What Causes Occasional Misfiring That Resolves After Restarting?
2 Answers
The following are reasons for occasional misfiring that resolves after restarting: 1. Ignition System: Aging ignition coils and spark plugs can cause the cylinder's ignition system to malfunction. Faulty ignition coils most commonly lead to reduced power and, in severe cases, can cause sudden engine stalling. 2. Spark Plug Wire Wear: To check if the spark plug wires are functioning properly, simply remove a wire, attach a spark plug, start the engine, and observe. Comparing each cylinder will reveal any issues. 3. Fuel Injection System: Clogged fuel injectors or fuel lines can prevent sufficient fuel from reaching the cylinder for combustion, naturally causing the cylinder to malfunction. 4. Excessive Spark Plug Carbon Buildup: Long-term poor combustion leads to carbon deposits accumulating on the spark plug's ignition point. When these deposits are wetted by fuel, they create a parallel shunt resistance, resulting in spark plug leakage, weak sparks, or even complete spark plug failure.
I've encountered a similar issue before. While driving, the car suddenly started shaking violently, as if it had lost a cylinder. But strangely, after restarting, it was completely fine, with no problems at all. I reckon it's most likely an intermittent issue with small components like spark plugs or ignition coils. Aged spark plugs might momentarily fail under high temperatures, causing a cylinder to misfire, but then resume normal contact after cooling down upon restart. Another possibility is loose wiring or sensor connections that cause poor contact when jostled, and the restart coincidentally resets the electrical connection. Fuel injectors can also behave this way—impurities in the fuel might clog them, but stopping the car allows the fuel pump to rebuild pressure and clear the blockage. Honestly, this kind of intermittent problem is quite annoying. Even though it seems fine after restarting, it hints at underlying issues that are accumulating. For example, leaving it untreated long-term could increase fuel consumption or damage the engine's catalytic converter. I recommend going to a professional shop as soon as possible for a detailed diagnostic scan, rather than waiting until it gets worse and costs more to fix.
