BMW triggers
I plan to summarize common BMW trigger info on this page.
Crank trigger on BMW engines from the 80's is 60-2 teeth inductive (VR). Engine codes are M10, M20, M30
First generation of camshaft pulse sender is an inductive pickup on the HV ignition cable for cylinder #1.
This appeared on later M20, M30 engines.
Second generation of cam pulse senders is inductive (VR) pickup on the camshaft end, single pulse before cyl #1 TDC. Apparently pulse is at the same time when the missing teeth are on the crank trigger. Engine codes: S38, M50
Scope printout of an S38 signal:
Apparently this coincidence of cam signal and missing teeth is problematic to synchronize on current VEMS firmwares. The cause is that secondary (cam) pulse is sometimes processed earlier than the first crank pulse, but sometimes later.
Triggerlog of this situation (from M50B25 non-vanos engine):
http://quasar.dynaweb.hu/~lezsi/vems/bmwtrigger/v3.3_u006408-2013-10-19-14.23.17.triggerlog
AFAIK the only solution with current firmware is running crank-trigger only, and wasted spark. (ignoring secondary trigger). This results in a simple 60-2 setup, running fine.
Triggerlog captured in 19200 baud is only good for cranking (at least with 36-1, 60-2 or higher toothcount), as a limitation of serial throughput. Beyond cranking RPM, switch to higher baudrate See the first sentence of the [related help]
http://quasar.dynaweb.hu/~lezsi/vems/bmwtrigger/v3.3_u006408-2013-10-19-16.28.17.triggerlog
This is a log of an engine startup and running fine without missing events or trigger errors in vemstune.