Abstract: Disclosed is a device for reducing the combustion instabilities of a combustion engine, this device including: an intake circuit admitting oxidizing air to the engine, a valve positioned on the engine oxidizing air intake circuit and designed to regulate the flow rate of oxidant gas admitted to the engine, an exhaust gas recirculation circuit connected to the intake circuit upstream of the oxidizing air flow rate regulating valve. The device is arranged in such a way that, at least when an injection of fuel to the engine is cut off, a minimum opening of the valve is assured so as to eliminate recirculated gases from the intake circuit.

Abstract: Disclosed is a method for controlling a combustion engine, the combustion engine including an inlet circuit and an exhaust circuit, the method including the steps: determining a temperature of the exhaust gases flowing through the exhaust circuit of the combustion engine; comparing the determined temperature with a maximum threshold; and if the determined temperature is less than the maximum threshold, controlling the engine by decrementing the richness of operation by a predetermined value and jointly incrementing by a predetermined value a level of exhaust gases recirculated between the exhaust circuit and the inlet circuit of the combustion engine.

Abstract: Disclosed is a method for estimating the flow rate QEGR of exhaust gases recirculated through an exhaust gas recirculation valve connecting an exhaust circuit and an intake circuit of a combustion engine, the method including the steps: —of determining a difference in pressure ?P between the upstream and downstream sides of the valve, determining a density ?EGR of the recirculated exhaust gases passing through the valve, determining a corrected effective area Seff_cor of the valve, estimating the flow rate QEGR of the recirculated exhaust gases from these three parameters.

Abstract: Disclosed is a method for diagnosis of an oxygen probe for a combustion engine, with the steps: When an engine's fuel injection is inactive, measuring the output electric voltage from the oxygen probe; If the measured output electrical voltage of the oxygen probe is greater than a predetermined minimum voltage threshold, measuring a pressure prevailing in an intake distributor of the engine; If the measured pressure in the intake distributor is less than a predetermined minimum pressure threshold, increasing the pressure to a value greater than the predetermined minimum pressure threshold; Determining the time period between the time when the output electrical voltage of the probe falls below a second predetermined voltage threshold and the time when the output electrical voltage of the probe falls below a third predetermined voltage threshold; and diagnosing the oxygen probe depending on elapsed the time period.

Abstract: Disclosed is a method for estimating the flow rate QEGR of exhaust gases recirculated through an exhaust gas recirculation valve connecting an exhaust circuit and an intake circuit of a combustion engine, the method including the steps: —of determining a difference in pressure ?P between the upstream and downstream sides of the valve, determining a density ?EGR of the recirculated exhaust gases passing through the valve, determining a corrected effective area Seff_cor of the valve, estimating the flow rate QEGR of the recirculated exhaust gases from these three parameters.