How to Check if Spark Plugs Are Damaged?
2 Answers
If spark plugs exhibit the following symptoms, it may indicate a malfunction: Difficulty starting the car, whether cold or hot, often requiring multiple attempts. Engine shaking, noticeable while driving. Reduced power, with a significant drop in performance compared to normal conditions. Increased fuel consumption. Engine stalling. Failed exhaust emissions. Common causes and diagnosis of spark plug failures: Several situations can cause spark plugs to stop working: Incorrect spark plug gap adjustment. If the gap is too small, it limits the contact area between the spark and the air-fuel mixture, suppressing flame kernel growth and resulting in weak sparks that make ignition difficult. If the gap is too large, the ignition system may not provide enough voltage to jump the gap. Cracked spark plug skirt. High-voltage current leaks through the crack, preventing sparking at the electrodes. Carbon buildup on the electrodes, causing leakage from the center electrode to the surroundings instead of jumping to the side electrode. Excessive carbon deposits can short-circuit the spark plug, preventing sparks and damaging the insulator. Damaged electrodes. Prolonged electrical erosion or chemical corrosion from combustion gases can cause electrode breakage, preventing sparking. Low insulation resistance of the spark plug. This reduces the ignition voltage applied to the spark gap, weakening or completely disabling the spark. Short circuit in the high-voltage wires. If the wire from the ignition coil to the distributor leaks, the entire engine may fail to start. If the wire from the distributor to the spark plug leaks, one cylinder's spark plug won't fire. Burnt or eroded contact points. This can prevent all spark plugs from firing, making the engine unable to start or run properly. Faulty spark plugs should be replaced promptly. Replacement steps: Open the hood, remove the engine's plastic cover, and disconnect the high-voltage wires, marking each cylinder's position to avoid confusion. Use a spark plug socket to remove the spark plugs one by one, checking for debris like leaves or dust and cleaning the area thoroughly. Insert the new spark plug into the hole, hand-tighten it first, then use the socket to secure it. Reattach the high-voltage wires in the correct firing order and replace the cover. Spark plug replacement interval: Typically, spark plugs should be replaced every 40,000–60,000 km under normal maintenance conditions. However, this may vary by brand and engine type, so consult the owner's manual for specific recommendations.
When I notice difficulty starting the car or unstable idling, I often suspect the spark plugs are the issue. First, park the car and let the engine cool, then use a specialized wrench to slowly unscrew the spark plugs—don’t rush to pull them out. Check if the electrodes are blackened, have excessive carbon buildup, or cracks. Also, measure the gap with a feeler gauge to ensure it’s between 0.8 to 1.2 mm; gaps too large or too small affect ignition. If they’re dirty, you can lightly clean off the carbon, but if the electrodes are severely worn, replacing them outright is the easiest solution. Don’t forget to check for loose connections—this is often overlooked. The whole process takes about 5 minutes. Early detection can prevent a spike in fuel consumption. Regularly inspect them every 20,000 km to extend part lifespan and save money. A well-maintained car runs smoothly.
