Case 1
Trouble symptoms: unable to go up at high speed, high fuel consumption, black smoke or basket smoke from the exhaust pipe.
The cause of the failure: the intake pipe is leaking or blocked by foreign matter.
Nature of failure: mechanical failure.
Treatment method: find out the location of the air leakage, eliminate the air leakage fault, or clear the blockage.
Fault analysis: At this time, the car generally has no obvious symptoms at low speed. When the accelerator is stepped on at high speed, the engine speed cannot reach the maximum speed. If it is blocked and severely, the exhaust pipe will produce a lot of blue or black smoke at high speed. . Vehicle-mounted fault The light does not light up at low speeds, and will start to flash at high speeds. Use the diagnostic instrument to detect the fault display of “intake pressure sensor voltage is too low”. After removing the foreign objects,
Troubleshooting; if it is a leak, the fault light will generally not display, and there may be multiple places where the intake pipe leaks, such as the damage of the intake pipe gasket, the installation of the intake pressure and temperature sensor is not sealed, and the intercooler is connected to the rubber tube Air leakage, air leakage in the rubber tube connected to the turbocharger, etc.
Case 2
Trouble symptoms: engine weakness.
The cause of the fault: the intake air temperature sensor (pressure) is faulty.
The nature of the failure: electrical failure.
Solution: Replace the intake air temperature (pressure) sensor.
Fault analysis: This fault is detected with a diagnostic instrument: “Intake air temperature (pressure) sensor voltage is too low” display.
Case 3
Trouble symptoms: engine weakness, high fuel consumption, and sometimes sudden flameout.
The cause of the fault: the fuel line leaks or air enters.
Nature of failure: mechanical failure.
Treatment method: Exclude fuel pipeline leakage and exhaust air.
Fault analysis: This fault is generally during driving. Because the fuel line leaks, sometimes air enters the fuel line to cause the engine power to drop. If the situation is serious, the engine will suddenly stop. Therefore, it is obvious to solve the air leakage problem before venting the air.
Case 4
Trouble symptoms: sudden weakness in engine operation, high fuel consumption.
The cause of the failure: oil leaking from the horizontal cavity of the injector.
Nature of failure: mechanical failure.
Treatment method: reinstall or replace the fuel injector and transverse cavity.
Failure analysis: This failure occurred in the 6DL National III machine. This is caused by improper installation when installing the horizontal cavity of the injector. Improper installation will cause leakage of fuel in the contact area between the transverse cavity and the fuel injector or severe abrasion, which will cause the engine to become weak.
Case 5
Trouble symptoms: acceleration is weak, and sometimes the flame is suddenly turned off.
The cause of the failure: the fuel line or the diesel filter is blocked.
Nature of failure: mechanical failure.
Treatment method: clear the blockage.
Fault analysis: The place where clogging and oil passages often occur is usually the diesel filter or the oil-water separator.
Case 6
Trouble symptoms: The speed cannot go up at a high speed, and sometimes the engine will suddenly turn off during driving.
The cause of the failure: the fuel inlet hose is bent and collapsed.
Nature of failure: mechanical failure.
Treatment method: straighten the oil inlet hose, fix the position, and the hose should not be too long.
Failure analysis: The bent and squeezed fuel inlet pipe will cause poor fuel inlet. When the engine is running, the fault diagnosis instrument will show that the voltage of the fuel pressure control valve is too low or too high.
Case 7
Trouble symptoms: engine jitter, abnormal sound, weak acceleration, black smoke from the exhaust pipe.
The cause of the failure: the injectors of individual cylinders do not work or work poorly. Mechanical failure.
Handling method: First, break the cylinder test, identify the bad injector, and replace it.
Failure analysis: This failure should be due to poor fuel quality or dirt entering the injector with the fuel, causing the injector valve to jam and fail to work normally.
Case 8
Trouble symptoms: engine jitter, abnormal sound, weak acceleration, black smoke from the exhaust pipe.
The cause of the fault: the wiring harness of the individual cylinder injector is faulty.
The nature of the failure: electrical failure.
Solution: Replace the injector harness. Fault analysis: This fault is generally caused by poor contact or open circuit of the injector harness, and the fault display of “TWV output open circuit” will be displayed with the diagnosis instrument.
Case 9
Symptoms of the malfunction: The engine starts to shudder when it reaches 1100 rpm or more.
The cause of the fault: the coolant temperature sensor is faulty.
The nature of the failure: electrical failure.
Failure analysis: This failure is caused by the fracture of the plastic body of the coolant temperature sensor, which leads to poor contact. Sometimes there is no sensor signal, which makes the fuel supply of the fuel system unstable, and the speed cannot be turned on. The maximum can only reach 1700 rpm. The coolant is replaced. Temperature sensor, troubleshooting.
