The ones I've done have DPFE hoses are a slightly different diameter to keep people from crisscrossing them. Sounds like you've done everything and some stuff twice. Follow the metal tube from the EGR down to the exh man. Remove the tube. Hacksaw the tube 1" above the bung where the big nut bolts it to the exh man. Pull out the little nipple you just hacksawed off and put two quarters in its' place(they fit perfectly). Put the big nut back on the exh man, but this time with the two quarters in it. Bolt the tube back in place, but this time only bolting the EGR side since the exh man side has been sawn off. Now the exhaust gasses go out the tail pipe instead if into your intake clogging it with soot. The EGR valve and DPFE and associated tubing all still work. The only difference is when the EGR is commanded open it pulls in fresh air intead of recirculated exhaust(SOOT which turns into tar in your throttlebody ports). Reset your P0401 DTC and you won't see the CHECK ENGINE lite again for that DTC.

 

Quarters were way too big. I used two pennies. They weren't even close to falling into the ex. manifold. I'm a welder by trade and if if don't work, I'll tig em back on. I've tried everything else. I also switched the dpfe hoses around and my truck died. I switched the back around and it fine. I reset the code and we'll see what happens. To be continued...

 

Ford has made millions on out of warranty work on these DPFE/EGR systems. The thing is after they get done cleaning it and changing for parts(about $1,100.00) it starts clogging up all over again as soon as you drive it off of their lot. With this system it will NEVER clog again. Maybe I didn't use quarters. It could have been nickles, but I don't think it was pennies. It's been a while since I did one. Your repair only cost you 2 cents. How often can you say that?

 

Before cutting the pipe off, can you plug the EGR side to see if this fixes the problem? I have a 1997 F150 4.6L, check engine light is on, throwing a P0401 code and it is now starting to hesitate when taking off from a start and while driving (have to give it more gas to stop it). Approx 140,000 miles.

 

There is a big difference between cutting and plugging the tube that goes from the exh man and the EGR valve and plugging it as you have suggested. You MUST have flow. Plugging the EGR tube will block flow. That is a formula for an Insufficient Flow DTC(P0401). You're barking up the wrong tree. This system is not that complex. The DPFE senses FLOW when the PCM commands the EGR to OPEN. The EGR is vacuum controlled. The DPFE can lie to the PCM, but you've got to be able to figure out if there really insufficient flow or if the DPFE is lying to the PCM and telling it there is insufficient flow when the flow is good. Check the vacuum solenoid, EGR valve, DPFE, rubber hoses, EGR ports and PCM. If these are ALL doing their jobs you should NOT have P0401. If one guy doesn't do his job everyone gets the blame. EGR should NOT cause the kind of poor performance you describe. It will have some effect, but not to the degree you have talked about.

 

I meant to say, unhook the metal line from the EGR vale and then plug it (leaving it loose). I just want to test before cutting.

 

You can't do that without plugging the EGR bung. If you don't plug it you won't like the sound you hear when you start the engine.

 

OK, so if I cut that metal line, plug it at the nut, will it mess with passing emissions? I take it that you leave the port where that metal tube connected to the EGR open? Does the EGR time delay switch have anything to do with this code? It's a black unit right next to the dpfe (EGR vacuum solenoid). I appreciate you answering questions, because I am not much of a mechanic.

 

The DPFE only looks for FLOW. Is there flow? Yes:don't turn on the SES,No:Turn on the SES and set DTC P0401. The DPFE can't tell the difference between fresh air flow and recirculated exhaust gas full of soot and tar. Which would you rather have flowing into your intake manifold. I think we all know the answer to that question.

 

Respectfully, modifying the system is not the proper answer.
Learning what the 401 code is and how it is generated is the way to find the answer to the problem.
The system has the following major parts all of which if defective will cause the code.
DPFE, Vacuum gate valve, EGR, calibrated pipe and wiring to the computer.
The computer operates the vacuum gate valve to alow the EGR to open as calculated amount.
The DPFE measure the pressure drop accross the calibrated orfice in the pipe that is fed to the computer for matching a program tolerence value. The combination of exhaut gas pressure and intake vacuum force the flow thru the pipe orfice.
Any part of the system can generate a failure if the pressure drop is out of limits.
The system is tested each time the motor is started and requires 2 failures in a row to fail and set a code, by design.
Testing: is the pipe internal orface open?
Is the pipe, exhaust tight? If not the pressure will be too low at test time.
Is the EGR able to be opened by application of vacuum to it's port?
If yes, will the engine get rough running (at idle) when opened as it should, indicatiing the valve is able to open and the port is clean enough to pass exhaust through the open orfice in the metal tube?.
Is the vacuum gate valve operational? It is a 3 port device that must also let outside air back into the EGR so it will close once operated. Is it hanging open a small amount from being dirty etc?
Is the plugup and wiring to the computer in tact?
You can test all the parts except the DPFE.
A scanner (not a reader) to access the program and look at/ operate the function will give all the answers, in the right hands.
This is all there is to the system operation.
These trucks and cars are not you dad's old carbed motors any longer and require knowing how things operate or you have ongoing grief until it's done correctly. This is why dealer techs go to school.
BTW, the EGR test functions and limits are very tight to the tune of less than 2% limits and hence the reason why they fail so often and need to be understood.
Also is the reason to use Ford DPFE for the tight tolerences held, over other vendor parts sources that fail even when new.
Good luck.

