A grain cleaning system of an agricultural combine directs a flow of high velocity air in a first direction about an inlet end of a cleaning shoe. The system further monitors the cleaning shoe in order to detect a change in an operational parameter of the cleaning shoe, wherein the operational parameter is one of a transient effect of a sieve of the cleaning shoe, a flow rate about and exit end of the cleaning shoe and a flow velocity about an exit end of the cleaning shoe. Further, the flow of high velocity air about the inlet end of the cleaning shoe can be redirected in a second direction in response to a detected change in the operational parameter.