Abstract: During the starting, a) the temperature (T) of the engine and the pressure (P) of the fuel delivered by said pressurizing means are monitored, b) if T is below a predetermined threshold temperature (Ts), an engine starting mode is established in which the engine is started with fuel at high pressure as soon as the pressure (P) becomes higher than a predetermined threshold pressure (Ps1), and c) an engine starting mode is established where the engine is started using fuel at low pressure if T>Ts.

Abstract: Fuel vapors leaving the fuel tank of a motor vehicle are recovered with a filter cartridge inserted between the tank and the intake manifold of the engine. An atmospheric connection duct of the cartridge can be selectively connected to the intake partial vacuum with a pneumatic distributor. The leaktightness of the device is thereby tested.

Abstract: An oxygen sensor, whose output signal switches between two levels, is arranged in the gas flow leaving the catalytic converter. During regulation at a stabilized speed, the injection time suitable for ensuring stoichiometry of the air/fuel mixture is determined. During a predetermined time interval a time variation of symmetric deviation, whose amplitude and shape is predetermined about a base injection time chosen from the determined injection time, is imposed on the injection time. The base injection time used during successive time intervals is modified progressively and in a monotonic manner so as to center the deviation of the injection time on that of the oxygen storage capacity of the catalytic converter. Catalyst efficiency is evaluated from an oscillation of this signal.