Hard Knocks- already replaced everything

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Babybird125, Sep 17, 2025 at 1:44 PM.

  1. Babybird125

    Babybird125 New Member

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    So car was knocking on startup. It has 190k on it so figured we would replace spark plugs. Still bad... replaced injectors... even worse...
    Replaced egr and cleaned out canister... even worse... drained gas and put in new just in case...
    Checked everything I can think of at this point any ideas?
    Codes are for cylender misfires
     
    #1 Babybird125, Sep 17, 2025 at 1:44 PM
  2. Tombukt2

    Tombukt2 Senior Member

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    Head gasket buddy this engine is known for it. Much documentation here
     
    #2 Tombukt2, Sep 18, 2025 at 9:15 AM
  3. Mendel Leisk

    Mendel Leisk MMX GEN III

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    A couple of head gasket links in my signature (on a phone turn it landscape to see signatures).

    Just curious: what do you mean by this, the evaporation charcoal canister?
     
    #3 Mendel Leisk, Sep 18, 2025 at 9:28 AM
  4. ASRDogman

    ASRDogman Senior Member

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    And how much is the price of rice in china????

    It is likely you have a damaged head gasket.
    Are you loosing coolant? Have you done a coolant pressure test and use a bore scope to
    looked into the cylinders for coolant leaking between cylinders?
    Most likely between #'s 1 and 2.



     
    #4 ASRDogman, Sep 18, 2025 at 9:29 AM
  5. rjparker

    rjparker Tu Humilde Sirviente

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    Sorry you spent a lot of money on unnecessary parts. Plugs, coils and injectors don't clear up after a startup. Keep your original parts, in many cases aftermarket parts are worse.

    Symptoms of Prius hg fail

    Losing coolant is not obvious in early stages

    Borescope is the only good hg test in early stages
    Car Care Nut HG Borescope at 660s


    Excellent Borescope Footage at 6:50


    Egr block flow test eliminates egr as a misfire cause

    At about 10:15 in the video he starts talking about the egr valve letting "air" into the intake manifold. He means exhaust gasses.
     
    #5 rjparker, Sep 18, 2025 at 11:50 AM
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