CNG

When engine is at operating temperature, and under deceleration, this is an Open Loop mode. During hard deceleration the Powertrain Control Module (PCM) receives the following inputs:
- Air conditioning select signal, if equipped
- Air conditioning request signal, if equipped
- Battery voltage
- Engine coolant temperature sensor
- Crankshaft position sensor
- Intake manifold air temperature sensor
- CNG fuel low-pressure sensor
- CNG fuel temperature sensor
- Manifold absolute pressure (MAP) sensor
- Throttle position sensor (TPS)
- Camshaft position sensor, in distributor
- Park/Neutral switch (gear indicator signal- auto. trans. only)
- Vehicle speed sensor

If the vehicle is under hard deceleration with proper rpm and closed throttle conditions, the PCM will ignore oxygen sensor input signal. The PCM will enter a fuel cut-off strategy, until idle is approached, in which it will not supply a ground signal to injectors. If a hard deceleration does not exist, the PCM will determine proper injector pulse width. Fuel injection will continue.
Based on the preceding inputs, the PCM will adjust engine idle speed through the idle air control motor. This is done to provide a smooth transition to expected idle mode.