Artigo Completo:

The paper describes and presents practical results of a method for detection of internal fuel leakage in an engine. The method is based in unexpected oxygen concentration changes measured in the exhaust gases together with the Engine Roughness (disturbance on the Low Idle controller). The concept is useful to detect small leakages or a fuel injector blocked in the open position. This strategy can be used when the fuel injectors are blocked in the open position and the engine is in one of these two states: no external torque demand and torque is controlled by the low idle controller (Low Idle) or no external torque demand and torque is increasing due to the drag of the engine external influence (Overrun). The measurements were performed on a system with natural gas injection in a Dual Fuel (Diesel + CNG) vehicle equipped with a lambda sensor on the exhaust pipe. The measurements were performed on a system with natural gas injection in a Dual Fuel vehicle.