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
MembersPage/PeterNassy question moved to the top.
But this also depends on what type of trigger wheel you use,right.I mean if i use a cam driven 5 window triggerwheel,time between valid trigger events cannot be the same if i would use a crank 60-2.Also want to know what is valid trigger event.
Lets talk about a 5 cyl.If camdriven 5 window hall,every window,right?If 60-2,every 60/5=12th teeth?Or every missing teeth?
Peter, (assuming 4cycle engine)
These settings are for a crank trigger. That assumes a 720d rotation for one cycle. For a Camshaft triggered event (360d per complete cycle) the period length is generally multiplied by two. I will be making a set of pages that describe how to do all this for these types of configurations, but right now this is limited to crank trigger driven events.
The plan is to have a page that describes how to get the values for a crank trigger and a cam trigger, followed by several pages that specifically address the different types of engines 4clyn, 6clyn(even/odd/straight), V8, V10, V12.. My expertise lies with the 4clyn VW/Audi (VAG) products. But there will be lookup tables for both crank and cam trigger. This is mostly because I actually have both solutions that I have to do. the NA GRM car is a 4 window Hall sensor (cam) and the Turbo GRM car is a 60-2 VR crank sensor.
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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 | ||||
Engine Phase, when reset | 240 | 240 | determines toothwidth unit; (equivalent to 720 crankdegrees = 2 crankrot= 120 teeth) | |
Angular width of tooth | 2 | 2 | 120 teeth is 240, so 1 tooth width is 2 | |
Angular width of missing tooth | 6 | 6 | 3 times the above (2 missing teeth) |
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 |
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. If they don't care, they should copy a working example and not mess with the numbers they don't know.
Min Crank Period (review this statement)
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.
Angular width, etc.. This should all be auto-calculated.
since an 8bit number only can goto 255 (8-bit unsigned) so the whole point of this is scaling.
Example 60-2 wheel
- 1 its a ratio..
- 720d / 255 = 120teeth/ x ; x = 8bit approximation of degrees / tooth but this has to be rounded down so that it is a nice root ie. divisible and integer like.
- 2 Given the number of teeth in a 720d rotation what is the new number in this ratio
- 120teeth/ rounddown(x)= 720d / y
- y is the new normalied max value (y <= real angle per tooth )
- (y)(number of teeth) = engine Phase
- Engine phase refers to the new number y * number of teeth that represents 720d
- The proper name would be scaled 720d value
- 3 Scaled Tooth angle is y
- 4 Scaled missing tooth angle is y * # of missing teeth
Proposed table
