New High Quality Diesel Injector 116-7150 131-7150 155-1819 162-0218 169-7410 169-7411 For CAT 3126

Abnormal injection pressure
1. Too low pressure
Common causes:
Wear of high-pressure oil pump and excessive internal plunger clearance lead to decreased oil pumping capacity;
Aging and leakage of common rail pipe, oil pipe or injector seal;
Injector needle valve stuck in the open state (such as impurities stuck), or insufficient spring force;
Clogged fuel filter leads to insufficient oil supply in low-pressure oil circuit.
Typical manifestations:
Lack of engine power and weak acceleration, which is obvious when climbing or overloaded;
Idle jitter and cold start difficulty (poor fuel atomization);
Black smoke from exhaust pipe (incomplete combustion leads to increased soot PM);
Increased fuel consumption (unburned fuel is discharged with exhaust gas or deposited as carbon deposits).
2. Too high pressure
Common causes:
Common rail pressure sensor failure, transmitting wrong signals to ECU (such as false low pressure);
Pressure regulating valve (pressure limiting valve) failure, unable to release excessive pressure;
Partial blockage of injector nozzle, resulting in obstruction of fuel reflux.
Typical manifestations:
Injector needle valve wear increases, abnormal injection or leakage may occur;
Combustion temperature is too high, causing knock (knocking sound), nitrogen oxide (NOx) emissions surge;
High-pressure components (such as oil pumps, common rail pipes) are overloaded, and there is a risk of oil leakage or even explosion;
The ECU of some models triggers the protection mechanism to limit the engine power output.

Injection timing deviation
1. Early injection
Common causes:
Camshaft position sensor signal inaccuracy (such as installation misalignment, sensor contamination);
ECU program error or poor line contact, resulting in early injection triggering time.
Typical manifestations:
Fuel is injected in advance during the compression stroke, the temperature and pressure in the cylinder are low, combustion is delayed, and power decreases;
Unburned fuel washes the lubricating oil film on the cylinder wall, resulting in oil dilution and increased wear;
Higher hydrocarbon (HC) and carbon monoxide (CO) emissions (incomplete combustion);
Diesel engines may experience "unstable idling" or "cold start white smoke" (unburned fuel vapor).
2. Fuel injection is too late
Common causes:
Crankshaft position sensor failure (such as dirty signal plate, damaged sensor);
Wear of mechanical transmission parts (such as loose timing belt/chain, excessive gear clearance).
Typical manifestations:
Fuel is injected during the power stroke, the mixing time is insufficient, the combustion is incomplete, and black smoke comes out of the exhaust pipe;
Unburned fuel enters the exhaust pipe, which may cause DPF (diesel particulate filter) blockage or SCR (selective catalytic reduction system) failure;
The peak combustion temperature in the cylinder increases, and NOx emissions increase;
The engine thermal efficiency decreases and fuel consumption increases.

Fuel injector blockage or leakage
1. Blockage
Common causes:
Fuel impurities (such as metal debris, colloid, water) are deposited in the spray hole;
Poor quality fuel additives or long-term low-load operation lead to carbon deposition in the nozzle;
Diesel waxing (paraffin precipitation in fuel at low temperature).
Typical manifestations:
The flow area of ​​the spray hole is reduced, the amount of fuel injection is reduced, and the engine power is insufficient;
The spray shape is abnormal (such as deflection, scattered mist), "rich oil area" and "lean oil area" appear in the combustion chamber, and soot and NOx increase simultaneously;
Multi-cylinder engines may work unevenly and vibrate more due to single cylinder blockage;
Severe blockage may cause cylinder failure (the cylinder does not work) and the fault light is on.
2. Leakage
Common causes:
Wear of the needle valve sealing surface (such as long-term high-pressure flushing, impurity scratches);
Failure of the electromagnetic coil or piezoelectric element, resulting in loose closure of the needle valve;
Cracks in the injector body or aging of the sealing ring.
Typical manifestations:
Dripping occurs at idle speed, low-pressure oil circuit pressure fluctuates, and the engine shakes intermittently;
During startup, fuel leakage causes "wet walls" (fuel accumulation) in the cylinder, which may cause difficulty in starting or flooding;
Continuous leakage will dilute the engine oil (fuel enters the crankcase), reduce the viscosity of the engine oil, and aggravate engine wear;
The diesel engine may emit "blue smoke" (engine oil participates in combustion) or "abnormal flameout".

Uneven injection amount (multi-cylinder engine)

Common causes:
The degree of wear of the injectors of each cylinder is inconsistent (such as differences in service life and fuel quality);
The correction value of the ECU for the injection amount of a single cylinder exceeds the limit (such as a cylinder is in a compensation state for a long time);
The length or resistance of the oil pipe from the common rail pipe to each cylinder is too different.
Typical manifestations:
Intensified engine vibration (unbalanced power of each cylinder), especially at idle speed;
Large fluctuations in emission pollutants (such as excessive carbon soot in a cylinder leads to an increase in the overall PM value);
Abnormal fuel consumption (cylinders with a large amount of fuel injection do not burn completely, and cylinders with a small amount of fuel injection have insufficient power).

Multi-stage injection function failure
Common causes:
The electromagnetic/piezoelectric element responds delayed or is damaged, and the segmented injection command cannot be executed;
ECU program failure or sensor signal loss (such as lack of in-cylinder pressure feedback).
Typical manifestations:
Pre-injection failure: combustion pressure rises suddenly during main injection, resulting in "knocking" noise and increased NOx emissions;
Post-injection failure: exhaust temperature cannot be increased to activate DPF regeneration, resulting in carbon soot particle accumulation and excessive emissions;
In-cylinder combustion smoothness decreases and power output fluctuates (such as turbocharged engine acceleration lag).
6. Sensor and circuit failure
Common causes:
Injector drive circuit short circuit or open circuit (such as harness wear, plug oxidation);
Solenoid coil burns out (such as current overload, ECU drive module failure);
Piezoelectric element breakdown (such as high-voltage pulse shock).
Typical manifestations:
The engine fault light is on, and the ECU stores the "injector drive fault" code;
The single-cylinder or multi-cylinder injector stops working, resulting in cylinder loss and power drop;
Some models may enter "limp mode" to limit the maximum speed.
Troubleshooting and prevention suggestions
Quick diagnostic tool:
Use the diagnostic instrument to read the ECU fault code, analyze the actual injection amount, injection timing deviation value, and pressure fluctuation curve of the injector;
Use the oscilloscope to detect the injector drive signal waveform to determine whether the circuit or component is abnormal.
Preventive maintenance:
Regularly replace the fuel filter (recommended every 10,000 to 20,000 kilometers), and use fuel from regular gas stations;
Avoid long-term idling or low-speed driving (easy to generate carbon deposits), and use fuel system cleaners regularly;
National VI and above models need to pay attention to the after-treatment system (such as DPF pressure difference sensor) to indirectly determine the impact of injector failure on emissions.