Ignition Coil Inspection

Perform the spark inspection and identify the malfunctioning cylinder. (See SPARK INSPECTION .)
Replace the ignition coil/ion sensor of the malfunctioning cylinder with that of a normal cylinder, and perform the spark inspection again. (See SPARK INSPECTION .)

If the spark is not normal due to a malfunctioning ignition coil/ion sensor, replace that ignition coil/ion sensor.
It is unlikely that all four ignition coil/ion sensors fail to operate properly. To prevent replacing a normal component, perform the above procedure, identify the malfunctioning ignition coil/ion sensor, and replace it.