Q: What is the function of the crankshaft sensor in a 2005 Lincoln LS 3.9 liter v-8 ?

Hello - the crankshaft position sensor (CPS) provides an ignition timing reference information for the engine management for both ignition and fuel injection. Originally, the CPS provided only timing information for the ignition, replacing old-fashioned distributors. However, with newer, more fuel efficient sequential fuel injection, which supplies fuel to each cylinder during the intake portion of the combustion cycle, precise timing is required for many events during each revolution of the engine. The crankshaft position sensor (along with its partner, the camshaft position sensor) provides this precise timing information. If it fails, the engine will stop running.