Method for diagnosing the integrity of a swirl generating system for an internal combustion engine

A method for diagnosing an integrity of a swirl generating system for an internal combustion engine, the swirl generating system comprising a plurality of swirl controlling elements that are individually located in a respective air passage connecting an in-take manifold of the internal combustion engine to an intake port of an engine combustion chamber, an actuator having a movable shaft, a cinematic chain for mechanically connecting the plurality of swirl controlling elements to the movable shaft, an actuator control unit adapted to normally move the movable shaft in a first direction towards a first final position and in a second opposite direction towards a second final position, and an sensor adapted to sense a position of the movable shaft, the method comprising the steps of:

• arranging at least a first mechanical stop on the in-take manifold to directly act on a component of the cinematic chain in order to indirectly limit a movement of the movable shaft in the first direction at a first checking position that is at least coincident or beyond the first final position;
• coupling at least a second mechanical stop to the in-take manifold to directly act on one component of the cinematic chain in order to indirectly limit the movement of the movable shaft in a second direction at a second checking position that is co-incident or beyond the second final position;
• coupling at least a third mechanical stop to the actuator to directly act on the movable shaft to limit the movement of the movable shaft in the first direction at a first extreme position that is beyond the first checking position and first final position;
• coupling at least a fourth mechanical stop to the actuator to directly act on the movable shaft to limit the movement of the movable shaft in the second direction at a second extreme position that is beyond the second checking position and second final position;
• moving the movable shaft in the first direction towards the first checking position based upon a command from the actuator control unit;
• verifying with the sensor whether the movable shaft stops in the first checking position or stops in the first extreme position;
• moving the movable shaft in the second direction towards said second checking position based upon a second command from the actuator control unit;
• and
• verifying with the sensor whether the movable shaft stops in the second checking position or stops in the second extreme position.