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No spark on cylinders 1 and 2

Discussion in 'XJ Technical Chat' started by Zack Lescowitch, Jul 7, 2019.

  1. XJ550H

    XJ550H Well-Known Member Premium Member

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    does that include spark plug caps? if so remove them the cap unscrews off the wire
     
  2. Zack Lescowitch

    Zack Lescowitch Member

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    No that’s directly from the end of each wire.
     
  3. mlew

    mlew Well-Known Member

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    We are on to something.
    With key on there should be 12v on the red/white wire on the TCI and red/white at the ignition coils. Unplug the coils and check the red/white there, should have 12v. If not there is a break n the wire from the TCI to the coils, or bad connection at those coil plugs.
    Since you only have .1V I suspect the wire from TCI to coils s broken somewhere in the harness.
     
  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    spec is
    Secondary side (spark plug wires, without their end caps):
    12K ohms +/- 20% = 9,600 ohms - 14,400 ohms acceptable range

    16k is high and out of spec
    the spec is for both wires combined they before buying a set of ignition coilsbeginning and end of same wire

    it could be your meter touch probes together see what you get.

    what do caps measure?

    if total wire and caps are added together it may come in spec
    measure other coil and compare

    I like to buy 1% resistors and measure them to see how close meter comes. remember that you are measuring a coil and its inductance can affect meter reading if you have access to another meter check with that.
     
  5. Zack Lescowitch

    Zack Lescowitch Member

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    So tonight I checked continuity between the tci and the coils. My meter confirmed a connection and then I checked voltage and I miraculously had power to the coils. I turned it over and I had spark. I did nothing other than leave the battery on the trickle charger over night. I had 12.5 volts after I turned it over and found spark.

    Another odd situation: I pulled the ignition fuse and I still get spark without the fuse in place. Something must be completing the circuit elsewhere.
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    maybe you pulled wrong fuse
     
  7. mlew

    mlew Well-Known Member

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    Maybe messing with the wiring plugs had something to do with it. I would clean the TCI and coil connections.

    Or someone has mis-labled the fuses. Has the fuse box been changed? Those old glass ones will give you problems.
     
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  8. Zack Lescowitch

    Zack Lescowitch Member

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    After a few attempts to diagnose the issue, I finally found a broken wire going to the coils from the stem. It broke in the casing and showed no signs of damage. It was only after I followed the wire and checked voltage every where possible that I was able to narrow it down and replace the broken section.

    I have plenty of spark now!

    I appreciate any and all help you guys provided!
     
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  9. KA1J

    KA1J Member

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    This is a wonderful forum with some truly knowledgeable & helpful members.
    Glad you got your spark & you'll love the X.
     
    Zack Lescowitch likes this.

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