Evaporative Emission (EVAP) Ejector Venturi Assembly
The EVAP ejector venturi assembly is used on turbocharged engines to create a vacuum in the EVAP purge line from the canister purge valve to the intake air system. During boost conditions, boost pressure flows through venturi inside the EVAP ejector venturi assembly creating a vacuum in the EVAP purge line to the intake air inlet to the turbocharger. When the second EVAP canister purge check valve is open, the purge vapor is drawn through the EVAP ejector venturi assembly into the intake air tube, through the turbocharger and charge air cooler, to the intake manifold.
Scheme 17
| Item | Number | Description |
|---|---|---|
| 1 | EVAP ejector venturi assembly |
ITEM DESCRIPTION CHART
Exhaust Gas Recirculation (EGR) Orifice Tube Assembly
The EGR 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 sensor which provides feedback to the PCM.
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Fuel Pump (FP) Assembly
The FP assembly contains the fuel pump and sender assembly. The fuel pump is located inside the FP assembly reservoir and supplies fuel through the FP assembly manifold to the engine and FP assembly jet pump. The jet pump continuously refills the reservoir with fuel, and a check valve located in the manifold outlet maintains system pressure when the fuel pump is not energized. A flapper valve located in the bottom of the reservoir allows fuel to enter the reservoir and prime the fuel pump during the initial fill.
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Fuel Pump (FP) Assembly and Reservoir
The FP assembly is mounted inside the fuel tank in a reservoir. The pump has a discharge check valve that maintains the system pressure after the ignition has been turned OFF to minimize starting concerns. The reservoir prevents fuel flow interruptions during extreme vehicle maneuvers with low tank fill levels.
Features of the Throttle Body Assembly include
- IAC valve assembly mounted directly to the throttle body assembly (some vehicles).
- A preset stop to locate the 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 TP sensor.
- A sealant/coating on the throttle bore and throttle plate makes the throttle body airflow 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 airflow.
Supercharger Assembly
The supercharger assembly is a positive displacement pump. The supercharger supplies 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 of the rotors 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.
