Bluegrass: What you write makes sense, but please clarify your point. I originally thought that you said the DPFE is a sensor only and will not cause drivability issues. In your most recent post, it seems that it wont leave you stranded somewhere...

I agree with you that its a sensor that measures pressure. Where I *think* I disagree with you is that the sensor can cause rough running. It seems logical that the DPFE would report back to the ECU a voltage that cooresponds to the pressure differential across both sides of the EGR. If the unit does not respond properly, it could cause the ECU to throw a code (insufficient or excessive flow). However, say the DPFE is slow to respond, out of cal or stuck, it will give incorrect voltage readings back to the ECU. The EGR system can no longer accurately meter how much exhaust gas is being introduced in the combustion chamber.

It is a sensor, but my understanding is that it provides closed-loop control to the EGR system. If EGR system is letting in too much gas, the system will run non-optimal. Your posts seem to indicate that the DPFE is merely a monitoring sensor that is not responsible for providing EGR feedback to the sensor and throwing codes if the pressures are not in the correct range.

To test my theory, I should be able to put a vacuum up the the DPFE lines and be able to force my truck into rough running state. Yes it will throw a code, but it will also impact drivability. I agree it wont leave me stranded, but the engine performance would not give passengers in my truck confidence to bo on vacation with it!

 

Not only are you smart............you explain in an understandable fashion......Thank You

 

EGR function is a result of throttle position, vehichle speed and engine rpm, not what the DPFE dictates.
If you research the 401 function it will tell you the other EGR fuctions must pass before the 401 test has any meaning.
Your logic is no substitute for how the system works and your ''Foci' people need to learn also.

 

EGR function is a result of throttle position, vehichle speed and engine rpm, not what the DPFE dictates.
If you research the 401 function it will tell you the other EGR fuctions must pass before the 401 test has any meaning.
Your logic assumptions are no substitute for how the system works and your ''Foci' people need to learn also.
Last reply to this.

 

