* The spark plugs are not gapped correctly. This is the most common cause of engine roughness after a spark plug change. When the spark plugs are not gapped correctly, they can cause the engine to misfire, which can lead to a rough idle and poor performance.
* The spark plugs are not the correct type for your engine. If you've installed spark plugs that are not the correct type for your engine, they can also cause the engine to run rough. This is because the spark plugs may not be delivering the correct amount of spark to the engine, which can lead to misfires and poor performance.
* The spark plug wires are not connected properly. If the spark plug wires are not connected properly, they can also cause the engine to run rough. This is because the spark plugs will not be getting the spark they need to ignite the fuel in the engine, which can lead to misfires and poor performance.
* There is a problem with the ignition system. If there is a problem with the ignition system, it can also cause the engine to run rough. This is because the ignition system is responsible for delivering the spark to the spark plugs, and if there is a problem with the ignition system, the spark plugs will not be getting the spark they need to ignite the fuel in the engine.
If you're experiencing engine roughness after a spark plug change, it's important to troubleshoot the problem to determine the cause. By following the steps outlined above, you can narrow down the possible causes and get your engine running smoothly again.
