Warning to anyone thinking of buying a Ford Focus car. The single cam split port 2.0 liter Ford Focus engine has a design defect in the valve seats. They eventually come loose and drop into the cylinders and destroy the engine. This is called a dropped valve seat. You can see what happened to my piston in this video. If you are thinking of buying a Ford Focus, or if you have one that's starting to run rough, your valve seats may be starting to go bad. My car ran rough for a while before it finally died. In this case it was possible to have the head rebuilt and install a new piston and connecting rod, and the engine runs great now.