Car in today and although i am totally confidant that the faulty coils i replaced were necessary,its actually now a different fault.
First i must say its actually an 03' 1.4 polo with a BBY engine, MARELLI 4MV mpi system (oops ,sorry!).Launch says p0301 cyl 1 misfire detected.
Worked out today that injectors have perm +ve with switched earth.
when prob occurs (intermittant)injector 1 switched earth greatly reduces in comparison to injector 2,3and 4.Pulled the connectors from the ECU to trace no 1 earth supply.Found the earth supply wire that connects to ECU ,but since i reconnected it,its been ok! If it aint broke i cant fix it!
I suspect duff ECU , but local VW dealer says never sold one!
I'll clean connector blocks properly tomorrow and run it around.Maybe it was just poor contact,but they sure looked clean.
I bet it'll be fine all day tomorrow,then soon as cust gets it back it'll play up again.Dont you just love these type of faults!

Anyone had similar earth or ECU probs on these?
Please!
Colin