What Causes Engine Idle Shaking?
2 Answers
Engine idle shaking can be caused by: 1. Severe engine carbon buildup; 2. Ignition system issues; 3. Unstable fuel pressure; 4. Aging engine components. Solutions for engine idle shaking include: 1. Cleaning the fuel system when there's severe carbon buildup in the engine or idle control valve; 2. Checking spark plugs for excessive carbon deposits and replacing them if needed; 3. Inspecting fuel pressure and replacing faulty components; 4. Replacing aged engine parts. Engine maintenance methods: 1. Using qualified engine oil; 2. Using proper coolant; 3. Regularly cleaning radiator scale; 4. Periodic engine decarbonization; 5. Timely replacement of air filters, oil filters, and fuel filters; 6. Monitoring spark plug condition; 7. Maintaining proper engine RPM.
After running an auto repair shop for so many years, I've seen countless cases of engine shaking at idle. The most common causes are ignition system issues—excessive carbon buildup on spark plugs, aging ignition coils, or high-voltage wire leakage leading to incomplete fuel combustion. Clogged or dirty fuel injectors can also cause unstable fuel supply, and when combined with intake manifold leaks causing uneven air intake, it triggers engine vibrations. Mechanically, worn or broken engine mounts reduce vibration damping, making idle shaking more noticeable. Heavy carbon deposits stuck in cylinders or the throttle body can have the same effect. I recommend first checking the spark plugs and air filter, then cleaning the throttle body. If the issue persists, use a diagnostic tool to check trouble codes. Leaving this problem unresolved will increase fuel consumption and may damage the catalytic converter.
