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Ignition issues? CHECK YOUR COIL PACK FOR RUST!!

Discussion in 'Stock 1995 - 2001 Explorers' started by eddie95, October 30, 2012.

^^Searches ExplorerForum.com^^





  1. eddie95

    eddie95 Member

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    Well, I've been having intermittent missing and my engine wouldn't run all that smooth and would have vibration. Well, I saw a video about checking for corrosion on the grounding plate as well as the contact on the coil pack on the 4.0 OHV.

    Well, you wouldn't believe it what I saw when I pulled the coil pack off. I swear the only thing grounding the coil pack was the screws. There was a band of rust around the entire mating surface of the coil pack and none of the metal was smooth and shiny. Well I hit it with some sandpaper, degreased, and reassembled.

    I absolutely couldn't believe what I heard when I started it up. The engine that used to send vibrations that you could feel in the drivers seat is running smooth enough to balance a quarter on it! I'm not saying that this is a miracle fix. As a matter of fact it is really just a simple problem and solution. There was a confined space with bare metal that rusted. The rust inhibited the electrical properties, and when it was cleaned, the properties were restored.

    So GO CHECK YOUR COIL PACK! It can't hurt and it sure as heck helped in my case.
     
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  3. koda2000

    koda2000 Explorer Addict

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    good catch! it would probably help to pevent further rust if you put some grease on the bottom of the coil, but i'm not sure what the best type of grease would be. i know dielectric would NOT be a good choice as it's non-conductive. i've purchased ignition parts before (modules) that came with a little packette of some kind of white grease to insure a good connection, but it don't know what it was. i had a simular problem on a GM V6 and it turned out to be rust on the coil's wire posts.
     
  4. SoNic67

    SoNic67 Well-Known Member

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    The problem is that Ford has sucky electrical engineers. Any average electrician knows that return path for electricity needs to be via a real copper (or aluminum) conductor.
    Only Ford geniuses decided that the iron plate and screws are "good" enough". Those coil packs really needed a dedicated copper ground wire.
     
  5. budwich

    budwich Well-Known Member

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    :) I don't think so

    that's where you actually need it. It stops the corrosion in the first place. The "non-conductivity" issue is not an issue as "mechanical contact" is there.
     
    Last edited: October 31, 2012
  6. eddie95

    eddie95 Member

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    I drove it today, and it is really amazing. It completely fixed some bucking issues I was having under hard acceleration. I'm still going to clean it off more and then do the dielectric grease. The difference is incredible.
     
  7. swshawaii

    swshawaii Elite Explorer

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    Most engines run best when all the plugs are firing. ;)
     
  8. eddie95

    eddie95 Member

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    Yeah, who'da thunk it :D
     
  9. sucker

    sucker New Member

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    I cleaned mine and seemed better for just a bit. Started pulling wires off while it was running and #4 made no difference in idle. Replaced coil pack and running much better. Marble noise under acceleration gone. They do run better on all cylinders!
     
  10. Runnin'OnEmpty

    Runnin'OnEmpty Well-Known Member

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    There's a product called 'Kopr-Shield' that's ideal
    for coating surfaces to enhance electrical contact.
    It looks like copper powder mixed into a thick
    grease. I use it on battery connections. You can
    find it at hardware stores or electrical supply houses.
     
  11. audiomax

    audiomax New Member

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    Read this post yesterday, and pulled the coil pack today, sure enough both surfaces were completely covered in rust, cleaned both, reinstalled coil pack, The 95 idles and runs as smooth as it did new, my slight miss at idle that I had just finally contributed to 235xxx miles of use is gone. Thanks for the post.
     
  12. Blue91Ex

    Blue91Ex Active Member

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    anyone know if this works with 1st gens? i know the ohv is the same motor but i wasnt sure if parts liek coilpack changed between years at all...
     
  13. KPT

    KPT Well-Known Member

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    I'm not convinced cleaning the rust under the coil pack does anything. I'd be more likely to believe there was a bad connection on one of the spark plug wires and moving the coil pack helped.

    Its a waste spark ignition system. Notice how there are only three coils on the bottom of the coil pack?

    The high voltage side grounds back through another spark plug.

    Cylinders 1 and 5, 2 and 6, and 3 and 4 always fire together.

