PH1 172 wont spark

[daniel c]

So...recently changed the engine in a friends PH1 172 as the old one dropped a valve, got the engine in fine, it turns over, it gets fuel but theres no spark!
the things we have checked;

• inertia switch is reset
• swapped coil pack for a known working one
• swapped leads and plugs
• tested loom for continuity (coilpack pins 1 and 32...crank sensor pins 24 and 54)
• swapped crank sensor for known working one
• immobilizer goes out as normal
• checked fuses and relays

The only strange thing we found was when testing the plug for the coil pack we was getting volts down all three cables, where as on a friends we was only getting volts down one, the one that is switched with the fuel pump, and no volts down the other two cables...
The only thing i can think of is the ECU?
is there any way this could be tested?
and what would be needed tp change it? ECU, decoder ring and key?
any help would be much appreciated!