I need help. I did a complete spark plug and coil swap on my 2016 m235. Sitting at about 103k miles. This was done in prevent and the car ran perfect prior.

Now, I am having a misfire on cylinder 2 and the idle is atrocious. I have swapped coils, the misfire doesn’t follow. I swapped the new plugs back to old, same cyl 2 code and the idle is even worse.

I truly have no clue what to do at this point and don’t really understand how the car is now running like a bag of shit after it being perfect this morning.

Edit:: I’m now getting multiple misfire codes after putting all old coils and plugs back in. I’m at a total loss.

Please help me figure this out.

  • LeatherMine@alien.topBEnglish
    1·
    1 year ago

    When I had a similar set of symptoms (just happened randomly at idle, but nothing touched mechnically beforehand), it was a broken valve spring. $$$ fix (but I think they charged me for taking off the head but they didn’t do that or shouldn’t have needed to).

    When one cylinder is lost, it can cause timing issues in other cylinders, so not surprising to see multiple cylinder misfire codes when it’s only one bad cylinder.

    But could still be an injector or frayed wire.

    Like another said, a compression test will tell you a lot at this point.

    • Alternative_Leader91@alien.topOPBEnglish
      1·
      1 year ago

      How much are we talking? Did you figure that out yourself or a shop? If yourself, what did you do?

      I appreciate your insight.

      • LeatherMine@alien.topBEnglish
        1·
        1 year ago

        if that is your problem. Cost me CAD$2300 from the Indy shop that did the repair (which I didn’t have any previous relationship with).

        Probably more now. That was early in the pandemic when most people stopped driving.

        Other costs were bmw dealership’s misdiagnosis and wrong part replacement recommendations (don’t go to a dealership, they’ll tell you to replace spark plugs and coils because they’re idiots following their flowchart).

        I figured the next proper step was a compression test, which the Indy did but the dealership did not. I did the same as you: swap coils and plugs around and if the problem stays in the same place, the coils and plugs are fine.