Engine Crank/Engine Running
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, 2011 Ford Fusion, 2010 Mercury Milan, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
During engine crank the PCM fires two spark plugs simultaneously. Of the two spark plugs simultaneously fired, one is under compression and the other is on the exhaust stroke. Both plugs fire until the camshaft position is identified by a successful camshaft position (CMP) sensor signal. Once the camshaft position is identified, only the cylinder under compression is fired.