Engine Control Module: Description and Operation
The PCM:^ accepts input from various engine sensors to compute the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operational range.
^ outputs a command to the fuel injectors to meter the appropriate quantity of fuel.
^ determines and compensates for the age of the vehicle and its uniqueness, also automatically senses and compensates in altitude (i.e. from sea level to above sea level).