Abstract: A method for controlling a direct injection internal combustion engine by measuring both the degree of actuation of an accelerator pedal and the engine speed to provide optimal engine tuning parameters. According to the method, a table showing the pressure/air temperature ratio in the intake manifold is established, during engine tune-up, for each degree of actuation/speed pair. The pressure and temperature of the intake air are measured during normal operation, and the measured pressure/temperature ratio is formed. The opening angle of a throttle in the intake manifold is adjusted to make the ratio dependent on a set value read out of the table. Reverse reading of the table is performed to determine a virtual degree of accelerator pedal actuation on the basis of the measured speed and ratio, thereby providing at least one of the optimal engine tuning parameters.

Abstract: The process assures the correction of the control of an actuator acting on the speed as a function of the error E=N.sub.c -N between a set-point speed (N.sub.c) and the actual speed (N), and of the time derivative (E') of this error. A correction (.DELTA.u) for the control of the actuator is derived from the addition of first (.DELTA.u.sub.1) and second (.DELTA.u.sub.2) partial corrections which are functions of the speed error (E) and the time derivative (E') of this error, respectively. These corrections are defined as a function of the relative position of the value of the error, or of the error derivative, with respect to at least two predetermined values of the error (or the derivative of the error), each of which has an associated predetermined value of the partial correction .DELTA.u.sub.1 (or .DELTA.u.sub.2).