Have a fiesta that started life as a 1.25 16v, after it threw a rod through the block we did an engine change and stuck the 1.6 16v out of a newer fez in. It has been going great for a few months now.

But it has started playing up, at first it had an intermitant missfire. Now its completely dead on two cylinders.

We have tried:

Another DIS pack.
Swopping the plug over to the DIS pack and the opposite two cylinders that worked then didn't and vice versa - so shows the DIS pack works, and its not the HT leads or spark plugs.
We have checked the signal wires back to the ECU for continuity, which it has so shows there is no break in the wire.

As far as I can see there is no ignition amplifier? So I am assuming there is a driver built into the ECU (nothing inside the box looks burnt out....)

Will any 1.6 16v ford ECU do the job, or do I have to get another CHCA one, just there seems to be a few different ECU codes?

Or is there anything else we can try?

Thanks in advance!