What Causes a Gasoline Engine Spark Plug Not to Fire?
3 Answers
Gasoline engine spark plugs may fail to fire due to damage or lack of electrical current. It is advisable to inspect the ignition wiring of the car engine to ensure it is functioning properly. The spark plug is a critical component of the gasoline engine's ignition system. It introduces high-voltage electricity into the combustion chamber, causing it to jump the electrode gap and generate a spark, thereby igniting the combustible air-fuel mixture in the cylinder. Under high voltage, the air between the spark plug's center electrode and the side electrode rapidly ionizes, forming positively charged ions and negatively charged free electrons. When the voltage across the electrodes reaches a certain threshold, the number of ions and electrons in the gas increases like an avalanche, causing the air to lose its insulating properties. A discharge channel forms in the gap, resulting in a "breakdown" phenomenon. At this point, the gas becomes a luminous body, known as a "spark." Along with thermal expansion, a "crackling" sound is also produced. The temperature of this electrical spark can reach 2000–3000°C, which is sufficient to ignite the air-fuel mixture in the cylinder's combustion chamber.
I've been driving for over 20 years, and it's quite common to encounter spark plugs not firing. The most common issue is a faulty ignition coil - the coil that supplies electricity to the spark plugs. When the coil ages or gets damp, it can't deliver power. There's also the problem with the spark plugs themselves - if they've been used too long, the gap may become too wide or there might be severe carbon buildup, and they need replacement when it's time. High-voltage wire leakage is another headache - when the wiring ages and the insulation breaks down, the electricity leaks away and can't ignite. The battery is also a factor - insufficient voltage means the spark plugs can't start. Plus, modern cars are all computer-controlled; if a sensor fails or the control unit malfunctions, the spark plugs won't receive the command to work. This issue can range from minor to serious, so I recommend going straight to a repair shop to diagnose the specific cause. Trying to fix it yourself might just make things worse.
I've researched the issue of spark plugs not firing. First, check if it's a battery problem. An aging battery with insufficient power supply can affect the entire system, and you should be cautious if the voltage drops below 12 volts. Then, the high-voltage wires are also crucial. After five or six years of use, the outer insulation tends to crack, and leakage becomes particularly noticeable when it rains. I've seen many cases of faulty ignition coils, especially in older vehicles. If everything seems normal, inspect the crankshaft position sensor. If it's dirty or misaligned, the engine control unit can't properly manage the ignition timing. Additionally, overfilling the engine oil might flood the spark plugs. In summary, you need to troubleshoot step by step, starting with the simple check of battery voltage before moving on to testing the ignition system. That's how mechanics usually do it.
