To control diesel combustion, the electronically controlled high pressure fuel injection system - KOMPICS has been developed. The system has been first evaluated by the single cylinder engine. The performance has been found to be better than that of air swirl type combustion. Then the system has been fitted to Komatsu SA6D155 engine (6 cylinder turbocharged and after cooled engine, 155 mm in the bore 170 mm in the stroke) and tested. The performance was very attractive, that is not only the fuel economy was attractive but also the performance at low speed was especially improved for industrial heavy duty engines. Transient response was also significantly improved. Preliminary endurance tests for 1,000 hours has been conducted and no significant failure has been found.