Operation method for an injection device of a direct injection combustion engine

The fuel injection system has a high pressure fuel pump with a control device (18) and a first injection valve (9) for each cylinder (3) of the combustion engine. The system also has at least a second injection valve (15) for injecting fuel into an intake pipe (7). The second valve is preferably located to inject fuel between the opening of the emission return pipe and a combustion chamber (4). Independent claims also cover a method, control device and computer program for the system.