Air mixer

[991hughes]

Can anybody help with a black smoke issue on ds3 no faults in ecu no air leaks new dpf filter fitted new maf sensor fitted egr follows command postions in live data noticed air mixer valve percentages change when car is cold once warm air mixer stays at zero postion is this normal also should egr retern to zero straight away with no throttle sometimes seems to take a while to tern to 0 percent in live data many thanks