Professional Manufacture 0 445 120 369 Diesel Injector Common Rail Injector Engine Parts Vehicle Parts 0445120369

1. Wear or damage of the nozzle parts
The injection hole is blocked or deformed
Impurities in the fuel (such as colloid, carbon particles, metal debris) are deposited in the injection hole, which will cause the aperture to become smaller or partially blocked, causing the spray to "deflect" (tilt to one side) or "cut off" (no spray in part).
After long-term use, the injection hole is deformed due to high-speed fuel scouring or mechanical wear (such as impurity impact), destroying the original spray angle and forming an irregular mist beam.
Poor sealing between the needle valve and the valve seat
The needle valve and the valve seat are precision parts. If the seal is not tight due to carbon deposition, adhesion, wear or scratches, there will be a "drip" phenomenon: a small amount of fuel still leaks after the injection is completed, forming an oil droplet-shaped spray, and even forming an oil film at the nozzle, interfering with normal atomization.
Needle valve stagnation (such as impurity jamming or poor lubrication) will cause abnormal injection opening/closing time, too long or too short spray duration, and "overspray" or "spray interruption".

2. Abnormal fuel system pressure
Injection pressure is too low
High-pressure fuel pump failure (such as plunger wear, poor SCV valve adjustment) or fuel pressure regulator failure will cause the injection pressure to be lower than the standard value (such as the normal pressure of the diesel common rail system 160-200MPa). When the pressure is insufficient, the fuel cannot be fully atomized, forming coarse droplets or columnar oil flow.
Blockage of the return oil pipeline (such as the return oil valve is stuck) will cause the internal back pressure of the injector to be too high, indirectly reducing the effective injection pressure and destroying the spray shape.
Fuel injection pressure fluctuation
Blockage of the fuel filter, leakage of the high-pressure oil pipe or loose joints will cause the fuel supply pressure to be unstable, and the spray shape will appear "strong and weak" and "intermittent poor atomization" with pressure fluctuations.

3. Failure of the electronic control system
Abnormality of the injector drive component
For electronic control injectors (such as solenoid valve type or piezoelectric type), if the solenoid valve coil is short-circuited or open-circuited, or the piezoelectric crystal is aged, the injector opening/closing delay or failure will occur, the spray time and angle will deviate from the design value, and "early spray", "late spray" or uneven spray dispersion will occur.
Poor contact of the wiring harness plug (such as oxidation and looseness of the pins) will cause the drive signal to be unstable, and the spray shape will be abnormal with the current fluctuation.
ECU control parameter deviation
The ECU (engine control unit) has incorrect control of the injection pulse width and injection timing (such as abnormal sensor signals, such as crankshaft position sensor failure), which will cause the injector opening time to be too long or too short, the spray volume and angle to be mismatched, and asymmetric or excessive spray will be formed.

4. Influence of external impurities and pollutants
Fuel quality problems
Poor quality fuel has high sulfur content and excessive colloid, which is easy to form hard carbon deposits on the surface of the injector nozzle, covering part of the injection hole and changing the spray direction; if there is too much water in the fuel, it will also cause the injector nozzle to rust and destroy the uniformity of the spray.
When refueling, dust and particulate impurities (if not filtered clean) mixed into the injector will directly scratch the spray hole or needle valve, causing permanent damage to the spray shape.
Engine oil intrusion
Aging of the valve oil seal and wear of the piston ring will cause the oil to enter the combustion chamber. After mixing with the fuel, it will form sludge at the injector nozzle, block the injection hole or change the fluidity of the fuel, causing the spray to appear abnormal in a "lump" or "block" shape.

5. Improper installation and maintenance
Installation error
When the injector is not tightened according to the specified torque during installation, or the seal with the cylinder head mating surface is poor, the injector will be tilted, the spray direction will deviate from the center of the combustion chamber, and a local deviation will be formed.
When replacing the injector, if the model does not match (such as the number and angle of the injection holes do not match the engine design), it will directly lead to abnormal spray shape.
Cleaning or maintenance operation errors
Improper selection of cleaning agents during ultrasonic cleaning (such as excessive corrosiveness) will corrode the injection hole; when manually cleaning carbon deposits, scratching the inner wall of the injection hole with hard objects will destroy the spray flow path and cause atomization disorder.
If the injector parameters (such as injection pressure and injection pulse width) are not recalibrated after repair, abnormal spraying may occur due to parameter deviation even if the parts are intact.