Made in China Good Quality LJBB03301A Diesel Fuel Injector Common Rail Injector Engine Parts

Electromagnetic drive system failure
1. Electromagnetic coil failure
Failure manifestation: Injector does not work, injection timing is disordered.
Cause:
Long-term high temperature aging of the coil, insulation layer damage leads to short circuit or open circuit;
Power supply voltage fluctuation (such as generator failure) causes coil overload and burnout;
Wire harness plug oxidation and poor contact lead to signal interruption.
Influence: When a single injector does not work, the corresponding cylinder is "missing cylinder" and the engine shakes; if multiple injectors fail, it cannot be started.
2. Armature stuck or displacement abnormal
Failure manifestation: Injector response delay, abnormal opening/closing time.
Cause:
Impurities (such as metal debris) enter between the armature and the coil core, causing jamming;
Reset spring fatigue deformation, insufficient elasticity.
Influence: Injection timing is inaccurate, such as delayed opening, resulting in late fuel injection, incomplete combustion, and increased fuel consumption by 10%-20%.

Mechanical seal component failure
1. Valve needle and valve seat seal failure
Fault manifestation: fuel dripping at idle speed, engine shaking; fuel seeping into the cylinder after shutdown, causing "flooding".
Cause:
Impurities in the fuel (such as colloid, metal particles) scratch the sealing cone surface of the valve needle and valve seat;
High temperature causes the valve seat to deform (such as the direct injection injector in the cylinder is subjected to high temperature above 300℃ for a long time);
Frequent start and stop causes the valve needle to repeatedly hit the valve seat, causing wear.
Impact: Fuel leakage causes the mixture to be too rich, the exhaust gas emits black smoke, and the OBD reports "oxygen sensor failure" or "misfire" code.
2. Valve needle stuck (open/close abnormality)
Fault manifestation:
Stuck in the open state: continuous fuel injection, the engine cannot be turned off, and even "backfire" occurs;
Stuck in the closed state: the corresponding cylinder does not spray fuel, starting is difficult or the idle speed is unstable.
Cause:
Poor fuel quality, carbon deposits or gelling attached to the valve needle guide hole;
Poor cooling causes the valve needle to overheat and deform.
Effect: In severe cases, the piston top will collide with the valve (because the fuel wet wall dilutes the engine oil, aggravating the wear of the cylinder).

Spray hole and fuel atomization failure
1. Spray hole blockage
Failure manifestation: reduced fuel injection, poor atomization, engine acceleration is weak, and emissions exceed the standard (HC, CO increase).
Cause:
The fuel has a high sulfur content, and sulfides are generated after combustion and deposited in the spray hole;
The fuel filter fails, and impurities (such as rust, plastic debris) block the spray hole (especially the 0.1-0.3mm fine holes of direct injection in the cylinder);
Long-term idling or low-speed driving, fuel evaporates to form colloids that block the spray hole.
Effect: When the spray hole of a single cylinder is blocked, the combustion efficiency of the cylinder decreases, the power output is uneven, and the engine shakes.
2. Expansion of nozzle wear
Fault manifestation: increased fuel injection volume, too-rich mixture, increased fuel consumption, and strong gasoline smell in exhaust gas.
Cause:
High-pressure fuel flushes the nozzle for a long time (such as 350bar pressure in direct injection into the cylinder), causing the aperture to become larger;
Hard particles in the fuel (such as unfiltered metal chips) wear the edge of the nozzle.
Influence: The air-fuel ratio deviates from the theoretical value (14.7:1), and the three-way catalytic converter is overloaded, which may cause it to fail.

