Number 1 cylinder misfire

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by tgotr, May 17, 2020.

  1. tgotr

    tgotr New Member

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    My 2010 had a massive shudder issue that i worked out was a misfire in the first cylinder.

    I replaced all four plugs after noticing that the anode was worn down on one of the old ones, it's running much smoother but still has a shudder and now an unconfirmed missfire. Put in four new irridium plugs.

    Does the computer have to relearn or is my next step replacing the coils?

    The gas mileage has been bad, 35 mpg.
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    How many miles?
    Engine coolant level stable?
    Ever cleaned the Exhaust Gas Recirculation circuit, and intake manifold?

    Just a heads up: this is very often head gasket failure, coolant getting into cylinder, and carbon-clogged EGR is a possible factor in its demise.
     
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  3. tgotr

    tgotr New Member

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    200K, coolant is stable, I inspected it and cleaning wasn't necessary. I then installed a catch can.
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Inspected EGR? By 200k it's pretty much guaranteed to be clogged.

    Maybe try a leak down test.

    The head gasket failure are almost always cylinder 1 and/or 2.

    EGR gasses, which help to cool the combustion chambers, enter from cylinder 4 end of the intake manifold.
     
    #4 Mendel Leisk, May 17, 2020
    Last edited: May 17, 2020
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  5. tgotr

    tgotr New Member

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    Yea, I inspected it when I installed the catch can. Very little carbon build-up.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    How many miles were on those old plugs, and where did you get them? Any chance they were fake?

    These Denso Iridium SC20HR11 are "double" Iridium plugs, so there is a little Iridium spot on the anode, which should show virtually no wear, maybe even up to 200k miles. But the fake ones aren't actually made with Iridium, and will wear through in a few 10's of k's of miles.
     
  8. JC91006

    JC91006 Senior Member

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    What did you exactly inspect?
     
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  9. tgotr

    tgotr New Member

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    The whole anode was burned away on the plug for the first cylinder. The ceramic part of the plug said they were platinum plugs, autolite brand.
     
  10. tgotr

    tgotr New Member

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    I looked into the EGR valve, saw it was relatively clean, not clogged up like I expected. Hit it with some carb cleaner to be sure and cleaned up the pipe that goes from the intake to the EGR.
     
  11. JC91006

    JC91006 Senior Member

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    So I'm going to assume someone has cleaned out that stuff you've inspected. It would be a miracle (as Mendel mentioned) to have that not clogged by 200k miles

    As with the spark plugs, most people only use the Denso or NGK brand ones, as they are the most compatible with the engine.

    I'm a big believer in the head gasket failure after 200k miles. This unfortunately is just the nature of these cars. But having a misfire could be multiple things. You'll just have to slowly go through all the diagnostics associated with spark and fuel delivery
     
  12. ChapmanF

    ChapmanF Senior Member

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    Mine also is relatively clean at 154,000, both according to flow testing in Techstream and confirmed with a recent visual check (though I didn't visual the cooler).

    One things we don't do a lot of at PriusChat is disassemble randomly selected non-problematic cars to find out the true population incidence of our favorite maladies. Miracles might be more common than we think.
     
  13. tgotr

    tgotr New Member

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    It is unlikely the head gasket has failed. None of the telltale signs are present. The spark plugs were fouled up, likely from before I bought it, and the 1st plug, the anode was not all there anymore. I think the plugs getting fouled up has been because of the cheap gas we've been getting during the outbreak, I think it's lower quality or has more ethanol in there than normal. Also I have been careless and not empty out the catch can every week so that crap got into the engine anyway.
     
  14. Grit

    Grit Senior Member

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    Still yielding lower to mid 60 mpg on mine so gas quality havent been affected at this time.

    Empty OCC every week? There’s definitely an underlying issue happening within the system.
     
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Ditto
     
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  16. tgotr

    tgotr New Member

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    It was likely where I was buying it. I started getting gas at different stations that cost more per gallon and a ton of things cleared up like white milky stuff in the OCC. I make it a point to empty the OCC when I put gas in and check my fluids.
     
  17. JC91006

    JC91006 Senior Member

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    I did my 2010 back when the car was around 100k miles. It was problem free at the time and I just wanted to do some routine maintenance. Mine was not a miracle, it definitely needed cleaning.
     
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  18. ChapmanF

    ChapmanF Senior Member

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    Yeah, there was recently a Gen 3 about the same age and miles as mine on here that was severely occluded (and a flow test showed it).

    So there are significant differences between cars, and what accounts for them hasn't been figured out.
     
  19. SFO

    SFO Senior Member

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    Others may find it helpful if you listed the gas brands, and the related things that manifested by using each (milky stuff, excess blow-by, etc)

    Curious about the brand and weight of oil you're using as well.
     
  20. pjksr02

    pjksr02 Active Member

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