Ignition settings, I need help

[eMTea]

I'm running a 1,8T 20v AEB engine by Audi.
It has a 60-2 crank wheel.
the missing teeth are under the VR sensor 90deg BTDC.
If i want to have max andvance 60deg (easy calcs).

then i would have:
#1 trigger pos A set to 5
#2 trigger return pos A set to 15
#2 trigger pos B set to 35
#4 trigger return pos B set to 45
May this be right?

this is an 4 cylinder with wasted spark. what should i fill in the other fields? leave them with 0?

[eMTea]

Ok, i think i finally figured this out, please take a look at my illustratoin attached here:

[Pete M]

eMTea

Took me quite awhile to get my head round this, so from one newbie to another

First off always count the first tooth after the gap as tooth 2

Think of it this way

On a 60-2 wheel each tooth equals 6 degrees, 360 divided by 60 = 6

So if you were to turn the engine back so that tooth 0 is in line with the VR sensor, even though it does'nt exist it's still tooth 0, your engine would be at 90 degrees BTDC

Each tooth counts as 6 degrees crankshaft movement which we already know so to get to 60 degrees BTDC we need to turn the crank forward 30 degrees or 5 teeth, 5x6=30 degrees 90-30=60 degrees

Don't forget that even though tooth 1 does not exist it still accounts for 6 degrees of crankshaft movement, so the first tooth after the gap is tooth 2 which is equal to 12 degrees of crankshaft movement

Using the above your trigger for spark A would be tooth 5

Use the same to calculate trigger return

To get to 12 degrees BTDC we need to turn the crank forward 78 degrees or 13 teeth, 13x6=78 degrees 90-78=12 degrees

So spark A trigger return is tooth 13

Spark B is easy just add 180 degrees or 30 teeth to the above figures which gives you

Spark B trigger tooth 35
Spark B trigger return tooth 43

For all the other fields you enter 0

As stated previously I'm a newbie but this is the way I understand it and it worked for me

Pete

[eMTea]

Ok, it worked for you, but the only differece between our setup, as i see, is trigger angle, you have trigger A at tooth 5, and trigger A return to tooth 13.
That is 8 teeth differece = 48degrees.

My trigger angle is 60, 10 teeth apart, the 12degree i mentioned, was an advance example from the spark table.

I thought it was naturally that the missing teeth were 59/60, but i may be wrong. then i can only decrease all my values by 1.?


Do you have a engine running with those settings?

[Pete M]

eMTea

Yes I do have an engine running using this theory the only thing different is that in my case the VR sensor is positioned 120 degrees BTDC

As I say I am very new here but the way I understand it is that the trigger angle sets your maximum advance and the trigger return sets your cranking angle

So from the figures I gave you your maximum advance would be 60 degrees and cranking angle would be 48 degrees later or 8 teeth which would be 12 degrees

I may be way off base here so perhaps someone else can confirm my theory

Pete

[eMTea]

as the way >I< understand it, you set the trigger angle to a level, OVER, your maximal advance, and you set trigger return (end of trigger angle spectre) to the place where the cyl is at TDC, then the ECU uses the table to set the Ignition advance. the ignition advance i used as an example, is 12degrees, an 60-12=48, (48/6 = 8teeth), then the ecu "counts" 48degrees (8teeth) from trigger A posison, and fire the coil.

I'm quite sure that is right, but i'm only a human ;)

My little question is, the missing teeth (2) are they?:
1 -> #1/2
2 -> #59/60
3 -> #60/1

[bens_cab]

hi guys as your talking about 20vt engines ive got some questions im just finishing of my 20vt conversion but having some wiring issues my main ones are the vr sensor and the fuel pump how do you have your vr sensors wired my car is a mk1 gti cabrio 88

engine is agu code runnign standard coilpacks cop just wondered if one of you would have a wiring diagram that you have made as the megasquirt one looks different evry time i look

sorry for hijacking the thread but i too will need to set my wheel decoder and trigger angles ect

and im a real novice to all this

many thanks
ben