What's with the exhaust pipe jitter at idle speed?

If the intake of the engine is incorrect, the mixture will be too rich or too thin, which will make the engine burn abnormally. Will lead to engine idling jitter. When the position of air leakage affects the vacuum degree of the engine, the engine will shake violently, which has a great influence on the idle speed of the cold car.

Common causes: air leakage caused by aging of intake manifold gasket, intake manifold damage or other parts leading to intake manifold perforation, vacuum tube plug falling off, broken EGR valve not closed properly.

2. There is too much scale on the throttle and air intake.

There is too much carbon and dirt in the throttle and the surrounding air intake, and the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake, resulting in the mixture being too rich or too thin, which makes the combustion abnormal.

Common causes: throttle carbon deposit, oil pollution, and carbon deposit at the air intake around the throttle.

3, idle air actuator failure

Idle air actuator failure leads to inaccurate idle air control.

Common causes: the throttle motor is damaged or stuck, and the throttle valve plate is stuck with carbon deposit.

4. Incorrect air intake

The control unit receives the signal from the wrong air flow sensor and sends out the wrong command, which leads to inaccurate air intake at idle speed and abnormal combustion of the engine due to abnormal mixture concentration, which is the indirect cause of unstable idle speed.

Common causes: air flowmeter or its line failure; Intake pressure sensor or its line fault; Poor contact of engine control unit harness or failure of engine control side itself.

Extended data

Causes of sudden noise from exhaust pipe when idling in place

1, exhaust pipe damage: because the engine exhaust emits high-temperature and high-pressure exhaust gas, it is also mixed with some tempering explosions. Therefore, it must be silenced and purified through the exhaust pipe. If the exhaust pipe is damaged (has a gap), waste gas will be ejected from the gap, resulting in sudden noise.

2. Engine lack of cylinders: The reason why automobile engines don't have intermittent sonic boom like motorcycles is because the exhaust processes of cylinders of multi-cylinder engines (automobile engines are mostly four cylinders) are interconnected. Once a cylinder of the engine stops working, the exhaust connection of each cylinder will be disconnected, and the exhaust pipe will also be pulled off.