Abstract: A method and apparatus disclosed provide dynamic prediction of re-circulated exhaust gas content in an engine intake manifold. An engine-controller combination, comprises a vehicle engine and an exhaust gas re-circulation valve providing re-circulation of engine exhaust gas. Several sensors determine measures of a set of engine parameters and provide measurement signals indicative of the measures. A microprocessor control unit receives the measurement signals, (ii) predicts future values of MAP and P.sub.o, where MAP represents an absolute pressure of an engine intake manifold and where P.sub.o represents a new air partial pressure of the engine intake manifold, and (iii) controls the vehicle engine in response to the predicted future values of MAP and P.sub.o.