thanks. No check engine light. Fuel additive isn't an octane boost, but a valve cleaner. I understand that higher octane fuel doesn't burn as easily.

    Battery has never been full with 10 green bars (though I do get nine). The engine stays on regardless of battery level, and regardless of AC. Always doing the sputter sputter. Could be 9 green bars, could be three. Sometimes I find that if I accelerate hard that the ICE then shuts down properly, without running post stop. That's what makes me think it has something to do with the valves, etc...

    -E
     
    #4 ematzen, Jun 10, 2010
  5. usbseawolf2000

    usbseawolf2000 HSD PhD

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    The ICE shutdown is "rough" when it enters S4. Search the forum for the stages of Prius operation. Once you understand it, you'll realize that the rough shutdown happens only once per start.
     
    #5 usbseawolf2000, Jun 10, 2010
  6. David Beale

    David Beale Senior Member

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    It can be frustrating, sitting there burning gas for no reason, but it is normal. Pearl often runs for up to 10 seconds for no apparent reason. I'd love to have an "anticipation switch" (push button) to tell it to shut down immediately if all other factors are there.

    If your engine "sputters" often, that is, more than when it's cold, you may have too heavy a grade of oil in it. Use 5W30. Or perhaps too much oil in it. It should be at the full mark at most. Most of us run it slightly below the full mark. It's common to have dealers over-fill it. They put in 4 qt just because they can. It needs slightly less.
     
    #6 David Beale, Jun 10, 2010
  7. ematzen

    ematzen Junior Member

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    Interesting...I'd been wondering about the oil. Was planning on putting Mobile 1 in. I'll do that sooner rather than later, to see if it makes a difference.

    The problem with the S4 theory is that there is no rhyme or reason to whether the engine runs or not at a stop. Car can be warm or cold. It isn't a one-time deal. I'm pretty observant about it.

    -E
     
    #7 ematzen, Jun 10, 2010
  8. JimN

    JimN Let the games begin!

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    If the 12v battery is weak the ICE will run just to try to charge it. Check the voltage readings on the MFD in Maintenance Mode.

    To clarify: As the traction battery discharges more trying to charge the 12v the ICE will run more to recharge the traction battery. It's been a long time since my battery died but I seem to remember that the traction battery SOC was below normal and that it wouldn't fully charge.
     
    #8 JimN, Jun 10, 2010
  9. David Beale

    David Beale Senior Member

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    ???
    The engine doesn't have to run to charge the 12V battery. Not sure what you're seeing to make you think this. I haven't seen this effect. Traction battery, yes.
     
    #9 David Beale, Jun 11, 2010
  10. hill

    hill High Fiber Member

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    You can even run 0-30w. Many here on the board do. Same warranty protection. One other thought, when the ICE runs longer than the usual 8 seconds after warm up. If the car is hot - I find the ICE will run sometimes, simply to circulate coolant.


    .
     
    #10 hill, Jun 11, 2010
  11. richard schumacher

    richard schumacher shortbus driver

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    The 12V battery is charged from the traction battery, and as that runs down the engine must run to recharge it. So indirectly, yes, the engine runs to recharge the 12V battery.

    As to the OP's problem:
    - check the oil level. Don't let anyone overfill it; among other things that can over time foul the MAF.
    - Check the 12V battery, which can be done with this procedure:
    http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html
    - Don't bother with fuel additives. In and near any large city you're burning plenty of E10 which nicely removes water and cleans injectors and valves all by itself.
     
    #11 richard schumacher, Jun 12, 2010
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