What is the reason for the unstable engine idling I know please reply thank you

It should be that the oil head or oil product is not good.

Unstable engine idling is mainly due to the following aspects of the car:

1. Failure of the air intake system.

1. Leakage of intake manifold or various valves.

When the air that should not enter, gasoline vapor, and combustion exhaust gas enter the intake manifold, the mixture is too thick or too thin, and the engine burns abnormally.

2. Excessive fouling of the throttle and inlet tract.

Common phenomena are: throttle valve oil or carbon deposits; There is oil and carbon deposits in the air intake tract around the throttle; Idle stepper motors, duty cycle solenoid valves, and rotary solenoid valves have oil stains and carbon deposits.

3. Failure of idle air actuator.

Inaccurate idle air control due to a faulty idle air actuator. Common causes are: throttle motor damage or card issuance; Idle stepper motors, duty cycle solenoid valves, rotary solenoid valves are damaged or hairpinned.

4. The air intake is inaccurate.

Common phenomena are: air flow meter or its line fault; Failure of the inlet pressure sensor or its wiring; The plug of the engine control unit is in poor contact due to water ingress or internal computer failure.

Second, the fuel system failure.

1. Injector failure.

The uneven amount of fuel injection and the mist of the injector cause an imbalance in the power emitted by each cylinder. Common causes are: clogged injectors, poor sealing, and linear fuel injection.

2. Fuel pressure failure.

If the oil pressure is too low, the atomization state of the fuel injected from the injector is poor or the fuel injected is linear, and only oil droplets are sprayed in serious cases, and the amount of fuel injected is reduced to make the mixture too thin; The oil pressure is too high, and the actual fuel injection volume increases, making the mixture too concentrated.

3. The amount of fuel injected is inaccurate.

The failure of each sensor or line causes the control unit to issue wrong instructions, so that the fuel injection volume is incorrect, resulting in the mixture being too thick or too thin, which is an indirect cause of unstable idling.

3. Ignition system failure.

1. The ignition module and ignition coil are faulty.

The ignition module or ignition coil is faulty, mainly manifested as a weak high-voltage spark or a spark plug that does not ignite.

2. Spark plug and high-voltage line failure.

Common include: incorrect spark plug clearance; Ablation or damage to the spark plug electrode; The spark plug electrode has carbon deposits; Cracks in the spark plug magnetic insulator; The resistance of the high-voltage line is too large; Leakage of high-voltage wire insulation sheath or plug; Poor electrode ablation or poor insulation of the fire splitter.

3. The ignition advance angle is inaccurate.

Because the fault of the sensor and the line is an indirect cause of the instability of the idle speed, the control unit issues an error command, which makes the ignition advance angle incorrect, or causes a wide range of ignition advance angle fluctuations.

Engine idle instability is the change of gas force in the cylinder, which causes the power imbalance of each cylinder, resulting in the inconsistent horizontal component of each piston during the power stroke, and the torque imbalance of the engine lateral rocking, resulting in engine shaking.

The change of gas force in the cylinder, the change of gas force of one cylinder or the change of gas force of several cylinders, causes the power of each cylinder to be unbalanced, resulting in the inconsistency of the horizontal force component of each piston when doing the power stroke, and the torque imbalance of the engine lateral shake, resulting in engine jitter. It can also be said that any failure that causes a change in the gas force in the engine cylinder can cause the engine to idle and shake.

There are many reasons for the unstable idle speed of the engine, and there are generally the following reasons: the throttle is too dirty, which leads to the excessive opening of the throttle, which leads to the unstable idle speed of the vehicle when it is just taken a taxi. The problem of spark plug or ignition coil ignition problem, this problem will generally lack the problem of cylinder, which is the unstable idle speed.

Moreover, the power is insufficient during driving, the problem of the intake pipeline, and there is a leakage, so that the power is generally insufficient, and the problem of gasoline pressure leakage generally occurs in the intake pipe and exhaust pipe. Generally, the oil pump does not work, and the fuel injector is blocked, resulting in poor fuel injection.

1. Cause analysis 1. Poor spark plug work; 2. Air leakage of vacuum tube; 3. High-voltage line leakage; 4. The PCV valve is blocked; 5. Throttle position sensor failure; 6. Idle stepping motor failure; 7. The idle control valve fails; 8. The throttle opening is abnormal; 9. Air leakage in the air intake system. 2. What should I do if the idle speed is unstable? Idle instability is manifested as:

When idling, the engine shuddes and revs unevenly. The reasons are: blockage of the idle air measuring hole, poor working of the idle device, weak sparks of individual cylinder spark plugs, poor sealing of individual valves, air leakage of the intake manifold, too early or late ignition time, improper idle speed adjustment, etc.

