Engine Warm-Up

This is an OPEN LOOP mode.

During engine warm-up, the Powertrain Control Module (PCM) receives input from:
^ Battery voltage
^ Crankshaft position (CKP) sensor
^ Engine coolant temperature (ECT) sensor
^ Intake air temperature (IAT) sensor
^ Manifold absolute pressure (MAP) sensor
^ Throttle position sensor (TPS)
^ Camshaft position (CMP) sensor
^ A/C select switch

Based on these inputs the PCM will:
^ Apply voltage to the injectors. The PCM then controls injection sequence and pulse width by switching individual injector ground paths on and off.
^ Adjust engine idle speed through the IAC motor.
^ Adjust ignition timing.
^ Operate A/C Compressor Clutch relay (if selected).
^ Operate the Up-Shift indicator light.
^ Begin to monitor oxygen sensor. When engine is at operating temperature, the system will leave warm up mode and go into closed loop operation.