    Unless the 12V side grounds through the mounting plate, I'd have to look at the wiring diagram.
     
  14. J_C

    J_C Well-Known Member

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    At the risk of reviving an old topic, I also wonder if there is really a ground needed there and wonder if the primary purpose might instead be to 'sink away heat and that removing it just wiggled the wires and connections enough to restore better contact to them. From a schematic I saw, there is no ground needed there, the circuit is complete through one plug to the coil to the other plug.

    There is a simple test you could do. Unbolt it, then slide a piece of cardboard under it for complete insulation of the bottom plate (leaving it unbolted), then see if the engine runs. If that is a critical ground then it won't run.
     
  15. Runnin'OnEmpty

    Runnin'OnEmpty Well-Known Member

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    I think you're right, JC & KPT. The secondary (high voltage)circuit
    completes through the 2 spark plugs and coils. The primary
    (12v) circuit completes through the single power wire and
    the three grounding wires from the PCM. If the coil(s) were
    grounded any other way they would be shorted and wouldn't fire.

    There's probably a stray magnetic field generated around the coil
    pack which might be absorbed through the coil baseplate.
    Maybe that's why the engines run better when that baseplate is cleaned and better grounded...?
     
  16. Runnin'OnEmpty

    Runnin'OnEmpty Well-Known Member

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    I had to remove the coil pack for another reason, and remembered this post. I happened to notice a strip of
    metal on the intake plenum that's obviously intended to
    ground the coil pack to the rear intake bolt. There's nothing
    to reference this ground in any of my wiring schematics,
    but it's there.

    It must be for grounding out stray electrical charges or
    for preventing a magnetic field from building around the
    coils...

    Sort of like a lightning rod being grounded.
     
  17. J_C

    J_C Well-Known Member

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    The thing is, I don't think it's obviously there to ground it.

    Metal is the obvious bracket material of choice and a plate of it on the coil pack could just be there to reinforce it, or for heat transfer.

    I feel the same way about "grounding out stray charges or... magnetic field" that it's not obviously there for that. A shield would need to wrap around the whole thing, not just be on the bottom where under it there is already grounded metal in that direction.

    Further, on some Explorers (not sure about our generation) the bracket it bolts to is painted, which it obviously wouldn't be if it were intended to be an electrical ground.

    To clarify, I'm not stating it "can't" be a ground, rather that the effectiveness is low and it's poor engineering if it needs to ground through it.
     
  18. SoNic67

    SoNic67 Well-Known Member

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    That ground is there for EMC (reduce the RF emissions from the coil).
     
  19. J_C

    J_C Well-Known Member

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    ^ I see you writing that but do you have proof from the source instead of just some urban legend being passed around? It is not designed to be very effective at that if that is the intention. RF emission reduction needs to have no gaps in the metal that are larger than the radio wavelength.

    Older ignition types often needed a ground strap but that doesn't necessarily translate into this type needing a strap or this as a ground point. I suppose I'll have to get to the bottom of this, some day after the holidays I'll pull mine off and drive her strapped on top of a piece of cardboard for insulation to see if anything including radio noise changes.
     
    • Disagree Disagree x 1
  20. SoNic67

    SoNic67 Well-Known Member

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    I am a licensed Electrical Engineer. So it is an educated guess... Every shield needs a drain to common electrode (ground) to be effective.

    Of course I have no Faraday cages to enclose an Explorer to prove you that I am right. But FCC requires all kind of similar tests. Even if your radio might still "work" it might be above the limits allowed for auto certification. Try AM band.
     
  21. Runnin'OnEmpty

    Runnin'OnEmpty Well-Known Member

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    Quite a mystery here.
    I took another look at my coil, and there's a metal band
    around the circumference of the pack, which appears to
    have an electrical contact with the metal strip on the
    plenum, which in turn connects to the rear manifold
    stud. The metal band is near the center of the coils, so
    this suggests to me the purpose of all this has something
    to do with the fields the coils generate.

    I suspect the band and ground keeps a (larger) magnetic
    field from forming around the coils and causing the coils
    to misfire, which seems to be happening when the ground
    connections corrode...

    If consecutively firing sparkplug wires are routed next to
    each other, the fields generated around the wires will
    cause crossfires in the plugs. I think similar crossfires might
    be happening with the coil packs (with poor grounds)...
     

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