Knock control with wasted spark ignition

[Josh Colombo]

I wanted to confirm that the knock control is setup this way for wasted spark ignitions.....based on the help file, the most I can get is knock detection on paired cylinders?  So for a 4-cyl boxer engine, cylinders 1 & 2 share the same coil, as do cylinder 3 & 4.  The firing order is 1-3-2-4.

I'm assuming cylinders 1 & 2 share the same trim table, and cylinders 3 & 4 share the same trim table.  Is this correct?  What happens if you set each cylinder to have its own trim table?  Do cylinders 2 & 4 just not have knock control on them, or does the knock control in general just not work?

In previous PC Link/firmware revisions, several years ago, I could have sworn the individual trim tables for each cylinder worked with the wasted spark setup.  Any feedback on past knock control?

Thanks
Josh

[Jurgen Biggelaar]

Hi Josh.

All you will effectively do is waste 2 valuable tables that can be used for something else.  You CAN set up a table for each cylinder, that's not the problem... It would still work (looking at the tables running each coil), it would just be completely pointless to do this.  With wasted you are firing the same 2 cylinders with one ignition channel so there is just NO WAY you can have any effect over 1 of those cylinders individually.

Going multi-coil or distributed (annoyingly enough) can see you individually controlling the timing on all cylinders.  This is one of the unfortunate drawbacks of a wasted spark system, a pure physical limitation of how wasted spark works.  As for the older ECU's, the same physical limitation will exist by pure nature of the wasted spark set up.

Jurgen

[Josh Colombo]

Thanks for confirming the limitations of the wasted spark setup.  I have thought of converting to the individual coil setup, but haven't done much research on what I can shoe-horn in there.  Unfortunately, the first generation Subaru turbo legacies in the US were setup with wasted spark ignitions vs. individual coils.

Thanks
Josh