Rough idle, misfire, need help

Discussion in 'General Subaru Discussion' started by 2013subiguywrx, Feb 2, 2021.

  1. 2013subiguywrx
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    2013subiguywrx Active Member

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    Good morning everyone. Have a friend who has a 2008 Impreza outback sport
    Rough idle, misfire on cylinder 3, horrible smell.
    Car dies when in drive. When the EGR was unplugged and plugged back in the car would run fine. But now it’s not bandaiding the problem. (Had to get it home) checked the spark plug, and wires and they are fine!
    Is this the EGR? Or something else entirely
    Thanks
     
  2. euro
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    euro Well-Known Member

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    I guess you could try a new set of freshly gapped plugs and see if that improves things. What codes was it throwing?
     
  3. 2013subiguywrx
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    2013subiguywrx Active Member

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    P0303 The car had all new plugs/wires Before a 1500+ mile trip. Then after 3 months and another 1500+ mile trip is when this issue started.
     
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  4. euro
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    euro Well-Known Member

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    Arguably sparkplugs can be DoA.

    Try regapping that plug or replacing it again. My next guess would be coil pack might be going bad on that circuit.

    I wouldn't take my word as gospel though.
     
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  5. Chux
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    Chux Well-Known Member

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    Pull up the FSM, there's a several-page diagnostic procedure on P030x codes.


    Off the top of my head:

    What plugs and wires were used?

    I'd do a compression test, and swap the injectors between 1 & 3.

    Does it consume oil? Assuming it doesn't follow the injector, I'd drop the exhaust and look to see if one of the valve guides is dropped.
     
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  6. Nhibbs
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    Nhibbs Well-Known Member

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    There are a lot of counterfeit spark plugs (especially NGK for whatever reason) on places like Amazon so it seriously could be that.

    How many miles on the car?

    Other than the stuff everyone else suggested it could just be doing normal subaru things and telling you it needs a new engine.
     
  7. pbedroske
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    pbedroske Well-Known Member

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    Clean the pcv, and or seafoam the intake and or put in a catch can. This cold weather is havoc on crankcase ventilation causing condensation of oil and water and clogging up vacuum tubes leading to misfires.
    Though, I too have run into counterfeit spark plugs that caused misfires. They'll also kill a coil pack.
     
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