Method to control a four stroke internal combustion engine, which internal combustion engine comprises, - at least one first and one second cylinder (C1, C4); - a first piston, arranged in the first cylinder; - a second piston, arranged in the second cylinder; - two first inlet valves, arranged in the first cylinder, which first inlet valves are connected to an inlet system; - two first exhaust valves, arranged in the first cylinder 1, which first exhaust valves are connected to an exhaust system; - two second inlet valves, arranged in the second cylinder, which second inlet valves are connected to the inlet system; - two second exhaust valves, arranged in the second cylinder, which second exhaust valves are connected to the exhaust system; - at least one first valve control means, which controls the first and the second inlet valves (18, 19); - at least one second valve control means, which controls the first and the second exhaust valves (24, 25); and - a crankshaft, controlling each valve control means (22, 28), wherein the method comprises the following steps: a) controlling the first inlet valve and the first exhaust valve, so that no air is supplied to the exhaust system from the first cylinder when the first piston moves backwards and forwards in the first cylinder, b) supplying a first fuel volume to the first cylinder during the expansion stroke of the first cylinder, c) supplying a second fuel volume to the second cylinder during the expansion stroke of the second cylinder, and d) reducing the air mass sucked into the second cylinder in relation to the air mass sucked into the first cylinder, characterised in that, in step e): - controlling one of the first inlet valves to open at a bottom dead centre for the piston in the first cylinder, between an expansion stroke and an exhaust stroke, and to close at a top dead centre for the piston in the first cylinder, between an exhaust stroke and an inlet stroke, - controlling the second of the first inlet valves to open when the one of the first inlet valves closes, and to close at the bottom dead centre, between the inlet stroke and a compression stroke, and - controlling the first exhaust valves, so that they remain closed during all the strokes of the engine. - at least one first and one second cylinder (C1, C4); - a first piston, arranged in the first cylinder; - a second piston, arranged in the second cylinder; - two first inlet valves, arranged in the first cylinder, which first inlet valves are connected to an inlet system; - two first exhaust valves, arranged in the first cylinder 1, which first exhaust valves are connected to an exhaust system; - two second inlet valves, arranged in the second cylinder, which second inlet valves are connected to the inlet system; - two second exhaust valves, arranged in the second cylinder, which second exhaust valves are connected to the exhaust system; - at least one first valve control means, which controls the first and the second inlet valves (18, 19); - at least one second valve control means, which controls the first and the second exhaust valves (24, 25); and - a crankshaft, controlling each valve control means (22, 28), wherein the method comprises the following steps: a) controlling the first inlet valve and the first exhaust valve, so that no air is supplied to the exhaust system from the first cylinder when the first piston moves backwards and forwards in the first cylinder, b) supplying a first fuel volume to the first cylinder during the expansion stroke of the first cylinder, c) supplying a second fuel volume to the second cylinder during the expansion stroke of the second cylinder, and d) reducing the air mass sucked into the second cylinder in relation to the air mass sucked into the first cylinder, a) controlling the first inlet valve and the first exhaust valve, so that no air is supplied to the exhaust system from the first cylinder when the first piston moves backwards and forwards in the first cylinder, b) supplying a first fuel volume to the first cylinder during the expansion stroke of the first cylinder, c) supplying a second fuel volume to the second cylinder during the expansion stroke of the second cylinder, and d) reducing the air mass sucked into the second cylinder in relation to the air mass sucked into the first cylinder, - controlling one of the first inlet valves to open at a bottom dead centre for the piston in the first cylinder, between an expansion stroke and an exhaust stroke, and to close at a top dead centre for the piston in the first cylinder, between an exhaust stroke and an inlet stroke, - controlling the second of the first inlet valves to open when the one of the first inlet valves closes, and to close at the bottom dead centre, between the inlet stroke and a compression stroke, and - controlling the first exhaust valves, so that they remain closed during all the strokes of the engine.