Three step cam defaulting strategy for engine position sensors

摘要

A method is provided for operating a three step camshaft system during engine position sensor fault conditions. The three step camshaft has multiple cam actuators each having an actuator pin. The method includes: disposing multiple camshaft barrels on a camshaft, each barrel having a slot receiving the actuator pin of a cam actuator during camshaft barrel rotation axially displacing each camshaft barrel to a high lift lobe position, a low lift lobe position and an active fuel management (AFM) lobe position; determining if an engine position sensor is in a fault condition; identifying if the fault condition occurs simultaneously with any of the camshaft barrels positioned in the AFM lobe position; energizing selected cam actuators in communication with the camshaft barrels positioned in the AFM lobe position to axially displace the camshaft barrel away from the AFM lobe position and to the low lift lobe position.