What are the symptoms of aging spark plugs?
2 Answers
Spark plug aging can cause the following symptoms: difficulty starting, low power, excessive exhaust emissions, and increased fuel consumption. Steps to replace spark plugs: Open the hood, lift the plastic cover of the engine, remove the high-voltage ignition 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 external debris such as leaves or dust and ensure thorough cleaning. Place the new spark plug into the spark plug hole, hand-tighten it a few turns, and then use the socket to tighten it further. Reinstall the removed high-voltage ignition wires according to the firing order, then secure the cover. Methods to determine if a spark plug is damaged: Remove the spark plug and inspect its appearance. A normal spark plug's insulator skirt and electrodes should appear gray-white, gray-yellow, or light brown. A properly functioning spark plug has a reddish-brown insulator skirt, with an electrode gap between 0.8-0.9mm and no signs of electrode burn. If the spark plug is fouled with oil or deposits but not damaged, it can be reused after cleaning. If the spark plug is severely damaged—showing signs of blistering, black streaks, cracks, or melted electrodes—identify the cause of the damage, resolve the issue, and replace the spark plug. Additionally, if the spark plug appears blackened as if smoked, it indicates incorrect heat range selection, a rich fuel mixture, or oil leakage.
When the spark plugs age, driving becomes particularly uncomfortable. The engine starts to shake noticeably, especially when idling at a red light or in neutral, making the car vibrate like sitting on a massage chair. The acceleration response is sluggish, and stepping on the gas pedal feels weak, making overtaking difficult. Fuel consumption also quietly increases—previously, a full tank could last 500 kilometers, but now it might only go 450. During winter or cold starts, the car often fails to start, requiring several attempts. Occasionally, the engine warning light comes on, indicating an issue with the ignition system. This is no small matter—it can lead to an overall drop in power, accelerate wear on other components, and while replacing spark plugs isn't expensive, delaying repairs can lead to much higher costs. I check them every 20,000 to 30,000 kilometers to keep the engine healthy and drive with peace of mind.
