A method of operating a piston engine , the method comprising the steps of - monitoring pressure in a plurality of cylinders of the engine , - based on the monitoring of cylinder pressure , determining the value of a first variable (CA 1 , HR 1 ), which represents the development of cumulative heat release in a single cylinder of the engine during one or more engine cycles up to a first reference point (R 1 ) , - comparing the value of the first variable (CA 1 , HR 1 ) to a predetermined first target value or target range, which represents desired development of the cumulative heat release in the single cylinder up to the first reference point (R 1 ) , - on the basis of the comparison, adjusting a first engine parameter, wherein the first engine parameter is a cylinder specific parameter affecting start of combustion in the single cylinder , - simultaneously with the determining of the value of the first variable (CA 1 , HR 1 ), based on the monitoring of cylinder pressure , determining the value of a second variable (CA 2 , HR 2 ), which represents the average development of cumulative heat release in a plurality of cylinders of the engine during one or more engine cycles up to a second reference point (R 2 ), the second reference point (R 2 ) being located at a later phase of combustion than the first reference point (R 1 ) , - comparing the value of the second variable (CA 2 , HR 2 ) to a predetermined second target value or target range, which represents desired average development of the cumulative heat release in the plurality of cylinders up to the second reference point (R 2 ) , and - on the basis of the comparison, adjusting a second engine parameter, which affects combustion in the plurality of cylinders , wherein the second engine parameter is the pressure of intake air. - monitoring pressure in a plurality of cylinders of the engine , - based on the monitoring of cylinder pressure , determining the value of a first variable (CA 1 , HR 1 ), which represents the development of cumulative heat release in a single cylinder of the engine during one or more engine cycles up to a first reference point (R 1 ) , - comparing the value of the first variable (CA 1 , HR 1 ) to a predetermined first target value or target range, which represents desired development of the cumulative heat release in the single cylinder up to the first reference point (R 1 ) , - on the basis of the comparison, adjusting a first engine parameter, wherein the first engine parameter is a cylinder specific parameter affecting start of combustion in the single cylinder , - simultaneously with the determining of the value of the first variable (CA 1 , HR 1 ), based on the monitoring of cylinder pressure , determining the value of a second variable (CA 2 , HR 2 ), which represents the average development of cumulative heat release in a plurality of cylinders of the engine during one or more engine cycles up to a second reference point (R 2 ), the second reference point (R 2 ) being located at a later phase of combustion than the first reference point (R 1 ) , - comparing the value of the second variable (CA 2 , HR 2 ) to a predetermined second target value or target range, which represents desired average development of the cumulative heat release in the plurality of cylinders up to the second reference point (R 2 ) , and - on the basis of the comparison, adjusting a second engine parameter, which affects combustion in the plurality of cylinders , <EOS>