What are the causes of unstable idle speed with shaking?

[ValentinaDella]

The causes of unstable idle speed with shaking are: 1. Improper air-fuel mixture ratio in the engine compartment; 2. Prolonged use of spark plugs leads to aging of the ignition coil, high-voltage line aging, and leakage issues, which reduce ignition capability; 3. Carbon deposits on the engine's valves and intake passages, which can absorb a significant amount of fuel, reducing the car's power; 4. Malfunctioning coolant temperature sensor; 5. Dirty air filter. The solutions for unstable idle speed with shaking are: 1. Replace the spark plugs; 2. Clean the valves and intake passages; 3. Check the coolant temperature sensor; 4. Clean or replace the air filter.

[FranciscoLynn]

I've been driving an old car for over a decade and often encounter idle vibration issues, which can stem from various causes. The most common culprits are aging spark plugs or faulty ignition coils, leading to uneven engine combustion. I remember last year when my car shook violently at stoplights – turned out the spark plug gaps were too wide, and replacing them fixed it. Another frequent issue is carbon buildup; when the throttle body or fuel injectors get clogged with grime, it disrupts airflow. Vacuum line leaks are another sneaky problem, allowing extra air into the engine and making the fuel mixture too lean. Don't underestimate these vibrations – they accelerate engine wear and increase fuel consumption. Left unaddressed long-term, they may cause bigger issues. I recommend regular maintenance checks on spark plugs and seeking professional repair when problems arise.

[MacCorbin]

As a car owner who frequently works on my own vehicle, I've observed that idle shaking primarily stems from several key issues. Ignition system failures are critical, such as worn spark plugs or faulty high-tension wires. Fuel supply problems, like clogged fuel injectors or low fuel pump pressure, can cause uneven fuel delivery. Intake system malfunctions, including faulty mass airflow sensors or vacuum line leaks, lead to imbalanced engine air intake. These vibrations increase fuel consumption and create driving discomfort. Modern vehicles may also shake due to sensor issues or ECU failures, where using an OBD diagnostic tool can quickly pinpoint the cause. Prompt attention can prevent engine damage and costly overhauls.

[JaylaRose]

My old car often suffers from unstable idling, mostly due to engine-related issues. For example, carbon deposits accumulate in the combustion chamber or throttle body, restricting air intake. Worn-out spark plugs can cause erratic ignition and shaking. Aging or cracked vacuum lines, especially rubber components, often lead to air leaks. Sometimes, insufficient or dirty engine oil can also affect balance. Don't ignore the shaking—it's not just annoying but also increases fuel consumption and reduces engine life. Simple solutions like cleaning the throttle body or replacing spark plugs are cost-effective and efficient.