Fuel

• The engine control module regulates the amount of fuel that is released when the gas pedal is pressed. It injects fuel according to how much air flows into the engine. When the engine is first started, the control module sends a signal for the release of more fuel to warm the engine up.
  
  

Timing

• An engine requires a spark in its combustion chamber to start properly. The engine control module regulates the timing of this spark and adjusts it when problems, such as engine knock, arise.
  
  

Speed

• The engine control module has idle speed control built into it. It uses the speed control to monitor the engine's timing while idle.
  
  

Variations

• Some vehicles have engine control modules which are programmable by the user. Programmable modules are used for vehicles with significant aftermarket changes made to the engine.