2500 4x2 Pickup V8-5.9L VIN Z (1994)
- Heated oxygen sensor (HO2S)
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.
- Monitor oxygen sensor and fine tune air/fuel ratio by varying injector pulse width.
- Adjust engine idle speed through the IAC motor.
- Adjust ignition timing.
- Operate A/C Compressor Clutch relay (if selected).
Ignition Switch Off
When the ignition switch is OFF the Powertrain Control Module (PCM) will stop operating the:
- Fuel injectors
- Ignition coil
- Automatic shutdown (ASD) relay
- Fuel pump relay.
Ignition Switch On
This is an OPEN LOOP mode.
When the sequential multi-point fuel injection (SFI) system is activated by the ignition switch, the following actions occur:
- The Powertrain Control Module (PCM) prepositions the idle air control (IAC) motor.
- The PCM reads atmospheric air pressure from the manifold absolute pressure (MAP) sensor and calculates the basic fuel strategy.
- The PCM monitors the throttle position sensor (TPS) and engine coolant temperature (ECT) sensor input. The PCM uses these inputs to
modify fuel strategy.
- Intake air temperature (IAT) sensor is monitored.
- The Automatic Shutdown (ASD) relay is energized for 3 seconds.
- Fuel pump is energized for 1 second, unless engine is running or cranking.
- Oxygen sensor heating element is energized.
- Up shift indicator light is illuminated (M/T only).
Wide Open Throttle
This is an OPEN LOOP mode.
During wide open throttle operation the PCM receives the following inputs:
- Battery voltage
- Camshaft position (CMP) sensor
- Engine coolant temperature (ECT) sensor
- Manifold absolute pressure (MAP) sensor
- Intake air temperature (IAT) sensor
- Crankshaft position (CKP) sensor
- Throttle position sensor (TPS)
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. Oxygen sensor input is ignored. The PCM will supply a predetermined amount of additional fuel.
- Monitor oxygen sensor and fine tune air/fuel ratio by varying injector pulse width.
