Patent ID: 7280912

Claim:
A method for controlling operation of an electronic control unit for use in an internal combustion engine, the electronic control unit being used to control different engine modes, the method comprising: providing a function mode map having a plurality of data map points wherein the function mode map is divided into at least a first type region containing data map points representing mode map output values only of a first mode type and a second type region containing data map points representing mode map output values only of a second mode type; and providing at least one further data map having a plurality of further data map points, each of the further map points representing a further data map output value; determining a current mode for an operating point on an operating path within the function mode map in dependence upon first and second engine operating parameters; determining a mode value for each of a plurality of hysteresis points within the function mode map in dependence upon the first and second engine operating parameters, the hysteresis points being arranged to surround the operating point; and determining a control function for the electronic control unit based on the current mode of the operating point and at least one further data map output value determined from the at least one further data map; wherein the operating point is associated with an existing mode and the current mode of the operating point is determined based on the following criteria: a) if the mode value of each of the plurality of hysteresis points is different to the existing mode of the operating point then setting the current mode of the operating point as equal to the mode value of the region of the function mode map that the operating point is currently located in; b) if one or more of the mode values of the hysteresis points is equal to the existing mode of the operating point then maintaining the existing mode value as the current mode of the operating point.