Hard shaking felt through the car on acceleration

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Wtfdustinwtf, Jun 19, 2025 at 5:23 PM.

  1. Wtfdustinwtf

    Wtfdustinwtf Junior Member

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    Hello everyone. My 2014 started having an issue today. If I am stopped and accelerate normally, after about 12mph, it shakes as if running over rocks for a few seconds. I've noticed it only happens when the gas engine kicks in. I've also noticed it will not do this if I accelerate hard. It won't do it under any other circumstances except accelerating at a normal pace from a stop. If I slow down and then accelerate it won't do it, if I coast and put on the gas it won't do it. I changed spark plugs and cleaned EGR about 30k miles ago. I am going to raise it and change the oil tomorrow, is there any specific areas I should look for damage? Any advice in general? I don't think it's engine related due to it only happening from a stop, under normal acceleration, once the gas engine kicks on. Thanks for any help!
     
    #1 Wtfdustinwtf, Jun 19, 2025 at 5:23 PM
  2. Tombukt2

    Tombukt2 Senior Member

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    You're heading for good repair antics this is a very common problem it's probably time to start working out and exit
     
    #2 Tombukt2, Jun 19, 2025 at 5:33 PM
  3. rjparker

    rjparker Tu Humilde Sirviente

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    Check your engine coolant reservoir. If it's low it's shaking that often you are in advanced hg repair territory.
     
    #3 rjparker, Jun 19, 2025 at 5:56 PM
  4. Wtfdustinwtf

    Wtfdustinwtf Junior Member

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    But could it be HG if it only shakes under one particular circumstance? It will not shake under any circumstances other than going from a complete stop, then accelerating normal speed, then when the engine kicks on. Under any other circumstances when the engine is off then turn backs on it acts perfectly normal?
     
    #4 Wtfdustinwtf, Jun 19, 2025 at 7:40 PM
  5. Wtfdustinwtf

    Wtfdustinwtf Junior Member

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    So it is common to only have a few seconds of shaking under one particular set of circumstances? If I accelerate a bit harder it doesn't shake. It really feels like maybe transaxle or some sort of component near the ecvt.
     
    #5 Wtfdustinwtf, Jun 19, 2025 at 7:41 PM
  6. bisco

    bisco cookie crumbler

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    did you put in oem plugs from a dealer?
     
    #6 bisco, Jun 19, 2025 at 8:35 PM
  7. rjparker

    rjparker Tu Humilde Sirviente

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    Yes gen3 Prii hg fails commonly shake on engine starts. They almost always clear up and run smooth seconds later as long as the engine stays on.

    Usually the early symptoms are occasional cold start shakes that go away in seconds and are gone for days, weeks or months.

    Sooner or later the coolant into the cylinder (dousing the spark) happens on most starts, even after stoplights.

    The hybrid drivetrain causes the severe shakes and rattles making this hg fail different from a conventional engine. A spring loaded damper that is similar to a clutch with no actuator is slipping under rapidly changing rpm caused by hg initiated misfires.
     
    #7 rjparker, Jun 19, 2025 at 9:16 PM
  8. Wtfdustinwtf

    Wtfdustinwtf Junior Member

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    No after market
     
    #8 Wtfdustinwtf, Jun 19, 2025 at 9:54 PM
  9. Wtfdustinwtf

    Wtfdustinwtf Junior Member

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    But it doesn't shake on start up. It starts up just fine, the only time there is any shaking is at the point I reach 12 MPH when accelerating. I was worried at first it was HG but something feels strange that it only happens under a specific circumstance at 12mph. I've had hard cold starts before in my 2010 and what I'm experiencing is different from that. It really doesn't feel engine related but more in the wheels.
     
    #9 Wtfdustinwtf, Jun 19, 2025 at 9:57 PM
  10. rjparker

    rjparker Tu Humilde Sirviente

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    Then look at the cv joints, wheel bearings and wheels.
     
    #10 rjparker, Jun 19, 2025 at 10:03 PM
  11. Wtfdustinwtf

    Wtfdustinwtf Junior Member

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    Yeah I think I'm going to have to crash course that tomorrow. I've changed brakes but never really inspected anything wheel axle related. I imagine it is possible that it could be HG but it feels so different to the morning death rattle that it makes me wonder. Thanks for the advice.
     
    #11 Wtfdustinwtf, Jun 19, 2025 at 10:04 PM
  12. rjparker

    rjparker Tu Humilde Sirviente

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    Any alignment shop could look at it and tell you what you may need.
     
    #12 rjparker, Jun 19, 2025 at 10:08 PM
  13. douglasjre

    douglasjre Senior Member

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    Chinese SP plugs are the most likely culprit. Coil packs possible too. Sometimes a spark jumps around boot. Some packs act like that when they're made in china. May also be clogged egr or leaking egr connections. Got pending codes to give me more direction?
     
    #13 douglasjre, Jun 20, 2025 at 12:48 AM
  14. Tombukt2

    Tombukt2 Senior Member

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    Correct you can step thru the rattle . My persona same engine change to JDM returns in 3 months not our kinda mill we used to getting 450K from any Toyoda in last 40 or so . Not these after 10 big changes to Toyoda like Hyundai and Ford Chevy Eco problems if ya will . This ain't dads toyodas . I am that dad 47 yrs with Toyoda . Not blindly ever again and what they making now whee.
     
    #14 Tombukt2, Jun 20, 2025 at 7:34 AM
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    #15 Mendel Leisk, Jun 20, 2025 at 9:43 AM
  16. bisco

    bisco cookie crumbler

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    any trouble lights?
     
    #16 bisco, Jun 20, 2025 at 1:31 PM
  17. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Dealer?
    EBay?

    If you got OEM plugs from Amazon they probably weren't....
     
    #17 ETC(SS), Jun 20, 2025 at 5:27 PM
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