Abstract: A method for controlling an internal combustion engine (10) is provided. The engine (10) includes an exhaust gas recirculation (EGR) system (18, 20). The method includes determining an air mass flow rate through the intake manifold at a location upstream of the exhaust gas introduction, and determining an engine volumetric efficiency based on an engine speed and an intake manifold air density. An EGR flow rate is determined based on the volumetric efficiency, the intake manifold air density, an engine displacement volume, the engine speed, and the intake manifold air mass flow rate. The engine (10) is controlled based on the EGR flow rate. Preferred techniques for determining engine volumetric efficiency and EGR flow rate are also provided.