What should I do if the idle speed of the car is unstable? What to do if the car idling is unstable

The inspection items such as the car cannot start, the idle speed is unstable, the speed is high and low, and the oil supply is abnormal

1. The battery voltage of the car is low; Specific detection method: test the battery voltage with a three-purpose meter voltage level, if it is below 10V, it is recommended to replace it. If it is around 11V, it is barely used; Be prepared for replacement. It can be used above 12V;

2. Check whether it is caused by carbon deposits; If you travel about 20,000 km, focus on checking and cleaning the throttle;

3. Inspect, test and replace spark plugs;

4. Confirm the quality of the gasoline added;

5. Detecting the ignition switch;

6. Test and detect the starter, gasoline pump, sensor and other related components of the starting and oil supply system;

7. After powering on, do not start immediately, wait for 30 seconds to 1 minute, and then ignite; See if it works;

Regardless of any of the above situations, pay attention to the time when the car cannot be hit once, be sure to play again after an interval of 15-30 seconds to protect the battery but not generate power and prolong its service life.

Unstable idling can be due to the following reasons:

1. The engine has serious carbon deposits.

When the carbon deposit inside the engine is too much, the gasoline sprayed out by the cold start fuel injection head will be absorbed by the carbon deposit in large quantities, resulting in the mixture of cold start being too thin, making it difficult to start, in this case, only when the gasoline absorbed by the carbon deposit is saturated, it is easy to get on the car, and the gasoline adsorbed on the carbon deposit after the car will be sucked into the cylinder by the vacuum suction of the engine for combustion, and the mixture becomes thick, and the combustible mixture of the engine is dilute and thick, causing idle shaking after cold start.

2. Excessive fouling of the throttle and inlet tract.

The excessive carbon and dirt deposits in the throttle valve and the surrounding air intake, and the change in the cross-sectional area of the air channel, make the control unit unable to accurately control the idle air intake, resulting in the mixture being too thick or too thin, and making the combustion abnormal.

3. The spark plug spark caused by individual spark plug failure is too weak.

Spark plugs can also build up carbon, which can be cleaned to restore spark plug activity, but some spark plugs are nearing the end of their useful life and their performance will be reduced. The spark plug spark on the individual cylinder is weak, which will affect the performance of the car, and the spark plug failure will cause the car to have the symptoms of "lack of fire", but the spark plug of the individual cylinder will have idle instability symptoms if there is a slight fault.

4. 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.

5. Failure of various parts.

Leakage of intake manifold or various valves, failure of fuel pressure, low oil pressure, failure of ignition system, etc., can also cause engine idling instability.

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.

If you find that the idle speed of the vehicle is unstable, high or low, you should go to the repair shop for inspection in time. Because engine idling has a great impact on fuel consumption, especially when running in urban areas, frequent stopping and starting have a greater impact. Generally speaking, the idle setting button of the engine is around 800 rpm.

If the speed is too high, fuel consumption will definitely increase. It is recommended to set the idle speed without the engine shaking. When the air conditioner is on, the idle speed of the car will be slightly higher; The idle speed of the car will be slightly higher when the car starts cold, but it will return to normal after a while.

Remedy: If you find that your car is idling unsteadily, high or low, you should go to a repair shop to repair it in time.

The main causes of unstable idling;

1. The most common cause of vehicle shaking is that the throttle is too dirty or the fuel injector has too much carbon.

2. When the carbon deposition inside the engine is too much, the gasoline sprayed by the cold start fuel injector will be absorbed by a large amount of carbon deposition, resulting in the mixture of cold start being too thin, making it difficult to start, in this case, only when the gasoline absorbed by carbon deposition is saturated, it is easy to get started, 3. After the car is adsorbed, the gasoline adsorbed on the carbon deposition will be sucked into the cylinder by the vacuum suction of the engine for combustion, and the mixture becomes thicker, and the combustible mixture of the engine is dilute and thick, resulting in idle shaking after cold start. The lower the temperature, the greater the amount of oil required for the cold start, and the more carbon deposits will affect the smooth cold start.

Severe idle vibration is generally caused by engine cylinder failure, aging or loose foot rubber, carbon deposits, fuel system failure, etc.

Solution; The best way is to clean the oil circuit, clean it regularly, and use PNF fuel additives to solve the above problems caused by carbon deposits. The fuel quality is not very good or the initial fuel of the new car is stored for too long, resulting in a rapid increase in the gelatinous composition of the oil circuit, which will continue to pollute the fresh fuel and cause no good fuel to participate in the combustion in the later stage. We can only maintain and clean oil circuits, so that we can gradually alleviate most of the problems.

