[cahme]

Long story short
After shutting down my car for 5 min, startup revealed very rough running and activated the SES light.

I pulled over after 1 block and disconnected my JB4 (disconnected battery, then swapped for factory connections and disconnected JB4 ground leaving power connected to fuse). After a long crank, I limped home. Once home, I disconnected battery and reconnected JB4 ground leaving the factory connections (ie JB4 TMAP/MAP/Boost are not connected, but DME wires are still connected), but I got no communication to JB4 either by steering wheel controls nor USB interface.

I got a bmwlogger cable and with their sw, I was able to get these codes (descriptions are from MEVD172 codes doc floating around):
29E1 Charge-air temperature sensor, electrical : Short
2C70 Boost pressure sensor, electrical: Short circuit
281B Absolute pressure sensor, intake pipe, electrical: Short
2C58 Boost pressure control, deactivation: Boost pressure build-up blocked
2EFE Random/Multiple Cylinder Misfire Detected (DTC Desc)
2F04 Cylinder 6 Misfire Detected (DTC Desc)
2EE0 Combustion misfiring, several cylinders: Fuel injection deactivation
2EF4 Combustion misfiring, cylinder 6: Fuel injection deactivation
2F03 Cylinder 5 Misfire Detected (DTC Desc)
2EF1 Combustion misfiring, cylinder 5: Fuel injection deactivation
2F02 Cylinder 4 Misfire Detected (DTC Desc)
2EE2 Combustion misfiring, several cylinders: damaging exhaust gas after start sequence
2EF3 Combustion misfiring, cylinder 5: damaging exhaust gas after start sequence
2EF6 Combustion misfiring, cylinder 6: damaging exhaust gas after start sequence
2EF0 Combustion misfiring, cylinder 4: damaging exhaust gas after start sequence
2EED Combustion misfiring, cylinder 4: Fuel injection deactivation
2EE1 Combustion misfiring, several cylinders: Fuel injection deactivation
2EEF Combustion misfiring, cylinder 4: damaging exaust gas
36FD DME main relay: implausibly open


I then cleared the codes and started the car long enough to get the SES light again ( 5 sec, note NO long start this time) and then got these codes:

2EFE Random/Multiple Cylinder Misfire Detected (DTC Desc)
2F04 Cylinder 6 Misfire Detected (DTC Desc)
2EE0 Combustion misfiring, several cylinders: Fuel injection deactivation
2EF4 Combustion misfiring, cylinder 6: Fuel injection deactivation

One other tidbit is that once home, I was unable to start the car again due to battery not turning over the starter (12.3 V).

I have an idea of my next step (HPFP), but wanted other opinions ...