With wasted spark you're best to get the cheapest, simplest type that you can. I was annoyed that I could only get a Gunson one with a retard dial ("I dont care what the light 'thinks' the spark is doing, I want the light to tell me what the ECU is doing to the spark").
The Nissan CAS is optical, it gives a very sharp Hall output, the outer four slots tell VEMS that a cylinder event is about to happen, the inner slot tells the VEMS that one complete sequence (all four cylinders have fired, all for plugs have sparked) has occured and from that the system synchronises itself. The ideal triggering point for the outer four slots is 90-60deg BTDC, it would be handy if you could line up the inner sync slot to indicate that cylinder 1 was about to fire, but it is not important - we can define the sequence to start on any cylinder in the MegaTune: Settings->Ignition Outputs
You set the number of ignition events per sequence in the Ignition Outputs in use in h2[] box. For four coils you select 03..00
When VEMS gets the inner slot it will start counting from 03 and with each outer slot it will count down (02, 01, 00) and of course by the time its set to count again the inner slot comes round to restart the count down.
You specify which coils are fired by the drop down boxes numbered 0 to 7, if you were to wire the coils cylinder 1 = 0 (EC36 pin35), 2 = 1 (EC36 pin33) etc you would specify the 1,3,4,2 firing order as:
0 = 1 (EC36 pin33)
1 = 3 (EC36 pin36)
2 = 2 (EC36 pin34)
3 = 0 (EC36 pin35)
With wasted spark you'd more than likely set it up as:
0 = 1 (EC36 pin33)
1 = 0 (EC36 pin35)
2 = 1 (EC36 pin33)
3 = 0 (EC36 pin35)
