What Causes a Car to Have No Idle Speed?
2 Answers
Spark plugs that have not been maintained for a long time accumulate excessive surface contaminants, often due to not being replaced every 30,000 kilometers. If there is oil or carbon buildup in the car's throttle body, it is necessary to promptly visit a 4S shop or a repair shop to clean the throttle body. Specific Reasons: A blocked intake tract can cause idle speed fluctuations, while carbon deposits or oil in the throttle body are the most common causes of unstable idle speed. Carbon buildup in the throttle body affects its opening degree and the intake air volume, leading to erratic engine RPM fluctuations and strong vibrations when the car is started cold. Precautions: Severe oil or carbon buildup in the throttle body, including a dirty intake tract, can make it difficult to start the car in cold weather. A dirty throttle body requires cleaning, which is considered a routine maintenance task. Spark plugs can also accumulate carbon deposits, and cleaning can restore their activity. However, some spark plugs may experience performance degradation as they near the end of their lifespan. Weak sparks from individual spark plugs can affect the car's performance, and generally, faulty spark plugs may cause the car to exhibit "misfire" symptoms.
I've been running an auto repair shop for over a decade and have seen numerous cases of idle speed loss. The most common issue is a stuck idle control valve - this component regulates air intake, and when clogged with carbon buildup or suffering from aged electronics, idle speed becomes uncontrollable. Dirty throttle bodies can cause identical symptoms; I recently fixed an old Volkswagen just by cleaning its throttle body. Another culprit is intake system leaks, such as ruptured vacuum hoses allowing excess air to enter, making the engine unable to maintain idle. Faulty spark plugs with mistimed ignition or insufficient fuel pump pressure cutting off gasoline supply will also eliminate idle speed. Sensors like malfunctioning mass airflow meters can trigger ECU errors too. Although these seem like minor faults, neglecting them risks sudden stalling while driving. I recommend car owners periodically inspect these components to avoid roadside breakdowns.
