A method for controlling dual independent camshaft phasers in an internal
combustion engine. The method has three basic steps: a) first,
determining if rate balancing between the two phasers is required; b)
second, determining the optimal rate balancing commands; and c) third,
applying the determined rate balancing commands to the appropriate
phaser(s). In determining the rate balancing commands, there are three
possible phaser options: the intake phaser requires priority; the exhaust
phaser requires priority; or neither phaser requires priority. Lookup
tables are stored in the engine controller for each option. When either
phaser has priority, the other phaser is actuated after a delay based
upon the position error of the priority phaser, generally at a lower
phase rate. When neither phaser has priority, both phasers are actuated
at a rate consistent with oil-delivery capabilities of the engine.