Cold start with vicious knocking.

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by steelphoenix3, Oct 19, 2015.

  1. steelphoenix3

    steelphoenix3 New Member

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    Good morning, everybody!
    .
    Last night I experienced a somewhat troubling event. My C had a horrendous knocking on a cold start @40 Fahrenheit or so. Shook the whole car. It lasted about 3-5 seconds, and ran perfectly afterwards, even making another cold start later on @30 without issue.
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    How worried should I be, and what's my recommended course of action?
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    2015 Prius C TWO, not II as uppercase roman numerals were used for model year 2010 Prius, w/5616 miles
     
  2. ryankokesh

    ryankokesh Junior Member

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    My understanding is that this will happen when the car did not run long enough during the previous start to burn off condensation that is formed somewhere (not sure exactly where). I've been told not to worry about this behavior and just try to always let it warm up as much as you can when you start it. It is really startling when it happens, though! Sounds like the whole thing's going to fall apart.

    Personally, I've not experienced it again after being aware that I need to avoid quick on/offs. My other strategy is to quickly get it into EV mode if I just need to move it down the driveway or something and try to prevent the engine from starting, if possible.
     
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  3. steelphoenix3

    steelphoenix3 New Member

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    Sounds like the same kind of experience, with one difference: I drove it for sixty miles before the troublesome start. Any other causes for this?
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    I guess I should harass Toyota about it this afternoon.
     
  4. ryankokesh

    ryankokesh Junior Member

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    Sounds like a good plan... good luck!
     
  5. TheTimob

    TheTimob Member

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    This problem commonly happens when the temperature drops fast in humid air.

    When conditions are quite perfect, water will condense on things like the inside of the intake manifold and your spark plugs. The temperature dropped very quickly last night. This causes a misfire on startup which is why the engine shook violently. It's not unique to the Prius, it can happen to any spark ignition car.

    Strangely it's more likely on a new motor because the inside of the manifold is not dirty and it's a very smooth nice place for water to bead up on.
     
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  6. bisco

    bisco cookie crumbler

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    should go away in a few years... this problem is such a minority of owners, i still wonder if there is not some sort of defect.
     
  7. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    This is something that bothers me: if there's specific driving situations that need to be avoided, and not really outlandish conditions, just something like a previous short drive for example, to avoid a violent shaking at start up. The engineers are not doing their job if this is the case. Neither is the dealership, assuming they're the ones who said "don't worry about it, just avoid this, and that, it'll all be good".
     
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  8. The Electric Me

    The Electric Me Go Speed Go!

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    Good Luck with that symptom.
    Enjoy your Prius c Two.
     
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  9. cyclopathic

    cyclopathic Senior Member

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    Any chance you started it just to move a few feet? Gen3 is known to show this behavior, if it was shut down when engine had ran for a few seconds. Has to do with ECU being confused which warm up stage it is on.
     
  10. steelphoenix3

    steelphoenix3 New Member

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    This is a far more plausible explanation than the myriad of absurd and catastrophic explanations running through my mind. Thank you kindly. Your wisdom is much appreciated. :)
     
    #10 steelphoenix3, Oct 19, 2015
    Last edited: Oct 19, 2015
  11. markp13

    markp13 Junior Member

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    Did you ever report this to Toyota or have your dealer check it out / try to diagnose steelphoenix3? I posted a video of potentially the same issue happening to my Prius C (called Knocking noise at startup). I suspect is is a design flaw and that Toyota are not acknowledging it.

    Knocking noise at startup | PriusChat
     
  12. bisco

    bisco cookie crumbler

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    it is a very common issue. toyota acknowledged it, at least in the lift back, and an updated intake manifold was supposed to be the solution. but it didn't fix it, and the problem continues.
     
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