A variable camshaft drive system for an internal combustion engine includes a primary camshaft phaser interposed between the engine crankshaft and a first camshaft. A secondary camshaft phaser determines the phase relationship between the first camshaft and a second camshaft driven by the first camshaft and which is located on the same bank of cylinders as the first camshaft. The operation of each phaser is controlled by an electronic controller which samples one or more engine operating parameters.