Exhaust Gas Recirculation (EGR) Orifice Tube Assembly
The orifice tube assembly is a section of tubing connecting the exhaust system to the intake manifold. The assembly provides the flow path for the EGR to the intake manifold and also contains the metering orifice and 2 pressure pick-up tubes. The internal metering orifice creates a measurable pressure drop across it as the EGR valve opens and closes. This pressure differential across the orifice is picked up by the differential pressure feedback EGR (DPFE) sensor which provides feedback to the powertrain control module (PCM).
Scheme 11
Features of the Throttle Body Assembly include
- Idle air control (IAC) valve assembly mounted directly to the throttle body assembly (some vehicles).
- A pre-set stop to locate the wide open throttle (WOT) position.
- An air supply channel upstream of the throttle plate to provide fresh air to the PCV system (some vehicles only).
- Individual vacuum taps for PCV, EGR, EVAP and miscellaneous control signals (some vehicles only).
- PCV air return (if applicable).
- A throttle body-mounted throttle position (TP) sensor.
- A sealant/coating on the throttle bore and throttle plate makes the throttle body air flow tolerant to engine intake sludge accumulation. These throttle body assemblies must not be cleaned and have a white/black attention decal advising not to clean.
- A non-adjustable stop screw for close plate idle air flow.
Supercharger Assembly
The supercharger assembly is a positive displacement pump. Its purpose is to supply an excess volume of intake air to the engine by increasing air pressure and density in the intake manifold. The supercharger assembly incorporates the bypass system to reduce air handling losses when boost is not required, resulting in better fuel economy. When integrated on the engine, the supercharger increases torque across the entire engine operating range from 25 to 50 percent without compromising driveability or emissions. The supercharger is matched to the engine by its displacement and belt ratio, and can provide excess airflow at any engine speed. It contains 2 screw-type 3-lobed rotors. The helical shape and specialized porting provide a smooth discharge flow and a low level of noise during operation. The rotors are supported by ball bearings in front and needle bearings at the rear. The drive gears are pressed into place; therefore, the supercharger is installed as a unit and is not repairable.
Scheme 12
Vacuum Reservoir Assembly
The vacuum reservoir assembly stores vacuum that is applied to the vacuum actuator when a condition such as overheating or a critical sensor failure is generated. This allows the vacuum actuator to bypass the supercharger.
