How dose the OBD2 know a cylinder is misfiring

Hello, yes, the engine processor determines more than ignition function - it sees if there is production from the cylinder in question. Cylinder misfiring can be coil and plug related -- in the ignition system -- or could be fuel related, air intake related, exhaust related or base engine timing and cylinder compression related. Testing is needed to find out what's going on. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops