What Causes Occasional Idle Shaking?
2 Answers
Occasional idle shaking may be caused by issues such as broken high-voltage wires, low idle speed, abnormal water temperature, or low cylinder pressure. Below are detailed explanations: 1. Broken High-Voltage Wires: This refers to a break in the conductor core of the high-voltage wire, which can affect ignition and cause engine shaking. Use a multimeter to measure resistance and replace the wire with significantly higher resistance. 2. Low Idle Speed: The engine's idle speed is preset in the car's computer. When the RPM drops below a certain range, the computer will automatically adjust it. If the idle speed is too low and causes shaking, it indicates that it has exceeded the computer's control range. 3. Abnormal Water Temperature: The engine operates within a normal temperature range. If the water temperature is too high, it can lead to advanced ignition timing, altered air-fuel mixture, thinned oil viscosity, and reduced lubrication performance. 4. Low Cylinder Pressure: Engines come in 3-cylinder, 4-cylinder, 5-cylinder, 6-cylinder, and 8-cylinder configurations. If one cylinder is not functioning properly, it can cause a misfire and engine shaking. This is most noticeable in 3-cylinder engines, followed by 4-cylinder ones. Adding oil to the engine or directly into the cylinder can help restore balanced cylinder pressure.
My friend also experienced idle shaking issues with his car, mainly due to several common causes: ignition system problems, such as worn spark plugs or faulty ignition coils, affecting combustion uniformity; fuel supply system issues, where carbon buildup in the injectors causes uneven fuel delivery; intake system problems, like a dirty throttle body or clogged air filter restricting airflow; or worn and loose engine mounts exacerbating the shaking. Long-term neglect of this issue could lead to skyrocketing fuel consumption, engine misfires, or even damage to the catalytic converter. It's recommended to stop and inspect immediately upon noticing shaking. Regular maintenance, such as replacing spark plugs every 20,000 kilometers and keeping filters clean, can prevent this. For a more reliable diagnosis, visit a professional shop for an ECU check—don’t cut corners and delay repairs.
