Update to whats not so rapidly turning into a nightmare..... Agreed with customer to send this to Hyundai to have injectors coded to rule out as the problem. After doing this engine was still running rough so customer requested Hyundai to take a look seen as it was with them. A report generated by Hyundai suggested internal engine damage, EGR valve faulty & blocked DPF filter all a result of the initial injector failure!! After returning the vehicle to me, upon customer request (against my better judgement) we have carried out the repairs as advised (engine re-conditioned, genuine EGR valve & DPF filter).
Still I have a rough running fault
If anyone can offer ANY thoughts on what to scope, probe or check that I may not have done already please chip in