Is Unstable Engine Idling a Normal Phenomenon?

[DiElizabeth]

Unstable engine idling is an abnormal phenomenon. Here is relevant information: 1. Definition: A car engine is the device that provides power to the vehicle, serving as the heart of the car and determining its power, fuel efficiency, stability, and environmental performance. Depending on the power source, car engines can be categorized into diesel engines, gasoline engines, electric vehicle motors, hybrids, etc. 2. Maintenance: Car engines require regular maintenance. When driving through particularly humid or dusty areas, it is also necessary to inspect and maintain relevant engine components.

[Karl]

Speaking of unstable idling, as someone who has driven for over 20 years, I don't believe this should be considered normal. New cars typically run very smoothly when they leave the factory, but if the engine noticeably shakes during idling, with RPMs fluctuating up and down, it could indicate a problem. Common causes include aging spark plugs, clogged air filters, or carbon buildup—especially when frequent short-distance city driving is involved. Carbon deposits blocking the intake ports or valves can make the engine run roughly, leading to increased fuel consumption in mild cases, or triggering warning lights or even stalling while driving in severe cases, significantly impacting driving safety. My advice is to develop a habit of checking wear-prone parts, regularly clean the throttle body, and don't delay when abnormalities are detected—head straight to a professional shop for diagnosis to prevent minor issues from turning into major repairs.

[McEliza]

From my perspective, idle instability is mostly caused by issues in the ignition system or fuel supply. Problems like faulty spark plugs, ignition coil failure, or fuel line blockages can all lead to engine shaking. For new vehicles with unstable idle, the oxygen sensor or idle air control valve should be checked first. For older cars, worn-out belts or weak battery voltage could be the root cause. A simple self-check is to observe whether the tachometer needle fluctuates excessively at idle. But remember, don't attempt DIY repairs blindly - high-voltage wires and electrical systems are complex, and mistakes can damage the engine. Regular maintenance like changing engine oil and filters every few thousand kilometers can effectively prevent such instability. Proper maintenance extends engine life and improves fuel efficiency.

[McBrianna]

I noticed that when commuting in a compact car, the idle speed keeps shaking non-stop, especially noticeable during long red lights. This isn't normal and is mostly caused by carbon buildup due to driving habits. Frequent short trips in the city or prolonged idling prevent the engine from reaching optimal temperature, leading to incomplete combustion and carbon deposits that clog components and cause imbalance. The solution is quite simple: take the car for a highway run once a week, letting the engine run at high RPM for a few minutes to clear out the deposits. Don't slack on maintenance—regularly cleaning the air filter or adding some fuel system cleaner can prevent the shaking. Don't wait for minor issues to escalate into major engine problems.