Air-Assisted Fuel Injection (Normally-Aspirated V8 Engines)

All normally-aspirated V8 engines are equipped with Air-Assisted Injection (AAI). AAI improves the atomization of fuel when cold, thus improving combustion when cold and reducing hydrocarbon emissions. The system uses manifold vacuum to draw air through the injector nozzles. During cold start and part throttle conditions, the Air Assist Control (AAC) valve, located on the throttle body, allows air to flow through the air supply rail to the injectors. AAC valve closes at higher engine loads, as manifold vacuum decreases.

The AAC valve is driven by a pulse-width modulated signal controlled by the Engine Control Module (ECM) or Powertrain Control Module (PCM). The valve is fully open when engine coolant temperature is 140°F (60°C) or less. The valve is fully closed when engine coolant temperature is 158°F (70°C) or more.