Duratec, MBE and Wasted Spark

[AdamQ]

I'm somewhat mystified by an ECU wiring issue on a Duratec.

I've connected an MBE ECU to a Duratec running wasted spark ignition.

The ignition is via a coilpack at the rear of the head (i.e. NOT coil-on-plug).

Initially, the ECU was not set up for wasted spark and I was not in a position to change it.  I therefore connected ECU pins 36 and 15 (Ignition A and D) to pin 1 of the coilpack and ECU pins 18 and 35 (Ignition B and C) to pin 3 of the coilpack (pin 2 of the coilpack being the coilpack feed).  This worked and the engine ran well.

The ECU setup was then changed to wasted spark and now the engine won't run.  Initially, I left the wiring exactly as described above figuring that there would simply be no outputs from the ECU on pins 35 and 15 (Ignition C and D) and that they'd be redundant and do no harm.  When the engine wouldn't run, I did disconnect them, but, as expected, it made no difference.

I'm sure I'm doing something daft, but I'm at a bit of a loss as to what it might be and any thoughts would be much appreciated.

Many thanks,
Adam