Ford Repair Questions? Ask a Mechanic for Answers ASAP
Greetings! Sounds like you have a pfe/Dpfe sesnor that has gone bad. If you have replaced this, you might have a bad new one. Make sure you have signal voltage at the sensor with the key on and a good ground. Next be sure there is a god clean signal coming out of the sensor with the egr system in use. Here a a chart to help you figure out the possible causes.
Well the dpfe is a sensor.
If you take a look at the chart in my last post, it gives you the possible causes.
The Differential Pressure Feedback EGR (DPFE) transducer/sensor is a ceramic capacitive-type pressure sensor. Exhaust pressure or vacuum is converted into a proportional analog voltage signal, which is digitized by the Electronic Control Assembly (ECA) . The DPFE sensor also monitors pressure in the exhaust system to allow for an accurate assessment of EGR flow requirements. The ECA uses the signal received from the DPFE transducer to compute optimum EGR flow rate, as well as to monitor EGR flow.
The Pressure Feedback EGR (PFE) sensor is a ceramic capacitive-type pressure sensor. Exhaust pressure or vacuum is converted into a proportional analog voltage signal, which is digitized by the Electronic Control Assembly (ECA) . The ECA uses the signal received from the PFE sensor to compute optimum EGR flow rate, as well as to monitor EGR flow.
Turn the key on and unplug the sensor. There should be three wires. One should have a reference voltage. (5 volts) One should be ground and the other is the signal return back to the computer.
If that checks out, we are going to want to monitor the voltage on the reference wire coming out of the sesnor while there is exhaust flow. The voltage should change while this is happening.
If all the wiring checks out ok, chances are the sensor is bad. But just to be sure, you are going to want to monitor the sensor signal voltage when exhaust flow is present. This will tell you if the sensor is working.
So you have checked one of the three wires to the sensor with it unpluged.
Next step I want you to do a voltage drop on the other two wires to ground.
To do this, turn the key on, (sensor unplugged) and with a voltmeter I want you to take one lead and go the negative side of the battery and touch the other lead of the voltmeter to the other two wires. Let me know EXCACTLY the voltage you come up with on both of them
One should be 5 volts
One should be ground. To test for this, take one lead of your voltmeter to the wire in the connector. The other lead of your meter on battery power. Then, and only then should you read battery power on your voltmeter.
and the other one should be nothing (or no reading)
Well so far we have just tested the inputs to the sensor. NOw we have to check the signal from the sensor.
With the car running and the sensor plugged back in I am going to want you to back probe the signal wire coming from the sensor with one of the leads from the voltmeter and the other lead on battery ground. (This is the wire that had no reading on it unplugged.) Start the car and slowly apply vacuum to the egr valve with a hand held vacuum pump. The engine rpm should change because this is creating a big air leak. At the same time the voltage from the sensor should change as well.
You got it! You are right on track! This is correct if you are testing with the sensor unplugged.
Well when you back probe the sensor, you are going to want to be on the signal wire.
One lead of the voltmeter on battery ground, and the other one back probing the sensor signal wire. (sensor plugged in)
The voltage should look something like this.
The sensor is not putting out the correct voltage.
Make sure when you back probe this sensor that you are using a small probing device. Like a paper clip. Be sure its pushed back in far enough so it makes contact with the metal prong on the wire.
You should be on brown with light green stripe wire.
If you are sure there is no voltage coming out and there is voltage going in the sensor, the sensor is bad and will need to be replaced.
Sorry for the delay!
I do this on my spare time. My boss does not appreciate it if I do this at work so I came home on lunch to answer any question waiting for me. I just got home now. Sorry, again.
If the engine stumbles when vacuum is applied to the egr valve it sounds like the air passages are not plugged.
Here is the test that ford gives to the technicians for this particular problem.
EGR Control/Vent Solenoids
1. Start engine and allow to reach operating temperature.2. Turn ignition Off.3. Connect a suitable hand held vacuum pump to the EGR valve vacuum supply port
4. Start the engine.5. Gradually apply vacuum to the EGR valve vacuum supply port. The engine should run rough or stall as vacuum is applied to the EGR valve.
Pressure Feedback Electronic & Differential Pressure Feedback Electronic Systems1986-95
1. Ensure all vacuum hoses are properly routed and securely connected, and replace any that are cracked, crimped or broken.2. Run engine until normal operating temperature is reached.3. With engine running at idle, disconnect EGR vacuum supply and inspect for vacuum signal. EVR solenoid has a constant internal leak. A small vacuum signal, less than one inch at idle, should be noticed.4. Install tachometer tool No. 059-00010, or equivalent.5. Disconnect IAC solenoid electrical connector.6. Disconnect an plug vacuum supply hose at EGR valve nipple.7. Start engine and run at idle with transmission in Neutral, then observe idle speed. If required, adjust idle speed to specifications. If engine will not idle with IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate or by creating an intake vacuum leak. Do not exceed a typical idle RPM.8. Slowly apply 5-10 inches vacuum to EGR valve nipple using hand held vacuum pump tool No. 021-00014, or equivalent.9. With vacuum applied, ensure idle speed drops more than 100 RPM and returns to normal, within 25 RPM, after vacuum is removed.10. Unplug and connect vacuum supply hose at EGR valve.
