Abstract: A system is disclosed for modifying fuel pressure in a high-pressure fuel injection system of an internal combustion engine for subsequent fuel system leak testing. The fuel pressure in a fuel collection unit of the fuel injection system is increased to a fuel pressure near a maximum allowable fuel collection unit fuel pressure value while maintaining low engine load.

Abstract: A system for diagnosing an air handling mechanism of an internal combustion engine includes an air handling mechanism actuator, an air handling mechanism position sensor, a sensor associated with an engine operating condition separate from the air handling mechanism yet responsive to changes in the position of the mechanism actuator, and a control computer. The control computer is responsive to the position sensor signal and the engine operating condition sensor to diagnose faults/failure conditions associated with any of the air handling mechanism, the mechanism position sensor and the mechanism actuator. The air handling mechanism may be any of an EGR valve, a variable geometry turbocharger, a wastegate valve and an exhaust throttle, and the engine operating condition sensor may be associate with any of air intake pressure, air intake temperature, mass flow rate of intake air, exhaust gas pressure, EGR mass flow rate or turbocharger speed.

Abstract: A system for diagnosing an air handling mechanism of an internal combustion engine includes an air handling mechanism actuator, an air handling mechanism position sensor, a sensor associated with an engine operating condition separate from the air handling mechanism yet responsive to changes in the position of the mechanism actuator, and a control computer. The control computer is responsive to the position sensor signal and the engine operating condition sensor to diagnose faults/failure conditions associated with any of the air handling mechanism, the mechanism position sensor and the mechanism actuator. The air handling mechanism may be any of an EGR valve, a variable geometry turbocharger, a wastegate valve and an exhaust throttle, and the engine operating condition sensor may be associate with any of air intake pressure, air intake temperature, mass flow rate of intake air, exhaust gas pressure, EGR mass flow rate or turbocharger speed.