Turbocharger and Charge Air Cooler (CAC) System

TURBOCHARGER AND CHARGE AIR COOLER (CAC) SYSTEM

The two stage variable turbocharger geometry is controlled by the turbocharger actuator, from the powertrain control module (PCM) commands through the controller area network (CAN). The turbocharger control is a closed-loop system that uses the exhaust pressure (EP) sensor to provide feedback to the PCM. In response to engine speed, load, manifold pressure and barometric pressure, the PCM controls the turbocharger actuator position to match manifold boost to the requirements of the engine.

Filtered air enters the low pressure turbocharger and is compressed and delivered to the high pressure turbocharger (variable turbocharger geometry). The high pressure turbocharger delivers the heated compressed air to the charge air cooler (CAC). The CAC is designed to cool the induction air which has been heated by the turbocharger. The removal of heat from the pressurized air going into the CAC increases the air density which improves combustion efficiency, engine horsepower, and torque. The CAC is positioned directly after the turbocharger in the intake air flow path. As the heated air flows through the CAC, heat is transferred to the outside air reducing the temperature of the intake air. Considerably more air is forced into the intake manifold causing the pressure to be much greater than normal atmospheric pressure. This results in increased power, fuel efficiency and the ability to maintain power at higher altitudes.

The intake manifold air temperature as measured by a second intake air temperature (IAT2) sensor in the intake manifold.