[flightlead404]

Originally Posted by spuggy

I think MAP-based maps are supposed to look very flat. Mine pulls -10% fuel at idle, and same again at high kPA (when the venerable K27/HF runs out of CFM, to keep AFRs correct).

Interesting to hear of the MS row/column restrictions; MoTeC allows you to insert/delete rows/columns anywhere you feel like - so if you want cells every 50 or 100 RPM or 5 kPA around, say, idle, to zoom in and get something sorted, no problem.

However, this mostly seems useful to isolate a specific area to get it sorted - and once done, you generally remove almost all of them. If the values on your ignition map are a straight line on the graph, you only really need the 2 end points as all the intervening points are extrapolated...

Remember, these are ignition maps we're talking about, not fuel maps.

Ignition advance needs to be adjusted for rpm regardless of the mixture. The speed at which the charge burns is fairly static, so as speeds increase the charge needs to be ignited earlier and earlier BTDC to keep the point of max pressure in the same location ATDC. So, regardless of fuel delivery being flat, ignition would change I think.

MS2 (which is what the microsquirt is) allows 12x12 tables for ignition, and up to three tables with a variety of ways to switch e.g. based on pressure, or an external switch for example. The 12x12 limitation is expanded to 16x16 for MS3 I think. The cells can be anything you want, they don't need to be equally spaced.

Regarding spacing of the bins, yes I agree. So where the slope on the graph hits a min or a max you need a cell. And where slopes are steeper cells need to be closer together, and where shallower they can be further apart.