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Discussion Starter · #1 ·
1996 5.8L EB

I have been working on EGR issues for quite some time. I recently changed my cracked EGR tube, I thought that would be the end of this EGR saga, but I was wrong. The fault code I currently have is 0402. 0402 is excessive flow over egr, I cleaned and inspected my EGR valve when I replaced the EGR tube, it looked to be in good working order. I have just began testing my DPFE and EGR by using the linked Tomco Techtips http://www.tomco-inc.com/Tech_Tips/ttt36.pdf

I found a few things that dont add up. I'll start with what checked out OK, I checked my hoses and they held a vacuum fine. I checked that the DPFE would hold a vacuum of 8.5 for over 1 min with key off on the downstream and with KOEO upstream.

I have the plastic 1 volt DPFE. This guide states that voltage to the DPFE Signal wire (test pin 27) should be 1.0 +/- .025 with KOEO. I think this is a typo, I believe it should be +/- 0.25. In figure 4, it shows +/- 0.25V.

I got a reading of 5.04 volts on the DPFE Singnal wire (test pin 27) with KOEO. At initial key on, voltage would start low and slowly but steadily rise to 5.05v every time I tested (3). If you look at figure 4, 4.95V is the upper limit, I think the 5.04V has something to do with that.

With the engine running at idle I got readings from 1.15V - 1.2V. That would put me within spec of 1 +/- .25.

Next I think is the key to this puzzle. I removed the vacuum line from the EGR valve. I applied 3 inches of vacuum which nearly stalled the engine. I monitored the DPFE Signal wire (test pin 27) while I applied the vacuum and saw no change in voltage. It held a steady 1.2V with the vacuum applied to the EGR valve.

I also applied various vacuums to the downstream hose of the DPFE with the KOEO. I saw no change in voltage to the DPFE Signal Wire (test pin 27) during this. I am not sure if I should have run this test with the engine running?

The DPFE Signal Wire (test pin 27) is the only wire I monitored during my tests, I am not sure if that was correct. Any comments from experienced EGR fighters out there? Bad DPFE? Whats with the 5.05V?
 

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I was getting P0401 and P0402 codes (P0401 is EGR flow insufficient). After screwing around with the EGR (pulling, cleaning, testing it with a vacuum pump, etc.) for a week or two, I just bit the bullet and bought a DPFE (It was about $50). I also replaced the two lines going to the DPFE, they are supposed to be some kind of high temperature silicone hoses, I had to find them at a speed shop (they connect to the exhaust system). Anyway, that fixed the CELs on my '96 302. Hope that helps.
 

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yo, I have the Asian flu and can hardly stay here long.
Vacuum/Voltage Parameters & pics on both older Aluminum & Newer Plastic Version; Source: by rockledge.home.comcast.net

EGR valve is free?
P0402 - EGR Flow Excessive Detected The EGR system is monitored for undesired EGR flow during idle. The EGR monitor looks at the DPF EGR signal at idle and compares it to the stored signal measured during key ON and engine OFF. The test fails when the signal at idle is greater than at key ON engine OFF by a calibrated amount. EGR valve stuck open
Plugged EGR vacuum regulator solenoid vent
Plugged EGR tube
Slow responding D.P.F. EGR sensor
Damaged DPF EGR sensor
Improper vacuum hose connection
Plugged vacuum hoses
EGRVR circuit shorted to ground
Damaged EGR vacuum regulator solenoid
Damaged PCM
A DPFEGR PID reading that is greater at idle than during key ON and engine OFF by 0.5 volt or a rough engine idle, may indicate a hard fault.
 

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yo,
Sorry for the delay; I tried to get back and stay but that flu got to me; lost a few days...


re; "This guide states that voltage to the DPFE Signal wire (test pin 27) should be 1.0 +/- .025 with KOEO. I think this is a typo, I believe it should be +/- 0.25"

No, it is +/- .025 between REF & Ground
I validated this a couple of yrs ago when my DPFE blew its wad;
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 via stangnet.com

Tomco uses same Charts for VOLTAGE RANGES of 0.2-1.3V w/KOEO

Here is the DPFE Wiring Diagram for the 96 5.8
http://www.broncolinks.com/gallery_images/96DPFEwiring5.8.JPG

You should have a voltage reading of 0.2-1.3 volts (Key On Engine Off). If your voltage is above 1.3 volts with the engine off, replace the DPFE sensor.

If as Tomco says; the voltage is off from the spec, check
to make sure the reference voltage and ground
are okay. If all else is okay the DPFE needs to
be replaced.

