Patent ID: 7597074

Claim:
A control system for an internal combustion engine including a plurality of banks and a plurality of variable valve actuating mechanisms, provided for the respective banks, for changing operating characteristics of intake valves, the control system comprising: a control device that controls the plurality of variable valve actuating mechanisms, by integrating a plurality of pieces of control information corresponding to the respective variable valve actuating mechanisms; wherein, when at least one of the plurality of pieces of control information becomes unknown, the control device learns the control information with respect to the variable valve actuating mechanism for the bank involving the unknown control information, and continues to control the variable valve actuating mechanisms for the remaining banks of the plurality of banks, using the known control information of the plurality of pieces of control information, and wherein, each of the variable valve actuating mechanisms includes an actuator that moves a drive element to adjust a lift of each of the intake valves of the corresponding bank, and a sensor that detects a change in a relative position of the drive element of the actuator; the control information includes an absolute position of the drive element which is calculated by adding the change in the relative position to a reference position in accordance with an output of the sensor; and when the absolute position calculated with respect to a first bank of the plurality of banks becomes unknown, the control device provisionally sets the absolute position to a value of a first operational limit of the drive element which provides the lowest lift of the intake valve, operates the actuator to gradually increase the lift until the drive element reaches a second operational limit which provides the highest lift of the intake valve, and learns a first reference position as the absolute position when the drive element reaches the second operational limit, and the control device causes the actuator to operate the drive element for another bank of the plurality of banks, in which the absolute position is known, so that the drive element moves within a specified range between the first and second operational limits, in accordance with the movement of the drive element for the first bank.