1. Engine deceleration and automatic flameout
The fundamental reason for releasing the accelerator pedal when the engine is running or automatically turning off the engine while the vehicle is moving is that when the engine changes from non-idling to idling, the idle speed is not easy to stabilize, so the engine is turned off immediately. Specific reasons include accelerator pedal failure; crankshaft position sensor and camshaft sensor signals are out of sync; fuel oil pressure failure; control unit signal error; incorrect injection timing, etc. Focus on checking the numerical changes from non-idling to idling.
2. Insufficient engine power or poor acceleration
The phenomenon of insufficient engine power is that the engine is basically normal when running without load, but when running with load, it accelerates slowly and is unable to go uphill. When the accelerator pedal is pressed to the bottom, it still feels lack of power, the speed does not increase, and the maximum speed cannot be reached. The phenomenon of poor engine acceleration is that the engine speed cannot rise immediately after pressing the accelerator pedal, there is hysteresis, or the engine has slight fluctuations during acceleration.
The reasons for insufficient engine power and poor acceleration include too high or too low oil pressure in the fuel system; poor fuel injection from the injector; wrong sensor signal; too small fuel injection volume; incorrect fuel injection timing; low cylinder compression pressure; The exhaust pipe is blocked, etc.
3. The engine cannot start or is difficult to start
There are many factors leading to starting failures of electronically controlled diesel engines, which generally manifest as inability to start (no initial combustion) and difficulty in starting. The inspection and troubleshooting methods are as follows:
Check whether there is a fault code. If so, check according to the content of the fault code.
Check whether the engine can rotate when starting.
① When starting, if the starter does not rotate, it should be checked according to the cause of the starting system failure. First check the battery storage condition and pole connection and contact condition; if normal, check the starting circuit, fuse and ignition switch. If the starter can rotate but the engine cannot rotate when starting, it is a fault in the meshing part of the starter and the engine.
② When starting, the engine speed is normal, but the engine does not start, the fuel injection system and the air intake system should be inspected separately.
For engines using electronically controlled fuel injection, there is no need to press the accelerator pedal when starting. If you fully depress the accelerator pedal when starting or depress the accelerator pedal repeatedly to increase fuel supply, the engine speed will increase instantaneously, resulting in an increase in fuel consumption of the engine.
- Disengage the accelerator pedal harness. If the engine can enter idling speed at this time, it means that the fault is the accelerator pedal.
- Appearance inspection: Check the air intake pipe for air leaks.
- Oil line inspection: Check the connection status of the oil pipe, the phenomenon of air intake and the quality of the fuel.
- Wire harness inspection: Check whether the wiring harness connection is loose or the connection is not firm.
- Sensor inspection: Check whether the sensor fails, the circuit is loose or broken, and the synchronization signal of the crankshaft and camshaft.
- Check whether there is a control signal from the injector. If there is no control signal, check the fuses, circuits and ECU. If there is a control signal, check whether the spray condition of the injector is normal.