Wrangler L4-150 2.5L VIN P MFI (1993)
^
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 equipped and 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.
Idle
THIS IS A CLOSED LOOP MODE.
With engine idling at operating temperature, the Powertrain Control Module (PCM) receives inputs from:
^
Air Conditioning Control Position (if equipped)
^
Battery voltage
^
Camshaft position (CMP) sensor
^
Engine coolant temperature (ECT) sensor
^
Manifold absolute pressure (MAP) sensor
^
Intake air temperature (IAT) sensor
^
Crankshaft position (CMP) sensor
^
Throttle Position Sensor (TPS)
^
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 equipped and selected).
Ignition Switch Off
WHEN THE IGNITION SWITCH IS OFF THE POWERTRAIN CONTROL MODULE (PCM) WILL STOP OPERATING THE:
^
Fuel injectors
^
Ignition coil
^
ASD relay
^
Fuel pump relay.
Ignition Switch On
THIS IS AN OPEN LOOP MODE.
When the Powertrain Control Module (PCM) is ACTIVATED by the ignition switch, the following actions occur:
^
The PCM preposition 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
