Btexpress;
While this DPFE discussion probably old hat, I have been experiencing a similar issue on my 96 Explorer XLT. Some time ago I had my EGR valve replaced. I think they also replaced the EGR valve regulator as well. Anyway, after installing the new EGR valve my vehicle ran rougher than a cob; I barely made it home. The next day I drove back to this shop and told them to replace the new EGR valve with the one they removed only to discover that the "new" EGR had a defect. Well about two years later after constantly being reminded by the 'Check Engine" light I decided to replace the old EGR valve. After installing the new EGR valve and checking the vacuum with a vacuum gauge to make sure the diaphragm was working properly, I cleared the P0401 DT code only to have it return 5 to 10 minutes later. I checked for any vacuum leaks but found none. The next culprit was the DPFE sensor. My DPFE sensor is nothing like the one in your photo. My DPFE sensor has two vacuum ports, so I tested each of the vacuum lines with a vacuum gauge All I saw on the gauge was some fluttering. In other words, no vacuum was reflected; and that was on both vacuum lines. I had REF voltage on the DPFE connector, however.
My understanding was that the DPFE sensor sends a pulse to the EGR valve and tells the EGR valve to open or close.
So, with no vacuum being shown from either of the DPFE vacuum lines, could this indicate that the DPFE sensor is bad?
"ExplorerDMB, post: 1491458, member: 22915"]Fords have an issue with their (Differential Pressure Feedback Exhaust Gas Recirculation [EGR]) DPFE Sensors. The DPFE sensor regulates how much exhaust runs back into the system for emissions reasoning.
Now, this is what it looks like:
If you notice the sensor above it is metal/aluminum. Now metal is a good conductor for heat, so when hot exhaust gas is passed through it, it eventually messes up the insides. This is why a DPFE issue is so frequent.
Ford tried to fix the issue with a plastic DPFE:
They last just as long as the metal ones. The voltage for the sensor (which can be found under Live Data or Data Stream in a scan tool) should be around .55-1 volt at idle. Anything higher and it should be replaced.
If you can graph out engine vaccum and the voltages you're likely to see, it would look similar to this graph:
The most frequent codes with a DPFE sensor issue is a P0401 and/or a P0402. These mean following:
P0401 Exhaust Gas Recirculation Flow Insufficient Detected
P0402 Exhaust Gas Recirculation Flow Excessive Detected
Now with the scan tool (I used a
NGS on my last DPFE situation on a '01 Ranger 3.0L) you can verify your voltage at idle. The voltage I had was a little over 2 volts at idle. And I had the two above codes in the system - with only the 402 code coming on with KOER, but the P0401 was in continous/current codes.
If you unplug the sensor and the voltage reads 5.0 volts - then this means that your circuitry is good and that a sensor is needed.
Hopefully that helps some people.
-Drew[/QUOTE]