Smoke tests are almost useless on modern BMWs.


Look for a bit of cracked rubber or plastic...somewhere on/under the intake manifold...a little hose...an elbow...a fitting. Just enough to whack out the AFR, drive the DME to add fuel.


This causes misfires all over the place, that also move around. KEEP IN MIND how a DME 'reads' misfires: It looks at the acceleration of the crankshaft after each 'fire' and when it doenst detect the right amount of movement/accel, it say 'oh, must have missed. Now combine this with how the DME senses these signals...analog edge transitions, detection circuits, all sorts of jitter and variation. No wonder it shows up as weird patterns of misfires. A single dead coil? easy. usually cleanly detected.



My car has not been a headache since mile 1..... just saying...