I think you really need to get a digital voltmeter. You are going to want to see about 1.0 volt, or .5 volt (depending on which one you have)on the signal wire at idle with no egr flow.
If you do not, the sensor is bad and needs to be replaced. I have seen these things come bad out of the box.
ITs just a circuit code. Its not saying that the ports are plugged up (or low flow).
This is the definition for this code is:
Code 327-Delta pressure feedback EGR, DPFE, is below 0.20 volts
This is the way ford engineers designed it. FOr some reason the computer is seeing the dpfe sensor voltage at only .2. This sounds like what you found when you had back probed the signal wire. I believe this is why the computer is flagging a 327.
I believe if I remember correctly that the big air intake just past the throttle plate (or that holds the throttle plate) needs to come off and cleaned out. It sounds like you have cleaned the exhaust ports, but not the intake ports.
If my answer was good enough for you, just hit accept and leave positive feedback.
Here is a picture of the intake manifold. There are two separate pieces. Do you see the top that goes down to the bottom part? It has a smooth 90 degree bend. This part needs to come apart and you will need to clean the carbon out of there. I bet it is plugged up!
If the code comes back right away, chances are that the problem is going to be an electrical issue. But if you have to drive it for a bit, I would be willing to bet that the problem is because of the plugged ports.
The elbow piece that you are talking about is exactly what I was talking about! We are on the same page. The horse shoe shaped grooves are what needs to be cleaned out.
What I was talking about the exhaust ports, is the one coming from the egr to the exhaust. Be sure thats not plugged up as well.
Other than that, I think you have are on the right track. I think that the signal coming from the dpfe sesnor is wrong and the dpfe sensor will need to be replaced.
Maybe on this particular egr system it does not need a lot of egr flow when the computer commands the egr open.
I bet the problem is just going to be electrical. We know the ports are super clean so we can forget about that. We are just going to need to get the signal voltage up to were it should be coming from the sensor.
If you hit accept, you will only be charged 9 dollars. You can leave more for a bonus if you feel I did a good job.
They go bad so often in fact that there is a technical service buletin on this. Here it is.
DELTA PRESSURE FEEDBACK EGR (DPFE) - DIAGNOSTIC TIPSFORD:1994-97 MUSTANG, THUNDERBIRD1995-97 CONTOUR, CROWN VICTORIA1996-97 ESCORT, TAURUS
LINCOLN-MERCURY:1990-97 TOWN CAR1994-97 COUGAR1995-97 CONTINENTAL, GRAND MARQUIS, MYSTIQUE1996-97 SABLE, TRACER
LIGHT TRUCK:1994-97 EXPLORER1995-97 ECONOLINE, F-150-350 SERIES, WINDSTAR1996-97 AEROSTAR1997 EXPEDITION, MOUNTAINEER1998 NAVIGATOR
ISSUE:The current DPFE sensor diagnostic reference values as published in the Powertrain Control/Emissions Diagnosis (PC/ED) Service Manual, and also accessed by either the Service Bay Diagnostic System (SBDS) or Service Bay Technical System (SBTS), can lead to the replacement of good DPFE sensors.
ACTION:Use the following revised DPFE sensor voltage ranges for all (black plastic or aluminum) DPFE system applications when checking the PID (Parameter Identifier Display) value "DPFEGR" or when measuring the DPFE sensor input directly at the breakout box. Refer to Figure 1.
NOTE : THESE LISTED VOLTAGE RANGES SHOULD BE USED FOR ALL (BLACK PLASTIC OR ALUMINUM) DPFE SYSTEM APPLICATIONS WHENEVER CHECKING THE PID VALUE "DPFEGR" OR WHEN MEASURING THE DPFE SENSOR INPUT DIRECTLY AT THE BREAKOUT BOX.
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 690000, 698298
Yup! Sounds like an air leak. This is very common! If it is hard to pinpoint, take some brake cleaner or starting fluid around the intake manifold and vacuum lines and see if the engine stumble or if the idle is affected. This is a good way to find a vacuum leak. Be extremely careful when doing this!
As for the screws, your best bet is to go to the hard where store for the screws.
Yes, an air leak will do this.
They should be tightened in a cross pattern until they are snug. Not tight. If you need a torque sequence, let me know.
Yes. I do agree!
Try some brake cleaner around the area that you hear the hissing. This will pinpoint the leak and just be sure its in that area that you are talking about.
Just be sure the new bolts that you are putting in there have the same thread pitch.
Let me know what you find.
Just as long as they screw in ok
yes, o2 sensors get lazy. But if yo have an air or vacuum leak, that should be fixed first.
Your last question should be asked in a different category. I just do cars, no web sites. Sorry!
Sure! You could try that!
Or, I would just rec to replace it with new parts from Ford.
Looks like you are just going to have to go a junk yard.
Or, rig up something that will seal it and hold it together at the same time.