And I am still messed-up so I can't correlate your connections and results w/Ford's info below

---------------
This is from the FORD EVTM/PCED
It is for P0402 in KOER - Continuous Memory is basically da same; exc for what I note @ end on this reply

Diagnostic Trouble Code (DTC) P0402 indicates that Self-Test has detected EGR flow at idle.

NOTE:
If DTC P1405 is in Continuous Memory, diagnose that first starting with «HE50».

Possible causes:
EGR valve stuck open.
EGR vacuum regulator (EGR V.R.) solenoid vent plugged or iced.
EVR circuit shorted to GND.
EVR circuit shorted to VREF.
Pinched/iced pressure hoses.
Improper vacuum hose connection.
Plugged/pinched EGR V.R. vacuum hose.
Plugged EGR tube.
Damaged EGR V.R. solenoid.
Damaged Differential Pressure Feedback EGR (D.P.F. EGR) sensor.
Damaged PCM.
,,,,,,,,,,,,,,

Key off.
Disconnect vacuum hose at EGR valve and plug hose.
Run Key On Engine Running (KOER) Self-Test.
Is KOER DTC P0402 output or unable to run KOER Self-Test due to engine stall or no start?

Yes
There is possible EGR flow at idle. INSPECT pressure hoses first for pinching and icing. If OK, REMOVE and INSPECT the EGR valve and EGR tube for signs of contamination, unusual wear, carbon deposits, binding and other damage. SERVICE as necessary (use Rotunda EGR Valve Cleaner 021-00056, if needed). RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test»

NO
RECONNECT vacuum hose to EGR valve. GO to «HE21»

HE21 CHECK FOR EGR FLOW AT IDLE WITH EGR VACUUM HOSE CONNECTED
Key off.
EGR vacuum hose connected.
Run KOER Self-Test.

Is KOER DTC P0402 output or unable to run KOER Self-Test due to engine stall or no start?

Yes
There is possible EGR flow at idle. GO to «HE22».

No
The fault that produced DTC P0402 is intermittent. INSPECT pressure hoses for pinching and icing. SERVICE as necessary If OK, GO to «HE30».

HE30 CHECK D.P.F. EGR SENSOR OUTPUT BY APPLYING VACUUM WITH HAND PUMP
,,,,,,,,,,,,,,,

Key off.
Disconnect pressure hoses at D.P.F. EGR sensor.
Connect a hand vacuum pump to the downstream pickup marked "REF" on the sensor.
Key on, engine off.
Access DPFEGR PID (formerly DPFE) with a Scan Tool. PID voltage should be 0.2-1.3 volts.
Apply 8-9 in-Hg vacuum to the D.P.F. EGR sensor. The PID voltage should be above 4.0 volts. Quickly release vacuum from sensor. PID voltage should drop to less than 1.5 volt in less than 3 seconds.
Does the DPFEGR PID voltage indicate a fault in the D.P.F. EGR sensor?

Yes
REPLACE damaged D.P.F. EGR sensor. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
RECONNECT D.P.F. EGR sensor. GO to «HE31».

HE31 CHECK D.P.F. EGR SENSOR VOLTAGE WHILE EXERCISING EGR VALVE
Key on, engine off.
View DPFEGR PID with a Scan Tool and make note of voltage.

NOTE:
Typical D.P.F. EGR sensor voltage with no EGR flow is 0.2-1.3 volts.
Disconnect vacuum hose at EGR valve and plug hose.
Connect a hand vacuum pump to EGR valve.
Start engine and bring to idle.
Observe DPFEGR PID at idle and compare to the key on engine off voltage. (A higher voltage at idle could be due to a non-seating EGR valve.)
Apply just enough vacuum to EGR valve to open it (2 to 3 in-Hg) without stalling engine and release vacuum. Repeat several times while observing DPFEGR PID on Scan Tool. (DPFEGR PID voltage should increase as valve begins to open and return to initial value as vacuum is released. A slow to return voltage could be an indication of a binding or a slow closing EGR valve.)

l Does the DPFEGR PID voltage indicate an open, binding or slow closing EGR valve?

Yes
REMOVE and INSPECT the EGR valve for signs of contamination, unusual wear, carbon deposits, binding and other damage. SERVICE as necessary (use Rotunda EGR Valve Cleaner 021-00056, if needed). RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
RECONNECT EGR vacuum hose. GO to «HE32».

HE32 MONITOR EGR VALVE VACUUM WHILE WIGGLING EVR CIRCUIT

NOTE:
An intermittent short to GND in the EVR circuit will cause the vacuum applied to the EGR valve to be higher than normal while the short is present. The vacuum available at the EGR valve at idle is normally below 1.0 in-Hg and it takes about 1.6 in-Hg for the valve to begin to open.

