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Need help reading a spark plug, possibly running lean

Discussion in 'Gen 3 Prius Technical Discussion' started by whazzup, Oct 28, 2022.

  1. whazzup

    whazzup New Member

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    Attached is a picture of my #3 and #4 cylinder spark plugs. The worse one is the #4. Back story is that I replaced a head gasket 10,000 miles ago. I'm having a similar problem again with the start up shakes. Doesn't happen all the time but frequent enough. I'm not losing any coolant like I was last time so I'm not sure where to begin looking. All I know is the spark plugs are not burning correctly and it appears to be a lean condition. Any thoughts? sparkplug.jpg
     
    #1 whazzup, Oct 28, 2022
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Who did the head gasket? What’s the miles? Has the intake manifold and EGR components been thoroughly cleaned?
     
    #2 Mendel Leisk, Oct 28, 2022
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  3. whazzup

    whazzup New Member

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    EGR and intake has been cleaned. I did the head gasket with OEM parts. The coolant was leaking into the #1 cylinder and washing the piston. The #1 spark plug came out clean this time with normal burn.
    It’s a 2013 Gen 3 with 143000 miles.
    Here is my old post when I did the head gasket:
    Multiple codes CEL after head gasket change 2013 | PriusChat
     
    #3 whazzup, Oct 29, 2022
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  4. mr_guy_mann

    mr_guy_mann Senior Member

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    The spark plug on the right is from a cylinder that's using / burning some oil. The other plug is fairly white, possibly a bit lean. What are fuel trim numbers- at hot idle, at higher idle, and at cruise? Is there any knock retard going on?

    Posted via the PriusChat mobile app.
     
    #4 mr_guy_mann, Nov 2, 2022
  5. douglasjre

    douglasjre Senior Member

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    To plug in the left looks normal. The one on the right is covered with oil
     
    #5 douglasjre, Nov 3, 2022
  6. whazzup

    whazzup New Member

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    How do I get fuel trim numbers? I don’t have anything I can hook up to the ECU. As for the knock retard, I can’t be sure but I don’t believe so.
    I’m definitely burning a little oil for sure. Is there a way I can check compression?
     
    #6 whazzup, Nov 3, 2022
  7. bisco

    bisco cookie crumbler

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    #7 bisco, Nov 3, 2022
  8. whazzup

    whazzup New Member

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    I don’t believe the engine will turn over without the ignition coils. Have you tried this method? I never heard of anyone successfully checking compression using maintenance mode.
     
    #8 whazzup, Nov 3, 2022
  9. bisco

    bisco cookie crumbler

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    i haven't. there are other videos available
     
    #9 bisco, Nov 3, 2022
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    Attached shows how to do compression test with Techstream:
     

    Attached Files:

    #10 Mendel Leisk, Nov 3, 2022
  11. whazzup

    whazzup New Member

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    Unfortunately, I don't have techstream.
     
    #11 whazzup, Nov 3, 2022
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