open circuit injector..

Hi all, I've mentioned before that my 2003 TD5 engine runs like it's slightly out of balance at low revs. I've changed the wiring loom and cleaned the ECU plug ,opened the ECU to check for oil ingress, set all the rockers, done the seals and copper washers just about everything I can think of. It's not bad like it's missing badly I can just feel it's slightly out somewhere. It sounds like a valve is tapping but the cams are smooth as are the lifters. I plugged it into my mates Snap On diagnostic and it came back with 'Injector 2 open circuit', I've had a read through most of the threads on this topic but am really no wiser. The questions I'm after is, Would this create a slightly out of kilter feel to the engine? What could be the reason for the 'Open circuit', is it the injector or the wiring at fault and how do I check which it could be. could it be oil still in the existing wiring. I've multi meters etc, and used to be a mechanic so have a good understanding but this is winding me right up now cause I can't put my finger on the reason for the imbalance. It pulls like a train and runs great otherwise. Cheers all.. ps, the wiring loom cost about £40, not sure what/ whose make.

You must rule out the injector first if the loom is new, anyway, give contact spray in that plug which connects to the injector loom first...the best and most certain way to rule out the injector is to swap it with another and read the fault code then... even if the coding will be different the engine must run at idle and low revs and if the injector is gone you'll get the same fault code on the new position... then it's certain that the injector is at fault, if you get the fault code again on nr.2 it's certainly a wiring issue...if you want to make continuity test on the wires from the ECM red plug to the upper plug use a very thin needle in that uppoer plug cos it's very sensitive and if you push something thicker than the injector loom's pins in it's cavities you'll ruin it... continuity test is easy cos the plugs are hardwired on that circuit so concentrate on the colours of traces on the yellow wires