p0401 and truck runs like crap

[hamilton8558]

hello, i have a 1996 ford bronco eb 5.8, i am getting a code of p0401, i put a new egr on and still get the same code, sometimes the truck runs good at idel, and sometimes it runs like crap? please someone help me please, need to get tags and cant till i get this fixed

i just put vacuum to the egr valve and it shut off, so im guessing i can cross that one off of the list, also i did noticed that when the truck starts running like crap i can unplug the vac line going to the egr and it starts to run fine?? this is driving me crazyyy lolol

[miesk5]

yo H,
P0401 - EGR Flow Insufficient Detected. The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum. Vacuum supply
EGR valve stuck closed
EGR valve leaks vacuum
EGR flow path restricted
EGRVR circuit shorted to PWR
VREF open to D.P.F. EGR sensor
DPFE sensor downstream hose off or plugged
EGRVR circuit open to PCM
VPWR open to EGRVR solenoid
D.P.F. EGR sensor hoses both off
D.P.F. EGR sensor hoses reversed
Damaged EGR orifice tube
Damaged EGRVR solenoid
Damaged PCM
Source: by miesk5 at FSB

DPFE Testing in a 96 5.0; "...DPFE comes in as .15 VDC during KOEO test between REF & Ground. TOMCO says it should read 0.45 +/- 0.25 volts for the .55 volt for this original Aluminum type sensor My Ford PCED/EVTM is frozen, so I can't view Ford's +/- values. &, when pulling REF hose off, fine particles fell out of DPFE. So, figuring DPFE Sensor is bad according to Ref voltage and particles... Yes, your voltage of 0.15V on the DPFE line is a typical sign of a bad one. Try to obtain a Motorcraft replacement, as the retail part store pieces don't last..."
Source: by SigEpBlue (Steve) & miesk5 at FSB http://fullsizebronco.com/forum/showthread.php?t=146687

Differential Pressure Feedback (DPFE) TSB 97-22-1 for 95-97 F Series, Aerostar, Econoline, Windstar (Bronco not Listed); miesk5 Note; test info & diagrams/depictions are correct for Bronco as well
Source: by Ford

[miesk5]

yo, I am dwelling on the DPFE and its hoses right now;
it is mounted on passenger side, high, next to throttle body and in front of intake manifold; just above alternator; - MIESK5 NOTE: only 95 5.8L California models & all 96 have the DPFE Sensor instead of EGR Valve Position Sensor (EVP)

Location pic in a 96 5.8

Source: by bergs at SuperMotors.net

The DPFE Sensor measures EGR flow across an orifice located inside the special EGR Tube (CHECK TUBE FOR CRACKS, etc.). The orifice is positioned between two hose ports coming off the tube which are connected to the DPFE sensor with special heat-resistant hoses. When the EGR Valve is open, a pressure differential is created across the orifice (intake manifold pressure vs. exhaust pressure). By design, this difference in pressure is measured by the DPFE sensor in terms of voltage. The DPFE voltage signal output to the PCM is directly proportional to the flow of exhaust gas entering the intake manifold.

The PCM determines optimal conditions for EGR flow and then, based on the DPFE voltage signal and some other sensor data, activates the EVR to open and close the EGR valve as necessary.

The EVR is a solenoid with two vacuum ports. One port is connected to a vacuum source/supply, and the other is connected to the EGR valve. There is also a passage that vents vacuum to the atmosphere.

A disc inside the solenoid is moved by electro-magnetic force, as directed by the PCM. If more EGR flow is required, the PCM increases the duty-cycle to the EVR, moving the disc to close off the atmospheric vent, which in turn increases the amount of vacuum flow to the EGR valve. If less EGR flow is desired, the PCM decreases the duty-cycle to the EVR, allowing for more atmospheric venting and hence less vacuum flow to the EGR valve.

The EVR is a "normally closed" solenoid, which means that when it is de-energized, the position of the disc allows for maximum venting to the atmosphere (resulting in negligible vacuum flow to the EGR valve).

Note that Ford EGR systems DO NOT engage when:
The engine is cold ;
The engine is at idle;
The engine is at WOT;
At low ambient temps (water vapor from the exhaust can freeze on the throttle plate).



Testing, Vacuum/Voltage Parameters & pics on both older Aluminum & Newer Plastic Version
Source: by rockledge.home.comcast.net http://rockledge.home.comcast.net/~r...tage-Test.html


To Test EGR valve, and other parts go to my EGR section @ http://www.broncolinks.com/index.php?index=146

[hamilton8558]

thanks for everyones help still trying to get it right,,, but i love my bronco

[gr8whitebronco]

Good luck I have that on my 96 460 with california emissions and still haven;t found the problem.

[mike0912]

http://easyautodiagnostics.com/ford_...gr_valve_2.php

Follow this link word for word to test the system. it helped me fix mine.

Sent from my Transformer TF101 using AutoGuide App

[96EB5.8]

the p0401 is the DPFE most likely. I do not usually see a rough idle with this though so you may have more than one problem.