Misfires are never good, and they're always a sign that there’s a problem with the engine that needs to be repaired. The problem won’t “go away on its own” and waiting too long can cause the situation to grow increasingly worse. Problems with the ignition system can definitely cause misfiring, and they can do so in a number of ways.
Possible causes of ignition-related misfires
The ignition system is responsible for igniting fuel in the engine's combustion chamber. If the system isn’t working correctly, the engine will misfire on one or more cylinders. Generally, only one cylinder is affected, but this isn’t necessarily always the case. What’s more, you may have misfires and not even know it, as wear on the ignition system components is gradual and mild misfires can be undetectable (although your Check Engine Light may come on, seemingly for no reason).
There are several potential ways that your ignition system problems could translate to a misfire:
Worn Out Spark Plugs: If your plugs are worn out, then the electrodes have gotten too short to provide the right amount of spark. This is a gradual process, and is the reason that you need to replace the plugs on a regular basis. If the wear becomes extreme, it’s possible that one or more plugs won’t fire at all, causing a misfire in the engine.
Damaged Spark Plug: Spark plugs are exposed to high heat and electricity, as well as vibrations. This can cause damage. If the ceramic insulator around the base of the plug is cracked or broken, it can cause a misfire.
Damaged or Failing Spark Plug Wires: If your car has spark plug wires (not coil packs), then the wires may be the source of a misfire. If the insulating coating on the wire has been compromised, it’s possible that the bare wire is touching a metal component in the engine and shorting out. This will cause a misfire. Another potential problem is an internal break in the wire – the charge won’t reach the spark plug and a misfire will result.
Dirty Spark Plugs: If a spark plug is fouled with carbon or oil, it may not spark properly, causing a misfire. This isn’t really an ignition problem, though. You’ll need to determine the cause of the carbon or oil buildup and repair it.
Problems with your ignition system can easily cause misfiring, but there are many potential causes. If your engine is misfiring, it’s vital to have the problem diagnosed and repaired by an experienced mechanic.
This article originally appeared on YourMechanic.com as How Can Problems with the Ignition System Cause Misfiring? and was authored by Valerie Johnston.