Input Trigger/Bmw Double Vanos - VEMS wiki www.vems.hu

InputTrigger/BmwDoubleVanos (2011-09-13 22:04:44)

BMW has many different VANOS systems. Only the M car engines have dual solenoids.

The most interesting app is the double-vanos with 4 solenoids and 3 VR-sensors

because all others are simpler
- the changes seem trivial: HALL signal is simpler than VR, disabling third trigger and changing "secignore" if necessary - easy after capturing triggerlog
if you have 3 VR sensors, write in the order comment: "secondary=VR and thirdtrig=VR capable to trig even a lower amplitude ~70% extrapulse".
- otherwise InputTrigger/RunOut is likely, possibly only at some higher RPM (eg. 6500 RPM), but way too low (firmware tests are done slightly above >10k RPM). We were looking for something complex (suspected firmware or config problem) when 1.1.97 (115200 baud) triggerlog revealed that LM1815 with the used resistors (eg R182 too low) some pulses simply didn't make it to the processor (scope showed that the VR signal was clean).

Fero reported that Double VANOS works perfectly

it follows the target cam position perfectly
it is actually easier to set up than the PWM type actuator (eg. suzuki)
but high-side driver was required (so the protection-diode need not be removed from the solenoid-connector)
- a 4-channel low-Z-extension board was modified (4 tracecuts) to act as high-side PFET driver. Using 10k Rgs resistor, and driven from p259 (or other) outputs (p259/0,p259/1 and p259/6,p259/7, remember: pairs must be neighbors), with 510 Ohm.
- high-side driver is also required for Honda, where the solenoid has 1 pin grounded to the body

Information needs some cleanup from

especially trigger setup and initial cam-position target tables.

The intake VR polarity was originally wrong (rising edge)

interestingly, the intake actuation worked that way too. After swapping the intake-cam VR polarity (LM1815 likes VR falling edge on its input):

Note that

exhaust-cam (which is 6+1 pulse) is connected to secondary trigger, the +1 pulse is toothcount=2
intake-cam (6 evenly placed pulse every 120 crankdeg, tooth_cnt=4,24,44,...) is connected to third cam (therefore "exhaust target" table is relevant for intake).
- Originally 1 pulse was inside the missing-gap, so this is different: implementation needs change, at least the configlet (possibly some other change needed, like separate "measure tooth" parameter for sectrig and third trig ?)

From engine-recorded ~1190 RPM triggerlog, Marcell extracted a 16 second section:

this, speeded up ("600%" and "700" percent in audacity) 7 and 8 times respectively, played in endless-loop, triggered v3 perfectly on the bench (~8400 and ~9600 RPM respectively), including sectrig position measurement (3d trigger was not saved into the stereo wav by VemsTune triggerlog dialog), with no trigger-errors or RPM dropouts at all.
- something is not right around the exhaust VR of the actual engine, because RPM occasionally drops to 0 around 6500 RPM. Maybe amplitude is too high ? (around +-6V at 1200 RPM, likely amplitude more than +-30V at high RPM). This is regardless of the intake cam (third trigger enabled/disabled), but problem disappears with only primary trigger (but that's not an acceptable solution as COP coils and VVTI requires camsync)
- we'll prolly need some code modification to only send the missing tooth primtrig (not all 58 teeth) so we see all relevant events in 115200 baud triggerlog upto 9000+ RPM. That should reveal what is happening in the actual engine: extra noise-pulse (seems most likely) or missing exhaust-pulse
- also note that the engine (VR sensor?) seems to behave somewhat better when cold. Maybe clearance is lowered when HOT, resulting in higher signal amplitude ?
- we only tried adding one 1k pulldown (maybe 2, 3 or 4 would help ?)