Diagnosis and Treatment of Insufficient Engine Power and Exhaust of Thick Black Smoke
Time:
2021-09-15
The engine power is insufficient, the speed is uneven, and the exhaust pipe emits thick black smoke. There are two kinds of phenomena: one is continuous black smoke discharge, and the other is intermittent black smoke discharge, and the engine vibrates.
The engine power is insufficient, the speed is uneven, and the exhaust pipe emits thick black smoke. There are two kinds of phenomena: one is continuous black smoke discharge, and the other is intermittent black smoke discharge, and the engine vibrates.
Insufficient engine power and continuous emission of black smoke means that most or all cylinders of the engine supply too much fuel, the mixing ratio of fuel and air is out of balance, severe oxygen deficiency during combustion, incomplete combustion of diesel, and suspended free carbon elements Exhaust gas is discharged together. If the exhaust pipe emits black smoke intermittently, and it is accompanied by a "sudden" sound, it means that the combustion of individual cylinders is incomplete. The reasons are summarized as follows:
(1) Improper adjustment of the fuel injection pump, resulting in excessive fuel supply and incomplete combustion.
(2) The injection quality of most injectors is poor.
(3) Improper oil supply.
(4) The opening height of the intake valve is reduced and the opening time is delayed, resulting in insufficient intake air.
(5) The air filter element is dirty or the air filter is installed incorrectly, so that the air is not smooth.
(6) The supercharging efficiency of the supercharger decreases.
(7) The fuel quality is too poor.
When diagnosing such faults, we should start from the obvious fault characteristics. Whether it is continuous or intermittent black smoke discharge, this principle should be followed.
(1) If the engine suddenly emits black smoke, but the fault disappears naturally after running for a period of time, it is mostly caused by the poor quality of fuel. After a period of time, impurities are washed away by high-pressure oil, and this kind of fault does not need to be dealt with.
(2) If black smoke is continuously discharged, consider checking whether the intake air is smooth and whether the deformation of the intake pipe increases the intake resistance. First remove the air filter cover, take out the filter element, clean and maintain it, and then test the machine again to see if the exhaust pipe still continues to emit black smoke. If the exhaust smoke is significantly reduced, it means that the air filter is too dirty or has installation problems, which affects the intake air volume, and the maintenance of the intake system should be strengthened.
(3) If the air flow in the intake port is smooth, you should check whether the fuel supply time is too late. If the fuel supply is too late, the fuel entering the cylinder will be exhausted before it can be fully burned to form black smoke.
(4) The injection quality of most fuel injectors is seriously deteriorated, and the fuel atomization is poor, which cannot meet the needs of the shape of the combustion chamber, which makes it difficult to form a combustible mixture, and part of the fuel is converted into free carbon and discharged. This is also one of the causes of black smoke, so the fuel injector should also be checked and repaired.
(5) Check whether the fuel quality conforms to the standard: the standard diesel oil that meets the normal operation of the engine at the ambient temperature in the area should be used.
(6) Check whether the supercharger works normally. When the supercharger fails: the pressure drop at the end of the engine intake: resulting in a drop in the temperature and pressure at the end of compression: affecting the injection atomization and combustion temperature of the fuel.
(7) If the maintenance time of the fuel injection pump is not long: black smoke is discharged from the exhaust pipe: insufficient power: it should be considered whether the fuel injection pump is improperly debugged and the fuel supply is too much: for this, the fuel injection pump should be recalibrated under various working conditions. Fuel supply: Make it meet the regulations.
(8) If the above are normal: and the engine has been running for a long time: consider checking whether the valve opening height and opening time are correct. Long-term use can cause wear and tear of valve transmission parts: normal valve timing and valve lift misalignment: reduced intake air volume: corresponding increase in the amount of residual exhaust gas in the cylinder: directly affecting the full combustion of fuel.
(9) For uneven rotation speed: black smoke is discharged intermittently: the diagnosis of engine weakness can be checked by cylinder-by-cylinder oil cut-off method.
When the fuel in a certain cylinder is cut off: the engine speed is significantly reduced: the black smoke is reduced: the abnormal noise also disappears: it means that the fuel supply of the cylinder is too much: the fuel injection volume of the cylinder should be checked and adjusted. If the engine speed change is small: the black smoke disappears: it means that the spray quality of the fuel injector in this cylinder is poor: the fuel injector should be checked and maintained. If the engine speed still does not change: it means that the cylinder is not working: check the high-pressure oil supply of the cylinder: such as the cooperation of the plunger pair of the fuel injection pump and the oil outlet valve pair: the fixing of the fork on the oil volume adjustment rod Whether the screw, or the fastening screw of the ring gear, is loose: whether the plunger spring is broken, etc. If all are normal: check the working condition of the injector and whether there is any mechanical failure in the cylinder.
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