Lincoln Corsair: Intake Air Distribution and Filtering - 2.0L EcoBoost (177kW/240PS) – MI4 / Description and Operation - Intake Air Distribution and Filtering - System Operation and Component Description

System Operation

Adaptive Airflow

Some vehicles equipped with electronic throttle control (ETC) have an adaptive airflow strategy that allows the PCM to correct for changes in the airflow. During idle, the PCM monitors the throttle angle and airflow. If the airflow is determined to be less than expected, the PCM adjusts the throttle angle to compensate.

The PCM only learns the adaptive airflow when the vehicle is at idle and normal operating temperature and the airflow is less than a calibrated limit. Whenever the battery is disconnected or the KAM is reset, it is necessary for the PCM to learn the new value and not use the default value.

Intake Air Systems

The intake air system provides clean air to the engine, optimizes airflow, and reduces unwanted induction noise. The intake air system consists of an air cleaner assembly, resonator assemblies, and hoses. Some vehicles use a hydrocarbon filter trap to help reduce emissions by preventing fuel vapor from escaping into the atmosphere from the intake when the engine is OFF. It is typically located inside the intake air system. The hydrocarbon trap is part of the EVAP system. The MAF sensor (if equipped), is attached to the intake air system and measures the volume of air delivered to the engine. The MAF sensor (if equipped) can be replaced as an individual component. The intake air system also contains a sensor that measures the intake air temperature, which is integrated with the MAF sensor (if equipped). Intake air components can be separate components or part of the intake air housing. The function of a resonator is to reduce induction noise. The intake air components are connected to each other and to the throttle body assembly with hoses.

Throttle Body System Overview

The throttle body system meters air to the engine during idle, part throttle, and WOT conditions. The throttle body system consists of single or dual bores with butterfly valve throttle plates and a TP sensor.

The major components of the throttle body assembly include the TP sensor and the throttle body housing assembly.

Features Of The Throttle Body Assembly Include:

• A preset stop to locate the WOT position.

• A throttle body mounted TP sensor.

• A coating sealant on the throttle bore and throttle plate makes the throttle body airflow tolerant to engine intake sludge accumulation.

• A non adjustable stop screw for close plate idle airflow.

Component Description

Barometric Pressure (BARO) Sensor

The BARO sensor measures barometric pressure to estimate the exhaust back pressure.

BARO sensor is mounted internally to the PCM . The BARO sensor measures the barometric pressure to estimate the exhaust back pressure.

For vehicles without a BARO sensor and with a MAP sensor, the BARO value is inferred by the PCM based on the MAP value under certain operating conditions. At, or near wide open throttle the BARO value is calculated to be slightly higher than the MAP value, with the difference calculated by the pressure drop across the throttle plate.

Intake Air Temperature (IAT) Sensor

The IAT sensor is a thermistor device in which resistance changes with temperature. The resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor pins and provides electrical signals to the PCM corresponding to temperature.

Thermistor type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM . This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The IAT sensor provides air temperature information to the PCM . The PCM uses the air temperature information as a correction factor in the calculation of fuel, spark, and airflow.

The IAT sensor provides a quicker temperature change response time than the ECT or CHT sensor.

Currently there are 2 types of IAT sensors used, a stand alone and an integrated type. Both types function the same, however the integrated type is incorporated into the MAF sensor, the MAPT sensor, or the TCIPT sensor instead of being a stand alone sensor.

The IAT2 sensor is typically located near the intake manifold and is used to measure the intake manifold temperature. The PCM uses this information to determine the air charge and provide input for various engine control functions. The IAT2 sensor may be integrated with the MAP sensor.

Manifold Absolute Pressure /Intake Air Temperature 2 (MAP/IAT2) Sensor

The MAP sensor is located on the intake manifold and measures the intake manifold pressure. The PCM uses this information to determine the air charge and to provide the input for various engine control functions. The MAP sensor is integrated with an IAT sensor.

Turbocharger Boost Pressure (TCBP) Sensor

The TCBP sensor is located in the intake air tube between the turbocharger and the CAC . The TCBP sensor measures the throttle inlet pressure. The PCM uses the information from the TCBP sensor to refine the estimate of the airflow rate through the throttle and to determine the desired boost pressure. The TCBP sensor may be integrated with a charge air cooler temperature (CACT) sensor.

. The TCBP/CACT has two analog signal outputs from the sensor. There is one reference voltage circuit and one signal return circuit for the sensor.