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P0300 0301 0303 misfire and engine knock problem

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by noctiluca, Apr 10, 2020.

  1. noctiluca

    noctiluca Junior Member

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    running like a dream since i replaced the two bad coils. lets hope it sticks!
     
  2. noctiluca

    noctiluca Junior Member

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    did not fix :( after everything ive done, she ran perfectly for a few days and then the problems started again, which points to maybe some kind of buildup. now all four cylinders have error codes and i'm losing coolant, super gasoline-y smell when misfiring...maybe i cracked part of the EGR system when doing the cleaning? tried to do a leakdown test but the tester i bought leaked so still trying to do that. otherwise not sure where to look next.
     
  3. ChapmanF

    ChapmanF Senior Member

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    Leaky leakdown tester. What is the world coming to?
     
  4. pjksr02

    pjksr02 Active Member

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    Sounds like it's the head gasket, unfortunately.

    If you had damaged the EGR system, you would likely see where coolant was leaking, or could hear where exhaust gas was leaking. Or are you thinking it's possible that coolant is going into the EGR gasses via a cracked EGR cooler--maybe check the egr pipe to see if it's wet. You'd probably see lots of white smoke in this case.

    What codes are you getting? Misfiring on all 4 cylinders?
     
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  5. feivel

    feivel Junior Member

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    I'm dealing with the exact same issue. No remedy yet. Thanks for sharing your efforts!

    Engine rattle at low RPMs with some load, even on startup now. Once the engine speeds up a bit, the issue is gone and there's no detectable loss of power/torque until it's slow again, then I get it again intermittently. Feels like the engine is trying to shake itself off the frame!

    I replaced the spark plugs / coils. Opened up the EGR valve and it moves super smoothly. Removed the the pipe in front of it and it wasn't clogged (had maybe 1mm of carbon buildup). I blew compressed air in while pushing the EGR valve, and it sounds like air moves smoothly, and changes resonant note when I push the EGR valve, so it's not clogged.

    What next?

    My non-Prius car guy is convinced it's the transmission slipping/chattering. But he also thinks that'll be a repair that costs more than the value of the vehicle. I've seen no indication here that it's the transmission and he can't prove it.

    The Toyota dealership wants $400+ just to start to diagnose it.
     
  6. Aaron Vitolins

    Aaron Vitolins Senior Member

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    I’d say it’s either a clogged EGR cooler, or the head gasket.

    it’s definitely not the transmission. The Prius uses a very simple but elegant planetary gear set utilizing two electric motors. Basically the only way for them to fail is an electrical short which is very rare.
     
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  7. Mendel Leisk

    Mendel Leisk Senior Member

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    Check/clean the intake manifold too, in particular the EGR passages: large EGR intake passage feeds into four capillaries, one per port.
     
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  8. pjksr02

    pjksr02 Active Member

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    ...and while you have the intake manifold off, put in a new PCV valve.

    How many miles are on the car?
     
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  9. feivel

    feivel Junior Member

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    @pjksr02 There are 168,000 miles on the car

    Thanks so much for the advice! That's super valuable to hear. I'm so glad it's not the transmission.

    How can I know if it's the head gasket or not? The coolant level was mid-way - haven't been driving it a ton so I don't know if it's eating coolant.

    So my half-way EGR check that showed the valve and front tube just wasn't enough? It sure looked like air could flow.

    Both issues seem like pretty substantial projects. I would love to figure out which problem is causing the issue before I go fixing the one that isn't.
     
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    EGR and intake manifold cleaning are not that hard. Head gasket is tough. Independent shops would charge around $2500?

    Leak down test is good to diagnose if head gasket is failing.
     
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  11. Aaron Vitolins

    Aaron Vitolins Senior Member

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    With the miles it’s a good chance It’s the head gasket. A proper test would be the leak down test, as stated above.

    you might try loosing the cap on the coolant fill reservoir to depressurize the coolant system. Drive around for a bit with the reservoir cap loose end and see if the shaking stops. If it stops that’s a good indication that your head gasket is leaking.

