Abstract: The invention concerns a method for automatic adaptation of an injection engine by a computer connected to sensors. The sensors supply an engine filling parameter. An oxygen probe in the exhaust gases, defines, at each adapting cycle, a new line of control magnitude based on the filling parameter and using new coefficients computed from coordinates of two points. Corresponding corrected values of the control magnitude from a working line are filtered and stored during a preceding cycle. One of the two points is acquired previously, and then in adopting a new working line, an intermediate line between the new line and the previous working line is used. The invention is applicable to injection engine control.