What is the reason for the unstable idling speed of the car at high speed?

Causes of unstable car idling.

1. Air leakage from the intake manifold.

When the air that should not be entered, gasoline vapor, and combustion exhaust gas enter the intake manifold, the mixture is too thick or too thin, causing the car to idle unsteadily.

2. Too much carbon deposition on the throttle.

Excessive carbon deposition in the throttle valve and surrounding air intakes, and changes in the cross-sectional area of the air channel, make it impossible for the control unit to accurately control the amount of air intake at idle, which will also lead to too thick or too thin mixture, resulting in unstable idling of the car.

3. Failure of the actuator of the air intake system.

There are many actuators in the engine intake system, such as throttle motors, idle stepper motors, duty cycle solenoid valves, air flow meters, intake pressure sensors, etc., which cause the car to idle unstable.

4. Fuel system failure.

Faults such as clogged injectors, clogged fuel filters, clogged fuel pump filters, faulty fuel pressure regulators, and clogged return pipes can all lead to incorrect fuel injection, resulting in over-concentrated or over-thin mixtures, resulting in unstable car idling.

5. Ignition system failure.

Faults such as ignition module failure, incorrect spark plug clearance, spark plug electrode ablation or damage, and excessive resistance of the high-voltage line lead to a decrease in ignition spark energy or misfire, resulting in unstable idling of the car.

1. Air intake system.

1) Intake manifold or various valves leaking.

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. When the leakage position only affects individual cylinders, the engine will shake more violently, which will have a greater impact on the idle speed of the cold car. Common causes are:

loose intake manifold clamp or cracked hose; Air leakage from the intake manifold gasket; Damage to the intake manifold or other parts to grind out of the intake manifold; Injector O-ring leakage; The plug of the vacuum tube falls off and cracks; The crankcase forced ventilation (PCV) valve has a large opening; The activated carbon tank valve is normally open; Exhaust gas recirculation (EGR) valve is not closed tightly, etc.

There are several reasons why the hair chain is judging:

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. The oil pressure is unstable, if the first 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; The excessive carbon deposits in the emissions of the bright motor absorb the carbon in the gasoline of the cold-start injector, which leads to a dilute cold-start mixture and difficulty starting.

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

1.Serious engine carbon deposits: Cars always have the problem of carbon deposits, including cylinder carbon deposits, throttle carbon deposits, spark plug carbon deposits, intake carbon deposits, etc.

When the engine has too much carbon deposit, it will affect the ignition energy, air intake efficiency and air-fuel ratio of the car, resulting in the unstable power output of the car, and the phenomenon of idle speed and acceleration jitter appears.

2.Unstable oil pressure: If you have cleaned the engine carbon deposits, cleaned the throttle, replaced the oil gasket and spark plug, etc.

And when idling, you still find that the body shakes, it is recommended that you go to the 4S shop to check whether the oil supply pressure and intake pressure sensor are normal, if the oil pump supply pressure is abnormal, or the intake pressure sensor value is wrong, and the work is not good, it will cause the body to shake.

3.Engine cylinder shortage: Engine cylinder deficiency mainly refers to the engine one or more cylinders are not working properly, which is generally manifested as:

The exhaust fumes coming out of the car are obviously intermittent, and the exhaust pipe shakes violently, and the engine shake can be clearly felt, sometimes accompanied by abnormal noises. This is mostly related to ignition coil failure.

4.Aging of engine parts: Shake in the car is also associated with the aging of the engine feet (also known as claw pads).

The engine foot is actually the shock absorber system of the engine. The engine feet are responsible for absorbing slight vibrations when the engine is running. If there is a problem with the hand-wide engine base, these vibrations can be transmitted to the steering wheel and cab, causing vibrations 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.

The spark plug has not been maintained for a long time, and there is too much dirt on the surface and it is not replaced for 30,000 kilometers.

The fuel injector and throttle are not cleaned and maintained.

The reasons for the unstable idle speed of the automobile engine are as follows: 1. The leakage of the intake manifold or various valves causes the engine to burn abnormally; 2. Excessive fouling of the throttle valve and air intake, resulting in excessive concentration or dilute of the mixture, resulting in abnormal combustion; 3. The failure of the idle air actuator will lead to inaccurate idle air control, and the car will be unstable at idling.

Generally, there are the following situations: 1Lack of cylinder 2

Bad idle motor 3Air intake system and vacuum booster system leakage 4Bad oxygen sensor 5

Timing belt skip teeth 6Individual valves are not closed tightly or do not open 7Throttle stuck The above is just a part, you refer to the following.

Clean the throttle and idle valve.