Hi Andrew

Never worked on one of these but can make the following general diesel comments....

1) We have had a large number of injector faults that show no codes stored
2) We have had plenty that have had mechanical issues with injector fault codes stored
3) We have had injector programming issues with several scanner tools

What scanner are you using

have you tried a different scanner

have you confirmed your different scope trace is on no 3 cylinder for sure

hth

tony