Does anyone here have any insight as to how an electronic retard works, and more specifcally, what sort of delay it introduces and how that delay relates to the degrees BTDC?

For example, the J&S safeguard intercepts the ignition signal. When the ECU sends the ignition signal, the piston is already heading up towards TDC. If the J&S adds a delay to the ignition trigger, it seems to me this would advance the timing rather than retard it, because the piston has moved closer to TDC.

I would asume what the box would have to do is wait for two ignition pulses so it can determine the delta between them. By ignoring the first, you could advance the second (by reducing the delta between ignition pulses). This does not strike me as ideal, but I can't see how the J&S (or MSD BTM) could be doing it differently based on the set of inputs they use.

If someone could shed some light on this, it would be great. I've already built myself a AFC style gadget for a/f tuning and am looking to do the same for ignition retard.

Many thanks.

 

That's something I would ask Filetofit in the FI forum.He's the only one that been able to explain this ignition stuff with-out qouting any texts. In my eyes that means he's the only one that can understand, but I've been wrong before.