2008 2.0 TDI BPW A4 Cab - 80k 16705/P0321/000801 - Engine Speed Sensor (G28): Implausible Signal Implausible signal G28 engine speed sensor rough running / engine cut / buck and some black smoke above 2k rpm with glow plug flashing around and above + 2k with aforementioned symptoms - settles back down fine when you lift off - some 128 faulty injector signals mentioned in measuring blocks but suspect thats the G28 causing it. Engine starts and idles fine. - Checked G28 engine inductive speed sensor wiring to/from ECU to sensor / checked relucter wheel for integrity - no missing teeth and running true / not loose - Both G28 and G40 camshaft hall sensor have been scoped and are being measured correctly. (also checked timing teeth on cam sprocket are not bent) - All earths in engine bay good with low resistance 002 Ohms. - Checked fuel pick up up - Clamped return hose of tandem to build pressure as didn't have the correct pump pressure tester but made no difference to symptoms. - Checked for signs of oil in filter. - Boost leak test - Compression tested- Intake checked for blockages / MAF functioning - Actuated EGR and V719 flap with both removed to confirm movement and clean enough - Checked intake and clean enough - Injector deviations -1.29 / 0.5 / 0.5 / -1.27 (something like that but within spec) torsion value -0.5. - Timing has obv been physically confirmed in the beginning. - Swapped in a 2nd hand donor ECU i have.I should add the previous mechanic confirmed injector wiring loom with overlay harness and the car came to me with his diagnosis that the cam was worn (which i confirmed) and i have now changed with genuine Kolbenschmitt / bearings and lifters yet before and after symptoms remain unchanged with exception of injectors now being in spec (one of the injector lobes was visibly worn and outside tolerance and on removal bearings showing copper etc) but truth is this is not whats causing the main issue. I feel i have pretty much ruled everything out except injectors - i think.... but am getting so frustrated i cannot get a good positive fail on anything but obv i am missing something! Any fellow mechanics out there with an opinion please chime in as i need some fresh eyes on this. TIA.