 

I'm not suggesting that everyone use this method. It's just an alternative for old, high mileage DPFE engines. Ford has made made millions servicing this DPFE system on out of warranty engines. The thing is when they are done with the repair the engine starts to gum itself up all over again as you drive it off of their lot. If you do this mod after you get your EGR system working properly you will never get P0401 again because you are flowing fresh air not recirculated exhaust filled with soot, carbon and tar. I've done this mod on one of the other brands(non-DPFE) and it works just as good. Once you get rid of this DPFE problem you can then concentrate on more important problems these engines have such as lean conditions(cracked rubber hoses) and misfires(defective COPs). I work on a lot of Ford V8 and the problems are almost always the same:EGR, lean condition and misfires. I'm not complaining because it's a money maker. I'd just rather get rid of P0401 once and for all and concentrate on things that make the engine run bad and kill fuel economy.

 

Oh, but you are missing something important.
The mod interfers with the system operation.
This may not mean much to some but to others it should.
The EGR operation advances the ignition timing,,,,, leans the fuel air/ratio,,,,, as well as reduces nox emissions. These actions are not controlled by any mod but are part of the computer software program.
These actions helps fuel mileage a small amount as well as does the main function of reducing NOX as mandated by the EPA.
The reason the ignition timing is advanced (when the EGR is called to function) is the a/f ratio is very lean and requires the timing to be advanced in order to fire the 'slower' burning mix and have the pressure peaks placed at the same relitive point after top dead center as the standard A/F ratio the motor runs at otherwise and has it's fuel controlled by the OX sensors.
A side effect of EGR operation with very lean mixes, is the spark requirement goes up quite a bit. If any coil has low output, a miss will happen and show it'self as a bucking during that time with light throttle and light loads. This normally never sets a code because the offending coil is not a hard fault such as a short or open winding but is a 'shorted turns' condition causing low output voltage.
If one is not subject to emission inspection and cares less about fuel mileage, your mod is for them even though actually illegal by law.
Guming up the motor is not a concern by the designer but a system to comply with EPA regs if Ford is to have their vehichles pass for sale in all states.
This system 'type' has been used on Ford motors since 1974.
.
My 02 has 145,000 with only a DPFE failure at about 35000 in the summer time. The EGR function works with the original parts otherwise and no gum or carbon in the port the last time it was looked at. Motor runs super clean as a result.
The cleaness the engine runs at determines the deposits in the exhaust.
This is where oil and filter changes are important over the long term as well as not running the motor for short time intervals, allowing contaminates to deposit on cold surfaces.
The EGR tube is cold for the most part for a long interval after startup.
The moisture in the exhaust along with unburnt carbon (blow-by) is the major culprit affecting the EGR system.
The EGR tube has an orfice of about .040", the DPFE measures across for the reading the computer looks at.
This small hole along with the cold intake condenses the contaminates and causes the problems in the long run, so it is omportant to run the motor long enough to full heat to minimize this action.
Parts were made to be replaced the same as oil, spark plugs, coils as well as other short term life items.
A means to detect the system failures and set codes are the ways the outside world was given to address the problems that develope.
The thing for owners is the complexity of how the system works and handling the diagnosis for repair they are not familuar with.
This is why this code and related codes are the largest single problem for owners as evidenced by the number of threads, replies and looks.
If enough searching were done on just this issue alone, all the info has been repeated many many times on this board and other boards, and should lead one to the best ways to handle the problem.
Bottom line is things are not so simple as people would like them to be hence the reason for all the hassle a single system failure causes.
As well, owners expect to much when wanting hear the easy fix the first time they ask, about a problem not so easy to address with no experience.
Good luck.

 

To me the EGR is just feel good stuff for the EPA. They have to justify their existance and they did so big time with the DPFE on Fords. I own two trucks(the other brand). The older one(99) has EGR similar to the Ford altho it doesn't use DPFE for flow detection. The newer one(09) does not have EGR because the engineers war able to pass smog without it by tuning the camshaft lift and duration. One of the first things I did when I got the 99 home from the dealer was to bypass the EGR and PVC. The inside of the throttlebody and intake manifold on that old truck are so clean the board of health could do the white glove test on them and they would pass after nearly 100K miles. No Ford with DPFE and functional PCV can make that statement. By that time the inside of the intake on a Ford with DPFE looks like the lungs of a person who has been smoking for 40 years.

 

I know what the problem is. Where the egr bolts to the plenum, there is a passage way where the gases flow to be re-burned. There will be two small holes. Those will be blocked with carbon. When I did mine I took a screw and a can of throttle body cleaner, dug it out with the screw and sprayed out the rest and broke it down. This worked for me. Now I'm dealing with the p0402.

Hope this helps.

 

And guess what? The entire inside of your intake, throttlebody and the intake runners on your heads are coated with that crap too. They don't get completely clogged like your 2 ports do, but they have a nice coating of tar and soot none the less.