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Coil broken, but shouldn´t there be 2 cyls misfiring?

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    #1

    Coil broken, but shouldn´t there be 2 cyls misfiring?

    I think that one of my ignition coilpacks is broken on my 1996 MGM.
    Cyl #4 get´s no spark.

    I want to replace both the coilpacks.

    But shouldn´t there be 2 cyls misfiring?


    Some cutting and pasting from other info:
    `The ignition coil fires two spark plugs simultaneously, one on the compression stroke and one on the exhaust stroke.
    When the companion piston is on exhaust stroke, the spark is wasted.`

    Thanks,

    Greetings,

    Arie
    BDRUP BDRUP BDRUP


    Tags: None
    #2
    usually, yes it would. Are you sure its not the plug wire thats bad? From what I've been told, those boots sometimes get cracked and they don't conduct anymore. I would try pulling the wire at the coil and checking for spark directly off the coil pack. If it fires there, replace the wires, especially if you don't know how old they are. The 4.6 engine is said to be hard on plug wires. I would also suggest if you get new wires, make sure they are a good brand. I'm not familier with what you have over there in Europe, but Motorcraft wires are original equipment and work well, but I don't know if the prices would be too high over there. Echlin (NAPA brand) and Belden also make good wires.
    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC grandpa spec white and cranberry

    1984 Lincoln Continental TurboDiesel - rolls coal

    Originally posted by phayzer5
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

    Comment

      #3
      Originally posted by gadget73
      usually, yes it would. Are you sure its not the plug wire thats bad? From what I've been told, those boots sometimes get cracked and they don't conduct anymore. I would try pulling the wire at the coil and checking for spark directly off the coil pack. If it fires there, replace the wires, especially if you don't know how old they are. The 4.6 engine is said to be hard on plug wires. I would also suggest if you get new wires, make sure they are a good brand. I'm not familier with what you have over there in Europe, but Motorcraft wires are original equipment and work well, but I don't know if the prices would be too high over there. Echlin (NAPA brand) and Belden also make good wires.
      I had a misfire on cyl #1.
      Then after swapping injectors from cyl #1 and cyl#2,
      swapping plugs from cyl #1 and cyl#2,
      I swapped the two coil packs.

      And then cyl #1 had spark again.
      but then cyl #4, who had spark all the time, did no longer, and misfires.
      The wire of cyl #4 is connected to the same coiltower als the wire of cyl #1 was, before the swapping.

      So, therefore I thought the coilpack is broken.
      But it puzzles me, why there are not 2 cyl´s misfiring.

      which other cyl should be misfiring if the coil pack is broken?

      Thanks,

      Arie
      BDRUP BDRUP BDRUP


      Comment

        #4
        the only way I can see to have one coil be bad misfiring 1 cylinder, is to have the failure at the tower connection. This is puzzling. do you have 2 missing now?

        Comment

          #5
          Originally posted by Johnnyiroc
          This is puzzling. do you have 2 missing now?
          No, just cyl #4 is misfiring.

          First cyl #1, but then I swapped the coilpacks.
          From then on cyl #4 was misfiring. En cyl #1 gets spark.

          Thanks,

          Greetings,

          Arie
          BDRUP BDRUP BDRUP


          Comment

            #6
            Section 03-07: Ignition, Electronic 1996 Town Car, Crown Victoria, Grand Marquis Workshop Manual

            DESCRIPTION AND OPERATION

            --------------------------------------------------------------------------------

            Ignition Coil
            The ignition coils (12029) contain two separate ignition coils which are controlled by the ignition control module (ICM) (12K072) through two coil leads. Each ignition coil activates two spark plugs (12405) simultaneously:

            One spark plug on the compression stroke; this spark plug uses the majority of the ignition coil stored energy.
            One spark plug on the exhaust stroke; this spark plug uses very little of the ignition coil stored energy.
            These two spark plugs are connected in series.

            The firing voltage of onespark plug will be negative with respect to ground.
            The voltage of the otherspark plug will be positive with respect to ground.

            Coil #1
            Coil tower 1 - Cylinder 1 & 6
            Coil tower 2 - Cylinder 3 & 5

            Coil #2
            Coil tower 3 - Cylinder 4 & 7
            Coil tower 4 - Cylinder 2 & 8

            So, the problem moved with the coil pack from 1 to 4 so the coil pack is probably bad. This assumes the wires stayed on the same plugs.
            99 CV HPP

            Comment

              #7
              ^ what he said

              4 and 7 fire simutaneously. when it's time for 4 to fire, 7 fires a waste spark. if 4 has no spark, but 7 is firing normally, the path to ground is still there on 7. since you moved the pack around, the pack is badzors

              replazors
              GMNRadio DJ, Podcast Co-Host
              1984 Ford LTD Crown Victoria - Drag Car.
              99 Ranger 2.5 - Parts hauler and Pit truck.
              03 Mustang 3.8 Convertable - Head Gaskets fukered up
              95 S10 93 Accord

              Comment

                #8
                Since I build in two new coils, my car runs like new.

                Thanks all for your help.

                Greetings,

                Arie
                BDRUP BDRUP BDRUP


                Comment

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