CEL, code 402 questions including 96 5.0 DPFE question

[daxb]

I have a stock 96 5.0

At autozone the code shown for my CEL was 402 which we all know by now is EGR flow excessive. Per a post by DirtyDog, these are all of the likely causes for that code (for a 99 explorer)

p0402: 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.

Possible causes:
-EGR valve stuck open.
-Plugged EGR vacuum regulator solenoid vent
-Plugged EGR tube
-Slow responding DPF 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

I have researched code as much as I can (here mostly, but on some other forums too) and it seems that the a faulty DPFE is often the most likely culprit or maybe that the IAC is all gummed up with carbon per this thread

http://www.explorerforum.com/forums/showthread.php?t=84220&highlight=DPFE

Does that sound about right so far?

But per this thread, supposedly my 96 5.0 does not have a DPFE

http://www.explorerforum.com/forums/showthread.php?t=82053&highlight=PO402

I am not super mechanically inclined, but I looked for the old aluminum style DPFE in my truck and couldn't find it. I did find what looks to be the IAC based on the pictures in the threads above.

What this all boils down to is that I am now clueless as to what I should do. Any thoughts aside from taking it to a mechanic who will likely charge me crazy amounts to fix this? I have to get a new inspection sticker by the end of the month and doubt I'd pass with the CEL on and a code showing.

Thanks in advance,

Dax

 

[daxb]

I called a local ford dealer (one of the larger ones in the Boston area) and the parts guy looked it up and said yes the 96 5.0 has a DPFE. I still cannot find it. Further searching indicates that year 5.0 did NOT have a DPFE but rather used another method/part per these theads:

PFE Sensor instead of a DPFE

http://www.explorerforum.com/forums/showthread.php?t=112285

And then this take:

http://www.obdii.com/ubb/Forum1/HTML/002086.html

Still clueless.

 

[rjwiser]

I have the same problem, with my 96 V8. I have been investigating the cause as well, but the egr valve is difficult to remove. Can one tell without taking these parts off if it is either the PFE (96 doesn't have the DPFE) sensor or the EGR valve itself?

 

[exploded99]

If you DO have a dpfe there will be a metal pipe coming off of the passenger side exhaust manifold and going to the egr valve. On the end of the pipe by the EGR valve will be two small hoses. Thses hoses will run from the metal pipe to your dpfe snesor which will be at the very back of the engine close to the firewall on the passenger side. No hoses, no dpfe.

The IAC valve has nothing to do with the egr code, but it doesn't hurt to clean it

 

[CarlsonCustoms]

Ok time to throw my stuff in here!

I have a 96 5.0 and the dealer told me I have a PFE sensor but I sure as heck can't find it. I followed the vacuum hoses off the egr regulator. One goes to the egr valve and one goes to the back of the engine (where I THOUGHT the pfe was) but it feels like it connects to a hard line thatgoes under the intake manifold in teh valley. SOO I think that this is the "intake manifold line" so that's where it draws vaccum. This all leads me to believe I have a "Sonic" system as described above.


My symptoms are a hard jerk at 1500 rpms. It actually threw a egr excessive code so I think the egr is just opening at the wrong time making the engine want to die.

Do you think I should replace the evr and evp sensors? I"m getting stumped here but this thread has a TON of useful information.


thanks alot guys
Zack

 

[410Fortune]

there are tow EGR systems on the 96-97 5.0L.
One has a pipe going to the EGR sensor from the exhaust manifold.
This EGR setup has botht he sensor and the vacuum controller, as well as the EGR valve.

The internal EGR (no tube from exhaust manifold) has only the sensor.

It is not that difficult to remove, you just have to do everything in the right order, take your time. It only takes about 30 minutes total really.

 

[Jayonator]

Some 96 and early 97 have neither the DPFE nor the PFE. IT uses a system called sonic egr. http://fordfuelinjection.com/files/FoMoCo_1996_OBDII.pdf It doesn't have a tube running from the manifold but rather gets the exhaust from within the head. I have this in my 97 Mountaineer, build date August 96. IT's kind of a stepchild system used as a transition to DPFE from PFE. It sucks. I believe the computer uses the sensor piggy-backed on top of the EGR valve (evp sensor) to infer the actual gas flow. I have replaced the egr valve, position sensor, vacuum regulator solenoid and the iac valve, without success. I still get the 402 or 401 codes. Yea, and Ive cleaned the MAF.

 

[MakinJeepsWeep!]

I'm glad I'm not alone in this even though this is a old thread. I have a 96 5.0 Internal egr setup. I have changed and cleaned everything and best I've gotten is it throws the cel and turns it back off when it feels like it. Might be a month might be on and off couple times in one trip. I even have 2 ecus now. I just don't know if mods are effecting this egr now. Anyone else have headers or intake etc?

 

[410Fortune]

Likely a leaky egr diaphram?

 

[MakinJeepsWeep!]

Possibly. I can hook a tube to the vaccum and suck on it and just about kill motor then release and it smooths right back out. That doesn't mean it isn't leaking against the seat though.

 

[410Fortune]

Egr base gasket? Had a Jasper reman 306 that ran perfectly except just one misfire.. after much testing and ruling things out we found the egr valve and gasket leaking… this was one of the very few parts we did not replace. I think he said the smoke test showed leaks around gasket and valve. Apparently that fixed it! Haven’t heard anything g but good news about that truck for 2 years now

 

[MakinJeepsWeep!]

I'll look into that good idea, I'm wondering now if I can still get egr off and out with the 1 1/2 manifold spacer on without yanking entire manifold. We shall see on my next days off.

 

[Turdle]

As I understand, high egr flow is determined merely by the position sensor.

 

[MakinJeepsWeep!]

Correct. I cleaned everything and even tried shaving the rod down a few 1000s to that sensor and it still reads excessive.

 

[410Fortune]

I believe the egr can be removed without yanking the intake you just need to remove the intake elbow
Might be a good idea anyways as your egr leak could be in the elbow gasket or at the upper plenum base, the egr feed on your 96’comes through the lower intake and all the way to the elbow. Your spacer maybe needs Re sealed? Lost a gasket? Worth a look see