Last update:

05/16/2006

  EGR Sensors

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EGR SENSORS

Test Data and Sensor View

This page details the EGR system sensors and hardware.

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DPFE

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EVR valve

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EGR valve

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Orifice Tube

Differential Pressure Feedback EGR Sensor
The DPFE sensor is a ceramic, capacitive type pressure transducer. The sensor outputs a voltage to the PCM in direct proportion to the pressure drop across the orifice in the EGR pipe. In this way the PCM can make an accurate assessment of the gas flow through the tube. Two different sensors are in use, one metal cased and the other plastic. These sensors should not be interchanged - further, some sensors have a modified voltage output.

Sensor view and data:

Below, troubleshooting details which may be of use for testing.

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Electronic Vacuum Regulator (EVR)

                        

The EVR regulates the vacuum to the EGR valve and is controlled by a pulse-width signal to open and close the EGR valve. As the duty cycle pulse width signal increases, the EVR increases the vacuum to the EGR which opens further and admits more gas into the inlet system.

Vacuum not directed to the EGR valve is vented to atmosphere. Even at zero duty cycle (no voltage) some vacuum will still pass the EVR, but this is not enough to overcome the spring pressure. It is not until the EVR is at 40% duty cycle that the vacuum is enough to overcome the EGR spring pressure.

EVR Duty Cycle is shown below:

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EGR Valve
A conventional vacuum operated EGR valve is used on the Scorpio. The valve increases or decreases the flow of exhaust gas into the inlet manifold and this is by a diaphragm operating on a pintle which is connected to a poppet valve. When no vacuum is present, the spring keeps the poppet valve closed. When the EVR allows sufficient vacuum to the EGR valve, the vacuum pressure overcomes the spring and the poppet valve opens, but as soon as the vacuum pressure is reduced spring pressure closes the poppet valve again.

To prevent unmetered air leaks the valve must be clamped firmly to the inlet manifold with the gasket properly aligned with the gas port, and the EGR pipe must be properly secured to the valve. The valve itself can be tested by using Vehicle Explorer to read the DPFE sensor while a vacuum is applied to the EGR valve. The DPFE should show a rise in volts corresponding to the opening of the valve. This is provided that the DATA page has not shown a DTC from the CCM showing a voltage out of range error for the DPFE.

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ORIFICE TUBE
The EGR Orifice tube requires no maintenance and is ironwork only. However, in order for the device to function correctly it must be gas tight both at the exhaust and the inlet ends.

Diagrams Ford (Europe)

 

 

 

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