    As far as the EGR cooler I can promise you it has a good bit of carbon buildup at your mileage, so just keep that in mind, not saying it is for sure the cooler but there’s a good possibility
     
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  12. HaYon Prius driver

    HaYon Prius driver New Member

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    Buy a cheap little borescope and remove the spark plugs and see if there is liquid running down the cylinder wall. Make sure you do this after driving for a while to pressurize the coolant system. I had a similar issue and did all the same steps. I actually missed it the first time because i scoped it when the car was cool. I had a small drip forming on cylinder #2. I could watch it form a drip and then run down the cylinder.
     
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  13. feivel

    feivel Junior Member

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    Thank you all sooo much for the advice. I tried opening the coolant tank cap as @Aaron Vitolins suggested, and it worked! After an initial vibration, I was able to drive without more vibrations. Which, while pleasant, is probably a bad sign. Yes? Also, noticed the engine coolant level in the reservoir has gotten low.

    Does that mean it's the head gasket? I have a fellow I typically take the cars to, but he doesn't know the Prius' idiosyncrasies. He doesn't do a leak down test, but he does a pressure test on the coolant system. I left it with him for that, but apparently his equipment won't fit the cap without some magic adapter he doesn't have yet.

    Is it worth buying a leak down tester and figuring out how to test it myself? Is it most-likely the head gasket?

    What do you recommend at this point? The car has a list of other things it needs (brakes, tires) and I'm debating if it's time to sell it vs fix it. The laundry list seemed reasonable, but probably not on top of a multi-thousand-dollar engine repair. How do I know when it's time to cut bait?

    I'll still be driving another Prius, even if this one finds a new home.
     
    #33 feivel, Jun 24, 2020
    Last edited: Jun 24, 2020
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  14. Aaron Vitolins

    Aaron Vitolins Senior Member

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    I would definitely say that’s your head gasket, especially since it’s so common. Not worth spending the money for the official test. With the cap loose, it will stop the leak for now, but the coolant level will keep going down, due to it not being a pressurized system now. So I’d top it off maybe once a week depending on how much you drive.

    it might be time to sell this Prius, depending how much you like this Prius. Or maybe buy a new one, I’m sure you could get a pretty good deal.
     
  15. jzchen

    jzchen Newbie!

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    K-Seal?

    moto g(7) power ?
     
  16. noctiluca

    noctiluca Junior Member

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    i think feival's situation is a bit different to mine. i had zero coolant leaks until i did the egr/intake system clean, now i have an enormous coolant leak. timing is a little too coincidental.

    my cylinder codes switch around but are mostly 1, 3 and multi.

    another fun symptom: misfire goes away completely for a few cycles after disconnecting the battery, so there must be at least some electrical/computer aspect to this.

    still diagnosing :(
     
  17. noctiluca

    noctiluca Junior Member

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    yup, this is what i was thinking. definitely lots of white smoke. havent had time to get back into it yet but when i do ill look at the pipe for signs.
     
  18. Tim Jones

    Tim Jones Senior Member

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    And people give me a hard time when I say don't purchase a used Gen 3.......
     
  19. noctiluca

    noctiluca Junior Member

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    confirmed head gasket via hydrocarbon leak test (why dont more of you recommend this? easiest way to diagnose considering the location of plugs!) and it blew completely while warming it up to do a confirmation test. engine is toast. f my life and this car.
     
  20. noctiluca

    noctiluca Junior Member

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    DONT BUY THIS CAR!!!!!! i tried to do due diligence on reported issues and this was supposed to be the golden model year, but didnt check the forums here. couldve saved myself a lot of money and heartache. and of course a new motor for the V is 2k instead of $500 like a regular prius. kdjhskdjhkjshehkjhwekjhe :( :( :( :(