I guess I will have to agree to disagree. Im all for learning something new, but your posts are contrary to the comments on the board, internet sites Ive referenced and tech manuals that I have. I will leave you with a cut and paste from a tech manual. Please read the last statement Ive bolded. This is why I believe that the ECU commands EGR flow based on info it gets from the DPFE. I dont believe the EGR is dictated from a look-up table programmed in the ECU - maybe 20 years ago, but not on these motors.... If Im wrong, please cite your references.
~~~~~
"Technical Tip: DPFE Testing

Application: 1993-2002 Ford, Lincoln, Mercury, Ford Truck with DPFE Sensor.

Symptom: DPFE Trouble Codes.

Theory: The DPFE sensor allows the PCM to check EGR flow. In the passage between the Exhaust Manifold and the base of the EGR valve, there is a restrictor. This restrictor causes the pressure to be higher on the Exhaust Manifold side than on the EGR valve side when the valve is open. The DPFE has two ports on it, one connected above the EGR restrictor and one below. The more EGR flow there is, the greater the pressure difference at the restrictor. This is how the PCM determines actual EGR flow and can adjust the EGR solenoid command accordingly.

 

Just thought I'd add my P0401 experience for reference. I only read about half of the posts in this thread, so please excuse me if my timing is off.
P0401 code showed up on my 1999 F250 V10 at 75,000 miles. I replaced the EGR valve, the check engine light came back on within a week. After reading a few threads on this great forum, I decided to replace the DPFE sensor. Of course I had to disassemble it to see if there was any chance of repairing it. What I found was extreme moisture/water intrusion. Cuircut board all rusty, beyond repair. I actually dumped approx 1 teaspoon of rusty water out of it upon disassembly. Replacing the DPFE cured the problem. If I know how to attach photo's on this forum, I'd do so... newbee.

Matt

 

Welcome to the forum Matt! Thanks for posting your experience with this "popular" topic.

 

"I guess I will have to agree to disagree. Im all for learning something new, but your posts are contrary to the comments on the board, internet sites Ive referenced and tech manuals that I have. I will leave you with a cut and paste from a tech manual. Please read the last statement Ive bolded. This is why I believe that the ECU commands EGR flow based on info it gets from the DPFE. I dont believe the EGR is dictated from a look-up table programmed in the ECU - maybe 20 years ago, but not on these motors.... If Im wrong, please cite your references."


Bluegrass 7 is totally wrong. I am experiencing DPFE problems right now with my 97 4.0 Ranger. My truck was not running smoth at low throttle and had lost power. I replaced plugs , wires TPS ect....still had the problem. Pulled my codes...P1400. I simply unplugged the DPFE and WOW...the truck ran like new.

Now to my present problem...I replaced the DPFE but it keeps filling up with water. I mean quick too...right about 0ne hundred miles and its full again. I have pulled it of and dumped it out three times now in about two weeks. Where do I go from here?

 

Per FORD MOTOR COMPANY:
Page 36 of overview. Oct 2001.
After the vehichle is warmed and normal EGR rates are being commanded by the ...PCM....

, the EGR flow checks are performed. (My addition here) > the EGR MUST BE FAULT FREE TO GET TO THIS POINT.
The flow check is performed once per driving cycle.
If a malfunction is detected, the EGR SYSTEM IS DISABLED UNTIL THE NEXT STARTUP.
************************************************** *************
Since the EGR ROUTINE IS NOT called at idle nor beyond about 7/8th throttle, in normal use, it is called when certain other conditions exist.
At least and not exclusive are; throttle position, vehichle speed, and a timing parameter delay to be sure these conditions are correct before calling in EGR..
This is how the system knows that NX emmissions are to be addressed during cruise.
How else do you think it is done and when?
When the EGR routine is called, the ignition timing is advanced and the fuel is cut back because the conditions in the cylinder are very lean and polluted making the timing and fuel changes prudent to save fuel and provide smoothe operation..
If you don't understand these operations, don't call me 100% wrong with no understanding and try to refer me to some other source, either.
Again the DPFE DOES NOT FULL TIME CONTROL the EGR operation but only performs testing functions. This is why you can remove it and will have little effect on the absolute engine operation "in the normal" sense.
Of course there can be RARE FAULT CONDITIONS it may cause interference but it does not full time control the EGR.

As for water in your sensor, I have a good idea whats wrong but since you are so well informed about all this, you figure it out.
I don't take kindly to being told I am 100% wrong by people who don't know either.
Have a good day.
</pcm>

 

@Bluegrass7...

You should quit posting information until you can get past your huge EGO problem. Your desire to be RIGHT overshadows the accuracy of you information. While I don't claim to be an expert, I'm not a beginner either.

When a person is seeking help for a hard to solve problem and goes looking on the net, it is hard enough to decipher the info WITHOUT having to sift through egomaniacs like you.

A person doesn't have to be an EXPERT in anything to tell the difference in the way an engine runs when a particular sensor is malfunctioning. So yes...you are WRONG in stating the (faulty) DPFE sensor will not cause driveability problems.

This statement by you is WRONG...

"
The DPFE is a monitoring and measureing device, reporting hardware faults by 'requested' tests from the PCM..
It has no direct control over engine control."

That is completely wrong...

It is a measuring device, you are correct in that. The DPFE measures exaust gasses...then sends that info to the PCM...The PCM then compares that info to PREDETERMINED values...then the PCM sends commands to the EGR solenoid to increase/decrease vacuum flow to the EGR valve based on these PREDETERMINED values. If the DPFE is MALFUNCTIONING it can be telling the PCM the wrong info...opening the EGR at incorrect times.


I don't know about other topics you have posted about on this forum, but you are 100% WRONG on this DPFE topic. You are doing more harm than good.

The site moderators should remove you!

 

This procedure fixed my problem! 1999 Lariat 4.6 V8. I had a little moisture inside the DPFE, just dried it up, used a lil WD and put er back together. Truck works alot better than it did! It was getting real bad these past few days, I thought it was the tranny goin south. I still feel a slight hesitation when going uphill before it shifts out of OD, but not like before, where it would miss like crazy. I think it could be due to my manifolds leaking as well. SEL is gone now too...

 

I posted asking about a P0401 code awhile back, I cleaned the intake elbow and egr. Same code came back so instead of going to ford for over $100 for this and not knowing whether or not it was going to fix the problem I went to the junkyard. I found one that was a totally different number on a 1997 Mustang 3.8. I figured what can it do besides set a code? I got the DPFE from the Mustang and installed it on my 2000 F150 4.6, reset the codes and haven't had any trouble since. I have over 1,000 miles since the change and it still runs great with no codes. This might be a solution for some out there who have the same problem.

 

So when's someone gonna post pictures of what's inside the unit? If you've got an old one, even if youaren't going to try to fix it, could ya drill it and post the parts as you found them?:

I may check mine out, but ATM I don't have a digital camera.

 

subscribing..

 

I'm in here too. Replaced two AZ units and have the problem back. Doesn't run much different but mileage has dropped .3 and acceleration is a bit sluggish.
I may stop at a boneyard and pick up one, see what it does.