2010 @120k miles. Misfiring after spark plug replacement and sulfur smell?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by snowglobes97, May 25, 2020.

  1. snowglobes97

    snowglobes97 New Member

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    Hello everyone,

    New poster here - I have an issue confused me quite a bit. I decided to change my spark plugs because I was getting some knocking when the engine started up in Park - just a few knocks and then the engine would run normally. In Drive, the engine wouldn't knock at all.

    Upon changing the spark plugs, I saw that the old ones were scorched around the ceramic. Everything went smoothly, but when starting the car again, the issue persisted, and in addition, the cabin filled with the smell of sulfur. The engine starting knocking violently when driven and the check engine light came on. The code was P0302, so my plan is to work on the second cylinder today.

    Is there anything else that this issue is indicative of that I should look at before/during attempting to fix the second cylinder? The sulfur smell was alarming, but I figured I would ask for more experienced advice.

    Thank you all
     
    #1 snowglobes97, May 25, 2020
    Last edited: May 25, 2020
  2. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Yeah sulphur/brimstone smell is always alarming... Not sure, I've heard this before, just not enough brain cells to recall what that was due to. Maybe the Catalytic Converter??

    Knocking and codes regarding cylinder misfire, in particular #1 and #2, often end up being failing head gasket. Try swapping the coils around first: swap coil #2 and #4, see if the code changes to P0304.

    If it doesn't:

    1. Check the coolant level, is it stable, or requiring frequent top-up?
    2. Boroscope inspect the cylinders, looking for coolant in cylinder 1 or 2 in particular, and/or they look particularly clean, compared to the rest.
    3. Do a leak-down test.

    Have you ever cleaned the intake manifold or Exhaust Gas Recirculation components?
     
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  3. pjksr02

    pjksr02 Active Member

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    Welcome to PriusChat.

    Was there a misfire code before you changed the plugs? What plug did you install?

    If you have looked around here, there's an issue with the EGR system clogging in the Gen-3 Prius. One manifestation of a clogged EGR, for some, has been a misfire code, caused by a leaky head gasket.

    Others will chime in but I'd suggest moving the #2 igniter to see if the misfire moves with it. If so, it's the igniter. If not, go on to the EGR system, and consider an inspection of the head gasket (scoping or leak-down test). Related: has your coolant and oil level been constant?
     
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  4. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Just googling the sulphur smell: one reason is the cat, another is an engine running hot. Clogged EGR will elevate engine temp.
     
  5. ChapmanF

    ChapmanF Senior Member

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    Though no one around here, it still must be pointed out, has ever ballparked the question "by how much?", or even how many digits might be in the number.
     
  6. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    If there's a misfire then the cat is not working well. That alone should be enough to get hydrogen sulfide.

    So far it sounds a lot like the classic high miles prius with gummed up oil rings & clogged EGR, gone to end stage. Don't panic though- confirm these elements and see if you can save it.
     
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  7. taxidriver50005

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    Sounds like gummed up,think I would start here with a clean, also fo a piston soak and engine flush to help with oil burning problems

    Posted via the PriusChat mobile app.
     
  8. taxidriver50005

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  9. tankyuong

    tankyuong Senior Member

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    Try old plugs back on, maybe new plugs are counterfeit
     
  10. snowglobes97

    snowglobes97 New Member

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    Thank you all for your replies! The problem persists, but I'll give you a rundown of what's been attempted so far. Really trying to eliminate the easier stuff before moving on to more difficult tasks.

    • Swapped the coils around. Misfires stayed on cylinders 2 and 4 - far more 2 than 4.
    • Swapped spark plugs to see if the problem followed. No change.
    • Cleaned the EGR pipe. There was some gunk in there, but nothing I'd imagine would be restrictive enough to cause an issue.
    • Cleaned airflow intake sensor.
    • Cleaned and rolled fuel injectors. I swapped injectors 1 with 2, and 3 with 4. The misfiring stayed on 2 and 4 (still far more 2 than 4. The report after starting said 72 misfires on 2 and 7 on 4).
    After putting it back together and running the engine today, a lot of clear liquid came out of the exhaust. I mopped some of it with a paper towel, and it smelled a bit burnt, but I'm not sure what this is an indication of. With all this in mind, what's the next step?

    Again, I appreciate all of the replies!
     
  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    With misfire persisting on cylinder 2, regardless of the swaps, sounds like head gasket. Try leak down test maybe next.
     
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  12. snowglobes97

    snowglobes97 New Member

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    All signs have pointed to a head gasket, so that’s the next step. When doing this, is there anything else that can be done at the same time or anything to watch out for?
     
  13. Mendel Leisk

    Mendel Leisk Sand Pounder

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  14. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    I'd be cautious. HG failure is a common event on these cars at higher mileage, and maybe it has become an overly common diagnosis. I don't think of 120k miles as being very high for these cars, and for report of HG issues.

    At the very least, I would try to get direct measurements (compression test, leakdown test, block test) before diving in. Any coolant issues?

    Clear liquid coming out of your exhaust upon startup can be a completely normal thing that happens when the condensed water vapor is expelled. Do you have any humidity down there in Texas? I assume you are running pink / red / green coolant rather than pure water as coolant, right?

    I'd be very concerned about any spark plugs you put in there being fake.

    Some "scorching" around the ceramic on the spark plugs that were in there may be normal, or at least not a critical problem.
     
  15. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Yeah I was thinking he's done leak-down test, maybe not. Just "all signs"?
     
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  16. snowglobes97

    snowglobes97 New Member

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    Back again - thank you for the replies!

    Leak-down test was attempted today on all four cylinders at TDC of the compression stroke at 30psi, and there wasn't any significant loss of pressure for any cylinder. The question that came to me next is if this test should be attempted while the engine is warmed up, at least to a point where I wouldn't burn myself while navigating around it and keeping the cylinders in place. Any other clues I should look at?


    No coolant issues at all so far - no change in coolant levels at all or signs of the liquid where it shouldn't be yet. Pink liquid here, and it can get a bit humid so hopefully that clears that up! Hopefully with the new info above from the leak-down test, that gives more insight into what it could possibly be.

    I can attempt new spark plugs, but this issue started with the old spark plugs, prompting me to get new ones. Though the new ones did seem to make the issue worse. Originally, it was just misfiring in Park while idling, and not while in Drive. Now it misfires at all times.
     
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  17. Grit

    Grit Senior Member

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    If leakdown test says pressure is within normal specs then buy non counterfeit oem plugs. Do a search here and you’ll be amazed how many victims it claimed because they wanted the cheapest of the cheapest purchased price.
     
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  18. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    It's not always the price. You'd be surprised how many autoparts get mail ordered specifically to avoid having to talk to the weird guy at the counter in the store. And that was before covid.
     
  19. Grit

    Grit Senior Member

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    I knew I forgot something

    Disclaimer- this reply may not apply in all situations.
     
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  20. snowglobes97

    snowglobes97 New Member

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    Any recommendations? I purchased the Autolite XP Iridium Spark Plug XP5683 from AutoZone. I wouldn't have expected to run into issues with these, but if switching them out for different plugs is all that's left to attempt I'm up for it. The question that came to mind is whether or not new plugs would make a difference because of the issue of the misfiring mainly occurring on cylinder 2 (and some on 4), regardless of which plug/coil/injector is in it.
     
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