Slicing E value or flow rate percentage no change in Gcode

[Lorenzo infn]

When i sliced a objet in the slicing a want to set different amount of flow in different region of my object for example more flow percentage in the outer shell instead of infill.
I have tried different approach:
1) if i set different flow rate in the slicer in the Gcode file there is no change both in E value and in M221 value (Set flow percentage)
2) If i set different width percentage in the Gcode there is no change in E value in the Gcode, for example if i change from 100% to 200% line width there is no difference. Is there some advanced or hidden setting to enable/disable?

Lorenzo