What are the reasons for misfiring after replacing spark plugs?
2 Answers
Reasons for misfiring after replacing spark plugs: First, improper spark plug selection. If a cold-type spark plug is chosen for an engine with low heat value, it will inevitably cause the spark plug to operate at too low a temperature, preventing self-cleaning. Second, improper spark plug installation. When replacing spark plugs, adding extra sealing washers arbitrarily can result in the spark plug operating at too low a temperature. Third, the influence of ambient temperature. Ambient temperature affects the engine's operating temperature; in winter, a slightly hotter-type spark plug should be selected. What are the effects of a faulty spark plug: If a spark plug is damaged, it can directly cause issues such as leakage in the vehicle's ignition system, increased fuel consumption, reduced power, and most importantly, difficulty in ignition, affecting the normal operation of the vehicle. Severe erosion of the spark plug, such as blistering at the top, damage, or electrode melting and erosion, indicates that the spark plug is damaged and should be replaced. How to determine if a spark plug is damaged: Remove the spark plug and observe its appearance to assess its condition. A normal spark plug's insulator skirt and electrodes are 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.
I once encountered a situation where the car still wouldn't start after replacing new spark plugs, which was honestly quite frustrating – wasting money on replacement parts. In reality, misfires aren't solely caused by spark plugs; other components in the ignition system can also be problematic. For instance, a faulty ignition coil or aged, short-circuited high-voltage wires can prevent current from reaching the spark plug, resulting in failure to ignite. If the car is old, issues might also be related to the fuel system, such as insufficient fuel pump pressure or clogged fuel injectors, leading to abnormal combustion of the air-fuel mixture and causing misfires. Sensors are also crucial; a failed crankshaft position sensor, for example, can prevent the ECU from controlling the ignition timing properly. I did some basic checks myself, starting with measuring the battery voltage and checking for loose connections. Otherwise, it's best to take it to a professional auto repair shop for diagnosis with specialized equipment. After all, misfires affect engine longevity, and driving with them causes severe vibrations – timely repairs are essential for safety. Also, don't forget to verify if the correct spark plug model was used during replacement. Using the wrong model in an older car can cause issues too – I've learned this the hard way, so don't waste time messing around unnecessarily.
