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Replaced spark plugs now runs worse. EGR? Head gasket?

Discussion in 'Newbie Forum' started by Timb88, Jul 6, 2022.

  1. Timb88

    Timb88 New Member

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    I have a 2012 Toyota Prius v 3.
    Had some cold start vibrating and rattling for about a year.
    I replaced the spark plugs and cleaned the intake manifold, and replaced the PVC valve while I was messing with it, just for a little tune up to help her out. But alas, now it's running more worse than it was before. Rattling, sputtering, and I don't think it's the EGR valve, because it's in no way having manipulation issues. Popping in and out like a greased bolt of lightning. Can I use a gasket sealer and fix it?
    194k miles.
    P.S.
    It has had a code
    P0441
    P0455
    P0456
    For a while. Seems to run just fine. Prior to this event. And I have a ton going on and just need advice on which way to go. Can't afford a new engine, I can replace the gasket myself.
    Also there was some foreign liquid in the manifold with the oil, wasn't water. But again not losing coolant. I'm perplexed. Help. Tia!
     
  2. PriusCamper

    PriusCamper Senior Member

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    Well the good news is your symptoms aren't throwing error codes related to a blown head gasket despite your previous symptoms pointing to that. Assuming you aren't using lots of coolant or oil your engine is ok for now.

    And all those codes point to evap/emission system, so something must of went wrong during the work, like a hose not properly connected or something that was already broken went from bad to worse. Hopefully @SFO sees this and he can post the diangnostic process for these three error codes that all seem to point to the same problem.
     
    Timb88 likes this.
  3. xliderider

    xliderider Senior Member

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    Edit, removed
     
  4. Timb88

    Timb88 New Member

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    @PriusCamper now those codes are gone and throwing P0303 -3rd cylinder misfiring.
    Was going to pull it into the garage again and now it will barely even turn over. 1 week ago almost perfectly running, to changing plugs and then down the poot shoot.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    194K is way overdue for EGR valve/cooler cleaning; just do it. When cleaning the intake manifold, did you get the small EGR passages, one per port. All that said, I think your head gasket is going, best dealt with first.
     
  6. Timb88

    Timb88 New Member

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    I would also like to mention that I haven't changed the oil for a while because it was burning almost a qt per 600 miles. Supposed to take it a mechanic Friday morning. I did clean everything very thoroughly. It was disgusting. Clogged bad in the ports for the fuel injection.
     
    #6 Timb88, Jul 7, 2022
    Last edited: Jul 7, 2022
  7. PriusCamper

    PriusCamper Senior Member

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    10 years ago before I got my first Prius I did the exact same tune up on my Subaru. I had the entire car completely detailed to perfection too and turned out the heat damage to heads were pushed to the point of failure when I changed the plugs and did a tune up. Never drove that car again.
     
  8. Timb88

    Timb88 New Member

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    It actually ended being cracked porcelain on the spark plug. Now its running fine
     
  9. PriusCamper

    PriusCamper Senior Member

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    Have you compared your plugs with the ones in youtube videos that document counterfeit plugs? Maybe you can get a refund?