Engine Control Module: Description and Operation

Powertrain Control Module (PCM):

The 104-pin Powertrain Control Module (PCM) for the EEC-V system is used to adjust air fuel mixture, spark advance, and exhaust gas recirculation.

The EEC-V systems use Sequential Multiport Fuel Injection (SFI).

WARNING: Do not smoke, carry lighted tobacco, or open flame of any type when working on or near any fuel related component. Highly flammable mixtures are always present and may be ignited, resulting in possible personal injury.

Typical Vehicle Emission Control Information (VECI) Decal:

To maintain the required exhaust emission levels, the fuel metering system must be kept in proper operating condition and adjusted to the specifications listed on, for example, the Vehicle Emission Control Information (VECI) decal.

Additional engine performance checks are required to keep the exhaust emissions at the specified minimum pollutant level.

With the preprogrammed performance data and the information from vehicle sensors, the PCM develops an adaptive strategy for operating the ignition, fuel, and EGR systems. The PCM will also adjust the electronically controlled automatic transmission if equipped.

This adaptive strategy is maintained in the PCM memory by a small amount of current from the vehicle's battery when the ignition is OFF.

NOTE: When battery voltage is removed from the PCM, all learned values will be cleared and reset to predetermined values. When battery voltage is restored to the PCM, the vehicle may exhibit certain driveability concerns. It will be necessary to drive the vehicle to allow the PCM to relearn values for optimum driveability and performance.

The PCM receives data from various sensors:
- Throttle Position (TP) sensor
- Mass Air Flow (MAF) sensor
- Intake Air Temperature (IAT) sensor
- Engine Coolant Temperature (ECT) sensor
- Heated Oxygen Sensors (HO2S)
- Camshaft Position (CMP) sensor
- Crankshaft Position (CMP) sensor
- Power Steering Pressure (PSP) switch

The EEC-V PCM contains specific calibrations for optimizing emissions controls, fuel economy, and driveability. Based on information received and programmed into its memory, the PCM sends signals to control:
- Fuel injector
- Ignition coil
- Idle Air Control (IAC) valve
- EGR vacuum regulator solenoid