An ECU that is a diagnostic device includes a calculation unit that is a water temperature obtaining unit obtaining the temperature of a discharge coolant which is a coolant discharged from an engine, a diagnostic unit that diagnoses a thermostat which is a temperature adjusting valve by comparing the temperature of the discharge coolant and a threshold, and a suspending unit that suspends a diagnosis performed by the diagnostic unit. The suspending unit suspends a diagnosis performed by the diagnostic unit in a case where the temperature of the discharge coolant is estimated to be lower than the threshold according to an operating condition of the vehicle even though the thermostat is normal.

A cooling device includes a first cooling medium circuit for circulating a cooling medium that passes through a main body of an engine to a first heat exchanger, a second cooling medium circuit for circulating a cooling medium that passes through the main body to a second heat exchanger, a control valve that is commonly used in the first and second cooling medium circuits, and a control device. The control valve includes a rotatable rotor, and is configured such that a rotation range of the rotor includes a water stop section in which the circuits are both closed. The control device restricts output power of the engine in a period in which the rotation angle is in the water stop section, when the rotor rotates via the water stop section at an operating time of the control valve.

Upon a valve rotation angle of a flow rate control valve exceeding a radiator-flow-path closed position during changing of the valve rotation angle of the flow rate control valve in an opening direction of a radiator flow path from a closed state of the radiator flow path, a cooling water starts to circulate through the radiator flow path, and an outlet water temperature or an inlet water temperature of an engine starts to drop. The radiator-flow-path closed position is learned as a valve rotation angle of the flow rate control valve immediately before the outlet water temperature or the inlet water temperature starts to drop during changing of the valve rotation angle of the flow rate control valve in the opening direction of the radiator flow path from the closed state of the radiator flow path.

A method of operating an engine with dual fuel injection capabilities to address fuel rail over-pressure due to stagnating hot fuel is shown. The method comprises operating an engine cylinder with only port injection, and selectively activating and deactivating the second injector in response to a rail pressure increase of a fuel rail, the fuel rail coupled to the second injector, and deactivating the second injector in response to a rail pressure decrease of the fuel rail to a lower threshold determined based on engine operating conditions. In this way, degradation of the second injector may be reduced while maintaining a desired level of engine performance.

An outdoor unit has a frame that carries a ground grooming or working implement, a traction drive, and a cooling fan, all of which comprises loads on a prime mover. A power management controller automatically reduces an operational speed of the traction drive when prime mover droop is present. The cooling fan cools two cooling fluids. The controller stores data representing variable fan speeds for cooling each cooling fluid in both normal and above normal temperature ranges and for use when prime mover droop is present. The controller uses the highest fan speed required for cooling the cooling fluids in the normal range unless the droop fan speed is lower in which case the lower droop fan speed is used but only to the extent that the lower droop fan speed is not lower than the highest fan speed required for cooling the cooling fluids in the above normal temperature range.

A cooling system of an internal combustion engine includes a first flow passage supplying a cooling medium of the internal combustion engine to a radiator, a second flow passage branching from the first flow passage by a flow control valve to supply the cooling medium to a first heat exchanging portion, a third flow passage provided separately from the first flow passage to supply the cooling medium to a second heat exchanging portion via an on-off valve and a control portion controlling the on-off valve and the flow control valve based on a temperature of the cooling medium.

A drive device comprising at least one control unit (10) for operating a first drive unit (16) with a first operating frequency (f.sub.b1) from a first operating frequency interval and a second drive unit (18) with a second operating frequency (f.sub.b2) from a second operating frequency interval, which at least partly overlaps the first operating frequency interval. The control unit (10), in at least one operating state, operates the drive units at least occasionally simultaneously with different operating frequencies (f.sub.b1, f.sub.b2) and varies the first operating frequency (f.sub.b1) and/or the second operating frequency (f.sub.b2) within the respective operating frequency interval.

A controller may cause, in a lubrication oil warm-up mode of a transmission, the transmission to operate in a stall mode that transfers heat to transmission oil for the transmission. The transmission oil may be diverted to a lubrication oil heater to heat the lubrication oil using the transmission oil. The controller may cause the transmission to disengage the stall mode and to engage a park mode, to pause the lubrication oil warm-up mode. The controller may cause the transmission to operate in the stall mode, to resume the lubrication oil warm-up mode, after the pause duration.