2007 Legacy Cylinder 2 Misfire

Discussion in 'Subaru Legacy' started by Steveio1687, Nov 23, 2020.

  1. Steveio1687

    Steveio1687

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    2007 Subaru Legacy, 2.5L 4 cyl. Non-turbo, 317,000+ mi.

    Head job including timing components done around 275k


    Car has been wonderful considering the mileage. Picked it up around 220k knowing what it needed and it’s done well. Until now.

    I have a misfire that I cannot nail down. Full disclosure, I had to punch the cat to unplug it and didn’t have 600 to spend to replace. I know. It’s on the list if I can figure out this misfire, especially if it’s responsible.

    Cylinder 2 will not fire. It misfires badly at idle, flashing CEL, nearly stalling. At highway speed it is barely noticeable but I think it is still misfiring though no flashing CEL then.

    I have replaced (noob mistakes I know): Coil pack, plug wires, traded 2 and 4 plugs (misfire didn’t move cylinders), swapped out a different battery to test, replaced injector seals on 2 and 4 while cleaning injectors. I also recently cleaned the butterfly valve and cleaned the MAF sensor in the filter box.

    Nothing changes the misfire and it stays in cylinder 2.

    I’ve thought-experimented my way to believing I’m not charging at the alternator because things like putting up the windows, or running a lot of electric (lights, blower, ac, windows up and down) it runs more poorly and it affects the idle even. This doesn’t explain why it’s always only cylinder 2.

    That or I somehow have a compression problem in 1 and can’t achieve combustion. This could be due to a valve issue, or leaking in that cylinder, or something I’m not educated enough to see. I’m less inclined to suspect the leaking because of the recent head job, but can’t imagine how a valve issue cropped up on only 1 cylinder after no issues till now post-head job.

    No other problems expect a recurring catalyst below efficiency code that is absolutely due to my free-flowing exhaust. I find the idea that the exhaust being unimpeded would affect combustion to have only cylinder 2 misfire to be far-fetched considering it’s the farthest away from the catalytic converter and would have the least affect from no back-pressure. If anything I’d expect cylinder 3 to be the worst affected from this.


    Please help me think of things. I am not very electrically inclined so haven’t checked charging or anything that way.


    Any ideas??
     
    Steveio1687, Nov 23, 2020
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