Analysis of common faults and influencing causes of diesel engines?

The gasoline engine has low noise and stable vibration, but there are many electronic auxiliary equipment and the failure rate is higher; The diesel engine has a large compression ratio, high torque at low speeds, and high efficiency.

The main reason is the failure of the sensor, the failure of the electronic control system.

FYI: 1. The sensor is damaged, the contact is poor, or the signal is interrupted; 2. Poor engine maintenance; 3. The quality of fuel and oil is not good; 4. The combustion of the mixture is insufficient; 5. Spark plug failure, ignition coil failure; 6. The fuel pump is faulty and the oil circuit is blocked; 7. The air conditioner filter is blocked.

The specific situation is analyzed as follows; 1. Sensor problems; The sensors mentioned here include water temperature, crankshaft position, air flow, intake air temperature, oxygen sensor, etc., when these sensors are damaged, poor contact or signal interruption, the ECU of the car can not accurately obtain the engine data, at this time it will cause the engine fault light to turn on. 2. Maintenance problems; Poor engine maintenance is the most common cause of engine failure to light up. We know that the vehicle has a certain maintenance cycle, if the owner does not maintain on time, coupled with bad driving habits, then it will increase the burden of engine operation, and finally can only remind you through the fault light to care about your car 3, oil quality problems; The oil quality here includes fuel and engine oil, we know that the fuel filled by the car is generally marked, and the engine oil is also semi-synthetic and fully synthetic, the manufacturer will generally recommend the owner to use which grade of fuel, which type of engine oil, if the owner does not add as required, it will cause wear and tear of the engine in the long run, and the fault light is not to blame.

Poor combustion of the mixture; The failure of the spark plug, ignition coil, fuel pump, and oil circuit blockage of the engine will cause poor combustion of the engine mixture. Poor combustion of the mixture is caused by the problem of engine carbon deposition or knocking, and these will eventually be detected by the engine's oxygen sensor and reported to the ECU, which will naturally turn on the fault light to warn of the intake air intake problem; When the engine burns, it needs to take intake, the air filter element is very important in this process, if the air filter element of the car is not clean, it will affect the air intake of the car if it is not cleaned regularly, and it will be blocked for a long time, and if it is serious, it will cause the engine failure light to turn on. pressurization issues; Intake booster lines and turbochargers can also cause engine failure lights to illuminate.

The most common of these is turbocharger damage, and at the same time, the vehicle will also have oil leakage, large oil consumption, and power loss.

Reasons affecting the insufficient power of diesel internal combustion engines:1diesel quality; 2.

Is the air filtration system unblocked? Directly affects the air-to-fuel ratio (the ratio of air to fuel); 3.cylinder pressure; 4.

Lubrication time; 5.the degree of fuel atomization; 6.Whether the exhaust system is unobstructed (insufficient exhaust affects insufficient air intake).

The phenomenon of insufficient power of diesel engine is that it is not easy to start or the speed is not easy to increase after starting.

There are several reasons for this:

1. The impact of the failure of the fuel supply system.

1) Insufficient oil supply.

The low amount of oil in the cylinder results in less heat from combustion, and when the heat is reduced to the point where it cannot meet the needs of the engine load, the engine is weak.

2) The spray quality is too poor.

When the engine is working, the injector spray is of poor quality, reacts less with oxidation, and emits less heat.

3) The effect of the injection advance angle.

The amount of fuel in the injector cylinder should be appropriate. If the pressure rise rate of the fuel increases in the tender period, it is easy to cause the engine to work roughly. The injection advance angle is too small, and the thermal efficiency decreases significantly.

4) Effect of inflation volume.

Clogged air filters reduce the cross-section of air circulation, resulting in less heat being released.

5) The parts containing the working medium are poorly sealed.

For example, the cylinder gasket is damaged, the valve is not closed tightly, and the matching gap between the piston and the cylinder wall is too large, which can cause air leakage and poor compression.

6) The influence of ambient temperature.

When the ambient temperature is too high, it often causes the engine to overheat.

2. The influence of engine resistance.

In addition to overcoming the friction and resistance of auxiliary devices, the effective power output of the engine is reduced.

Hello, we are glad to answer the diesel engine oil circuit fault and troubleshooting methods for you.

<>1.The oil supply of the low-pressure oil circuit is not smooth.

When the pipeline joints, gaskets and oil pipes leak due to damage, the air will enter the oil circuit to produce air yin, resulting in poor oil supply, engine difficulty in starting, slow acceleration and other fault phenomena, and it will automatically turn off in serious cases. When the oil pipe is reduced due to aging, deformation, impurities and blockage, or when the oil filter screen and diesel core are blocked due to oil, it will cause insufficient fuel supply and make the engine power decrease and start difficult. The inspection and elimination of this fault can be done on the vehicle.

Use the hand oil pump to pump the oil to a certain pressure, loosen the air screw, if there is a bubble overflow and the exhaust is not exhausted, it means that the oil circuit is inlet air; If there are no bubbles but the diesel oil is not able to spill from the bleed screw, it means that the oil circuit is blocked. The normal phenomenon is that the screw is slightly loosened, and immediately a column of oil is ejected at a certain pressure. The method of troubleshooting with ballast spike is to find out the damaged or aging gasket, joint or oil pipe and replace it; The way to prevent such failures is to clean the inlet filter and diesel filter element frequently, check the pipeline frequently, and solve problems in time when they are found.

2.The piston spring of the oil transfer pump is broken.

The engine suddenly stalled in operation and could not be started, unscrewed the deflating screw to check and found that the low-pressure oil chamber of the fuel injection pump had no fuel or very little, and the hand oil pump was used to pump oil until the entire low-pressure oil chamber was filled with oil, the exhaust air was restarted, and the engine returned to normal, but it automatically turned off again after driving a certain distance. This fault phenomenon is likely to be a broken piston spring of the oil transfer pump. This fault can be eliminated on the car, unscrew the plug, and replace the spring.

3.The check valve of the oil transfer pump is not tightly sealed.

The engine works normally after starting, but it is difficult to start after turning off and stopping for a certain period of time, and the air needs to be discharged again before it can be started. This kind of failure is mostly caused by the poor sealing of the check valve of the oil pump. The method of travel inspection is to unscrew the oil outlet screw of the oil pump, and the pump uses the oil pump to fill the oil chamber of the oil outlet joint, if the oil level in the joint drops quickly, it means that the check valve is not well sealed.

Remove the check valve to check whether the sealing surface is intact, whether the check valve spring is broken or deformed, and whether there are particles and impurities on the sealing seat surface. The normal situation is that the oil level does not drop in more than 3min, and the pump uses the oil pump to spray out the oil column from the oil outlet joint.

4.The high-pressure oil line is clogged.

When the high-pressure oil pipe of a cylinder is blocked due to deformation or impurities, there is an obvious knocking sound in the oil pipe part after starting the engine, and the engine power decreases due to the cylinder not working normally. The inspection method is to loosen the oil inlet end nut of the high-pressure oil pipe one by one, when the knocking sound disappears after loosening a cylinder, it can be concluded that the cylinder is a faulty cylinder, and the fault can be eliminated after replacing the oil pipe.

5.The injector is jammed.

When the injector needle valve is stuck in the closed position, there is a regular knocking sound near the cylinder head. It is caused by the pressure being impinged on the injector when the injection is measured. The judgment method is to loosen the high-pressure oil pipe at the end of the injector, if the knocking sound disappears immediately, it can be concluded that the needle valve of the fuel injector of this cylinder is stuck.