A method for detecting a disturbance of the torque observed on the output shaft of an internal combustion engine propelling a motor vehicle

This is to detect a disturbance due to the ascent in the driveline of the vehicle by moving the motor, forces due to the vehicle running on an uneven surface. According to the invention, a) estimating the mean torque (CPMH (k)) observable on the crankshaft (2) of the engine, the transition to the top dead center of a piston of a cylinder of the engine using the relation: CPMH (k) = J. PI. (Ni-Ni-1). Or where J is the moment of inertia of the drive train of the vehicle, viewed from said crankshaft (2), (Ni-1) and (or) the mean engine speed, measured in two angular sectors (alpha i-1, alpha i) of the rotation of the crankshaft extension equal and symmetrical with respect to the position of the crankshaft (2) in the portion of said top dead center point and b) detecting a disturbance of said pair when the estimated torque, or a predetermined linear combination of successive values ​​of said torque, exceeds a predetermined threshold.