METHOD FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE

A method for controlling an internal combustion engine (100) operating at least partly on gaseous fuel with a varying gas quality (400) is disclosed. The internal combustion engine (100) includes a gaseous fuel admission valve (58) configured to supply the gaseous fuel to charge air. The method comprises operating (step 600) the internal combustion engine (100) to provide a preset power output with a valve opening duration (402) of the gaseous fuel admission valve (58) set within a preferred valve opening duration range (404). The method further comprises allowing (step 602) the valve opening duration (402) to change in order to maintain the preset power output, monitoring (step 604) the valve opening duration (402) and determining (step 606) that, during operation of the internal combustion engine (100) at the predetermined power output, the valve opening duration (402) changed to a value outside the preferred valve opening duration range (404). The method further comprises adapting (steps 610, 614, 618) a fuel supply parameter (412, 503, 507) such that the valve opening duration (402) returns to the preferred valve opening duration range (404), while continuously providing the preset power output.