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.