Ignition/Crank Signal
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
The PCM monitors initial cranking (RPM) signal to determine when the engine is being started. This information is used for starting enrichment. If this signal is intermittent or not available, hard starting or a no-start condition will result.