Insufficient diesel engine power
When the engine electronic control system component fails, the CU will activate the engine failsafe mode and record the fault code at the same time. With failsafe mode enabled, the engine does not
It will stop immediately, but will limit the power of the engine, the speed can only be 1500r/mi, and the driver can drive the car to the nearest maintenance station for maintenance.
1. The injector is faulty
The failure of the injector is generally divided into mechanical failure and wiring failure.
Mechanical failure (needle valve stuck):
Due to the large amount of dirt in the diesel oil or the corrosion of the water, the needle valve is stuck in the injector and cannot move. Note: The ECU may not report an error.
Wiring fault:
Due to vibration, wear, etc., the wiring harness is disconnected or directly connected to the cylinder head and shorted to ground. The ECU will report an error.
The judgment method is as follows:
The idle speed is unstable, and the sound of the diesel engine is abnormal.
Use the cylinder-breaking method or the high-pressure oil pipe tactile method to judge (the diagnostic tool does an accelerated test to judge).
Troubleshooting instruments generally have the function of testing the fuel injector.
2. Coolant temperature, oil temperature and intake air temperature are too high
When the coolant temperature, oil temperature and intake air temperature are too high, the CU will enter the overheat protection mode to limit the engine power
Reasons and solutions for high coolant temperature:
Radiator water level is too low. Check for leaks and add water.
Radiator clogged. Check radiator, clean or repair.
The pump belt is slack. Adjust the tension as specified.
The water pump gasket is damaged and the water pump impeller is worn. Check and repair or replace.
Thermostat failure. replace.
Damaged water pipe seals, leaking air. Check water pipes, joints, gaskets, etc., and replace damaged parts.
Reasons and solutions for high oil temperature:
The oil level in the oil pan is low or lacks oil. Check the oil level and oil leakage, repair and refuel.
Oil temperature is high. Check the above reasons for the high oil temperature and eliminate them.
Oil cooler has poor circulation. Check and clean up.
Reasons and solutions for high intake air temperature:
Check the cooling capacity of the intercooler.
3. Failure of fuel metering unit
The fuel metering unit is an actuator that controls the rail pressure. It is installed on the high-pressure fuel pump. When the metering unit fails, the high-pressure fuel pump delivers fuel to the fuel rail with the maximum fuel supply.
The pressure relief valve on the common rail pipe will generally open, and the diesel engine will have a "click" noise. A problem with the rail pressure sensor will also have a similar phenomenon.
In this case, check the electrical circuit to determine whether it is the fault of the fuel metering unit or the fault of the fuel rail pressure sensor.
4. The leakage of fuel pipeline causes abnormal fluctuation of rail pressure
resulting in insufficient engine output. During the operation of the car, the speed of the car will be unstable, and the car will move forward. At this time, the sealing condition of the fuel line should be checked.
and repair leaks.
5. Sensor failure
The intake pressure sensor is a sensor used by CU to estimate the intake air volume (installed on the intake pipe), the coolant temperature sensor is a sensor used to judge the thermal load of the engine (installed on the water outlet pipe), and the rail pressure sensor is used to A sensor that detects the fuel pressure of the common rail pipe (installed on the common rail pipe).
Check whether the intake pressure sensor, coolant temperature sensor, and fuel rail pressure sensor work normally, and use the fault diagnosis instrument to check the data flow output by them to judge whether they work normally. Replace the faulty sensor in time. If the oil rail pressure sensor does not work properly, it should be replaced together with the common rail pipe.
6. Check the working condition of the turbocharger
Check whether there is noise during operation, whether there is oil leakage, air leakage, heat dissipation of the intercooler, etc. It should be noted that the turbocharger compressor rotates at a high speed, and it is most likely to be damaged if the lubrication is not in place. When the vehicle is stopped, it cannot be turned off immediately. The engine temperature and the speed of the supercharger should be lowered before turning off to protect the supercharger.
