This page is about Multitooth Trigger Wheel that is often used to trigger GenBoard (especially v3.x).

Actually, best named missing tooth wheel to distinguish from InputTrigger/MultiToothNoneMissing, InputTrigger/ShortGapTrigger and extrapulse (and special rover / elise) trigger setups.

12-2 pattern (missing 10 and 11'oclock drill) crankwheel for 3cyl, 4cyl, evenfire 6cyl, 8 cyl

12-1 wheel: D=12mm drills (D=14mm would be better) into 5mm steel disk (not stainless). Ddrill=130mm, Douter=159mm.


Here is an [example 24-2 triggerwheel CAD files] suitable for almost any engine

Jorgen designed a 15-1 and 10-1 wheels for the 1GT101 Honeywell HALL sensor ,he says its the BEST.

I made some modification to the wheel to make it lighter.Please check it,will this affect the performance of the wheel?

The odd number is because its made for the 5cyl Audi engine.



V3 supports either HALL or VR sensor (jumper selectable). Multitooth factory wheels used to be mostly VR type, but more and more HALL after 2000.

HALL (audi AAN addon):



VR also exists (audi AAN addon, HALL recommended for new installs):


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:

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.


HALL and VR work with magnetic field, which is not disturbed by Al. So steel (not stainless) is the common wheel material.


If you want to fit a trigger wheel and don't have one fitted from the factory, there are many sources: