How to Determine Whether to Replace Spark Plugs?
3 Answers
Methods to determine whether to replace spark plugs include: 1. During idle speed, use a screwdriver to perform a short-circuit test on the spark plug, carefully listening to changes in the engine's speed and sound. If there is no change compared to before, it indicates the spark plug is normal; 2. Remove the spark plug and identify color changes. If it is reddish-brown or rusty in color, the spark plug is normal. If there is oil contamination, it means the spark plug gap is misaligned or short-circuited and needs replacement; 3. The working environment of spark plugs is high temperature and high pressure. After a period of use, part of the electrode will be oxidized and then eroded, causing the electrode gap to become too large, reducing ignition energy and preventing normal ignition, thereby affecting the engine's normal operation. In this case, the spark plug must be replaced.
I've found that determining whether spark plugs need replacement mainly depends on daily driving experience. For instance, if my car suddenly shakes at idle or feels sluggish when accelerating with noticeably less power than usual, it's likely the spark plugs are worn out. Mileage is a key reference – most manuals recommend replacement every 40,000-80,000 km, but personally I believe we shouldn't rigidly adhere to this number. You should also inspect their appearance – after the engine cools down, pull them out to check. If the electrodes are burnt black or the gap is too wide, it's time for replacement. Delaying replacement can lead to soaring fuel consumption, starting difficulties, and even engine damage. Remember, it's safer to have a mechanic check them during routine maintenance.
As an enthusiast who frequently tinkers with cars, I have a simple method to check spark plugs. After the engine cools down, remove one and observe the electrode condition: if the gap is too wide, there's heavy carbon buildup, or it's rusted/deformed, it's a sign to replace them. Also, listen to the engine sound while driving—clicking noises during startup or intermittent power while driving often indicate faulty spark plugs. I check them every 30,000 kilometers to avoid being stranded. The cost is low; buying new ones for DIY replacement is inexpensive, and the improved acceleration and fuel efficiency afterward are noticeable. The maintenance manual lists recommended models—just get the correct OEM parts.
