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Thread: swapped 4.3 to 6.0 and not getting spark to one cylinder NEED HELP

  1. #1
    Join Date
    Feb 2010
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    santa fe, tx
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    20

    swapped 4.3 to 6.0 and not getting spark to one cylinder NEED HELP

    just had my 2004 silverado 4.3l swapped out with a 6.0 and all but one cylinder is getting spark. had new heads, intake and cam installed. and installed motor ready to go but looks like one cylinder not getting spark. its got me puzzled. have swapped a coil pack from a cylinder that is getting spark knowing its coil pack is good to the bad cylinder and still no spark. have tried swapping out a whole group of coil packs that work and that same cylinder still has no spark. have tried just swapping spark plug wire still nothing. have tried 3 different computers that did nothing. checked to make sure from the computer to that one coil packs plug makes a circut in the wiring harness and it does so that was ok. just swapped to the wiring harness that came wth motor out for another wiring harness. and that cylinder still has no spark. i dont know what else it could be or where to go from here. any help would be nice so can get back to driving it.

  2. #2
    Join Date
    Sep 2008
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    McAlester, OK
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    131
    have you changed spark plug just asking

  3. #3
    Join Date
    Feb 2010
    Location
    santa fe, tx
    Posts
    20
    yeah put new ones in when put the motor in. hasnt even left driveway since the swap cause didnt sound right running then when used timing light the one cylinder shows nothing. light doesnt come on.

  4. #4
    Join Date
    Feb 2010
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    santa fe, tx
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    yeah i will try that and then maybe try checking the grounds. i onno if that would cause it or not. might just get a thick wire to connect to frame good and connect it to motor.

  5. #5
    Join Date
    Aug 2005
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    St. Anthony, Indiana
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    1,592
    try swapping that spark plug to another cylinder, that will let you know if it is a bad spark plug.

  6. #6
    Join Date
    Feb 2010
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    santa fe, tx
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    yeah true i will do that tom and see if that spark plug works.

  7. #7
    Join Date
    Mar 2003
    Location
    San Antonio, TX
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    11,038
    Quote Originally Posted by butler145 View Post
    yeah true i will do that tom and see if that spark plug works.
    it's work to do, but run a new wire from the coil pack to the pcm, there could be an open in the circuit, due to a bad terminal or corrosion on the terminal when it's plugged in.
    we've seen the actual terminals not make contact and not fire the injector or coil.

  8. #8
    Join Date
    Feb 2010
    Location
    santa fe, tx
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    could the piece on the crankshaft that tells the computer when to send spark have broken a gear off that would keep that cylinder from getting spark at that one point?
    but just that one cylinder isnt getting fire even after swapping a whole other wiring harness. and where harness connects to coil packs have tried 3 different coil packs. so would think that would eliminate any connection issues.

  9. #9
    Join Date
    May 2009
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    hot & windy
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    1,117
    i don't believe the crank position sensor has gears in it. at least it didn't look like it when i was checking mine.
    when i did my swap, none of my coils were firing, but that turned out to be a computer issue
    00 FRC - just top end, exhaust, and a hot-air intake
    99 Sierra - 5.3 / 5spd
    ↓ click the pic for the build ↓

  10. #10
    Join Date
    Aug 2007
    Location
    Honeywood, Ontario
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    6,994
    swapped plugs yet?
    2006 Silverado
    Little Black Bitch

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