Di-Fa
Differential Pressure Feedback Exhaust Gas Recirculation (EGR) SensorThe differential pressure feedback EGR sensor is a piezo resistive type pressure transducer that monitors the differential pressure across a metering orifice. The differential pressure feedback EGR sensor receives this signal through 2 hoses referred to as the downstream pressure hose and upstream pressure hose (note the upstream pressure hose uses a larger diameter hose). The differential pressure feedback EGR sensor outputs a voltage proportional to the pressure drop across the metering orifice and supplies it to the PCM as EGR flow rate feedback.
Electric Exhaust Gas Recirculation (EEGR) Valve
Depending on the application, the EEGR valve is either a water cooled or an air cooled motor/valve assembly. The motor is commanded to move in 52 discrete steps as it acts directly on the EEGR valve. The position of the valve determines the rate of EGR. The built-in spring works to close the valve against the motor opening force.
Electronic Throttle Actuator Control (TAC)
The electronic TAC is a DC motor controlled by the PCM. There are 2 designs for the TAC, parallel and inline. The parallel design has the motor under the bore parallel to the plate shaft. The motor housing is integrated into the main housing. The inline design has a separate motor housing. Both designs use an internal spring to return the throttle plate to a default position. The default position is typically a throttle angle of 7 to 8 degrees from the hard stop angle. The closed throttle plate hard stop prevents the throttle from binding in the bore. This hard stop setting is not adjustable and is set to result in less airflow than the minimum engine airflow required at idle. For additional information, refer to Torque Based Electronic Throttle Control (ETC).
Electronic Throttle Body Throttle Position Sensor (ETBTPS)
The ETBTPS has two signal circuits in the sensor for redundancy. The redundant ETBTPS signals are required for increased monitoring. The first ETBTPS signal (TP1) has a negative slope (increasing angle, decreasing voltage) and the second signal (TP2) has a positive slope (increasing angle, increasing voltage). The two ETBTPS signals make sure the PCM receives a correct input even if one signal has a concern. For Fiesta, there is one reference voltage circuit (ETCREF) and one signal return circuit (ETCRTN) for the sensor dedicated to the ETBTPS. For all others, there is one reference voltage circuit (ETCREF) and one signal return circuit (ETCRTN) for the sensor shared with the reference voltage circuits (APPVREF and APPVREF2) and signal return circuits (APPRTN and APPRTN2) used by the APP sensor. For additional information, refer to Torque Based Electronic Throttle Control (ETC).
Engine Coolant Temperature (ECT) Sensor
The ECT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance changes the voltage drop across the sensor terminals 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 varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor (pull-up resister) in 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 ECT sensor measures the temperature of the engine coolant. The PCM uses the engine coolant temperature input for fuel control and for cooling fan control. The ECT sensor can be a threaded or twist lock type. The ECT sensor is located in an engine coolant passage.
Evaporative Emission (EVAP) Canister Vent Valve
The EVAP canister vent valve (located near the EVAP canister) is part of the enhanced EVAP system controlled by the PCM. During the EVAP leak check monitor, the EVAP canister vent valve seals the EVAP canister from the atmospheric pressure. This allows the EVAP purge valve to achieve the target vacuum in the fuel tank during the EVAP leak check monitor.
Evaporative Emission (EVAP) Check Valve
EVAP Check Valve
The EVAP check valve is used on turbocharged engines to prevent boost pressure from forcing open the EVAP purge valve and entering the EVAP system. The valve is open under normal engine vacuum. The valve closes during boost conditions to prevent the fuel tank from being pressurized and hydrocarbons forced out of the EVAP system into the atmosphere through the EVAP canister vent valve. When the engine is OFF, or at atmospheric pressure, the EVAP check valve is in an indeterminate state. The EVAP check valve is an integral part of the EVAP purge valve assembly.
EVAP Dual Check Valve
The EVAP dual check valve is used to allow purge flow during boost conditions. Fuel vapors flow through the EVAP dual check valve to the intake air system upstream of the turbocharger before entering the intake manifold. When the engine is OFF, or at atmospheric pressure, the EVAP dual check valve is in an indeterminate state.
Evaporative Emission (EVAP) Ejector
The EVAP ejector is used on turbocharged engines to create a vacuum in the EVAP purge line from the EVAP purge valve to the intake air system. During boost conditions, boost pressure flows through a venturi inside the EVAP ejector creating a vacuum in the EVAP purge line to the intake air inlet to the turbocharger. When the second EVAP check valve is open, the purge vapor is drawn through the EVAP ejector into the intake air tube, through the turbocharger and charge air cooler, to the intake manifold.
