Deceleration Mode

When the driver releases the accelerator pedal, the air flow into the engine is reduced. The corresponding changes in the throttle position and manifold air pressure are relayed to the control module. The control module reduces the injector pulse width in order to reduce fuel flow. If the deceleration is very rapid, or for long periods (such as long closed throttle coast-down), the control module shuts OFF the fuel completely in order to protect the catalytic converter.