Firing on one Cylinder

Discussion in 'Electrical' started by 173ABN, Jul 29, 2013.

  1. 173ABN

    173ABN Active Member

    My Chopper has a 1999 S&S 96CI engine and is only firing on the rear cylinder I have checked the plugs and the wires they are fine there is no fire coming from one side of the coil. The coil is a TwinTec single fire coil pn/2005 I am pretty good with the wrenches but not to good when it comes to the electrical side. Can a coil go bad on just one terminal? Any help would be great before I start spending $$$
  2. Apyle

    Apyle Junior Member

    I can't speak for a Harley coil, but I know it does happen on other waste spark coils. Such as the ones used on a gm v-6 engine, one tower cracks and leaks spark to ground.
  3. Hoople

    Hoople Account Removed

    I assume this bike was running fine and it started to have this problem, and your not installing a new ignition system for the 1st time.

    Yes, only one side of a single fire coil can be bad. Not the case with dual fire waste spark system. Since the 2005 is a single fire coil, it is two coils in one package. One side can be bad with other side being good..

    As a test... What you can do is reverse both the secondary and primary sides to see if the problem is the coil or the ignition module that is driving it.

    To do this,,,1st make a current diagram of what color wires are going where. Same with spark plug wires. Make a diagram

    Now swap the two outside primary wires of the coil and leaving the middle terminal alone (that is the power lead).

    Now swap spark plug wires in the coil output towers. (Pull both spark plug wires at coil and swap towers)

    Start the engine. If the rear cylinder is still the only one that is working, the ECM or ignition module is the problem. But if the front cylinder now becomes the one that is working & the rear cylinder is the dead one,,, that tells you the coil is bad.
  4. xcavater

    xcavater Member

    This is similar to a problem a friend is having with his 2005 Springer. Is there a bench test for the ignition module?
  5. 173ABN

    173ABN Active Member

    Ok guys did as Hoople advised switched the two leads coming into the coil left the two wires going to the spark plugs alone one is long and the other to short to reach the front cylinder. now I have fire to the front cylinder. My thought is that the coil is Ok because its now firing from the other tower looking at the ignition it is a Crane HI-4 single fire race Ignition with adjustment on it. I am hoping that is not the problem because its very $$$$$$$
  6. Jack Klarich

    Jack Klarich Guest

    That has separate pick ups for each cylinder, get a hold of Crane and see what hey are on Beach Street in Daytona, The Hi4 is a good system, I have seen lots of Dyna pick ups go bad but only a couple of cranes:s Crane Cams | Contact Us
    Last edited by a moderator: Jul 29, 2013
  7. 76_shovel

    76_shovel Member

    IMO you are correct, by swapping the primary side wires you effectively "switched coils" and the side not firing is now firing so one would conclude the coil (both) are good.
    aside from making sure wiring is intact I would next start thinking the ignition pickup was bad.
  8. Jack Klarich

    Jack Klarich Guest

  9. 173ABN

    173ABN Active Member

    Unable to open
  10. dbmg

    dbmg Guest

    Hey Jack unfortunately that link is broken......:(