Mine 1.9 TDI 85KW PD suffer from vibration and booming noise between 1400-1800 rpm.
Injector number 4 reading is close to 1.0. Sum of other three injector’s readings is close to minus 1. So, ECU is trying to equalize injection. In my opinion ideal situation will be where sum of readings from two injectors are equal to sum of values from other two injectors – two positive against two negative readings.
Also, after removing the engine cover I spotted worn exhaust camshaft’s lobe on 4th cylinder. Could this be related to injector’s readings on injector number 4?
From my point of view you can expect DMF to fail from problem(s) originating to engine – in other way, you cannot expect DMF to make faulty injector or engine.