A short update as I played around a bit with this, and it’s kind of challenging to setup the VR sensor it seems…
I’ve routed a direct shielded pair of wires from sensor to EMU, just to be sure.
VR+ goes to B21, VR- goes to Sensor Ground, Shield goes to Power Ground.
As the effect I have nice signal on the real scope, engine running on idle in wasted spark config.
What I realised is that with VR CAM sensor to see anything in V3 client scope during cranking (1 tooth) there has to be no pull down nor any filters applied as it seems the signal is to weak when pull down is applied or filter and scope won’t show it (real scope showed the amplitude of c.a. 1V during cranking).
Only when engine is running (higher RPM than during cranking), the electromagnetic field is strong enough to induct more voltage (my scope showed the amplitude of c.a. 3.8V at c.a. 1400 RPM) that can be then manipulated by the pull-down and filter.
This leads me to conclusion, that just to be on the safe side, with VR CAM sensor the ignition should be never used in full sync, but wasted spark during cranking.
Despite a nice signal on the real scope EMU scope shows some garbage.
Only after plying around with pull-down and filters I was able to achieve something that seems to be stable for the time being (1k pull-down and low filter seems to give me best results). When I changed edge for falling, there was no difference basically, just the sync tooth number changed by IIRC like 40 or so.
I tried also to play with the CAM sync tooth window, but it seems it has zero effect at this time, at least that’s what I observed in the EMU Scope (don’t look at the tooth number in the screenshot, just a sample screenshot with wrong value when playing around). I was hoping that I could narrow down the “real” spikes of the VR sensor down to the few teeth I knew the rising edge will be there (teeth between 80 and 85 for example), but… this feature is coming??? With that feature I might get away without pull-down and filter, maybe…
This is a screen with pull-down 4k7 and filter low, I still had some issues at cold engine just after cranking:
CAM sync tooth fluctuates between 22 and 82 (this is 60-2 crank trigger wheel, so It kinda tried to sync with every turn of the crank rather than two rotations - which is odd, as camshaft rotates two times slower than crank, so why?).
Also I’ve noticed the same sync issue down to tooth 22 (60 lower than expected) not just right after cranking.
As seen above with initial sync first tooth 22 is “synced” then it goes to 82 and stays there, until 3x drops back to 22 (misfire happens there instantly).
This is something that bothers me to be honest, although when I changed pull-down to 1k it seems it went away (will confirm that tomorrow with cold engine).
Questions:
- Is it true that CAM sync is used only once during the engine start/stop cycle? I’ve noticed cam sync tooth significant changes for a moment or so, that caused a misfire, which makes me believe it’s not used only for initial sync, but all the time?
- How do filters work (low/medium/high)?
- Is it possible to get a scope from EMU for a longer period when engine running/cranking?
- Is the feature cam sync tooth window working?
Thank you
PS. Attaching logs from above two runs with re-sync between teeth 22 and 82.
20240702_2248-cold-start-cam-tooth-sync-issue.emublog3 (132.1 KB)
20240702_2250-cold-start-cam-tooth-sync-issue.emublog3 (67.4 KB)