Ignition table axes questions - rotary specific

[Pete_89t2]

Hi,

I'm working on a modified single turbo FD that is running a wired in G4+ Fury that I purchased recently. While reviewing the prior owner's timing settings, I noted that his "Ignition Table 1" (aka Leading timing) and his "Trailing Split" table (trailing timing) had a different # of columns & rows, and different axis values assigned to them. I noted that the base S6 RX7 map that Link provides also has different axis values -- e.g., "Ignition Table 1" goes from 0 to 8500 RPM, while "Trailing Split" is 0 to 7500 RPM; "Ignition Table 1" uses MAP(psi) from 0 to 35.5, while Trailing Split also uses MAP, but from 0 to 36.2

Since it's my understanding that the actual trailing timing (i.e., when trailing plug fires) is based on the cell in the Ignition Table 1 plus its corresponding cell value in the Trailing Split table, shouldn't one use the same axis values on both tables for engine speed & load? In this case, the 2 tables have a different # of rows & columns, and the end limits differ, so what is really going on to set trailing timing?

I tried to change the trailing split table axes to match up with the "Ignition Table 1" axis values, but PCLink would not allow me to add the additional columns/rows that were necessary. Is this a limitation for this particular table? If it's not a hard limitation, how do I add rows/columns to the table? I followed the steps in the help file to add rows/columns, but it didn't work as expected.

Thanks!

[Adamw]

No you do not need the same parameters on the axes and they dont need to span the same ranges or even have the same breakpoints.  From memory I think the main fuel and ignition tables cam have a max breakpoint size of 22 x 20, while many of the less critical tables will have a max size of 16 x 11.

Trailing split does not generally need a high resolution table as it usually only changes a small amount (if at all) over the full operating range.  I often see rotary maps with 12deg in every cell - so no point having aal 176 cells populated all with the same number in them...

My general tuning philosophy is to start as simple as possible and only make it more complicated when/if it needs to be.  So I will usually start with the bare minimum breakpoints that I think it will need.  For the main ign table I will usually do 500RPM increments up to about 5000RPM, then 1000RPM above that.  For the MAP breakpoints 20kpa around idle/cruise then 40kpa on boost.  If in the process of tuning that ign table I find there is some area where the timing requirements are vastly different cell to cell then I will just add a new column/row at that point only.  When you add a new row/column in the Link software it doesnt mess up the rest of your tune like it does with many other ecu's so you only need to tune the newly added row/column.

Same idea with your split table - the few turbo engines I have tuned only varied from about 8deg at light loads to 12deg at high loads, so you likely will only need something like a 6x6 table in most cases.  NA engines typically just have a flat 10deg all over so will only need one cell.

When the engine is running you will have crosshairs on all of your tables showing where in the table the engine is operating, and you can also add "gauges" to your page showing live the commanded ign timing and split that it is pulling from those tables.

[Pete_89t2]

Thanks! That detailed explanation helps a lot. Looks like there's no need for me expand beyond the 16 x 11 limits of the trailing split table.