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 | |
This part needs to be made either transparent to the end user or extremely well explained with a shortcut on howto do it. | ||||
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 edge angle from TDC
- Trailing edge angle from TDC
So using these values how do we get the other ones.
Suggestion
Do the number trunkation etc in the make mtt portion. Most NON - EE/CompEE/CS engineers will not get the howto about converting decimals to an arbitrary (seemingly) number less than 255 ( 8-bit micro unsigned issue)...
So basically a good picture and straightforward equation, IF it is not automagically done for the config..
Min Crank Period
This definately needs to be calculated somewhere else.. I thought it was for "cranking" aka starting the car. but it is directly related to Rev limiter.. you could call this the OVERREV point or something. I'm guessing its an early variable.