P0300 P0301 P0302 P0303 Cylinder Misfire. Shaking on startup Help!

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Levi Gonzalez, Dec 3, 2021.

  1. Levi Gonzalez

    Levi Gonzalez Junior Member

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    There's plenty of threads on this BUT my situation is a bit specific...

    Recently my Water Pump went out and also Roughly around that time (can't remember before or after water pump issues), car was a little rough on startup. ONLY cold startup. And it was intermittent...

    After I replaced my pump, it was driving fine, albeit with a couple rough start ups here and there...

    Then yesterday it gave me a dash code and on my OBD2 I got cylinder misfires for ALL the cylinders. Next day on startup I scanned again and it's only giving me 301 and 303 codes.

    So I Tore out the EGR pipe and looked at it, and it's definitely dirty but I wouldn't say "clogged". I'm cleaning that currently.

    I'm also going to rip out the manifold and clean out the EGR pathways.

    After doing that I plan on replacing Spark plugs, Coils AND injectors (Time is money for me. I don't want to keep tearing this apart. Plus it's at 147k and I rather throw a new set of all that in my Prius anyway).

    My question is, what are the odds that this is a head gasket?

    Is ripping out the entire EGR assembly / valve etc necessary even after doing all this?

    And, after doing all this and the problem still persists, would adding a head gasket / leak additive work?
     
  2. Levi Gonzalez

    Levi Gonzalez Junior Member

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    I find it strange that all the codes came on at once? Does that sound like a head gasket? online people usually say usually one cylinder comes on at first of it is a head gasket...

    Backround information: Coolant levels are perfect and stable. No leaks underneath car. Nothing strange BESIDES occasional rough start ups. Haven't drove it once I got the check engine light.

    Should I Test my coolant for oil?

    Any suggestions please?
     
  3. ttou68

    ttou68 Active Member

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    I would check spark plugs first, and drain engine oil to see if milky if we you're due for oil change.,
    A leak down test should tell you if you have a blown head gasket...

    Posted via the PriusChat mobile app.
     
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  4. Levi Gonzalez

    Levi Gonzalez Junior Member

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    Combustion Leak Detector

    would something like that be ok?
     
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  5. ChapmanF

    ChapmanF Senior Member

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    You generally learn something from whether a single-cylinder misfire shows up or you get four at once, but it's not like one case has to be something more severe than the other.

    Misfiring in a single cylinder or two usually indicates you have some kind of issue specific to a cylinder or two. Misfiring across all cylinders usually indicates you have the sort of issue that affects all of them.
     
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  6. The Critic

    The Critic Resident Critic

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    Coils and Injectors are unlikely to be your issue, at least not at the same time. The coils and injectors are very expensive for this car and should not be shotgunned.
     
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  7. Levi Gonzalez

    Levi Gonzalez Junior Member

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    What's the best salution to soak the EGR / Manifold and then brush it out? I'd there something I could soak it in for a few hours?
     
  8. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Not sure if it's "best", but for the cooler, "Oxi-Clean Versatile Stain Remover", mixed with hot tap water, as concentrated as you can manage, worked for me. I corked one end. poured it in, prop upright in a corner of the laundry sink, let sit for about an hour. It'll bubble up, then subside. Rinse and repeat about five times.

    I would try a leak-down test. A competent mechanic familiar with the process is probably the simplest approach

    Don't do that.

    .
     
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  9. ASRDogman

    ASRDogman Senior Member

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    Oven cleaner is the quickest. Along with a pressure washer.
    The pressure washer clears it out, and the oven cleaner cleans out the carbon and soot.

    If it is super clogged, it will probably take several passes to get it cleared.
    Wear gloves for the oven cleaner and spray it at both ends a few times to make sure it gets
    all the way in. Let it soak for 30 minutes or so then use the pressure washer to clear it out.

    I almost forgot... for the intake, Gunk, and a small caliper brass bore brush in a drill.
    It will clear out the 4 passages on the intake manifold really fast.


     
    #9 ASRDogman, Dec 3, 2021
    Last edited: Dec 3, 2021
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  10. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Oh, neglected to mention: I would only use caustic cleaners (Oxi-Clean, or even more caustic Oven Cleaner) on the (stainless steel) EGR cooler. The EGR valve is mostly aluminum, and will likely react with caustic solution. Might just be cosmetic, but not sure. Ditto for the intake manifold: mostly plastic, but it does have metal embeds that react adversely. The EGR pipe (between EGR valve and intake manifold) is also stainless steel, but is very easy to clean, without caustic cleaner. I think it'd be ok to use though.
     
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  11. rjparker

    rjparker Senior Member

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    Yes for a couple months but you will also know it was a head gasket. Its a pretty cheap and easy hg diagnostic but in the end things may be far worse, costing you a radiator, cabin heat or even an engine. Most of the time all the previous expense will be wasted.
     
  12. Raytheeagle

    Raytheeagle Senior Member

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    Just use a pressure washer and save the cleaning solutions for other jobs;).

    Good luck and keep us posted(y).
     
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  13. Levi Gonzalez

    Levi Gonzalez Junior Member

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    pool of oil in the intake manifold. PCR
     

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  14. Levi Gonzalez

    Levi Gonzalez Junior Member

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    type on the last post. Meant to say "PCV ssue?"

    should I replace PCV while in here?
     
  15. Levi Gonzalez

    Levi Gonzalez Junior Member

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    Anything else I should do while I'm in here? I'm cleaning the manifold, replacing PCV (probably), clean the entire EGR assembly... anything else?

    If not, then I'm going to assemble it all back together and check. then if that doesn't work, I will move on to Plugs, coils, injectors when they come in the mail in a few days.

    the manifold gasket looks ok... should I still replace it since I'm in here?
     
  16. Levi Gonzalez

    Levi Gonzalez Junior Member

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    And to clarify, the oil in the manifold was not as bad as I thought. only a bit dropped out
     
  17. xliderider

    xliderider Senior Member

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    The oil puddle in the intake manifold is normal.

    Since you've got everything apart, and changing out the PCV valve, you should install an oil catch can.

    But if you have a failed head gasket, it might be too late.

    Posted via the PriusChat mobile app.
     
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