Isuzu 4HK-1 and 6HK-1 Engine Fuel System Repair Manual
Isuzu 4HK-1 and 6HK-1 Engine Overview
The Tier III CX330 Excavators are equipped with an Isuzu 6HK-1 model common rail fuel system Engine. The Isuzu 4HK-1 model will be used in at least one other Excavator model. These engines have 4 valves per cylinder, operated by a single overhead cam to optimize air flow, fuel economy and emissions. The injector is now located at the center of the piston under the valve cover. The fuel system is now totally electronically controlled. These engines use an water cooled Exhaust Gas Recirculation, (EGR) system, which allows a controlled amount of exhaust gas to return back to the intake. This EGR system is used to reduce the emissions level of the engine. These engines also use an air to air after cooling intake air system. The air to air intake system ports pressurized air flow between the turbocharger and the intake manifold through an air to air heat exchanger in front of the radiator. The 4HK-1 model has a displacement of 317 cubic inches (in3 ) or 5193 cubic centimeters (cc). The 6HK-1 model has a displace ent of 475 cubic inches (in3 ) or 7790- cubic centimeters (cc).
The ECM calculates the basic injection amount based on the signals from throttle position sensor, boost pressure sensor, crank position sensor, cam position sensor, etc. It regulates the opening/closing period of common rail pressure control valve and the electric activation of each injector according to the common rail pressure, engine coolant temperature, etc. at this time, to correct the optimum injection timing and injection amount.
At engine start (after the key switch is turned to the START position to start the engine, and until the return of the key switch to the ON position), the fuel injection quantity is controlled based on information from the start signal, engine speed, and engine coolant temperature. At low temperature, the fuel injection quantity increases. When the engine starts completely, this boosted quantity mode at starting is cancelled and normal running mode is restored.
The ECM calculates the current altitude based on the barometric pressure sensor signal. It corrects the fuel flow according to the altitude etc. at this time. The Excavator machine controller communicates with the engine controller (ECM) via the CAN Data Bus system to control engine speed, return to idle co`
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