Dynasty L4-153 2.5L SOHC VIN K TBI (1992)
Engine Control Module: Description and Operation
Modes of Operation
Ignition Switch on (Zero RPM)
PCM READS:
Atmospheric Pressure (MAP sensor)
Engine Temperature (ECT Sensor)
Throttle Position (TPS)
PCM OPERATION:
The PCM calculates basic start-up fuel strategy, using current; atmospheric pressure, engine temperature, and throttle position.
- PCM pre-positions the idle air control motor.
- PCM energizes ASD and fuel pump relays for up to 3 seconds.
- PCM energizes oxygen sensor heating element.
Note:
If the key is in the ON or START position and the PCM does not receive an ignition reference signal, (engine is not running), the PCM will
deactivate the Automatic Shutdown (ASD) and fuel pump relays within 1 to 3 seconds.
Engine Start-Up (Cranking)
THE PCM LOOKS FOR AN IGNITION REFENCE SIGNAL:
If a signal is received within 0.5 seconds, the PCM energizes (grounds), the ASD and fuel pump relays. Supplying battery voltage to the fuel
pump, fuel injector, ignition coil and oxygen sensor heating element. After the PCM energizes the ASD and fuel pump relays, the PCM fires the
fuel injector 4 times per revolution, (instead of the normal 2 pulses per revolution).
If NO signal received within 0.5 seconds, the PCM does not energize the ASD and fuel pump relays.
PCM MONITORS:
- Engine Temperature (ECT Sensor)
- Manifold Vacuum (MAP Sensor)
- Throttle Position (TPS)
- Engine speed (distributor pick-up)
PCM CONTROLS:
- Injector pulse width, (switching the ground on and off twice per engine revolution).
- Idle speed, through the IAC motor.
- Ignition timing.
PCM TESTS MAP SENSOR OPERATION:
When engine idle comes within ±64 rpm of target idle speed, the PCM, compares the current MAP sensor reading to the atmospheric pressure
measurement, taken during Ignition ON (Zero RPM) mode, and if a minimum difference is not detected, a MAP sensor Diagnostic Trouble Code
(DTC) is set in memory.
Engine Warm-Up
PCM MONITORS:
- Engine Temperature (ECT Sensor)
- Manifold Vacuum (MAP Sensor)
- Engine rpm (distributor pick-up)
- Throttle Position (TPS)
- A/C Switch Status
- Battery Voltage
PCM CONTROLS:
