What Happens When the Idle Speed is Unstable?
1 Answers
Unstable idle speed in a car is mainly manifested by the fluctuation of the tachometer needle up and down, pointing unstably, moving up and down, often accompanied by idle vibration. Unstable idle speed can be considered one of the most common engine faults, which can range from minor to severe. Under normal circumstances, the engine idle speed is fixed, with the specific level depending on the tuning of the particular model. Generally, a higher idle speed leads to relatively higher fuel consumption, but an idle speed that is too low can cause the engine to vibrate or even stall. Below is relevant information about unstable idle speed: 1. Oil residue and carbon deposits in the throttle body, dirty intake manifold: A clogged intake manifold can cause idle pull, while carbon deposits or oil in the throttle body are the most common causes of unstable idle speed. Carbon deposits in the throttle body can affect its opening, influencing the intake air volume, causing the engine speed to fluctuate erratically after a cold start, being very unstable and accompanied by strong vibrations. 2. Weak sparks from faulty spark plugs: Spark plugs can also accumulate carbon deposits, which can be cleaned to restore their activity, but some spark plugs may be nearing the end of their lifespan, leading to decreased performance. Weak sparks from spark plugs in individual cylinders can affect the car's performance. It is known that spark plug faults can cause the car to exhibit "misfire" symptoms, but minor faults in spark plugs of individual cylinders can lead to unstable idle speed symptoms.