The treatment method of vehicle idle instability: 1. Idle instability is generally caused by carbon deposits inside the throttle and idle motor, and it can be solved by cleaning the throttle and idle wax pin motor; 2. The quality of gasoline is not good, resulting in poor nozzle atomization effect, and the mixture is not fully burned in the cylinder, so it will also lead to unstable idling. 3. The spark plug does not ignite, resulting in one or more cylinders not working in turn, and it will also lead to unstable idling speed, check whether there are cracks in the ceramic part of the spark plug, and also check whether the ignition module is normal.

Causes of unstable idling:

1. Fuel system.

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.

Common causes are: clogged fuel filter; Fuel pump strainer clogged; The fuel pump's pumping capacity is insufficient; The spring elasticity of the fuel pump safety valve is too small; deformation of the inlet pipe; The fuel pressure regulator is faulty; The oil return line is deflated and blocked.

3) Inaccurate fuel injection.

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.

The specific causes are: malfunction of the air flow meter (or intake manifold pressure sensor); Faulty throttle position sensor; throttle idle switch failure; Coolant temperature sensor failure; Faulty inlet air temperature sensor;

Failure of the oxygen sensor; The lines of the above sensors have open circuits, short circuits, and ground faults; The plug of the engine control unit is in poor contact due to water ingress or internal computer failure.

2. Mechanical structure.

1) Gas distribution mechanism.

The failure of the valve mechanism causes the power of individual cylinders to drop too much, resulting in an imbalance in the power of each cylinder.

The common reasons are: the timing belt is installed in the wrong position, which changes the opening and closing time of the valves of each cylinder, resulting in the inaccuracy of the gas distribution phase and the abnormal combustion of each cylinder.

Excessive carbon deposits on the valve working surface and valve seat insert, and poor valve sealing, make the compression pressure of each cylinder inconsistent. The camshaft cam wear, and the inconsistent wear of each cylinder cam leads to the inconsistent amount of air entering each cylinder.

Faulty valve-related parts, such as worn or bent valve actuators, worn rocker arms, jammed or leaking valves, broken valve springs, etc.

2) Engine block and piston connecting rod mechanism.

These failures can cause the power of individual cylinders to drop too much, resulting in an imbalance in the power of individual cylinders.

Common causes are: ablation or damage to the cylinder gasket, resulting in air leakage in a single cylinder or between two cylinders; The piston ring has too large end backlash, counter-jointing or breakage, and the piston ring loses its elasticity; Excessive carbon deposits in the piston ring groove;

The piston and cylinder are worn, and the roundness and cylindricity of the cylinder are out of tolerance; The compression ratio is changed due to the bending of the connecting rod caused by water ingress into the cylinder; Carbon deposition in the combustion chamber will change the compression ratio, and the carbon deposition will cause instability in idling speed due to serious carbon deposition.

3) Other reasons.

The dynamic balance of rotating parts such as automobile crankshaft, flywheel, crankshaft pulley is unqualified, the engine foot pad is broken and damaged, and the engine bottom guard plate collides with the oil pan due to deformation, etc., these reasons will only cause the engine to vibrate without affecting the speed.

The six main causes of unstable car engine idling:

1. The mixing ratio is not appropriate, resulting in jitter.

If the oil-gas mixing ratio in the engine compartment of the car is not adjusted accurately, the car will easily shake. In a closed-loop controlled car, the minimum operating temperature of the oxygen sensor is 370 degrees Celsius, and if the car is just started, the oxygen sensor does not work because the temperature in the exhaust pipe does not reach 370 degrees Celsius. At this time, the ECU misjudges, and the control of the oil and gas mixing and ignition time through the actuator has an error, thereby reducing the power output of the car and causing shaking.

2. Low ignition energy leads to jitter.

3. The different working conditions of each cylinder lead to jitter.

4. Carbon deposits in the valve and intake tract cause jitter.

5. The water temperature sensor fails and causes jitter.

6. Other factors cause jitter.

The main reasons for the instability of the idle speed of the car are: serious carbon deposition in the engine, excessive carbon deposition in the throttle and intake tract, failure of the fuel pressure regulator, blockage of the injector, blockage of the fuel filter, spark plug accumulation, incorrect spark plug clearance, and excessive resistance of the high-voltage line. When there is too much carbon deposition inside the engine, the gasoline sprayed by the cold start fuel injector will be absorbed by a large amount of carbon deposition, resulting in the cold start mixture being too thin and the car will be difficult to start, and the gasoline adsorbed on the carbon deposit will be sucked into the cylinder by the vacuum suction of the engine after landing, so that the mixture becomes thick and causes idle shaking after cold start.