Diesel engine cylinder skip firing system

A high horsepower diesel engine is operated in a skip firing mode in which the engine includes a plurality of individually controllable, fuel injected cylinders. The system senses that the engine is operating in a low horsepower mode and has a low fuel demand and thereafter selects a firing pattern of cylinders to be fired during each revolution of the engine crankshaft based upon the values of the sensed fuel demand and engine horsepower. The pattern selected for firing the cylinders is arranged such that all cylinders of the engine are fired within a preselected number of crankshaft rotations. The system also senses the engine air-fuel ratio and adjusts the pattern of cylinders being fired so as to maintain exhaust emissions below a preselected level. Additionally, the pattern of fired cylinders may be adjusted to maintain engine operating temperature and as a function of engine speed.