The only help an OBDII scanner will be is to pinpoint a misfire cylinder after it has occured. This doesn't mean that the coil caused it or even that it is an ignition problem.

A proper scanner will give burn time and firing voltages which are a help in ignition diagnosis.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician