A method of stoichiometrically operating a diesel-fueled internal combustion engine. A control unit is provide with stored data representing, within a range of exhaust valve timing or event modifications, an amount of fresh air flow and exhaust gas residuals resulting from each modification. During operation of the engine, the control unit is used to determine a desired amount of exhaust gas residuals for a given engine load; to access the stored data to determine a modification that will provide the desired amount of exhaust gas residuals; and to generate a control signal that will result in the desired modification.