Wrangler L4-150 2.5L VIN P MFI (1993)
Powertrain Control Module: Description and Operation
Modes of Operation
Acceleration
THIS IS A OPEN LOOP MODE.
^
The Powertrain Control Module (PCM) recognizes an abrupt increase in throttle position or Manifold Absolute Pressure (MAP) pressure, as a
demand for increased engine output to accelerate vehicle.
^
The PCM increases injector pulse width, in response to increased fuel demand.
Cruise
THIS IS A CLOSED LOOP MODE.
With engine 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 (CKP) 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).
Deceleration
THIS IS AN OPEN LOOP MODE.
During deceleration the the Powertrain Control Module (PCM) receives inputs from:
^
Air Conditioning Control Position
^
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
