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misfire coil issues

Discussion in 'SN-95 and New Edge Mustangs' started by hitmix300, Dec 8, 2018 at 3:46 PM.

  1. hitmix300

    hitmix300 Member Established Member

    Messages:
    725
    Joined:
    Jan 8, 2013
    Location:
    detroit
    hi

    i just picked up a 2004 mustang gt 4.6 for a super good deal of 200 bucks. basically the car has a new fuel pump and timing chains, it starts right up, but it has some hard misfires.. i started looking into it and it appears that when i unplug the coil wire(s) to cylinders 5,6 & 8 the engine sound doesn't change. i tried changing the coils and plugs with no luck.

    out of curiousity, i grounded a plug and plugged in a coil into those wires and found that it isn't sparking on those three cylinders for sure.

    has anyone ever seen this problem before? i used a multimeter and it appears there is a good ground on all three of those coil connectors, but they aren't firing.

    if i remember correctly, doesn't the coils have constant power and the pcm sends the ground signal or is that incorrect? not sure why my meter showed good constant ground at those three wires that aren't firing

    looking for any advice or if anyone has a ignition wiring schematic i would greatly appreciate it!1


    thanks and happy hotrodding
     
  2. hitmix300

    hitmix300 Member Established Member

    Messages:
    725
    Joined:
    Jan 8, 2013
    Location:
    detroit
    some bad information on my first post. i made the mistake of telling ya'll that i had ground all the time @ the coil wires. i was wrong; the red wire when the key is on is alright with the proper power.

    nevertheless; four of the 8 coils on the car appeared to not have the ground trigger from the pcm. i found breakage in the wiring harness. Rather than to make repairs; i ran four new wires directly from the pcm connector at the passenger kick panel and all is well...

    little rant: ford electrical engineers suck big timebecause they have pins 79 & 80 the same color wire and gauge; real dick move.

    i attached the pcm wiring layout ( diagram pinout ) for those who need it
     

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