What is the reason for the unstable idle speed of the engine?

Causes of unstable idle speed of engine;

1, throttle oil accumulation and throttle carbon accumulation, air intake is too dirty, air intake is blocked, which will cause unstable idle speed, and throttle has carbon or engine oil, which are the most common reasons for unstable idle speed. Due to carbon deposition, the throttle will affect the opening and air intake, which makes the engine speed rise and fall after the car is started, which is very unstable and accompanied by strong jitter.

2. The throttle valve has serious oil storage or carbon deposition, including the dirty air inlet, which makes it difficult to start the car in cold weather. When the throttle is dirty, it needs to be cleaned, and the throttle cleaning itself is also a daily maintenance item;

3. Spark plugs caused by individual spark plug failures are too weak, and spark plugs will also deposit carbon. Carbon deposition can clean up and restore the activity of spark plugs, but the service life of some spark plugs is approaching, and the performance will also decline;

4. The spark plugs on individual cylinders are weak, which will affect the performance of the car. We know that the spark plug failure will lead to the "fire" symptom of the car, but the spark plug failure of individual cylinders will lead to the idling instability symptom. Therefore, when the idle speed of the car is unstable, cleaning or replacing the spark plug is also an option to solve the fault.