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Gas motor goes on-off-on-off, several times, while car is stopped

Discussion in 'Gen 2 Prius Main Forum' started by ~newpriusowner~, Nov 6, 2010.

  1. ~newpriusowner~

    ~newpriusowner~ New Member

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    I've had this happen twice: I'm stopped at a light (on relatively level ground--only slight incline). My gas engine kicks off. OK, fine. As it should. But then it comes on again, maybe a second or two or maybe three or four later, while I'm still stopped. First time, it did this a few times back and forth, all while stopped, waiting for the light.

    Has anyone had this? Is this reason for concern? Do you know what causes it?

    Thanks!

    Molly
     
  2. john1701a

    john1701a Prius Guru

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    That's normal behavior if having just finished driving down a long descent. It's the smaller motor spinning up the engine to consume the excess electricity that had been generated. The engine doesn't actually start. It's just the startup process without fuel, repeatedly, to ensure long battery life.

    Next time, look at the battery charge-level. 8 bars confirms the situation.

    In that case, use "B" mode next time. That will reduce the amount of electricity generated as you descend.
    .
     
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  3. Wolfie52

    Wolfie52 Senior "Jr" Member

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    I've noticed this happens to my car when the temperature is colder. Don't worry about it. I still get the impression (occasionally) that my car has stalled and I better turn the key quick!
     
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  4. David Beale

    David Beale Senior Member

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    If it's the engine appearing to "stutter" on shutoff, then you will notice it more often when the engine is cold. It will also do it more if you have thicker oil in it. This is the engine trying to stop at a specific crankshaft position. If the oil is thick, either from being cold or too heavy a grade, it sometimes misses on the first few tries and the system will "bump" the engine to get it there.
     
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  5. edthefox5

    edthefox5 Senior Member

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    Hi Molly,
    Don't worry about it. The engine will come at what seems like starnge times. Most reasons surround the traction battery level of charge. To see that just hit the "Energy" button lower left on the MultiFunctionDisplay to see what the present charge level of the battery is. Anything less than one blue bar or maybe even a one purple bar or capacity and the engine will come on to charge the battery back up.

    The engine will also come on more in very cold weather to keep the catalytic converters warm to meet its Zero emissions mission. Especially when just started cold.

    Bottom line is everything is OK in your car if no diagnostic codes (check engine lights CEL's) thrown.
     
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  6. ~newpriusowner~

    ~newpriusowner~ New Member

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    Bellissimo! GREAT NEWS! And great information! This is exactly why I've joined this forum--to get these really well-informed and helpful replies. Thanks so much, everyone!

    All the best,

    Molly
     
  7. edthefox5

    edthefox5 Senior Member

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    Hi Molly,

    Your very welcome. There is so many helpful peeps here...

    Our car does so many strange things. I can't imagine if your not a hard core car person or have some electrical engineering background how confusing alot of it must be. But hang in there as its really a very good car.

    You just have to get used to its whacky behavior.

    Its going to get real cold soon by you. Ithaca is beautiful though.
    I'm from Vermont and moved to Florida in 1980 as I could not take that cold anymore. I know Ithaca cold.

    Your gas mileage will plummet soon because of the cold. Alot of people use an engine block heater to "pre-heat" the motor before they start there day to prevent exactly what your complaining about which wastes gas. In severe cold the motor will have an excessive run up to come to operating temperature and heat its cats. Sometimes exactly what your seeing.

    Alot of people block off the front air vents under the hood to restrict frigid winter air coming into the engine area which keeps the engine very very cold. Cold engine is a bad thing in a hybrid.
    Very inefficient.

    I'm talking about blocking the vent/slits on the front of the car. It really helps warm the engine up as the freezing cold air is no longer forced into the engine compartment while your trucking down the highway at 60 mph's. It will really help your mileage if you start taking a big big mpg hit. You'll know as the engine will run excessively.

    Do some searching on this as its pretty easy to block the vents and very cheap.
    Basicly just jamming some insulation material in the vents.

    Lots of posts on it here. Please search as I have not had to do this myself and there are many experts out there. Or you can post:

    How do I block the vents for winter?
     
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  8. biff_debris

    biff_debris WOOF!

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    Correct. I've had that happen after stopping at the bottom of a long grade. Absolutely normal and nothing to worry about.
     
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