Key off.
Disconnect vacuum hose at EGR valve and connect hose to a vacuum gauge.
Key on, engine running.
Observe vacuum gauge for an indication of a fault while performing the following:
Lightly tap on the EGR V.R. solenoid; wiggle the EGR V.R. solenoid connector and vehicle harness between solenoid and PCM. A fault is indicated by a sudden jump in vacuum reading.

Is a fault indicated?

Yes
ISOLATE fault and SERVICE as necessary. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
RECONNECT vacuum hose. GO to «HE33».

HE33 INSPECT EGR V.R. SOLENOID AND VACUUM HOSES FOR POTENTIAL PLUGGING

Key off.
Remove EGR V.R. solenoid vent filter and inspect for contamination and excessive water absorption. (In cold climate, excessive water in filter could freeze and plug the EGR V.R. solenoid vent.)
Inspect EGR vacuum hose for possible blockage or pinching.
Is EGR V.R. solenoid vent or filter contaminated or vacuum line plugged?

Yes
SERVICE EGR V.R. solenoid or EGR vacuum hose as necessary. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
Unable to duplicate and/or identify fault at this time. GO to Pinpoint Test Step «Z1» with the following data: DPFEGR and EGRVR (formerly EVR) PIDs and list of Possible Causes.


======
P0402 in Continuous Memory is basically da same; exc for;

HE20 DTC P0402: CHECK FOR EGR FLOW AT IDLE WITH EGR VACUUM HOSE DISCONNECTED

Diagnostic Trouble Code (DTC) P0402 indicates that Self-Test has detected EGR flow at idle.

NOTE:
If DTC P1405 is in Continuous Memory, diagnose that first starting with «HE50»
Possible causes:
EGR valve stuck open.
EGR vacuum regulator (EGR V.R.) solenoid vent plugged or iced.
EVR circuit shorted to GND.
EVR circuit shorted to VREF.
Pinched/iced pressure hoses.
Improper vacuum hose connection.
Plugged/pinched EGR V.R. vacuum hose.
Plugged EGR tube.
Damaged EGR V.R. solenoid.
Damaged Differential Pressure Feedback EGR (D.P.F. EGR) sensor.
Damaged PCM.
,,,,,,,,,,,,,,,,,,,,,,,

Key off.
Disconnect vacuum hose at EGR valve and plug hose.
Run Key On Engine Running (KOER) Self-Test.
Is KOER DTC P0402 output or unable to run KOER Self-Test due to engine stall or no start?

Yes
There is possible EGR flow at idle. INSPECT pressure hoses first for pinching and icing. If OK, REMOVE and INSPECT the EGR valve and EGR tube for signs of contamination, unusual wear, carbon deposits, binding and other damage. SERVICE as necessary (use Rotunda EGR Valve Cleaner 021-00056, if needed). RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
RECONNECT vacuum hose to EGR valve. GO to «HE21»
Ths is shown above in KOER Section
 

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and,
re:
"Should I be testing the return wire"?
NO,
you prob did test correct pin on DPFE which is DPFE Signal (top pin I believe, because I can't go back & forth to the EVTM
 

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delete duplicate reply
 

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Discussion Starter · #8 ·
Is there an actual pin somewhere? I am probing into the wire. I dont really understand the wiring diagram. How do I check the reference voltage and ground?
 

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yo, Sorry.. had to lay down again.... this is abd Flu and 1/2 the rea is down w/it

The "pin" is on the DPFE... I use a strg pin (w/Meter lead clamped to it) to insert into conn to back probe

SIG ret is Ground
 

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yo
V REF is 5 volt reference
 

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ford had HORRIBLE problems with their DPFE sensors in the early days. Many models had a TSB that basically said: if you get an egr code, replace the DPFE before you diagnoise anything.

I would replace the DPFE and go form there. Even if it came into work with an egr code, I would probably replace the DPFE first, clear codes, run the KOEO And KOER tests, and test drive it to set the EGR monitor. If all those pass its fixed. If not i would start the diag.

If you need it i do have a copy of the entire Diag procedure for the '96 bronco/truck dpfe egr system
 

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yo magnumpi.
Glad you're here with that!!! I have to go now and prob get to a clinic for ths Flu.

btw, A lot of that testing was from my 96's EVTM/PCED disc
 

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Yeah, thats what i kind of figured. The document i have is a straight copy of the whole PCED EGR system diag.

I need to find a file hosting site to put it on, along with alot of the other stuff i have..
 

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Yeah, thats what i kind of figured. The document i have is a straight copy of the whole PCED EGR system diag.

I need to find a file hosting site to put it on, along with alot of the other stuff i have..
did you every find a host ?
 
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