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Prius engine slightly stumbles..

Discussion in 'Gen 3 Prius Main Forum' started by Rob Stone, Feb 11, 2019.

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  1. Rob Stone

    Rob Stone Junior Member

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    My 2015 Prius recently started a strange thing. When I let off the gas pedal to coast, the engine stumbles slightly and I feel it. When I gently press the gas, the engine slightly stumbles and starts. I can also press the gas pedal barely and hit a point where the engine stumbles slightly as long as I’m barely pressing the gas pedal.

    Another issue I noticed is when I accelerate hard on slick pavement, the traction light comes on but system is not retarding engine. I can spin the tires for a good distance...... any ideas as to how to troubleshoot this issue?
     
    #1 Rob Stone, Feb 11, 2019
  2. JC91006

    JC91006 Senior Member

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    Sounds like the EGR circuit/Intake ports should be cleaned. Too much carbon buildup. probably good idea to change spark plugs if you have high miles

    On your Avatar photo, what on earth are you doing there under the car?
     
    #2 JC91006, Feb 11, 2019
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  3. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    How many miles?
     
    #3 Mendel Leisk, Feb 11, 2019
  4. Grit

    Grit Senior Member

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    Traction light comes on because your tires are spinning while car is stationary thus traction control kicks in to stop the tires from spinning, feels like a horrible knock also. The way to troubleshoot is replace current tires with more grip.
     
    #4 Grit, Feb 11, 2019
  5. Rob Stone

    Rob Stone Junior Member

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    That’s not what’s happening. Engine is not being controlled at all during tire spin. When it works right, the engine stalls to allow tires to gain traction.
     
    #5 Rob Stone, Feb 11, 2019
  6. Rob Stone

    Rob Stone Junior Member

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    #6 Rob Stone, Feb 11, 2019
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  7. bisco

    bisco cookie crumbler

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    start of a head gasket fail?
     
    #7 bisco, Feb 11, 2019
  8. Rob Stone

    Rob Stone Junior Member

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    That’s my son in my Avatar. Trying to remember what we were doing that day. That was our 2004 Prius.
     
    #8 Rob Stone, Feb 11, 2019
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  9. Rob Stone

    Rob Stone Junior Member

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    Hope not!
     
    #9 Rob Stone, Feb 11, 2019
  10. bisco

    bisco cookie crumbler

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    me too!:)
     
    #10 bisco, Feb 11, 2019
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  11. Rob Stone

    Rob Stone Junior Member

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    Seems like we had to remove wheel well for something. I know we removed nose of that car to replaced headlights once....now I am going to wonder about that the rest of the evening. Lol
     
    #11 Rob Stone, Feb 11, 2019
  12. JC91006

    JC91006 Senior Member

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    Looks like he's turning some tool, but that area, I don't know what's there.

    But I was thinking it looks a bit dangerous to be under there using a scissor Jack
     
    #12 JC91006, Feb 11, 2019
  13. Rob Stone

    Rob Stone Junior Member

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    That’s a jack stand. We never rely on jacks to hold a car up.
     
    #13 Rob Stone, Feb 11, 2019
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  14. Rob Stone

    Rob Stone Junior Member

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    So my plan is to replace spark plugs and inspect EGR plus EGR tubing.
     
    #14 Rob Stone, Feb 11, 2019
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  15. Rob Stone

    Rob Stone Junior Member

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    It still seems like a control module is not working right with traction control issue I am observing.....
     
    #15 Rob Stone, Feb 11, 2019
  16. bisco

    bisco cookie crumbler

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    do the intake mani while you're in there. how's the throttle body?
     
    #16 bisco, Feb 11, 2019
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  17. Rob Stone

    Rob Stone Junior Member

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    Have not inspected yet. Will be weekend project.....
     
    #17 Rob Stone, Feb 11, 2019
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  18. bisco

    bisco cookie crumbler

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    wouldn't an eco give you a code?
     
    #18 bisco, Feb 11, 2019
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  19. Rob Stone

    Rob Stone Junior Member

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    No lights on dash. Will read codes with my code reader this week.
     
    #19 Rob Stone, Feb 11, 2019
  20. JC91006

    JC91006 Senior Member

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    If there are no warning lights, it shouldn't be any failing electronic systems.

    I would do a whole tune up on the car.

    1. Change spark plugs
    2. Change coolant
    3. Clean EGR circuit
    4. Clean intake ports
    5. Clean throttle body
    6. Change pcv valve

    All in a days work
     
    #20 JC91006, Feb 11, 2019
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