Sick and tired of p0401 code

[R1dd1cK]

Ok I am finally asking for some help getting rid of my p0401 check engine code. I have done a few things and cant get it to go away. So now its time to get some suggestions on what to do. Anyways here is what I have done:

Replaced dpfe sensor twice
replaced lines going to dpfe and made sure the metal egr tube was free flowing.
did vacuum test on egr valve. truck tries to die when I applied vacuum to the egr valve.
seafoam though brake booster vacuum line.
has new spark plugs and wires
tps sensor has been set to .96 volts.
Replaced both upstream O2 sensors.
Tested EVR and any vacuums lines that go with it.


I just dont know where else to check. please help.

 

[zukman]

Change your o2 sensors

 

[R1dd1cK]

Now that I think about it I rhink I have one o2 sensor not reading right.

 

[R1dd1cK]

Well I have not changed any o2 sensors yet. I did do a seafoam treatment and now the Check engine light comes on sooner with the same code.

 

[2000StreetRod]

what year 5.0?

What year 5.0L V8 did you put in your 1999 Sport?
Have you tested the EGR vacuum regulator (EVR)? Is the hose good between it and the EGR valve? Is there good vacuum at the EVR? If so, then check its electrical functionality.

 

[Bobmbx]

Check the hoses running to your DPFE. I changed the DPFE on the wifes' Mounty, and found that both hoses were completely solid with carbon.

 

[zukman]

there is a little elbow hose back of block under the manifold did you check that? they go away and cause the truck to 1 stop or not run right and 2 send a cheerful code.

 

[R1dd1cK]

I'm still fighting this code. I just replaced the upsteam o2 sensors and the code still comes back. Should I replaced the down stream o2 sensors also?

What year 5.0L V8 did you put in your 1999 Sport?
Have you tested the EGR vacuum regulator (EVR)? Is the hose good between it and the EGR valve? Is there good vacuum at the EVR? If so, then check its electrical functionality.

It is a 2000 motor with a 99 wiring harness and computer.
I have good vacuum at the EVR and have tested the line going from it to the egr valve. I have also replaced the evr once.

 

[R1dd1cK]

Is there a test for the EVR? I hook 12volts to it and it does not seam to do anything. So I tested the LT blu/org wire with the evr unplugged and I have 12 volts. If I test the brown/pink wire witch is ground by the computer on pin 47 I have no voltage there. Now when I do the same test with the EVR hooked up I have voltage all the way to pin 47. So does the mean my evr is shorted or is that how it is made to be.

 

[Turdle]

I have a suggestion. try "reversing" the DPFE hoses. disconnect one end and swap them around.

Second thing I would try is the rear 02 sensors. If all else fails-clogged cat.

 

[R1dd1cK]

I will try reversing the hoses. I dought it would be a clogged cat since I don't have cats.
The thing I don't get is when I hook up my scan tool and command the evr to on the truck does not stubble like it does when I hook vacuum to the egr.

 

[R1dd1cK]

Ok so you cant swap the dpfe hoses the lines and fittings are 2 different sizes. Well I guess I'm going to try 2 new rear O2 sensors.