I don't know the names by heart in M3.8, but in older Motronics (M2.X) there were two maps based on RPM for Lambda adjustment.
The values in those map were LOAD. First map was for normal running and second map usually with higher values for limp mode without MAF.
If the LOAD was higher than in the map, then lambda control was disabled.

So for tuning you set it to 0, and after you are done, you set it back to values which match your fueling targets.
After you re-enable it, you can monitor the fuel trims.

If this table works like in older Motronics then when you set everything to 0 motronic will be open loop the entire time.
The values are closed loop threshold.

Come on man, I'd like to think explained it quite well now.
This map does not affect WOT. Just read what I wrote before.

This is working for idle and part throttle. Thank you !