Intermittent spark + misfiring | FerrariChat
Buy

Intermittent spark + misfiring

Discussion in '308/328' started by AFmarcus, Jul 25, 2025 at 12:47 PM.

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

  1. AFmarcus

    AFmarcus Rookie

    Jul 17, 2025
    7
    Full Name:
    Marcus Feather
    #1 AFmarcus, Jul 25, 2025 at 12:47 PM
    1979 US Spec (I believe to be converted to euro spec on the carbs)

    Currently tackling a misfire issue on my 308, on tickover all is well no pops and bangs. As soon as the revs are brought off idle the car pops and has significant backfiring.

    So naturally I clipped on the timing light and looked at the timing, on the bank closest to the front of the car, all is well, consistent spark and all. On the bank closest to the back, the spark was intermittently missing 1 every 3 or 4 revolutions sometimes more sometimes less. This was true on all 4 leads so I believe it to be something pre-individual leads. Possible rotor arm, dizzy cap, points, king lead or coil.

    Anyone come across this before?
     
  2. Andy 308GTB

    Andy 308GTB F1 Rookie
    Lifetime Rossa

    Jun 2, 2004
    2,669
    Essex, UK
    Full Name:
    Andy M
    #2 Andy 308GTB, Jul 26, 2025 at 6:37 AM
    Is it points or ignition module?
    If it's the ignition module, swap the units (i.e. the whole thing - coil/ignition module/heatsink) and see if the problem transfers to the front bank - if so, test the coils -if they are OK, then swap just the ignition modules over. A process of elimination. If it is a faulty ignition module - replace with a Petronix D2000 unit
    Check your distributor cap - there have been a number of instances recently of holes appearing in them! Picture of mine below.

    If it is points - someone else will have to chime in! But swapping stuff over between banks is a good way to identify problems.


    Image Unavailable, Please Login
     
  3. AFmarcus

    AFmarcus Rookie

    Jul 17, 2025
    7
    Full Name:
    Marcus Feather
    #3 AFmarcus, Jul 26, 2025 at 6:41 AM
    So it's a twin dizzy system, I have been in the workshop all morning and have now resolved it.

    Swapped coils, no change. Removed dizzy cap, cleaned points and rotor arm and changed condenser as it wasn't charging like the spare I had. It's now resolved so it was one of those 3 that I did that resolved it.
     
  4. Andy 308GTB

    Andy 308GTB F1 Rookie
    Lifetime Rossa

    Jun 2, 2004
    2,669
    Essex, UK
    Full Name:
    Andy M
    #4 Andy 308GTB, Jul 26, 2025 at 6:48 AM
    Well done!
     

Share This Page