Shadow Convertible L4-153 2.5L SOHC (1994)
Powertrain Control Module: Description and Operation
Modes of Operation
Acceleration (Except Wide Open Throttle)
NOTE: For Wide Open Throttle (WOT) operation, SEE OPEN LOOP MODES OF OPERATION.
PCM INPUT:
Powertrain Control Module (PCM) recognizes an abrupt increase in throttle opening, (TPS voltage increase), or drop in engine vacuum, (MAP
sensor voltage increase), as a demand for increased engine output to accelerate vehicle.
PCM OUTPUT:
PCM increases injector pulse width to accommodate increased fuel demand.
Cruise
PCM MONITORS:
-
Engine Temperature (ECT Sensor)
-
Manifold Vacuum (MAP Sensor)
-
Engine rpm (distributor pick-up)
-
Throttle Position (TPS)
-
Exhaust Gas Oxygen Content (O2S)
-
A/C Switch Status
-
Battery Voltage
PCM CONTROLS:
-
Air/fuel ratio, by varying injector pulse width. Switches injector ground on and off twice per engine revolution.
-
Idle speed, through the IAC motor.
-
Ignition timing.
-
Monitor oxygen sensor and fine tune air/fuel ratio by varying injector pulse width
-
Operate A/C Compressor Clutch relay (if selected)
Deceleration
PCM MONITORS:
-
Engine Temperature (ECT Sensor)
-
Manifold Vacuum (MAP Sensor)
-
Engine rpm (distributor pick-up)
-
Throttle Position (TPS)
-
Exhaust Gas Oxygen Content (O2S)
-
A/C Switch Status
-
Battery Voltage
UNDER NORMAL DECELERATION, PCM:
Continues normal (reduced) injection.
De-energizes EGR system, by grounding Electronic EGR Transducer (EET) solenoid.
UNDER HARD DECELERATION, (CLOSED THROTTLE AND ABRUPT INCREASE IN MANIFOLD VACUUM) THE PCM:
Ignores oxygen sensor input, and initiates fuel cut-off strategy, firing injector only once per engine revolution.
Disables EGR system, by grounding EGR solenoid.
