Method for synchronizing an internal combustion engine on the basis of data from signals representative of air pressure in cylinders

A method for synchronizing an internal combustion engine during a start phase, the combustion engine comprising four cylinders,

• each of the cylinders being associated with an air intake pressure sensor in said cylinder,
• the engine being associated with a control unit configured to cause the engine to go from a configuration of selection of activation of the four cylinders to a configuration of selection of activation of two of said four cylinders, referred to as active cylinders, and vice versa,
• the method comprising, in the configuration of activation of two of said four cylinders, the following steps:
• receiving an event signal indicating starting of said combustion engine, then
• selecting a so-called current combustion engine position assumption on starting from among a plurality of possible assumptions on starting, then
• on receiving a signal representative of passage of the crankshaft through a first predetermined angular position carrying out a first step of acquisition of a first current value of air intake pressure in one, referred to as the first cylinder, of said two active cylinders and a second current value of air intake pressure in the other, referred to as the second cylinder, of said two active cylinders,
• executing a first test step to validate or invalidate the current assumption by comparing the first current value and the second current value, as a function of the current assumption and a predetermined margin:
• then, in the event of validation of the current assumption by the first test step:
• on receiving a signal representative of passage of the crankshaft through a second predetermined angular position carrying out a second step of acquisition of a third current value of air intake pressure in said first cylinder and a fourth current value of air intake pressure in said second cylinder, then
• executing a second test step to validate or invalidate the current assumption by comparing the third current value and the fourth current value, as a function of the current assumption and said predetermined margin,
• if the second test step validates the current assumption, a state of synchronization of the engine is reached,
• if not, the assumption is invalidated, the engine is physically rotated by one revolution of the crankshaft, then the steps of the method are repeated.