Patent ID: 8594909

Claim:
A method of stoichiometrically operating a diesel-fueled internal combustion engine, comprising: providing an engine control unit having stored data representing, within a range of early exhaust valve closing timing modifications, an amount of fresh air flow and exhaust gas residuals resulting from each modification; during operation of the engine, providing a stoichiometric air-fuel ratio to the engine; during operation of the engine, using the engine control unit to perform the following tasks: determining a desired amount of exhaust gas residuals for a given engine load; accessing the stored data to determine a desired exhaust valve lift modification that will provide the desired amount of exhaust gas residuals; and generating a control signal that will result in the desired exhaust valve lift modification wherein the desired amount of exhaust gas residuals is predetermined to displace fresh air that would otherwise be inducted into the engine, to allow stoichiometric operation at the same intake manifold pressure and temperature as when fresh air is not displaced.