When the engine idle speed is unstable, the idle speed should be adjusted first, if the fault can not be eliminated after the idle speed adjustment, the idle speed measuring hole and the idle air measuring hole should be checked whether it is blocked, if the measuring hole is blocked, it can be cleaned with gasoline or acetone and blown through with compressed air; If the measuring hole is not blocked, the engine speed should be stabilized at a certain speed, and whether there is air leakage in the intake manifold or carburetor or the lower gasket. If the idle speed is unstable and accompanied by the decrease of engine power, the working condition of the spark plug, the sealing performance of the valve and the ignition time should be further checked, and the maintenance and adjustment should be carried out if necessary.

The specific reasons why the engine of the car shakes and idles unsteadily:

1. Excessive carbon deposition in the engine: When there is too much carbon deposition inside the engine, the gasoline sprayed by the fuel injector of the starting vehicle will be absorbed by a large amount of carbon deposition, resulting in too thin mixture, resulting in difficulty in starting, and the vehicle will be easy to start only when the gasoline absorbed by carbon deposition reaches the saturated state.

Solution: It is recommended to clean up the engine carbon deposits frequently.

2. Air filter: If it is not replaced in time, it will cause insufficient air intake, and the idle speed of the engine will be reduced, so that the engine will shake.

Workaround: Replace the air filter.

3. Low ignition energy: the internal temperature of the engine is not enough when the vehicle is cold started, and the fuel injector sprays more gasoline to meet the power requirements during cold start. Fuel requires higher ignition energy, and a larger gap between the spark plugs will lead to a decrease in ignition energy, which in turn will affect the dynamics and cause the vehicle to shake.

Solution: Replace the spark plug.

4. Abnormal water temperature: If the water temperature of the engine is high, the ignition time will become earlier, which will change the oil-gas mixing ratio and the viscosity of the oil will become thinner (the lubricity will become worse). The causes of the water temperature anomaly are:

Caused by lack of coolant, thermostat not opening, fan failure, and inaccurate temperature of the temperature control switch.

Solution: It is recommended to go to the 4S shop for inspection and maintenance.

5. Carbon deposition in valves and inlet tracts: If carbon deposition occurs in valves and intake tracts in the engine, jitter will occur.

Solution: Clean up the carbon deposits in the valve and intake tract.

6. Fuel injector blockage: The fuel injector is blocked, which will lead to inconsistent fuel injection volume of each fuel injector, resulting in different working of each cylinder, which will cause the engine to shake.

Solution: Clean the injector and replace it if necessary.

The first reason is to check the failure of the intake pipe, because if the intake pipe of the car has a leakage, the accuracy of the internal air flow meter is not high, and finally the proportion of the mixture is out of balance, which also causes the engine to idle stably. There is also a blockage of the oil pipe, which will also cause insufficient oil supply pressure, if you want to solve this problem, you can.

2.The second is that the spark plug has carbon deposits, which is also one of the reasons for the instability of the idle speed, the spark plug is one of the most important auto parts, it is inside the cylinder of the car, once there is a problem, it will cause the phenomenon of lack of fire in the engine, so there is also an unstable idle speed. To solve this problem, the spark plug needs to be cleaned or replaced.

3.The third is the failure of the relevant sensor, the most important manifestation is the problem of the water temperature sensor, the fuel consumption of the car will increase accordingly, and there will also be the phenomenon of unstable idling. At this time, it is necessary to check whether there is a problem with the relevant sensors of the car, and replace them in time if there is a failure.

4.The fourth is the fuel storage of the throttle and the carbon deposition of the throttle, which are also the causes of unstable idling. When the throttle has oil or carbon deposits, which affects the air intake of the car, the engine speed is very unstable when the car starts cold, so checking the throttle is also a useful method.

The idle state refers to the working condition of the engine when it is idling, that is, when the engine is running, the accelerator pedal is completely relaxed, and the engine is in the idle state. The speed at which the engine is idling is called idle speed, which is the minimum speed at which the engine can maintain normal operation without external output. Engines with good working performance generally have an idle speed of 550-800 rpm.

Unstable idle speed is in the idle state, the speed fluctuates high and low and changes greatly, which is the most common fault of the engine, and the main common reasons are:

1) The idle switch is not closed.

Diagnosis method: Turn on the air conditioner and turn on the steering wheel when idling, and the engine speed does not rise, which can prove to be this fault.

Exclusion: Adjustments, repairs, or replacements of throttle position sensors.