Evaporative Emission (EVAP) Natural Vacuum Leak Detection (NVLD) Module
The NVLD module is located in the EVAP canister vent hose, under the vehicle. Battery voltage (VBAT) is supplied to the NVLD module to allow EVAP system diagnostics to run after the ignition is turned OFF. The NVLD module electrical connector also incorporates a communication (NVLD) circuit and a ground (GND) circuit between the NVLD module and the PCM.
Internal to the NVLD module is a normally open vacuum switch (closes with vacuum), a normally closed vacuum relief valve (opens with excessive vacuum), a normally closed pressure relief valve (opens during refueling), an internal ambient air temperature sensor and a timer. The NVLD module completes a series of checks to confirm the integrity of the enhanced EVAP system components in the engine running state and the ignition OFF state. When the ignition is turned ON and the engine is running the NVLD module sends the information stored during the ignition OFF tests to the PCM.
Evaporative Emission (EVAP) Purge Valve
The EVAP purge valve (located near the engine) is part of the enhanced EVAP system controlled by the PCM. This valve controls the flow of vapors (purging) from the EVAP canister to the intake manifold during various engine operating modes. The EVAP purge valve is a normally closed valve. The EVAP purge valve controls the flow of vapors, eliminating the need for an electronic vacuum regulator and vacuum diaphragm. For Flex 3.5L 4V, Fusion 3.5L, MKS 3.7L, MKT 3.7L, MKZ 3.5L, Taurus 3.5L 4V and Transit Connect the PCM outputs a variable current between 0 and 1,000 mA to control the EVAP purge valve. For all others, the PCM outputs a duty cycle between 0% and 100% to control the EVAP purge valve.
Exhaust Gas Recirculation (EGR) System Module (ESM)
The ESM functions in the same manner as a conventional differential pressure feedback EGR system. The various system components have been integrated into a single component called the ESM. The flange of the valve portion of the ESM bolts directly to the intake manifold with a metal gasket that forms the metering orifice. This arrangement increases system reliability, response time, and system precision. By relocating the EGR orifice from the exhaust to the intake side of the EGR valve, the downstream pressure signal measures manifold absolute pressure. This manifold absolute pressure signal is used for EGR correction and inferred barometric pressure (BARO) at ignition ON. The system provides the PCM with a differential pressure feedback EGR signal that is identical to a traditional differential pressure feedback EGR system.
Exhaust Gas Recirculation (EGR) Vacuum Regulator Solenoid
The EGR vacuum regulator solenoid is an electromagnetic device used to regulate the vacuum supply to the EGR valve. The solenoid contains a coil which magnetically controls the position of a disc to regulate the vacuum. As the duty cycle to the coil increases, the vacuum signal passed through the solenoid to the EGR valve also increases. Vacuum not directed to the EGR valve is vented through the solenoid vent to the atmosphere. At 0% duty cycle (no electrical signal applied), the EGR vacuum regulator solenoid allows some vacuum to pass, but not enough to open the EGR valve.
Exhaust Gas Recirculation (EGR) Valve
The EGR valve in the differential pressure feedback EGR system is a conventional, vacuum-actuated valve. The valve increases or decreases the EGR flow. As vacuum applied to the EGR valve diaphragm overcomes the spring force, the valve begins to open. As the vacuum signal weakens, at 5.4 kPa (1.6 in-Hg) or less, the spring force closes the valve. The EGR valve is fully open at approximately 15 kPa (4.4 in-Hg).
Since EGR flow requirement varies greatly, providing repair specifications on flow rate is impractical. The on board diagnostic (OBD) system monitors the EGR valve function and triggers a DTC if the test criteria is not met. The EGR valve flow rate is not measured directly as part of the diagnostic procedures.
Fan Speed Sensor (FSS)
The FSS is a Hall effect sensor that measures the cooling fan clutch speed by generating a waveform with a frequency proportional to the fan speed. If the cooling fan clutch is moving at a relatively low speed, the sensor produces a signal with a low frequency. As the cooling fan clutch speed increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the FSS as a feedback for closed loop control of the cooling fan clutch. For additional information on the cooling fan clutch, refer to the Cooling Fan Clutch.
