2000 2.5L Ranger ignition operation

Am working on a 2000 2.5L Ranger ignition and can't seem to find any data on the operation of this system. This is a dual spark plug engine and I am a little foggy on exactly how this system works. I know that one plug is the ignition and fires the cylinder and the other plug fires on the exhaust stroke to burn any excess combustible gases remaining in the exhaust. The literature I have been able to find states that the two plugs fire simultaneously and that is clouding my feeble mind. The stroke after the combustion is the power stroke followed by the exhaust stroke (last stroke in the cycle). I can't get my head wrapped around how a simultaneously firing plug in the same cylinder would affect he exhaust stroke. Can anyone out there tell me where I might find some literature that would better explain how all this works?

Try this explanation:

http://www.fordforumsonline.com/threads/identifying-and-understanding-ford-ignition-systems.3764/


tom