Air Bleed Control Valve (ABCV)
The ABCV/stepper motor modifies air/fuel ratio at idle and cruise by controlling air bleeds to idle and primary main metering circuits. When the ECA determines a lean condition exists, or conditions exist which require a richer air/fuel ratio, the ECA responds by energizing the stepper motor windings. A magnetic field is then created in the windings which steps the ABCV plunger upward, counteracting internal spring pressure and restricting airflow. De-energizing the windings of the ABCV allows internal spring pressure to return the ABCV to its rest position, leaning the air/fuel ratio.