What does it mean when a cylinder misfires occasionally but returns to normal after restarting?
4 Answers
The following are the reasons for occasional cylinder misfires that return to normal after restarting: 1. Ignition system: Aging of ignition coils and spark plugs can cause the cylinder's ignition system to fail. When ignition coils malfunction, it most commonly leads to a decrease in power, and in severe cases, can cause the engine to stall suddenly. 2. Cylinder wire wear: To check if the cylinder wires are functioning properly, simply pull out the distributor wire, insert a spark plug, and start the engine to observe. Comparing each cylinder will reveal any issues. 3. Fuel injection system: Clogged fuel injectors or fuel lines can prevent the cylinder from receiving sufficient fuel for combustion, naturally causing the cylinder to malfunction. 4. Excessive spark plug carbon buildup: Long-term poor combustion leads to carbon deposits accumulating at the spark plug 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 been driving for over a decade and encountered similar issues. When the car suddenly shakes like it's misfiring but returns to normal after restarting, it's most likely caused by carbon buildup or wear on the spark plugs—especially in older or high-mileage vehicles. If you don't pay attention to maintenance, carbon deposits on the spark plugs can intermittently affect ignition. Restarting the engine might temporarily melt some carbon deposits with residual heat, restoring normal operation. Additionally, aging ignition coils can cause this issue, as their insulation performance degrades at high temperatures but recovers after cooling down. Slightly clogged fuel injectors could also be the culprit, as restarting resets the fuel injection program. Ignoring such problems for too long increases engine strain, so I recommend checking the spark plugs and coils at a repair shop sooner rather than later. Using high-quality gasoline can help prevent impurity buildup in daily driving.
As a car owner, occasional misfires that resolve after a restart are quite common. I've found they're often caused by poor electrical connections - like loose spark plug boots or corroded ignition coil harness connectors that vibrate loose and cause short-circuit misfires. After restarting, successful reconnection restores normal operation. Fuel system issues are similar - unstable fuel pump pressure or injector clogging can cause temporary blockage under specific driving conditions, resolved by system reset after restart. Brief signal drift from sensors like O2 or crankshaft position sensors may also trigger this fault. Don't underestimate it - a highway misfire could be dangerous. Always use an OBD scanner to confirm the fault source.
The car suddenly shakes as if misfiring, but it returns to normal after restarting. This is usually caused by aging spark plugs. Over time, the electrode gap of spark plugs widens or excessive carbon buildup leads to unstable ignition and intermittent failure. Restarting the engine clears some blockages temporarily, improving the condition. Ignition coil issues can also cause this—internal material degradation makes them temperature-sensitive, causing misfires at high temperatures but working again after cooling. Clogged fuel injectors or unstable wiring connections may have similar effects. Checking spark plugs is simple, and replacing them yourself is inexpensive. Long-term neglect may increase fuel consumption and damage the engine. It's recommended to inspect these components during an oil change.