Fuel pressure and oil circuit failure
1. Internal oil circuit leakage of the injector
Fault manifestation: The fuel rail pressure holding capacity decreases, and the pressure decays rapidly after shutdown (normally it should be maintained for more than 5 minutes).
Cause:
Aging and cracking of the injector inlet seal;
Cracking of the internal oil channel weld (common in high-pressure direct injection injectors).
Influence: Due to insufficient fuel pressure and too-thin mixture during startup, starting is difficult (especially cold start).
2. Fuel impurities cause fuel line blockage
Fault manifestation: Insufficient fuel supply from the injector, and fluctuation in fuel injection volume.
Cause:
Water and impurities deposited at the bottom of the fuel tank enter the fuel line;
The fuel pump filter is blocked, resulting in unstable fuel supply pressure.
Influence: The engine "stutters" when the load changes (such as overtaking and acceleration), and the power response is slow.

Electronic control system and signal failure
1. Abnormal control signal
Fault manifestation: Incorrect injection timing and inaccurate injection volume.
Cause:
ECU failure, output of incorrect injection pulse signal;
Failure of the crankshaft/camshaft position sensor, resulting in incorrect injection timing reference;
Poor line contact (such as oxidation of plug pins), signal transmission delay.
Influence: Unstable engine power output, excessive emissions, and OBD reports the "injection timing error" fault code.
2. Abnormal injector resistance
Fault manifestation: ECU detects that the injector resistance value deviates from the standard range (such as the standard resistance of the electromagnetic injector is 12-16Ω, if the actual measurement is <10Ω or > 20Ω).
Cause:
The coil is damp and short-circuited, and the resistance is reduced;
The coil is burned out, and the resistance is infinite.
Influence: ECU triggers the protection mechanism, limits the engine power, and the instrument panel lights up the fault light.

Carbon deposits and high temperature related faults
1. Carbon deposition
Fault manifestation: The valve needle movement is blocked, the spray hole is blocked, and the atomization cone angle is offset.
Cause:
The high-temperature gas in the combustion chamber is backflowed (such as poor exhaust valve sealing), resulting in carbon deposits on the injector head;
After the inferior fuel is burned, carbon deposits are generated and attached to the surface of the injector.
Influence: The injection volume is reduced and uneven, the operation of each cylinder is unbalanced, and the engine idle jitter is aggravated.
2. High temperature causes component deformation
Fault manifestation: The injector housing or internal parts are deformed, and the seal fails.
Causes:
Cooling system failure, engine overheating, injector in an environment above 300℃ for a long time;
Direct injection injector improperly installed, poor heat dissipation.
Effect: Fuel leaks into the combustion chamber, which may cause pre-ignition or detonation, and damage the piston and cylinder head.

Specific faults of different types of fuel injectors
Fuel injector type Specific fault Cause and impact
Direct injection fuel injector High-pressure seal failure, needle valve carbon deposition and sintering High-pressure fuel leakage causes combustion chamber pressure fluctuations, and carbon deposition and sintering cause the valve needle to jam, requiring disassembly, cleaning or replacement
Piezoelectric fuel injector Piezoelectric crystal performance degradation, drive circuit failure Response speed slows down, multiple injections (such as pre-injection + main injection) cannot be achieved, and combustion efficiency decreases
Manifold injection fuel injector Rubber seal ring aging, fuel back-spray causes needle valve rust Seal ring aging and oil leakage, back-spray fuel (intake manifold negative pressure fluctuation) causes valve needle to contact air oxidation, affecting sealing

Fault diagnosis and typical cases
Case 1: Idle jitter of a 1.4T direct injection engine
Detection: The cylinder pressure of each cylinder is normal, but the injector flow test found that the spray hole of the 2-cylinder injector is blocked, and the flow is 30% lower than that of other cylinders.
Cause: The sulfur content of the fuel exceeds the standard, and sulfide deposits are formed in the spray hole.
Solution: Ultrasonic cleaning of the injector, replacement of high-grade fuel.
Case 2: Diesel vehicle difficult to start, white smoke
Detection: The return oil volume of the injector is too large, and the valve needle and valve seat sealing surface are worn.
Cause: The diesel has a high water content, and long-term use leads to electrochemical corrosion of the valve seat.
Solution: Replace the injector assembly and install a fuel water separator.