2) Idle control valve (ISC) failure.

Diagnostic method: Check the actuation sound of the idle control valve, if there is no actuation sound, the idle control valve is faulty.

Troubleshooting: Clean or change the idle control valve, and use a special decoder to set the idle speed basically.

3) Air leakage in the air intake line.

Diagnostic Method: If you hear a snorting sound of a leak in the intake pipe, it is evidence of a leak in the air intake system.

Troubleshooting: Find leaks, reseal or replace phase parts.

4) Injector dripping or clogging.

Diagnostic method: Use a stethoscope to check whether the injector makes a "click" actuation sound or measure the fuel injection volume of the injector, if the injector does not make a sound or the fuel injection volume exceeds the standard, the injector is faulty.

Troubleshooting: Clean the injectors, check the amount of fuel injected into each injector and confirm that there is no clogging or dripping.

5) Exhaust system blockage.

Diagnostic method: Use a vacuum gauge to detect the px, if the px is low and the acceleration is often accompanied by the phenomenon of stuffiness, it can be determined that this fault is the fault.

Troubleshooting: Replace the three-way catalytic converter.

In addition to the above fault causes, there are many faults that can also cause idle abnormalities, including: ECU failure; main oxygen sensor circuit; EFI main relay circuit; Standby power circuits; cold-start injector circuitry; Variable resistor resistance for gas mixture; fuel quality; Vacuum leakage in the inlet pipe; clogged air filter; Poor cylinder compression, etc.

Normally, the idle speed of the engine is stable between 600 and 800 rpm, and then it will not exceed 100 rpm if it fluctuates up and down, and if it exceeds 100 rpm, it is generally considered to be unstable.

See if the fuel injector and throttle are dirty, wash and see.

Most of the cold start jitter is caused by poor fuel combustion, the fuel tank has more gum moisture, and the cold start is not brought to the combustion chamber and then mixed in the fuel tank is driven into the combustion chamber, and the jitter caused by poor combustion.

There are several causes of engine shake;

1. The engine has serious carbon deposits, and the most common car with serious shake is that the fuel injector throttle valve is too dirty or too much carbon;

2. Ignition system problems, check the working conditions of spark plugs, high-voltage wires and ignition coils;

3. If the oil pressure is unstable, if the pressure of the pump is abnormal or the error and poor work of the inlet pressure sensor will cause the body to shake;

4. Aging of engine parts; Excessive carbon deposits in engine emissions absorb carbon from the gasoline of the cold-start injector, which leads to a dilute cold-start mixture and difficulty starting.

Specific solutions to idle jitter:

1. The engine has serious carbon deposits. The most common cause of idle judder is excessive carbon build-up on the throttle or injector. When there is too much carbon deposit inside the engine, the gasoline sprayed by the fuel injector during cold start will be absorbed by the carbon deposit, resulting in a mixture that is too thin and making it difficult to start.

After landing, the gasoline adsorbed on the carbon deposits will be sucked into the cylinder by the engine and burned, which will thicken the mixture. The mixture is sometimes dilute and sometimes thick, which will cause idle jitter after cold start. The lower the temperature, the greater the amount of oil required for cold starts, and the more the presence of carbon deposits affects cold starts.

The solution is to clean the carbon deposits at the throttle and injector.

2. Poor ignition system and poor ignition of spark plugs will also lead to engine idling and shaking. If there is a problem, check if the ignition system is faulty and if there is too much carbon deposited in the spark plug.

3. The oil pressure is unstable. If you have cleaned the engine carbon deposits, cleaned the throttle valve or replaced the spark plug, and there is still the problem of body shaking when idling, it is recommended to go to the 4S shop to check whether the fuel supply pressure and intake pressure sensor are normal. If the oil pump is not properly supplied or the intake pressure sensor is incorrect, it will also cause the body to shake at idle.

Solution; The best way is to clean the oil circuit, clean it regularly, there is no specific experience in the research and development parameters of the clean engine from the new car, coupled with the continuous improvement of emission standards, can not adapt to the change of fuel, all manufacturers of the engine are unable to solve this jitter problem in the short term, plus the fuel quality is not very good or the initial fuel of the new car factory is stored for too long, resulting in a rapid increase in the colloidal composition of the oil circuit, which will continue to pollute the fresh fuel and cause no good fuel to participate in combustion in the later stage. The occurrence of excessive carbon deposits is especially common for China VI vehicles. We can only gradually alleviate most of the problems by maintaining clean oil circuits. The use of PNF dope fuel additives can solve the problems caused by carbon deposition.