Engine ignition question | FerrariChat
Buy

Engine ignition question

Discussion in 'Technical Q&A' started by vinuneuro, Aug 6, 2012.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. vinuneuro

    vinuneuro F1 Rookie

    May 6, 2007
    2,574
    Chicago
    Full Name:
    Vig
    #1 vinuneuro, Aug 6, 2012
    Last edited by a moderator: Sep 7, 2017
    This is not a Ferrari. About 5k miles ago I forgot to ground my plugs/wires while doing a compression test and killed the ignition coil. I guess charge built up in the coil and had no where to go? Friend had an extra used coil which I used since. Recently the coil failed again in the same way as the first one. Resistance in the highlighted circuit is supposed to be 13-20k ohm. First one was 8-9k after failing, this last one was 10k. I've replaced the coil and the car's running again.

    The circuit that failed is the one from the coil to the cap. The other side from the coil goes to the ignition control module (circled red), and resistance on that side was in spec. Since the ICM is grounded can I assume it wouldn't have been damaged? There's no real way to test it with a multi-meter, only continuity checks to determine failure.

    Other question is, if the rest of the ignition system is in good shape can I just chalk this up to a coincidental result of putting in used coil after the first one failed, or should I be suspicious of anything?

    Thanks in advance.
    Image Unavailable, Please Login
     
  2. 2NA

    2NA F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 29, 2006
    18,221
    Twin Cities
    Full Name:
    Tim Keseluk
    #2 2NA, Aug 6, 2012
    Coils fail from a variety of reasons (heat, vibration, age). It is possible that they were coincidences.
     
  3. smg2

    smg2 F1 World Champ
    Sponsor

    Apr 1, 2004
    16,440
    Dumpster Fire #31
    Full Name:
    SMG
    #3 smg2, Aug 6, 2012
    you really should disconnect the coil when doing a compression test. a coil can fail for a number of reasons, commonly it's heat induced damage that causes the dielectric to breakdown and the secondary windings short internally. the real old ones filled with transformer oil tended to explode.

    without knowing what car and coil type it's hard to state what may be happening on the ECM side. but with most all ECM's the signal is from an op-amp and simply triggers the coil to ground thru a transistor circuit. more than likely there is a diode to protect the ECM. if that went the car wouldn't run.

    I'm not following how the coil failed, was both instances due to running the coil without leads?
     
  4. vinuneuro

    vinuneuro F1 Rookie

    May 6, 2007
    2,574
    Chicago
    Full Name:
    Vig
    #4 vinuneuro, Aug 6, 2012
    Last edited by a moderator: Sep 7, 2017
    The car is 01 Honda Prelude. First coil failed because of my carelessness, second went on it's own.

    Rather than the ECM I'm wondering if the ICM might have also taken any damage?

    I have no idea what type of coil this is.

    Thanks.
    Image Unavailable, Please Login
     

Share This Page