Typical Meaning | Variable names | 1-10 | 1-12 | 1-16 | 1-36 | 60-2 | ||
Total Teeth | Entered | internal | 10 | 12 | 16 | 36 | 60 | |
missing teeth | Entered | Number of teeth missing | 1 | 1 | 1 | 1 | 2 | |
Teeth Present | Calc | Number of teeth on wheel | 9 | 11 | 15 | 35 | 58 | |
Crank Rotations per complete clycle | Entered | internal | 2 | 2 | 2 | 2 | 2 | (2 for 4cycle 1 for 2 cycle) |
Degrees per complete cycle* | Calc | internal | 720 | 720 | 720 | 720 | 720 | |
720 / Total Teeth = Angle Per tooth (degrees) | Calc | 36.0 | 30.0 | 22.5 | 10.0 | 6.0 | ||
Total Degrees scaled to 8 bit unsigned: 255/total teeth | Calc | 12.8 | 10.6 | 8.0 | 3.5 | 2.1 | ||
Truncate for integer math | Calc | 12 | 10 | 7 | 3 | 2 | ||
Scaled degrees per cycle | Calc | EnginePhase when reset | 240 | 240 | 224 | 216 | 240 | |
Scaled degrees per tooth | Calc | Angular width of tooth | 12 | 10 | 7 | 3 | 2 | |
Scaled degree of missing spaces(teeth+1) | Calc | Angular width of missing tooth | 24 | 20 | 14 | 6 | 6 | |
Now you have to Determine what the next trigger tooth is
Number of Clynders | |||||||
4clyn | Entered | 4 | Good | Good | Good | Good | Good |
Teeth until next clyn event | Calc | Next trigger tooth | 5.00 | 6.00 | 8.00 | 18.00 | 30.00 |
Calc | Scaled deg/ cylinders | 60.00 | 60.00 | 56.00 | 54.00 | 60.00 | |
5clyn | Entered | 5 | Good | NotValid | NotValid | NotValid | Good |
Teeth until next clyn event | Calc | Next trigger tooth | 4.00 | 4.80 | 6.40 | 14.40 | 24.00 |
Calc | Scaled deg/ cylinders | 48.00 | 48.00 | 44.80 | 43.20 | 48.00 | |
6clyn | Entered | 6 | NotValid | Good | NotValid | Good | Good |
Teeth until next clyn event | Calc | Next trigger tooth | 3.33 | 4.00 | 5.33 | 12.00 | 20.00 |
Calc | Scaled deg/ cylinders | 40.00 | 40.00 | 37.33 | 36.00 | 40.00 | |
8clyn | Entered | 8 | NotValid | Good | Good | Good | Good |
Teeth until next clyn event | Calc | Next trigger tooth | 2.50 | 3.00 | 4.00 | 9.00 | 15.00 |
Calc | Scaled deg/ cylinders | 30.00 | 30.00 | 28.00 | 27.00 | 30.00 | |
10clyn | Entered | 10 | Good | NotValid | NotValid | NotValid | Good |
Teeth until next clyn event | Calc | Next trigger tooth | 2.00 | 2.40 | 3.20 | 7.20 | 12.00 |
Calc | Scaled deg/ cylinders | 24.00 | 24.00 | 22.40 | 21.60 | 24.00 | |
12clyn | Entered | 12 | NotValid | Good | NotValid | Good | Good |
Teeth until next clyn event | Calc | Next trigger tooth | 1.67 | 2.00 | 2.67 | 6.00 | 10.00 |
Calc | Scaled deg/ cylinders | 20.00 | 20.00 | 18.67 | 18.00 | 20.00 |
The min_crank_per describes the minumum time between 'valid trigger events. If you use this table select your # of clynders and RPM limit. and then just plug in that number
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minmum period in microseconds(us) between trigger events | |
Assumes Crank Trigger | # of clynders |
RPM limit | Safety Margin | 2 or 4 cycle | 4 | 5 | 6 | 8 | 10 | 12 |
