* Mass Airflow Sensor (MAF): Measures the amount of air entering the engine. This is a crucial input for determining how much fuel is needed.
* Throttle Position Sensor (TPS): Indicates how much the throttle is open, providing information about the engine's load.
* Oxygen Sensor(s) (O2): Located in the exhaust, these sensors measure the amount of oxygen in the exhaust gases. This feedback loop allows the PCM to fine-tune the fuel mixture for optimal combustion and emissions. There's typically one before the catalytic converter and one after.
* Engine Coolant Temperature (ECT) Sensor: The PCM uses this to adjust the fuel mixture based on engine temperature. A cold engine typically needs a richer mixture.
* Manifold Absolute Pressure (MAP) Sensor (or Barometric Pressure Sensor): Measures the pressure in the intake manifold, providing information about engine load and air density.
The PCM uses all this information to calculate the proper pulse width for the fuel injectors. The longer the injector stays open, the more fuel is injected. So, the PCM is the "brain" of the operation, constantly adjusting the fuel mixture to maintain the optimal air/fuel ratio for performance and emissions.
