Abstract: The amount of fuel injected in an engine with variable cam timing is more accurately reflective of engine operating conditions by accounting for the phase angle of the camshaft relative to the crankshaft in the calculation of the cylinder air charge. The cam phase angle for the existing engine speed is sensed and used in the calculation of a manifold filling coefficient which modifies the leakage compensated air flow data obtained from a mass air flow meter. A predicted final cylinder air charge is calculated based on the modified air charge from the manifold filling model and the required fuel for a desired air/fuel ratio is based on the calculated cylinder air charge.