Intake Manifold Operation

The intake manifold is made up of the upper and lower manifold assemblies. The upper manifold assembly is a variable tuned split plenum design that includes an intake manifold tuning valve, Manifold Absolute Pressure (MAP) sensor, TP sensor and an air inlet that is fitted with a throttle valve. This assembly replaces the individual conventional throttle body assembly and plenum components. The throttle valve is used to control air flow into the engine, thereby, controlling engine output. The throttle valve is opened by the vehicle operator, through the accelerator controls. During engine idle, the throttle valve is almost closed and air flow control is handled by the Idle Air Control (IAC) valve. Vacuum ports are located above and below the throttle valve to generate vacuum signal needed by various components. The nonadjustable, throttle shaft-driven, Throttle Position (TP) sensor is attached to the upper manifold assembly opposite the throttle cam lever.

The lower manifold is a single casting that houses the CMFI injector assembly, fuel inlet and return tube fitting assemblies, and provisions are provided to accommodate the linear EGR and Engine Coolant Temperature (ECT) sensor.