ok guys I finally went and did it. I paid for a dealer DPFE. Reset the code....drove it....D!@# code came back again. I have nightmares about P401 now. I am at my wits end here. I got nothing. Totally lost. Gone gray and then bald from pulling my hair out. Suggestions????? Anyone????

AAAHhhhhhhhhhhhhhhh!

 

Yep, your missin somethin, - You would have to have an exhaust leak on bank 2 or electrical problem then. You've done everything else right ?

I bet you didn't remove the TB elbow and clean ALL the ports, - just a hunch lol.

 

Jbrew
I've cleaned that TB so clean you could eat out of it. When I take it off I cleaned the two prime EGR ports, the EGR valve throat and everything in between. I read something about an IAC? Is that something in this system that could cause the P401 code? What possible electrical problem would turn this code on?

 

I FEEL your pain!!!!!

I can't even speak in complete sentences at the moment

 

Not the IAC.

DPFE-
Check the reference voltage to the harness connector, verify that it is equivalent to battery voltage. Reconnect the DPFE and check the output voltage, if it is not changing you will have to replace the DPFE , again.

Testing -

http://www.fordscorpio.co.uk/egrsensors.htm

 

OK so here is my update. OEM DPFE and EVR replaced. EVR resistance was between 30-70 ohms as called out on this forum and in manual. Previously checked vacuum lines found some cracked and repaired them behind battery at firewall. Did a suck test of EGR valve; engine stumbles but does not stall. Cleaned all ports spick and span once and then again after DPFE and EVR did not correct code. I did not remove IAC from Throttle body when I cleaned it but can not find on forum where the IAC can be a cause of the p401 code. I do not know how to check the egr hard tube going to bottom of engine to see if calibrated orifice is blocked. I do feel flow from both upper and lower ports when DPFE hoses are removed from the hard line. Is it possible something is blocked in the lower manifold? Is there anything else I need to do before turning it over to someone else which I am sure is going to really cost me big? Someone also told me to go get a new fuel cap? Don't read where that can cause this code either. What about the charcoal canister? Can that be the problem? I am really grasping now for the answer.

 

To check the IMS, and EMS ,you can just connect a piece of hose to them and blow to make sure their open, or you can hook up a little hand vacuum pump and make sure there is flow through them also. Either way works. To test flow through the orifice in the pipe between the The IMS and EMS, just blow air into the IMS and make sure you can here it flowing through the pipe down to the exhaust. With the engine off, the EGR is closed so any airflow through there has no place else to go but through the EGR pipe.
In the Scorpio link, there are voltage references you can check for the DPFE and EVR. I have studied them, but haven't actually checked them yet.
I can't remember, did you check the PCV line and elbow for leaks?
I'll finish mine when I can, I just have to many crocodiles on my but right now. But at least I found the primary problem.
Also note, that the IMS and EMS can be hooked up backward, carefully review the chart. To make sure yours are connected right.

 

You didn't listen and check what I said. Do you really want to fix this? I suggest doing that and also - all you have to do is blow in the top DPFE hose to check the orphis. Your EGR valve is shut when she's shut off, so if the orphis is blocked, there's no where for the air to go.

Blow in the lower hose as well with engine off. Check passageways, make sure their both clear and do what I told yuh - Check DPFE VOLTAGE

 

Sorry I did not add that info. I did check the reference voltage to the harness connector of the EVR and it was equivalent to battery voltage. The ref voltage to the DPFE was only 5.06 volts with engine off key on. This is correct per the instructions in my Haynes manual. Where does it state that the ref voltage to the DPFE should be equivalent to the Battery voltage? I also checked the output voltage of the DPFE (Top wire to middle wire), I had 1.0 volts and waited. Engine got hot but no change. Then I read that I can not put a true load on the engine sitting in the drive way so I have to wait until tonight to test it cold, then drive and come back and test it again. I will test teh orifice air flow prior to starting tonight as well. thanks for your help. Bear with me I do listen and am trying to do everything I can to get it fixed.

 

I checked the orifice tonight by blowing through the top DPFE hose and air did go in continually. I also blew in the bottom hose and air passed easily again. I then did another voltage check this evening of the DPFE doing a back probing of the wires. With engine totally cold I read less than 1 volt on the top signal wire to ground. I let it heat up in the driveway and it moved to 1.03 volts. Went for a 15 mile drive and then checked again immediately after returning and voltage was 1.08. I would assume now that either the DPFE is bad again or the EGR valve is not opening to allow gas to pass but I am betting it is the DPFE again which I got from the dealer.

Did I check everything you instructed me to test this time? What do I do now?

 

oh yeah i also removed and cleaned the IAC.

 

Just for my personal knowledge. What voltage did you get on the incoming voltage on the bottom pin(VREF? ithink)

 

From memory I believe it was 5.06 volts

 

Thanks I feel better now about having just 4volts.

On the scorpio link, the image of the EVR, that is labeled "resistance: supply and control. ECA/PCM disconnected" and then the chart beside it says 30 to 70 ohm = normal. I do not understand how to mesure that. I'm not an electrician so some of this is Greek to me. But it appears they have isolated it and joined the Vpwr and center wire together, and the measured the resistance through the EVR.
Using that diagram, where do you place the probes of the vohm and what is connected and what is not

I just plugged the EGR off and drove the truck to work today. It sure felt good. I'm almost tempted to leave it that way:o

 

You haven't got that fixed yet ?

ohm = resistance #'s

That's what they mean by ECA/PCM disconnected = Just the wires (isolated).