Acceleration and Deceleration Modes

ACCELERATION MODE
The Engine Control Module (ECM) provides extra fuel when it detects a rapid increase in throttle position and manifold pressure.

DECELERATION MODE
On deceleration, fuel remaining in the intake manifold can cause excessive emissions and backfiring. To prevent this, the ECM reduces the amount of fuel injected when it detects a decrease in throttle position and manifold pressure. When deceleration is very fast, the ECM may cut off fuel completely for short periods of time.