What are the hazards of not replacing spark plugs for a long time?
3 Answers
Long-term failure to replace spark plugs can directly cause various problems such as leakage in the vehicle's ignition system, vehicle shaking, increased fuel consumption, difficulty in acceleration, and reduced power. The main issue is difficulty in ignition, which affects the normal use of the vehicle. The purpose of spark plugs is to ignite. During use, the electrodes of the spark plugs consume electricity through spark discharge from areas prone to discharge. Typically, the service life of spark plugs is 15,000 km, while long-life spark plugs can last up to 30,000 km. Generally, as the engine runs or the driving distance increases, the required discharge voltage for the spark plug electrode gap continuously rises, gradually approaching the voltage limit provided by the ignition coil. This makes ignition increasingly difficult and eventually leads to misfiring.
Last time my neighbor Lao Wang's car suddenly broke down because the spark plugs hadn't been changed for 200,000 kilometers. When these things fail, they directly cause engine misfires and shaking—it feels like driving on a massage chair. Over time, fuel consumption can spike by 15%-20%, which adds up to hundreds more in gas costs every month. The worst part is that after the electrodes erode, the high-voltage electricity can damage the ignition coils, and replacing just one coil can cost hundreds. During one maintenance check, I saw the old spark plugs were completely worn down at the tips, and the mechanic said delaying further could even harm the piston rings. If you wait until the car struggles to start, the cost of an engine overhaul would be enough to buy ten sets of platinum spark plugs.
When my car had run 80,000 kilometers without changing the spark plugs, I clearly felt sluggish acceleration. The mechanic took them out and found the electrode gap had widened to 1.8mm. This severely weakened the ignition energy, causing incomplete combustion of the air-fuel mixture, with carbon deposits rapidly sticking to the cylinder walls. What made it worse was the excessive exhaust emissions, which caused my car to fail last year's inspection, forcing me to make three extra trips. Now I've learned my lesson and replace them every 60,000 kilometers as per the manual. A set of nickel alloy ones costs just a few dozen bucks, much cheaper than cleaning the fuel system.
