MFB50 Timing Better to Reduce Transient NOx Emissions: Because operation of a diesel engine on PCI combustion is limited in its operating range, the combustion mode needs to be switched between PCI combustion and conventional diesel combustion depending on engine operating conditions for full-range operation. Researchers at Mitsubishi Fuso Truck and Bus continue development of technology that enables smooth transitions between combustion modes particularly under transient operating conditions and while exhaust emissions are controlled to remain low. A method to control combustion was developed to reduce NOx spike that occurred when the combustion mode was switched.