Misfire question

[Absolomb]

We all know that pulling the plug to a coil pack can determine whether a cylinder is firing.
My question is, if your engine has an rpm drop when you pull the plug, can it still have a misfire?

[amc49]

Yes, absolutely. The rpm drop does not occur only when the misfire is really bad, but an engine misfires in percentage and a 10% misfire will still make the rpm drop when plug is disconnected yet codes often set at that number. It's only when the miss goes beyond say 50% of the time that the drop becomes unnoticeable to be able to say there is no drop.