1000 | 1000 | 4 | 15000 | 12000 | 10000 | 7500 | 6000 | 5000 |
1500 | 1000 | 4 | 12000 | 9600 | 8000 | 6000 | 4800 | 4000 |
2000 | 1000 | 4 | 10000 | 8000 | 6667 | 5000 | 4000 | 3333 |
2500 | 1000 | 4 | 8571 | 6857 | 5714 | 4286 | 3429 | 2857 |
3000 | 1000 | 4 | 7500 | 6000 | 5000 | 3750 | 3000 | 2500 |
3500 | 1000 | 4 | 6667 | 5333 | 4444 | 3333 | 2667 | 2222 |
4000 | 1000 | 4 | 6000 | 4800 | 4000 | 3000 | 2400 | 2000 |
4500 | 1000 | 4 | 5455 | 4364 | 3636 | 2727 | 2182 | 1818 |
5000 | 1000 | 4 | 5000 | 4000 | 3333 | 2500 | 2000 | 1667 |
5500 | 1000 | 4 | 4615 | 3692 | 3077 | 2308 | 1846 | 1538 |
6000 | 1000 | 4 | 4286 | 3429 | 2857 | 2143 | 1714 | 1429 |
6500 | 1000 | 4 | 4000 | 3200 | 2667 | 2000 | 1600 | 1333 |
7000 | 1000 | 4 | 3750 | 3000 | 2500 | 1875 | 1500 | 1250 |
7500 | 1000 | 4 | 3529 | 2824 | 2353 | 1765 | 1412 | 1176 |
8000 | 1000 | 4 | 3333 | 2667 | 2222 | 1667 | 1333 | 1111 |
8500 | 1000 | 4 | 3158 | 2526 | 2105 | 1579 | 1263 | 1053 |
9000 | 1000 | 4 | 3000 | 2400 | 2000 | 1500 | 1200 | 1000 |
9500 | 1000 | 4 | 2857 | 2286 | 1905 | 1429 | 1143 | 952 |
10000 | 1000 | 4 | 2727 | 2182 | 1818 | 1364 | 1091 | 909 |
10500 | 1000 | 4 | 2609 | 2087 | 1739 | 1304 | 1043 | 870 |
11000 | 1000 | 4 | 2500 | 2000 | 1667 | 1250 | 1000 | 833 |
11500 | 1000 | 4 | 2400 | 1920 | 1600 | 1200 | 960 | 800 |
12000 | 1000 | 4 | 2308 | 1846 | 1538 | 1154 | 923 | 769 |
12500 | 1000 | 4 | 2222 | 1778 | 1481 | 1111 | 889 | 741 |
13000 | 1000 | 4 | 2143 | 1714 | 1429 | 1071 | 857 | 714 |
13500 | 1000 | 4 | 2069 | 1655 | 1379 | 1034 | 828 | 690 |
14000 | 1000 | 4 | 2000 | 1600 | 1333 | 1000 | 800 | 667 |
14500 | 1000 | 4 | 1935 | 1548 | 1290 | 968 | 774 | 645 |
15000 | 1000 | 4 | 1875 | 1500 | 1250 | 938 | 750 | 625 |
15500 | 1000 | 4 | 1818 | 1455 | 1212 | 909 | 727 | 606 |
16000 | 1000 | 4 | 1765 | 1412 | 1176 | 882 | 706 | 588 |
16500 | 1000 | 4 | 1714 | 1371 | 1143 | 857 | 686 | 571 |
17000 | 1000 | 4 | 1667 | 1333 | 1111 | 833 | 667 | 556 |
17500 | 1000 | 4 | 1622 | 1297 | 1081 | 811 | 649 | 541 |
18000 | 1000 | 4 | 1579 | 1263 | 1053 | 789 | 632 | 526 |
18500 | 1000 | 4 | 1538 | 1231 | 1026 | 769 | 615 | 513 |
19000 | 1000 | 4 | 1500 | 1200 | 1000 | 750 | 600 | 500 |
19500 | 1000 | 4 | 1463 | 1171 | 976 | 732 | 585 | 488 |
20000 | 1000 | 4 | 1429 | 1143 | 952 | 714 | 571 | 476 |
20500 | 1000 | 4 | 1395 | 1116 | 930 | 698 | 558 | 465 |
21000 | 1000 | 4 | 1364 | 1091 | 909 | 682 | 545 | 455 |
21500 | 1000 | 4 | 1333 | 1067 | 889 | 667 | 533 | 444 |
22000 | 1000 | 4 | 1304 | 1043 | 870 | 652 | 522 | 435 |
22500 | 1000 | 4 | 1277 | 1021 | 851 | 638 | 511 | 426 |
23000 | 1000 | 4 | 1250 | 1000 | 833 | 625 | 500 | 417 |
23500 | 1000 | 4 | 1224 | 980 | 816 | 612 | 490 | 408 |
24000 | 1000 | 4 | 1200 | 960 | 800 | 600 | 480 | 400 |
24500 | 1000 | 4 | 1176 | 941 | 784 | 588 | 471 | 392 |
25000 | 1000 | 4 | 1154 | 923 | 769 | 577 | 462 | 385 |
25500 | 1000 | 4 | 1132 | 906 | 755 | 566 | 453 | 377 |