I don't think I'm explaining it very well and that is because I don't fully understand it myself.
As they say if you cannot explain it to a 5 year old then you don't really understand it yourself!
What doesn't help is the lag in reporting values to screen.
One reason why I still use Windows TuneECU over the Android, you have this lovely cell tracer thing that highlights the column and row in the tables that the ECU is referencing from for fuel or ignition, as the engine runs.
Where the column and row intersect, is the cell containing the value that the ECU is working off.
E.g. in this screenshot, the yellow outlined cell is the one.
Based on MAP value (650hPa) and engine speed (1290 RPM) received, the ECU is taking 3452 x20 mg as the mass of air being inducted, and then via its invisible injector spec, is determining the pulse time to open the injector for, to achieve an air/fuel ratio of whatever is in the corresponding cell in the AFR table.
PCV has a similar feature, except it actually highlights the cell itself, which is better.
Anywho the above is with the 1 bar MAP sensor.
The red outlined cell is around where idle is, with the 2.5 bar MAP sensor.
So that is around where I must adjust the values in the cell until I get a nice air/fuel ratio at idle.
And just use L tables to fuel real small throttle positions like 0 - 3%.
If that don't work good (probably because there is not much room on the left side of that cell), I will have to work around it with good ol PCV.
I asked Alain for a special TuneECU turbo map that has up to 2500hPa in the L tables but he doesn't seem interested.