What Causes Engine Shaking After Replacing Spark Plugs?
2 Answers
The reason for engine shaking after replacing spark plugs may be due to damaged or partially broken cylinder wires when removing the spark plugs, resulting in abnormal ignition. Other possible causes include incorrect spark plug installation (threads not aligned properly) or cylinder wires not fully inserted. What are spark plugs: Spark plugs are crucial components in a gasoline engine's ignition system. They introduce high voltage electricity into the combustion chamber and create sparks by jumping across the electrode gap, thereby igniting the combustible air-fuel mixture in the cylinder. Main types of spark plugs include: Standard spark plugs, extended insulator spark plugs, electrode-type spark plugs, seat-type spark plugs, pole-type spark plugs, and surface-gap spark plugs. Effects of faulty spark plugs: Damaged spark plugs can directly cause various issues such as ignition system leakage, increased fuel consumption, and reduced power output. The most significant impact is difficulty in ignition, affecting normal vehicle operation. Severe spark plug erosion - including top scarring, electrode damage or melting, and burn marks - indicates that the spark plug is damaged and should be replaced.
I just encountered this issue and asked in the car enthusiasts group. Everyone analyzed several points: the spark plug model was not selected correctly, causing a mismatch with the engine ignition; the spark plugs were not tightened properly during installation, leading to air leakage; the gap of the new spark plugs was not adjusted correctly; the ignition coil wiring harness was damaged during disassembly and installation; or the old spark plugs were not completely replaced, causing inconsistency between old and new ones working together. In my case, the mechanic had loosened one, and after reinstalling it properly, the issue was resolved. I recommend supervising the mechanic when changing spark plugs, ensuring they use a torque wrench for proper installation. Replacing all spark plugs is more reliable than replacing just some.
