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5 Tips Injector Common Fault Analysis

In the process of using the injector, it is inevitable that some faults will be encountered. As a dealer or maintenance master, if you can know some common faults of fuel injectors which are not only the embodiment of your professional ability, but also the embodiment of increasing customer trust. Let us introduce the five common faults of the injector.


Injector common fault analysis:

Failure case one

Fault phenomenon:

The owner of the car reported that the engine was heavily smoky and the vehicle was underpowered.

Exclusion step

1) After checking the diagnostics, there is no problem appeared.

2) There is no problem in checking the gas path.

3) So we decided to do the “broken cylinder test”,

4) It is found that the injector of the engine is not working properly.

5) The injectors are turned off one after the other, and the displayed engine speeds are too different.

6) Decided to dismantle the injector

7) After the injector was pulled down, it was found that the injector was also heavily carbonized.

8) And there is a piece of white spot on the fuel injector head.

9) There is a serious problem with the fuel added to the car.

10) Causes serious carbon deposits, and water in the fuel causes white spots on the injector head.


Clean up the charcoal and install the injector. The car emits black smoke.


Failure case two

Fault phenomenon:

1) The same owner reflects that the engine is seriously smoky. After the vehicle is stopped, the vehicle cannot start and cannot start.

2) However, after inspection, it was found that the airway was unblocked, and the rail pressure at the start of inspection was found to be only 160 Bar.

3) It is suspected that the injector leaks oil and causes pressure relief.

4) Immediately check the injector to find that the 2-cylinder injector has a large amount of oil return.

5) Making sure the injector is damaged.

6) Replace the 2-cylinder injector for troubleshooting.

7) Disassemble the injector and find that there are no copper washers.


Failure case three

Fault phenomenon:

1) The same engine emits black smoke with a maximum speed of 1500 rpm.

2) According to the driver, everything is normal when the car is bought back.

3) After using it for more than a month

4) There is a strong smoke in the engine during idle and acceleration.

5) Report the failure at the same time:

6) The oil metering unit current exceeds the upper threshold

7) Failure of the pressure limiting valve to open

8) The error code can be cleared,

9) The engine can run normally for a while after the flash code is cleared.

10) It is normal to observe the change of the current value of the oil metering unit, and the oil metering unit is tested normally.

11) It is stated that the oil quantity measuring unit is normal, and the current value overrun is not caused by the oil quantity measuring unit itself, but is caused by the external oil circuit.

12) Check the oil inlet and return oil of the low pressure and high pressure oil lines, where there are leaks and blockages.

13) Now the problem is concentrated in the middle of the injector, which is not working properly.

14) Do the acceleration test. Now the engine speed after the 4th cylinder is broken, which is more than 60 turns higher than the other cylinders, indicating that the fourth cylinder work is indeed problematic.

15) Remove the 4th cylinder injector and find that it has been burned with the water jacket, the water jacket and the injector have been deformed, and the cylinder head and injector are replaced after normal.

16) Pull out the injector and find that the copper washer on the front of the oil head is gone. I don’t know if it’s burnt or missing.

17) After replacing the 4th cylinder injector, the problem is solved.


Failure case four

Fault phenomenon: The car owner reports that the car is weak and emits black smoke.

Failure analysis

1) Using the diagnostic instrument to detect, the engine has no fault flash code, it may be a mechanical fault. The single-cylinder test is performed with the diagnostic instrument. The engine can not meet the test conditions, so the cylinder can only be manually broken. There is no obvious change after the test. After the removal, it was found that the oil head had rust, which could be judged to be due to the presence of water in the diesel fuel.

2) The fault is that the oil is unqualified, and there is water in the oil, which causes the injector needle to be stuck, causing the injector to bleed or not spray.

Only the engine is unable to smoke black smoke.


Failure case five

Symptoms: The speed can only be maintained at 1500 rpm. The fault code P0699 is interpreted as: “The sensor power supply voltage 3 in the ECU is higher than the upper limit”; P100E is interpreted as: “the pressure reducing valve is open”; P100F is interpreted as: “Fault Pressure shock rail pressure limiting valve request”.

Inspection process: The car is a bus with running mileage of 14,000 kilometers. According to the power supply 3, the rail pressure sensor and the power supply of the throttle 1 are provided, and the two sensors are inspected. After checking, it is found that the voltage of the accelerator pedal signal 1 is too high, and the fault is eliminated after the wiring harness is replaced.

Fault analysis: Since the accelerator pedal and the rail pressure sensor are both powered by “power supply 3”, when the accelerator pedal signal line is shorted to the power supply or to the ground, the supply voltage of the rail pressure sensor is affected, which causes the system to misidentify that the system has insufficient oil pressure. The oil is continuously supplied to the rails, causing the oil pressure to be too high and the pressure limiting valve to open.

The above description is a brief introduction to the five major common failures to fuel injectors. Other injector related articles will be updated afterwards. If you want to know more about injectors, you can leave a message below this article and we will get back to you as soon as possible. Finally, thanks for your reading.

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