This page lists some useful knowhow related to InputTrigger verification
Also see [VemsTune Help]
The InputTrigger is the most important signal in the system. A multitooth trigger, especially the 60-2 contains an extreme amount of information that could be utilized for tuning. However, since many things can go wrong during an install, this page focuses on debugging, examining the trigger events that GenBoard sees (often during cranking attempts).
Initially, triggerlog is captured:
- disable ignition or injection
- remove fuse, disconnect
- or (experts can) configure fuelcut and igncut (or "safe mode" with wrong ECU calibrations/prohibit value, but don't leave it that way to confuse someone else, set it back)
- if the engine has sectrig: enable sectrig ("camsync mode"). Burn, reboot.
- min 8 seconds of cranking, without ign or injection
- rename files to add important details, like ...falling_rising_unpoweredcams... (primtrig_sectrig_cam position details first)
- use underscore_in_filename (not space), avoid accented characters
- add link to thematical project page, and add more notes about the files (at what second you see weird symptom if any, things like that)
BMW S54 example: 3 triggers
(the red should be name "third trig", not "camshaft exhaust", because thirdtrig on this BMW is actually on the intake):
The relative times (changing because of compression forces) are indicated by the height (and the distance of pulses of course). note: Pulses were originally displayed with equal heights, like some examples below. Some important events, like spark positions are also displayed when enabled (enabled by default in VemsTune since about 2009, for each cylinder).
Spark ign to trigger interference example
- selection from missing tooth gap-gap and checking number of pulses (top right corner) should alarm the installer... After zooming in (eg. good to look around the point where sparks stop being delivered), it becomes clear.
- most likely cause: interference in wiring (more pronounced if VR sensor signal amplitude is low, eg amplitude<1V = peak to peak<2V).
- check that VR shield is only connected to GND at ECU end
- check grounds
- of course, if doing the install step by step: capturing first triggerlog with ign,inj and wbo2 fuses removed, it will most likely become apparent (trigger error happens when sparks are actually fired), even without careful inspection of the triggerlog
- inverted VR signal, also see GenBoard/Manual/VrSensor/Polarity
- unknown position of missing tooth
- noise ( GenBoard/Manual/GroundConnections )
- new triggerlog implementation (since 1.1.78) can also log secondary trigger timestamps (and use CRC checksum)
- so the margin between secondary and primary trigger pulses can be measured without scope.
- This must be minimum 10 crankdegrees from the missing tooth (if a missing tooth wheel)
- or min 10 crankdegrees from the last tooth for other triggers, eg. coil type or InputTrigger/MultiToothNoneMissing.
- Except InputTrigger/AudiTrigger where it's quite close to the previous tooth (often around 1 crankdegree), that is OK.
- On newer non-PS2 firmwares the triggerlog can Log the Speed sensor signals and Spark events
- Note: the Speed sensor is not sampled continuously. Groups of 5 pulses seen. This is normal.
60-2 example log including secondary trigger data:
- missing tooth is 58 teeth after the previous missing tooth
- normally 532 (*4 usec) between teeth, but 1560 (*4usec) for the missing tooth, that is appr 2.93* longer (appr 3 since 2 are missing: good)
- sectrig pulse is 23 teeth (+291 * 4 usec) after the missing tooth (that is 23 + 0.55 toothtime), 116 teeth (=2*58) after the previous sectrig pulse
- file was made with VemsTune, Tools / Record triggerlog
- (analyze triggerlog file works similarly but displays from file, not from a connected ECU)
- file was made with brayterm Manmde40 command and 470 RPM signal, but VT since 2010-06-03 is able to record from v3 (use newest nightly)
Under firmware 1.1.78 the trigger logging has different method, see:
Low pulsecount trigger without sectrig - for the curious
- When sectrig pulses are received, primtrig pulses are sent to VemsTune without delay.
- When sectrig pulses are missing (either because not properly connected or disabled in config), the primtrig pulses are sent to VemsTune with some delay (in hope of more primtrig pulses coming: this allows 60-2 or more pulses to be sensed at higher RPM at any given baudrate).
- This delay is on average 32 primtrig pulses in 1.2.2x firmware (used to be average 128 primtrig pulses in earlier fw)
- For a Ford Cosworth trigger (4 pulses per crankrot) this is 8 crank rotations (appr 3 seconds during cranking) - but Cosworth depends on sectrig anyway (because 8 pulses per engine cycle while only 4 spark events, so distributer setup is not possible).
- in short: if no pulses at all, for a low pulsecount primtrig: get the sectrig working first (usually the setup needs sectrig anyway)
- or apply the recommended procedure: record triggerlog during cranking for min 8-10 seconds (don't get surprised that primtrig-only packets come in batches - this effect is likely unnoticed for a 60-2 or even a 24-2 trigger).