Self-adapting method for controlling titre in an injection unit for an internal combustion engine

A self-adapting method for controlling titre for an internal combustion engine provided with a first and a second sensor of stoichiometric composition disposed respectively upstream and downstream of a system for reducing pollutant emissions and generating respective upstream and downstream composition signals. The method comprises the stages of determining a correction coefficient as a function of the upstream composition signal, the downstream composition signal and an objective signal indicative of an objective exhaust titre, determining an operating quantity of fuel to be injected into each cylinder of the engine as a function of the correction coefficient, memorising a plurality of current values of an adaptation signal each associated with a respective combination of values of the number of revolutions and the load of the engine, updating the current values as a function of the downstream composition signal, on each engine cycle, selecting one current value corresponding to the number of revolutions and the load of the engine in this engine cycle, generating the adaptation signal as a function of the current value selected and determining the correction coefficient also as a function of the adaptation signal.