V3 reference trigger tooth

Subpage of Base setup menu


Trigger Reference Tooth table

This table specifies which trigger teeth represent each ignition event from the Ignition Output Table.

It is recommended to have tooth 0 on top, it will make the system synchronize to the engine quicker and initiate fuel and ignition events.

This table is traversed backwards just as the Ignition Output Table.

Example settings for auditrigger: (last three rows not used)
0: 0
1: 72
2: 54
3: 36
4: 18
5: 0
6: 0
7: 0

Special configuration for rotary trailing spark

Full trailing-spark support is implemented since firmware 1.1.77 for these types of engines:

  • Rotary (usually 2 or 3 rotor Wankel engines) or
  • Twin-sparkplug

With the latter system there are usually 4-8 cylinders where each cyl has 2 sparkplugs (many Alfa-Romeo). Low trailing spark delay is common here (often just a 0.5 degree to be softer on the harness and supply and for less electro-noise).

Important note for benchtesting: remember to generate double RPM, eg. "10000 RPM" signal when you want 5000 RPM signal for a wankel/rotary. Reason: the mazda wankel has 1 sectrig pulse every 360 degree. While the signal generators assume 1 sectrig per 720 deg. (eg. VemsTune Tools / Play trigger).


Rotary trailing spark configlet examples

Below we assume 12 primary trigger pulses for 1 secondary trigger pulse, but almost any other trigger should work (including missing tooth and even subaru/fiatstilo which does not allow HALL-dirac filtering, but works with rotary).

  • Adjust everything (including ign_tdcdelay) for the leading spark
  • then configure reftooth=128 for trailing spark

This means : timed from the same tooth as the leading, just with the configured RPM-dependent delay, and using different output.
In practice every second reftooth will be 128. The first (topmost in VemsTune) must not be 128 ... normally 0 anyway for faster sync.

2 rotor example

(note: hexadecimal 80 = 128)

ignout2 and ignout3 are leading sparks (at 0 and 6 tooth offset respectively). The trailing spark is wasted spark on ignout6.

  • Another_trigger_tooth=06
  • h[1]=00 80 06 80 ...
  • h[2]=20 60 30 60 ...

3 rotor example

(ignch 2,3,4 are leading, 5,6,7 are trailing)

  • another_trigger_tooth=04
  • h[1]=00 80 08 80 04 80 ...
  • h[2]=20 70 40 60 30 50 ...

The delay is adjustable (0..63.75 degree) in function of RPM
Note that the definition of degree is not as self-evident as for the alternating piston engines.