1. Engine Deceleration and Automatic Stalling
Releasing the accelerator pedal while the engine is running, or the engine automatically shuts down while the vehicle is moving, is primarily due to the engine failing to stabilize at idle speed, causing it to shut down immediately. Specific causes include a faulty accelerator pedal; signals from the crankshaft position sensor and camshaft sensor are out of sync; a fuel pressure fault; an erroneous control unit signal; or incorrect injection timing. The change in values from idle to idle should be examined specifically.
2. Underpowered Engine or Poor Acceleration
Underpowered engine means the engine operates normally under no load, but accelerates slowly under load, feels weak climbing hills, and lacks power even when the accelerator pedal is fully depressed. The engine speed remains constant and does not reach its maximum speed. Poor acceleration means the engine speed does not increase immediately after the accelerator pedal is depressed, exhibiting a delay or slight fluctuations during acceleration.
Causes of underpowered engine and poor acceleration include excessively high or low fuel system pressure; malfunctioning injectors; erroneous sensor signals; insufficient fuel injection; incorrect injection timing; low cylinder compression pressure; and a clogged exhaust pipe. 3. Engine Failure and Starting Difficulties
There are many factors that can cause starting failures in electronically controlled diesel engines, generally manifesting as failure to start (lack of initial combustion) and difficulty starting. The inspection and troubleshooting methods are as follows:
1. Check for any fault codes. If present, conduct an inspection based on the fault code.
2. Check whether the engine can crank during starting.
① If the starter does not crank during starting, investigate the cause of the starting system failure. First, check the battery charge and terminal connections and contact. If these are normal, check the starting circuit, fuses, and ignition switch. If the starter cranks but the engine does not, there is a problem with the starter-engine engagement.
② If the engine speed is normal during starting but the engine will not crank, inspect the fuel injection system and intake system.
For electronically fuel-injected engines, starting does not require pressing the accelerator pedal. If the accelerator pedal is fully depressed or repeatedly pressed during starting to increase fuel supply, the engine speed will often increase momentarily, leading to increased fuel consumption.
1. Disconnect the accelerator pedal wiring harness. If the engine can now idle, the fault is with the accelerator pedal.
2. Visual Inspection: Check the intake line for leaks.
3. Fuel Line Inspection: Check the fuel line connection, air intake, and fuel quality.
4. Wiring Harness Inspection: Check for loose or loose connections.
5. Sensor Inspection: Check for sensor failure, loose or broken wiring, and the crankshaft and camshaft synchronization signals.
6. Check the injector for control signals. If no control signal is present, check the fuse, wiring, and ECU. If a control signal is present, check the injector for normal spray patterns.
