Bit of an update on this...

if i disconnect the "ZME" valve the vehicle still starts and runs with no change to the way it behaves, although it does flag a fault code and the glow plug light flashes..

I have scoped the "ZME" feed we can see a clean duty cycle (matches what i can see in live data as a %) However the ZME doesnt seem to be responding to the change in duty cycle when you opperate the accelerator pedal..