What are the causes of engine shaking in a Focus?

[VonAlexa]

Here are the reasons for engine shaking in a Focus and their solutions: 1. Ignition system failure: Spark plugs, high-voltage wires, and ignition coils may experience poor performance after a certain period of operation. Solution: Inspect the working condition of spark plugs, high-voltage wires, and ignition coils, and replace the spark plugs if necessary. 2. Aging engine components: When the car's engine is idling and the electrical system is turned on, it increases the engine load, causing idle speed to drop. To compensate for the shaking caused by the drop in idle speed, the engine will automatically raise the RPM slightly. Solution: Replace the engine mounts. 3. Unstable oil pressure: Abnormal fuel pump pressure or incorrect readings and poor performance of the intake pressure sensor can also cause engine shaking. Solution: Visit a 4S shop to check the fuel pressure and the intake pressure sensor for proper functioning, and replace related components if necessary.

[SanSarah]

My Focus has also shaken a few times before. Common causes include ignition system issues, such as aging spark plugs or faulty ignition coils, leading to uneven ignition and making the engine jerk like it's convulsing. It could also be a fuel system problem, like clogged fuel injectors or a dirty fuel filter, causing insufficient fuel supply, which is most noticeable when the engine is idling. Additionally, carbon buildup in the engine can cause valves to stick, affecting combustion efficiency and making it shake as if the motor is broken. Worn-out mounting components or aged rubber that can't absorb vibrations, especially during acceleration, can also lead to severe shaking. Sensors like the oxygen sensor malfunctioning can mislead the ECU into incorrect adjustments, resulting in an imbalanced air-fuel mixture. I think the Focus's design makes it prone to carbon buildup, so it's important to pay extra attention to cleaning carbon deposits during regular maintenance, check spark plugs and filters periodically, and prevent issues before they arise.

[OAva]

When the Focus engine starts shaking, don't panic. First, perform some simple checks: see if the spark plugs need replacement, as old ones with unstable ignition can easily cause engine vibration. If the fuel filter or injectors are clogged, poor fuel supply will make the engine run unevenly. A dirty air filter restricts airflow, leading to more frequent shaking. Carbon buildup blocking the valves can be resolved by cleaning the throttle body or injectors, which solves most shaking issues. If the engine mounts are broken and the rubber buffers fail, vibrations will transfer to the car body. It's recommended to visit a professional shop for diagnosis and read the fault codes to pinpoint the exact problem. Safe driving is crucial—if the shaking is severe, stop driving to avoid risks. Regular maintenance, such as changing the oil and using high-quality fuel, can reduce the failure rate.

[VonClara]

Focus engine shaking may be caused by the ignition system, where spark plugs or coil damage lead to uneven ignition; fuel system issues such as faulty injectors or clogged filters affect fuel supply balance; excessive engine carbon buildup jams valves and disrupts combustion; worn engine mount rubber amplifies vibrations; or sensor problems like inaccurate oxygen sensors misleading the ECU. These factors combined can result in unstable ignition causing misfires and shaking, insufficient fuel pressure leading to lean mixtures, and carbon deposits obstructing airflow. During diagnosis, prioritize using tools to check fault codes to identify the root cause for repairs. Regular maintenance is the best prevention. Focus models are prone to carbon buildup, so it's recommended to clean every 10,000 kilometers.