Isuzu 6HK1 6SD1 Common Rail Engine Complete Workshop Service Repair Manual

June, 2003 Diesel Injection Pump Common Rail System for ISUZU Operation No. E-03-02 SERVICE MANUAL 6HK1/6SD1 Type Engine 00400018 For DENSO Authorized ECD Service Dealer Only

GENERAL The common rail system was designed for electronic control of injection quantity, injection timing and injection pressure to obtain optimal operational control. Features • Lower exhaust gas and higher output due to high pressure injection in all usage ranges. • Reduction in noise and exhaust gas due to injection rate control. • Improved performance due to increased flexibility in the injection timing setting. • Independent control of injection pressure in response to engine speed and load. Main Elements Manufacturer Vehicle Model Engine Model Cylinder Configuration Total Displacement (cc) ISUZU Forward 6HK1 Straight 6 7,800 6SD1 9,800 6WG1 15,600

1 1. Outline 1.1 System Outline This system also provides the following functions: • A self-diagnosis and alarm function using computer to diagnose the system’s major components and alert the driver in the event of a problem. • A fail-safe function to stop the engine, depending upon the location of the problem. • A backup function to change the fuel regulation method, thus enabling the vehicle to continue operation. 1.2 System Configuration Divided by function, the system can be classified according to the fuel system and the control system. [1] Fuel System High-pressure fuel that is generated by the supply pump is distributed to the cylinders using a rail. Electromagnetic valves in the injectors then open and close the nozzle needle valve to control the start and end of fuel injection. [2] Control System Based on the signals received from various sensors mounted on the engine and the vehicle, the ECU controls current timing and the duration in which the current is applied to the injectors, thus ensuring an optimal amount of fuel is injected at an optimal time. The control system can be broadly classified according to the following electronic components: sensors, computers, and actuators. Fuel tank Supply pump Rail Electronic control Injector Discharge volume Solenoid valve to control the needle lift Q000080E Sensors Computers Actuators Accelerator sensor Injectors Rail Supply pump Other sensors and switches NE sensor (Crankshaft position sensor) TDC sensor (Cylinder recognition sensor) (Accelerator opening) (Engine speed) Cylinder recognition signal Fuel injection quantity and injection timing control etc. (Fuel pressure control) ECU ( ) ( ) Q000081E

2 [3] System Configuration (1) Q000082E Signals from switches ACCP Accelerator position sensor ECU Charge-up circuit Starter signal Air cleaner Water temp. sensor THW THL STA Fuel temp. sensor Leak pipe Flow damper NE sensor TDC sensor Fuel filiter Fuel tank Supply pump Pressure limiter Rail

3 [4] System Configuration (2) Q000083E Fuel Injection ·Injection Quantity Control ·Injection Timimg Control ·Injection Pressure Control Engine Vehicle ·A/T Control ·Exhaust Break Control ·Engine Shut-down control ·TECH COMMUNICATION Communication Service Tool (Scan Tool) (Dealer) Rail Pressure sensor Flow Damper Injector (inside Head Cover) Rail Pressure Limiter Crank Position Sensor (NE Sensor) Boost Pressure Sensor Accelerator Position Sensor (inside ECU) ·Coolant Temperature Sensor ·Fuel Temperature Sensor ·Atmospheric Air Temperature Sensor Cylinder Recognition Sensor (TDC Sensor) Supply Pump Injection Rate Control Injection Quantity Control Injection Timing Control Injection Pressure Control (Pressure Control in Rail) TECH ECU Atmospheric Air Pressure Sensor

4 1.3 Construction and Operation of the System The rail system is comprised of a supply pump, a rail, and injectors, and also includes an ECU and sensors to regulate those components. The supply pump generates the internal fuel pressure in the rail. Fuel pressure is regulated by the quantity of fuel discharged by the supply pump. In turn, the fuel discharge quantity is regulated by electronic signals from the ECU that turn the PCVs (pump control valves) ON and OFF. Upon receiving fuel pressurized by the supply pump, the rail distributes the fuel to the cylinders. The pressurized fuel is detected by the rail pressure sensor (installed in the rail) and undergoes feedback control so that actual pressure will match the command pressure (designated according to the engine speed and load). Pressurized fuel in the rail passes through the injection pipes that lead to the cylinders, and applies pressure to the injector nozzles and the control chamber. The injector regulates injection quantity and timing by turning the TWV (two-way valve) ON and OFF. When the TWV is ON (current applied), the fuel circuit switches over, causing the high-pressure fuel in the control chamber to flow out via the orifice. As a result, the force of the high-pressure fuel at the nozzle valve opening causes the needle valve to lift, thus starting the injection of fuel. When the TWV is turned OFF (current not applied), the fuel circuit switches over so that high- pressure fuel, traveling via the orifice, is introduced to the control chamber. As a result, the needle valve lowers, thus ending the injection of fuel. Thus, through electronic control, the timing of the current applied to the TWV determines the injection timing, and the duration in which current is applied to the TWV determines the injection quantity. Q000084E Additional information (temperature, pressure) Engine load ECU Supply Pump · Injection quantity control · Injection timing control · Injection rate control TWV Leak Orifice Control chamber Hydraulic piston Nozzle Needle Injector TWV control pulse Rail pressure sensor Rail Injection pressure control

