In the picture look directly behind the highlighted object and you see a cylindrical black piece with knochs on the top....that is the dpfe

 

So now that I have removed and cleaned the throttle body ERG ports, what should I do if the light came back on after only 23 miles?

Replace the ERG valve?

Replace the DPFE?

They both look loke easy jobs, I know AutoZone has the ERG Valve for my 2000 4.6L for $54.99, Not sure about teh DPFE?

 

Sorry Tex but Im sticking with this picture.

Anybody else care to comment on whether this picture is a DPFE Sensor?

 

For what it's worth, I thought the black disc thing was the ERG Valve.

 

Does this photo look correct?

 

Another vote for the black disc thing (Saucer) as the EGR valve.

 

As the pictures show, The rectangular metal piece is the DPFE , it has two rubber hoses that goes down to the exhaust tube and an electrical plug.. This tells the computer how much egr flow there is. It senses the differential pressure across a orifice inside the exhaust supply tube to the EGR tube. Then gives feedback to the computer.

The round notched top device is the EGR vacuume regulator relay.. It supplys vacuume to the EGR valve when the computer tells it to.. It has two vac lines, one comes from the supply tank and the other goes to the top of the egr valve. Also has an electrical connector.

I had a P0401 on my wifes 5.4 Expy.. I found the vac lines from the supply tank to the regulator, had rotted right behind the battery. This didnt supply any vacuum to the regulator and the computer couldnt open the EGR causing insuficient flow.
With the engine running pull the vac plug off the regulator and feel with your finger.. There should be strong vac on one of the lines that will hold your finger firmly. This seems to be a common problem and really easy to check.

 

Another simple test to make when troubleshooting P0401, is to take the vacuum line off of the EGR valve and replace it with a piece of vacuum hose.

With the engine running at idle,, apply vacuum to the hose, using a handheld pump or your mouth.
Most likely if the EGR valve is working properly you should be able to make the engine stumble .

Found this procedure in lots of other egr threads...
Quick and easy check before replacing parts.

 

Thats just too cool, 486Lightning. I pulled the vacuum connector off the EGR vacuum regulator and then "jumped" it with a short piece of tubing. It killed the engine right away. I guess the Air/Fuel ratio got really out of whack when the EGR valve opened wide and let all that extra exhaust gas into the throttle body.

The vacuum feeding the EGR vacuum regulator is really strong, however, the vacuum on the EGR side of the vacuum regulator is a lot less when the vacuum regulator opens up. Is this reduced vacuum on the EGR side of the regulator normal?

Thanks!

 

That sounds about right.I am guessing you shouldnt feel hardly any vacuum on the EGR side of the regulator, because the computer doesnt call for EGR flow at idle..
Sounds like its DPFE time. If yours is aluminum you can try giving it a cleaning. The aluminum ones corrode from the acids and moisture in the exhaust gas.. When I was chasing my P0401, mine was almost corroded shut with a white crystal. I took my DPFE apart and cleaned out all the crap and it worked ,, still replaced it with a new plastic one anyways.

Good luck.

 

The engine was warmed up and I had the engine rpm's up there and the vacuum on the EGR side of the regulator went from none to a slight vacuum. I was wondering if it was normal for the EGR side of the regulator to have a reduced vacuum like this. The hose will stick to my finger on the feed side of the regulator because it is so strong but the vacuum on the EGR valve side is very weak when the regulator opens up.

I had already pulled the DPFE before I did this and the holes in it were not restricted.

 

it is important to remember, that the EGR valve is only used at high operating temperatures. the EGR valve does not open when at idle. so there is always going to be virtually no vacuum at the EGR valve when the truck is parked. it is also important to remember, that if the EGR valve is worn, then a lesser amount of vacuum will cause the EGR valve to open more then it should, thus causing too much exhaust gas to reenter the combustion chamber. this will cause lack of power or what feels like a miss at highway speeds.

 

Interesting! 864Lightning said that applying vacuum to the EGR should make the engine stumble but mine died right away. Should I consider this as a possibilty that my EGR valve is worn?

 

If it was opening too much and allowing excessive gas in, then you would be getting a different code... EGR excessive flow

Sound like you are about to the point of changing parts or getting the factory manual and going thru all the checks..

My only base of knowledge on the obdII egr stuff came from trouble shooting the problem I had on my Expy and searching this board.. There are some good factory techs on here that can go really in depth on the tests.

My old 1947 cj2a sure is alot easier to work on LOL..

 

I like the idea of being able to troubleshoot without major tools if I get stuck on the hiway. Pulling vacuum hoses or bypassing components has my ears wide open!