CNG

This is an Open Loop mode. The following actions occur when starter motor is engaged. The Powertrain Control Module (PCM) receives inputs from:
- Battery voltage
- Engine coolant temperature sensor
- Crankshaft position sensor
- CNG fuel low-pressure sensor
- CNG fuel temperature sensor
- Intake manifold air temperature sensor
- Manifold absolute pressure (MAP) sensor
- Throttle position sensor (TPS)
- Camshaft position sensor, in distributor

The PCM monitors the crankshaft position sensor. If the PCM does not receive a sensor signal within 3 seconds of cranking engine, it will shut-down the fuel injection system. A Diagnostic Trouble Code (DTC) will be set.

The high-pressure fuel shut-off solenoid is energized by the powertrain control module (PCM) through the high-pressure fuel shut-off solenoid relay. This solenoid will operate for approximately 2 seconds unless the engine is operating or starter motor is engaged

Voltage is applied to fuel injectors with the PCM controlling injection sequence, rate and injector pulse width. This is done by turning the ground circuit to each individual injector on-and-off at the PCM.

The PCM determines the proper ignition timing according to the input received from the crankshaft position sensor. This is done by switching the coil on and-off through control of its ground path.