This page is about Multitooth Trigger Wheel that is often used to trigger GenBoard (especially v3.x).
V3 supports either HALL or VR sensor (jumper selectable). Multitooth wheels are usually VR type, but HALL is also possible.
- 24-1, 36-1 and 60-2 are common multitooth wheels: these are used successfully
- 135-136 cranktooth requires some help from external HW, like: InputTrigger/AudiTrigger board, or an improved trigger handler in firmware (rewrite some part in ASM).
It is a good idea to have someone verify the trigger settings. To allow this, make a comment sentence in your config.txt, something like the following:
- as .... (image, link to another page) shows
- TDC of cyl1 (and cyl4) comes
- 83 degrees after the point, when
- the first tooth after the missing tooth just passes the trigger (considering the rotational direction).
- that is 8 tooth and a little on the 36-1 wheel.
- we place trigger_tooth to 20 degrees (02 teeth)
- so 63 degrees remains for ign_tdcdelay
- so the sum is 83 degrees
If these are correct, the n[] table will reflect real ignition advance (not with offset). If there is a big difference (eg. the cylinder number is wrong, or rotational direction), that can be a serious problem.
GenBoard v2 hardware mod: first thing you need to do is to make a small change in the input trigger on the board:
You need to connect the output signal of the opto (inside the board!) to the IC3 pin of the avr(available on jumper J2). INT6 input was used originally, but we changed to use the IC3 pin for the primary trigger, because it has hardware-capture capability (more precision), and reserved INT6 for the CAM signal for dual-trigger applications.
Material
HALL and VR work with magnetic field, which is not disturbed by Al. So steel (not stainless) is the common wheel material.
Sources
If you want to fit a trigger wheel and don't have one fitted from the factory, there are many sources:
- http://www.racerpartswholesale.com/electro2.htm
- http://www.electromotive-inc.com/
- EdisIgnition
- Napa part number CSS304 (tooth wheel), CSS400 (sensor)
- many others