2012 prius 84k miles random misfire

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by DodgeTransmissionsGoBoom, Oct 10, 2022.

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  1. DodgeTransmissionsGoBoom

    DodgeTransmissionsGoBoom Junior Member

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    I've had quite a few gen 3 priuss and this is the first one that I think might have a headgasket leak but it only has 84k miles and runs great and gets 55mpg. The issue I keep having is cylinder 2 and 3 will get a misfire when transitioning from eletric to gas for a few seconds then smooth out but only when the engine has warmed up. Never does it when the engine is cold starting and sometimes live data says its 2 and other times it's 3. No overheating, no codes at all, and no smoke out the tailpipe. There was coolant loss but it was due to a loose worm gear clamp on a radiator hose. Haven't driven much since fixing the leaky hose but the misfire still persists after refilling and bleeding the system. I swapped the coils around but that made no difference and replaced 12v battery. Pulled egr tube off and it was somewhat dirty but not obstructed and I've had priuss with much worse clogged egr systems still misfire less then this. Engine coolant temp never gets higher then 202 on the interstate mostly hanging around 195. Anything else to look into or is the headgasket the only thing left? And again it never misfires on cold startup.
     
    #1 DodgeTransmissionsGoBoom, Oct 10, 2022
  2. tankyuong

    tankyuong Senior Member

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    keep driving it and will end up with a hole in the engine
     
    #2 tankyuong, Oct 10, 2022
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  3. PriusCamper

    PriusCamper Senior Member

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    Sounds to me like normal rough running when atkinson engines are cold...

    How do you know there's misfires in #2 & #3 if you don't have any error codes?

    A compression test would of course confirm if that's the problem, but you're jumping to the worst conclusions too quickly. Why not move the ignition coils around to see if the misfire moves to different cylinders? Why not inspect the spark plugs to see what it looks like inside of each cylinder? And lastly, once you get a couple quarts low in oil the lack of oil going to the crank shaft can cause misfire codes, so maybe you have issue with oil pump / bottom end and not the top end?
     
    #3 PriusCamper, Oct 10, 2022
  4. bisco

    bisco cookie crumbler

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    did you clean the four small ports in the intake manifold
     
    #4 bisco, Oct 10, 2022
  5. DodgeTransmissionsGoBoom

    DodgeTransmissionsGoBoom Junior Member

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    Did you read it closely? It doesnt do it when its cold at all and I did move the coils around and it made no difference. And I saw the misfires from live data. And I haven't gotten around to the plugs I've just never seen one with such low mileage have bad plugs only time i had failed factory plugs was on a 210k oil burner. I guess compression test is next after checking plugs tomorrow. Also it burns no noticeable amount of oil
     
    #5 DodgeTransmissionsGoBoom, Oct 10, 2022
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  6. DodgeTransmissionsGoBoom

    DodgeTransmissionsGoBoom Junior Member

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    I'll check that tomorrow
     
    #6 DodgeTransmissionsGoBoom, Oct 10, 2022
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  7. Tombukt2

    Tombukt2 Senior Member

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    This is exactly our 13 persona last year. Exactly .put HG and 16 miles from shop. rod lil end let go . Hole in girdle. Etc trashed . Meccie didn't see piston crown trying to roll over . Because he's 23 yrs old . And likes low rider winged cars with big wheels. Matchbox and Corgi type kids. Never again.
     
    #7 Tombukt2, Oct 11, 2022
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    How long have you had it? Wondering how it would come to have (non OEM) worm-gear style clamp on coolant hose.

    also doesn’t bode good that misfire stays on particular cyl’s when coils moved around.

    Recent purchase with rolled-back odometer?
     
    #8 Mendel Leisk, Oct 11, 2022
  9. DodgeTransmissionsGoBoom

    DodgeTransmissionsGoBoom Junior Member

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    Previous owner replaced radiator last year after a minor front end collision caused a pin hole leak and replaced the spring clamps with worm gear style but I replaced it back with the good spring type and it hasn't leaked again and carfax says the mileage is correct along with the interior looking like showroom condition. Over the 10 or so priuss I've had its always been the low mileage ones that have the worst issues unfortunately.
     
    #9 DodgeTransmissionsGoBoom, Oct 11, 2022
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