Why does the car still shake after replacing spark plugs?
2 Answers
The reason the engine shakes after replacing spark plugs is that the spark plugs are not tightened properly. Therefore, the force used when replacing spark plugs should be based on the required torque for the specific spark plugs being used, as spark plugs of different sizes require different amounts of force. Steps for replacing spark plugs: Open the hood, lift the plastic cover of the engine, remove the high-voltage distributor wires, and mark each cylinder's position to avoid confusion. Use a spark plug socket to remove the spark plugs one by one. While removing them, check for any external debris like leaves or dust and ensure everything is cleaned thoroughly. Place the new spark plugs into the spark plug holes, hand-tighten them a few turns, and then use the socket to tighten them further. Reinstall the high-voltage distributor wires in the firing order and secure the cover. Spark plug replacement intervals: Under normal maintenance conditions, spark plugs should be replaced every 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it's recommended to follow the owner's manual. The following standards can be used as a reference for maintenance and replacement: Platinum spark plugs should be replaced at 40,000 kilometers, standard nickel alloy spark plugs at 20,000 kilometers, and iridium spark plugs at 60,000 to 80,000 kilometers.
After replacing the spark plugs, my car still shakes, which may be caused by improper installation or defective spark plugs. If the spark plugs are not tightened to the correct torque or the selected model does not match the original model, it can lead to unstable ignition. However, the problem is often not just with the spark plugs themselves. If the ignition coils are aged or cracked, they cannot provide stable high voltage to the new spark plugs, resulting in ignition failure in one or more cylinders. Issues in the fuel system, such as clogged fuel injectors or insufficient fuel pressure, can cause an imbalance in the air-fuel ratio and also lead to shaking. Excessive engine carbon buildup or faulty sensors, such as an inaccurate signal from the air flow meter or oxygen sensor, can prevent the ECU from correctly calculating the combustion ratio. It is recommended to immediately check whether the spark plugs are tightened properly and verify the model, and scan the OBD fault codes to identify hidden issues. Shaking affects driving safety, so it is wise to promptly visit a professional repair shop for troubleshooting.
