This page is to help with setting up the Primary Trigger option
Specifically for the VAG 60-2 wheel, but it will contain general information
MegaTune is an easy way to setup the trigger values, but you need to know what you are changing.
current decimal values
| Primary Trigger | GRM setup | Mcel | ||
| Edge | Rising | Rising | ||
| Type | Multitooth | Multitooth | ||
| Filtering | Disabled | Disabled | ||
| Tooth Relation (Usually Disabled) | Disabled | Disabled | ||
| Trigger Settings | ||||
| TDC after trigger (degrees) | 60.0 | 60.0 | VAG wheel on ABA block is 90d off TDC at the center of the missing teeth via calibrated eyeball | |
| Number of teeth on wheel | 58 | 58 | actual nubs | |
| Trigger Tooth | 3 | 15 | The third nub after the space actually the missing ones are counted, 3= the first after the space | VAG ABA wheel appears to have the center of the missing teeth @ 90d off TDC, would this make this value 2 |
| Next Trigger Tooth | 15 (V8)/20 4clyn | 15 | Manual states NextTrigTooth= imaginary teeth * 2 / cylinders (60 *2 / 4 = 30) | |
| Crank minimum period (usec) | 1280 | 1280 | ||
| Tooth Width | ||||
| Angular width of tooth | 2 | 2 | shouldnt this be 360/(# of teeth + missing teeth 360/60 = 6 No, fake degrees, 720/240=3-> 6/3=2 | |
| Tooth Relation to Normal (usually 181) | 181 | 181 | ||
| Tooth Relation to Missing (usually 118) | 118 | 118 | ||
| Phase | ||||
| Angular width of missing tooth | 6 | 6 | ( shouldn't this be 12) actually 18, but in fake degrees it's 18/3=6 | |
| Engine Phase, when reset | 240 | 240 |
These are all you settings, but these are not normally how motorheads describe thier motors or triggers.
Typical Descriptions
- TDC -- Regular meaning when #1 cylinder is at top of rotation
- Number of actual teeth on wheel
- Number of missing teeth on blank spot on wheel if there were teeth there
- Relation of blank spot to TDC this would be in degrees
- Leading egde angle from TDC
- Trailing egde angle from TDC
So using these values how do we get the other ones.