DPFE Sensor VS EGR Sensor
Elder User
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From: South Texas
They perform a similar function but are not the same sensor.
DPFE gives a more precise reading of the EGR flow by measuring a pressure drop across 2 ports of the sensor as the EGR valve opens/ closes.
EGR sensor just measures the amount of travel when the EGR valve diaphram moves. From that the computer assumes a certain amount of EGR flow is taking place, but cannot tell for sure if it is.
Where DPFE sensor is depends on the engine involved, but usually they are somwhere close to the EGR valve itself, and it has 2 small (1/4 inch or so) hoses attached to the measurment ports. The EGR sensors are attached directly to the backside of the EGR valve and only has an electrical connector to it, but the EGR valve has a vacuum hose attached.
Dialtone
DPFE gives a more precise reading of the EGR flow by measuring a pressure drop across 2 ports of the sensor as the EGR valve opens/ closes.
EGR sensor just measures the amount of travel when the EGR valve diaphram moves. From that the computer assumes a certain amount of EGR flow is taking place, but cannot tell for sure if it is.
Where DPFE sensor is depends on the engine involved, but usually they are somwhere close to the EGR valve itself, and it has 2 small (1/4 inch or so) hoses attached to the measurment ports. The EGR sensors are attached directly to the backside of the EGR valve and only has an electrical connector to it, but the EGR valve has a vacuum hose attached.
Dialtone
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Well the guys at auto zone didn't know what a DPFE sensor was. They pulled up an EGR Sensor with two hose connections and an eletrical connnection port..I'm getting an error code, 0401, and from what I read here that points to a bad DPFE....I've got 127 k on the truck so it could be....
Elder User
Joined: Aug 2001
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From: South Texas
Here is a link to what the sensor looks like.
http://autorepair.about.com/library/...s/bl398lib.htm
The original probably has a metal housing, but the replacement may have a plastic housing with the ports side to side rather than front/rear as does the original equipment. I have been told that the plastic housing is preferrable as the metal can leak where the housing halves are joined.
If changing the sensor does not fix the problem, other possibilities are
1. EGR valve itself
2. Blockage in the exhaust tube orifice feeding EGR valve
3. Cracked / broken hoses to DPFE sensor (note: these are special high temp hoses)
4. Vacuum hose problem to EGR
5. EGR vacuum actuation and dump off valves
The one the auto store looked up is probably correct, at least the description was correct. They may call it an EGR flow sensor or some such name, but Ford calls it a DPFE (Differential Pressure Feedback Egr sensor)
I do not think the old type EGR travel sensors have been used since mid to late 80's.
Here is a link to a pdf document that says it all regarding EGR
http://www.tomco-inc.com/Tech_Tips/ttt35.pdf
Dialtone
http://autorepair.about.com/library/...s/bl398lib.htm
The original probably has a metal housing, but the replacement may have a plastic housing with the ports side to side rather than front/rear as does the original equipment. I have been told that the plastic housing is preferrable as the metal can leak where the housing halves are joined.
If changing the sensor does not fix the problem, other possibilities are
1. EGR valve itself
2. Blockage in the exhaust tube orifice feeding EGR valve
3. Cracked / broken hoses to DPFE sensor (note: these are special high temp hoses)
4. Vacuum hose problem to EGR
5. EGR vacuum actuation and dump off valves
The one the auto store looked up is probably correct, at least the description was correct. They may call it an EGR flow sensor or some such name, but Ford calls it a DPFE (Differential Pressure Feedback Egr sensor)
I do not think the old type EGR travel sensors have been used since mid to late 80's.
Here is a link to a pdf document that says it all regarding EGR
http://www.tomco-inc.com/Tech_Tips/ttt35.pdf
Dialtone
Last edited by Dialtone; Jul 9, 2005 at 11:21 PM.
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From: Phoenix
Differential pressure is a bornoulli principle. Measure the pressure drop across 2 known oriface diameters and you get a velocity. This is what the DPFE does. So this sensor tells the PCM how fast the exhaust is flowing. This is what tells the PCM how much to open the EGR valve. If there is minimal flow, at idle, you don't want too much EGR or the motor will die. You can't use just RPM, right, because on a high RPM engine but a braking condition, there is no flow through the motor - adding EGR will kill the motor. So now that the EGR is opening in response to the real flow through the motor, the PCM wants a feedback to how far open the EGR valve really is. There is a sensor that tells the PCM this - on the back of the EGR valve itself. In response, PCM reduces the fuel flow as not to go too rich - EGR has no Oxygen left, right? So if you put in gasses that don't help burn the fuel, you will be too rich.
I'm too tired now to go look up your codes. I hope this or this link helps you understand how the sensors/actuators work to help solve your problem.
http://www.fordfuelinjection.com/
I'm too tired now to go look up your codes. I hope this or this link helps you understand how the sensors/actuators work to help solve your problem.
http://www.fordfuelinjection.com/
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From: 3rd Rock
Originally Posted by Mountaineer Boy
Well the guys at auto zone didn't know what a DPFE sensor was. They pulled up an EGR Sensor with two hose connections and an eletrical connnection port..I'm getting an error code, 0401, and from what I read here that points to a bad DPFE....I've got 127 k on the truck so it could be....
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