5 1.4 Comparison to Conventional Pump Inline Type Common Rail System System Injection quantity regulation Injection timing regulation Distribution of generated pressure Distribution Injection pressure regulation Pump (governor) Pump (timer) Pump Pump (Dependent on engine speed and injection volume) ECU, injector (TWV) ECU, injector (TWV) Supply pump Supply pump (PCV) Rail Q000085E Pipe Instantaneous high pressure Timer Pump Governor Nozzle Supply pump Rail Constant high pressure Injector

6 2. Construction and Operation of Components 2.1 Supply Pump [1] Outline The function of the supply pump is to regulate the fuel discharge volume, thus generating internal fuel pressure in the rail. [2] Construction The supply pump consists of a feed pump, similar to that of the conventional in-line pump, and the PCVs (pump control valves), provided at each cylinder, to regulate the fuel discharge volume. The supply pump uses a three-lobe cam to reduce the number of engine cylinders supplied by the pump to one-third (e.g. a two-cylinder pump for a six-cylinder engine). Furthermore, smooth and stable rail pressure is obtained because the rate at which fuel is pumped to the rail is the same as the injection rate. Q000086E 3-lobe cam PCV (Pump Control Valve) Gear of TDC sensor Feed pump

7 [3] Operation A: The PCV remains open during the plunger’s downward stroke, allowing low-pressure fuel to be drawn into the plunger chamber by way of the PCV. B: If the valve remains open because current is not applied to the PCV, even after the plunger begins its upward stroke, the fuel that was drawn in returns via the PCV, without being pressurized. C: When current is applied to the PCV in order to close the valve at the timing that accommo- dates the required discharge volume, the return passage closes, causing pressure in the plunger chamber to rise. The fuel then passes through the delivery valve (check valve) to the rail. As a result, an amount of fuel that corresponding to the plunger lift after the PCV closes becomes the discharge volume, and varying the timing of the PCV closure (plunger pre- stroke) varies the discharge volume, thus regulating rail pressure. A’: After surpassing the maximum cam lift, the plunger begins its downward stroke, causing pressure in the plunger chamber to decrease. At this time, the delivery valve closes, thus stopping the pumping of the fuel. In addition, because current to the PCV valve is cut off, the PCV opens, allowing low-pressure fuel to be drawn into the plunger chamber. Thus, the pump assumes condition “A”. Q000087E Suction process Delivery process Cam lift Valve open Pre-stroke PCV operation Valve closed H h Increasing dischargevolume Reducing discharge volume Discharging required dischrge volume Rail Pump operation PCV Plunger Delivery valve A B C A' φd Discharge volume Q= πd 2 (H-h) 4

8 [4] PCV (pump control valve) The PCV regulates the volume of fuel discharged by the supply pump in order to regulate rail pressure. The volume of fuel discharged by the supply pump to the rail is determined by the time at which current is applied to the PCV. [5] Trochoid Type Feed Pump The feed pump, which is housed in the supply pump, draws fuel up from the tank and delivers it to the chamber via the fuel filter. The feed pump rotor is driven by the camshaft. The rotation of the camshaft causes the outer and inner rotors to rotate. At this time, the suction port side pump chamber volume (the space surrounded by the outer and inner rotors) increases gradually, causing the fuel entering from the fuel inlet to be drawn into the pump chamber via the suction port. Along with the rotation of the rotor, the fuel that has been drawn in moves to- wards the discharge port and is discharged. The discharged fuel travels via the fuel outlet and is fed into the supply pump body. [6] Coupling The coupling is an intermediary device that transmits the engine driving torque to the supply pump camshaft. Key switch PCV relay +B PCV1 PCV2 Q000088E ECU PCV Q000090E Outer rotor To pump chamber Inner rotor Discharge port From fuel tank Suction port Volume decreased (while moving to discharge port) Volume increased (while drawing in fiel) Volume increased (while drawing in fiel) Volume decreased (while discharging fuel to discharge port) Coupling Q000091E

Isuzu 6HK1 6SD1 Common Rail Engine Complete Workshop Service Repair Manual

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