Open Loop & Closed Loop Operation

During open loop operation the PCM receives input from some engine sensors, but operates only on preset PCM programming. Oxygen sensor input is not monitored by the PCM during open loop operation. During closed loop operation the PCM monitors all sensor input (including oxygen sensor) to calculate and control fuel and ignition system operation. The fuel injection system has several operating modes. See MODES OF OPERATION  under FUEL CONTROL under FUEL SYSTEM.