Turbochargers and Induction System

The twin turbochargers are controlled by vacuum-actuated wastegate valves which are in turn controlled by an Electronic Vacuum Regulation Valve and a Vacuum Control Solenoid Valve. The mechanical vacuum pump described earlier provides vacuum to a vacuum accumulator. The vacuum accumulator system shape and location varies depending on vehicle application.

Vacuum actuated recirculation valves (also known as "bypass valves") are also used in the system. The recirculation valves are activated under high boost conditions when the driver quickly lets off the throttle, redirecting some of the boost pressure back into the compressor section of the turbocharger. This helps prevent a "stall" condition of the turbo blade similarly to how an airplane wing can stall. The stall at the turbo blade can create noise and, under extreme conditions, even turbo damage due to buffeting; the recirculation valves prevent noise and potential damage.

Both turbochargers are covered by heat shields to shield nearby components. The turbochargers are connected to both oil and coolant at the block and turbos in a variety of ways: flanged, gasketed joints, banjo fittings, and Jiffy-tite® quick connect fittings. The Jiffy-tite® quick connect fittings are 8mm, 3/8", and 5/8" in size, and require commercially-available tools to disconnect the tubing. Mass Air Flow (MAF) sensors with inlet air temperature and humidity sensors are located in the air induction system, as are integrated resonator assemblies to help control intake noise. There is also a turbo inlet pressure sensor near the airbox, and both a lower- and mid-plenum air pressure sensor on the Integral Charge-Air Cooler Module.