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Misfires

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Suspenderman, Aug 9, 2024.

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  1. Suspenderman

    Suspenderman Junior Member

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    Have rough starts with P0303 and P0304 misfires. Replaced plugs and coil packs. No difference. Replaced fuel injectors, no difference. What next please? 2010 Prius
     
    #1 Suspenderman, Aug 9, 2024
  2. bisco

    bisco cookie crumbler

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    #2 bisco, Aug 9, 2024
  3. Brian1954

    Brian1954 Senior Member

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    How many miles on the car?

    Research head gasket problem on a 2010 to 2015 (Gen 3) Prius.
     
    #3 Brian1954, Aug 9, 2024
  4. Suspenderman

    Suspenderman Junior Member

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    #4 Suspenderman, Aug 9, 2024
  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    For next time, with misfire codes for specific cylinder(s), try swapping coils around first, see if code changes.

    seconded: need to know the miles.
     
    #5 Mendel Leisk, Aug 9, 2024
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  6. V Sport Wagon

    V Sport Wagon Active Member

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    Boroscope the cylinders after the car has sat for at least 12 hours, that will tell you all you need to know. It's leading to a head gasket though.
     
    #6 V Sport Wagon, Aug 9, 2024
  7. Tombukt2

    Tombukt2 Senior Member

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    Use the camera like said above and look up at the mating surface of the head to the block you'll see the water droplets they're very easy to see If you just pulled the plugs and look with a magnifying glass you'll see the micro drops of water coolant mix right on the bottom of the plug that's sitting in the engine and look at all four of them can even touch your finger to the insulator and touch it to your tongue if you know what ethylene glycol tastes and smells like and whatnot there's your problem.
     
    #7 Tombukt2, Aug 10, 2024
  8. bisco

    bisco cookie crumbler

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    gotcha
     
    #8 bisco, Aug 10, 2024
  9. Suspenderman

    Suspenderman Junior Member

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    #9 Suspenderman, Aug 10, 2024
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  10. Suspenderman

    Suspenderman Junior Member

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    thank you
     
    #10 Suspenderman, Aug 10, 2024
  11. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    They’re usually blown by then; do you know if it’s had a head gasket or engine replacement?
     
    #11 Mendel Leisk, Aug 10, 2024
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  12. Suspenderman

    Suspenderman Junior Member

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    Thank you for all of your help. Though my gas mileage is as good as ever, 40 mpg, I do notice a slight decrease in coolant which is an indicator as has been noted. Of course I regret this news as this is not my kind of DIY and so will be a very expensive repair on a high milage car. I've had a front end repair due to a deer strike, covered by comprehensive, but $2500 wasn't enough to be considered as a total.
    Thanks again for your time and help.
     
    #12 Suspenderman, Aug 13, 2024
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