MAP A / B config thoughts

[gunni]

Hello all.

I would like to share my thoughts with how VEMS does its A / B map switching, as I understand it every calibrate-able value is in both configs.
I think we should re-consider how VEMS does this as the current setup wastes precious map space with values that never change between configs, things like

injection and ignition setups, crank, cam setups, wideband settings, ecu calibrations, sensor calibrations, idle control settings, outputs etc.

Things that should change with map switching are :

fuel tables, ignition tables, lambda tables, boost control tables, variable cam targets etc.

I don´t know how much space there is to work with in total, but I feel we are wasting alot of if, I´d personally rather skip all map switching and put in more anytrim functions or incorporate them as standard functions.

Thoughts?

[fphil]

I have switched the maps to compare dwell times, idle settings, wideband settings etc, besides these values probably takes only few octets in the memory space.

[gunni]

When fully calibrated you dont need switchable dwell or wideband settings.
You just tune those settings and leave them, why do you want switchable dwell?

In any case, they may not take up much, but perhaps and I am not sure a secondary memory switch can be added to increase the map size capability of VEMS?
We need resolution and we need singularly adjustable X and Y axis for each table.

[VEMS]

Hello Gunni,

I may be mistaken, but i think you may have mentioned these things before; Could you elaborate exactly which maps you feel need to be increased in size, make some size suggestions and explain to me why its needed (showing some example of engine you are not able to map properly currently) ?

Best regards, Dave

[gunni]

I have mentioned the VE size before yes.

Lets take a NA ITB engine that I recently mapped, the max VE values are close too 200 in the fuel map, while idle region is 44. lowest values is 20 on the overrun.

So when I put in 45 in the idle region, that is a 2.2% step change. At overrun and low load higher rpm where values are even lower it is simply compounded. I have a value of 30 in one place, 31 is 3.3% fuel change. These values give as close to possible as I can get to the target I have set.

If I scale the top fuel values to 255 to make max use of the resolution available the idle region would be 56, 57 is 1.7%, that is literally the least amount of fuel change I can put in, maybe its the other ecu's I have worked with but this is just not good resolution.

For MAP based engines its far less of an issue obviously due to the nature of calculation the VEMS does

[fphil]

We could probably map properly an engine with a 12x12 VE map 

I would have preferred  an ignition map and an VE map with the same size of 16x16 since my base for tuning was the Marelli-Weber Ecu fw which maps are 16x16 and that I had guessed tuned to avoid detonations at specific regime (engine is turbo)

I had to use many columns/speeds to set up the idle (stabilizing, reaching and returning from overrun). I still need a low map entry of 0.20. For the boost, Weber's map set values for 1.50, 1.71, 1.85, 1.03 bar, I only entered  values for 1.50, 176, 200. Of course if I was able to tune the idling with less entries and if the engine was not turbo the sizes of the maps would have been alright

Truly it is better to start tuning on short maps and few values but afterwards more entries could be requested, sometimes unnecessary, but that's the tuner concern. So 16x16 maps  could give more easiness and convenience for tuning whatever the type of the engine and the experience of the tuner.

[gunni]

I hope there is no confusion I do not have any problems with the axis values, only the cell values,

I have mapped a ECU with 8x16 Alpha N (8tps, 16rpm) map with secondary single axis MAP compensation, the main map and the secondary map did not interpolate between cells. If you want trouble tuning that is what you work with !

when using speed density and the MAP based multiplication which VEMS uses indeed you could map an engine pretty well with a 6x6 map.

[VEMS]

Hello Gunni,

Ah i understand what you mean, you are referring to the table resolution (/stepsize) rather than the number of table cells, when tuning Alpha-N that makes sense.

Best regards, Dave

[gunni]

Yes,

but I also feel that our implementation of copying the whole map is not the best idea as many things are being used in two places in the complete map space when they should only be used in one.