What Causes High Idle Speed and Shaking in Cars?
2 Answers
Car high idle speed and shaking can be caused by: 1. Dirty throttle body; 2. Faulty spark plugs; 3. Non-functioning engine cylinders; 4. Aging rubber components in engine and transmission mounts. The car engine is the device that provides power to the vehicle, determining its power performance, fuel economy, stability, and environmental friendliness. Idle speed refers to the engine running without load, needing to overcome internal friction resistance without outputting power externally, maintaining the minimum stable operating speed. The idle speed is adjusted by modifying the throttle opening size and idle fuel supply quantity.
I once experienced high idle speed shaking while driving, with the engine RPM noticeably higher than normal and the car shaking violently. The mechanic later told me that this is usually caused by excessive carbon buildup, especially when the throttle body and fuel injectors get clogged with sludge, leading to poor air intake and aggravated engine shaking. Worn-out spark plugs are another common issue—if the ignition is uneven, the idle speed tends to become unstable. Another factor is a faulty idle control valve, which is responsible for maintaining idle RPM. Once it fails, the RPM fluctuates erratically. It's advisable to first check if the air filter is dirty yourself. If the problem is severe, it's best to visit a professional shop for a thorough cleaning. After all, delaying repairs can affect fuel efficiency and even damage the engine's core components. I must say, regular maintenance is truly important to prevent such issues.
