Method for controlling a high pressure gas injection internal combustion engine

A method of controlling a diesel type high pressure gas injection internal combustion engine, the method comprising

• injecting, in a first combustion mode, by means of a first gas injection system, a first gaseous fuel into a cylinder of the engine, the step of injecting the first gaseous fuel comprising injecting the first gaseous fuel after a crankshaft angle of 90 degrees before a top dead centre position at the end of a compression stroke of the cylinder,
• accumulating in a container of a second gas injection system excess gaseous fuel from the first fuel system, and
• shifting, in the cylinder, from the first combustion mode to a second combustion mode comprising
• determining a value of an air flow related parameter indicative of an air mass flow into the cylinder,
• wherein the second combustion mode further comprises determining, based on the determined air flow related parameter value, a value of a fuel flow related parameter indicative of a mass flow of the excess gaseous fuel, and
• supplying from the container, in accordance with the determined fuel flow related parameter value, the excess gaseous fuel to provide a premix of air and the excess gaseous fuel to the cylinder,
• wherein the premix has a lambda value of 1.3-1.7.