Overrun Fuel Cut-Off

To reduce emissions and to improve fuel economy, the fuel delivery is aborted during engine overrun conditions. Engine overrun is determined by the ECU from engine speed, throttle position and coolant temperature input signals. With a closed throttle and engine speed in excess of 1100 RPM the ECU shuts off all fuel delivery provided that the coolant temperature is above 86°F (25°C) and that engine speed has reached 1500 RPM first. The engine must reach 1500 RPM for the fuel shut-off to occur. Ignition timing is compensated for the reentry of fueling.