Abstract: The invention applies to the control of the variable opening and closing of an intake valve.According to the invention, a set-point position (.alpha..sub.c) for an event related to the valve is calculated continuously. Upon the detection of a change in the set-point (.alpha..sub.c) or in the engine speed (N), the establishment of the new set-point is controlled in an open loop during at least the first engine cycle following the detection of the set-point change, and b) the adjustment to the new set-point is controlled in a closed loop during subsequent engine cycles. The control is applied to a mechanism for triggering the event with an advance (AV) on the event. In each open-loop control cycle, this advance is read in a stored table, as a function of the engine speed (N) and the set-point position (.alpha..sub.c)calculated for the event.

Abstract: A value (RFD.sub.tab) of a lag in the closure of an intake valve (2) associated with the cylinder (4.sub.1), as a function of the engine speed (N), is obtained from a table, and the closure of this valve (2) is controlled as a function of this lag. During operation at a stabilized speed under a heavy load, the applied closure lag is gradually varied from the stored value in steps (.epsilon.), the load of the cylinder is measured and compared before and after each successive step, and the stored value (RFA.sub.tab) of the lag is updated when a comparison reveals an increase in said load, until a maximum for the latter is detected.