5.4L Rough Idle - EGR block off didn't fix
 

So a few months ago my Expedition (5.4L) threw the code for the DPFE, the truck started running rough, hesitations, no power, horrible gas mileage, etc.

Before I could replace the DPFE (funds), I tossed a piece of aluminum can between the EGR and the manifold to see if that would make the symptoms go away, it didn't. The rough idle/running is still there, so I parked it and used it only for emergency trips.

I then replace the DPFE and the code is cleared but the rough idle/running still exists, I'm curious if anyone has any ideas what it could be now since I had the EGR blocked off and still had the rough running. Anyone have any ideas? I've got to get this thing back in operation for a camping trip in the middle of August.

Thinking I need to clean the IAC and then spray around the engine bay with some carb cleaner to see if I have a vacuum leak. But wanted to start a post here first.

Thanks for any help

Adding link(s) to DPFE troubleshooting thread(s):
Focus Shacks - DPFE Sensor and EGR Information

Good idea to do this first. Don't be shy with the cleaner, give it a good soak and spray.

Will do, tearing it apart tonight once the heat gives me a break. Oregonians don't do well once the temp goes over 70. :D

I suggest that you do a "google" search for "DPFE". There is a post listed from the Focus forum that has a great description with pics in regards to this sensor and it's operation.
It's not always the item that the code reader seems to pinpoint that is the real problem, It is often something else in the system that causes the item pinpointed to malfunction, which in turn causes us to start by replacing the item the code reader specifies and then we eventually find the base cause of the problem. We have to remember that code readers are only tools to aid in the diagnosis and repair of a problem.

This is gonna soumd dumb, but does the computer have to be reset after this procedure? Maybe disconnect the battery for a day then see what happens when you fire it up. Good Luck!

It would be helpful to me to know the model year of this 5.4, the specific DPFE DTC code, if there were any other codes, and the number of miles on this vehicle.

This can cause a P0400 or P0401 DPFE code.

More than likely the infamous PCV elbow at the back of the intake manifold is leaking, and is not related to the EGR issue.

Thanks, I'll look for that thread and then link it here at the top so others who run across this can quickly find it. :-X22

Yes, you should disconnect power to reset the ECU however you only need to pull it for 10 seconds to make sure all power is out of the system. I typically will pull it after tearing everything apart and then put things back together so I can just reconnect the battery as the last step of assembly and there's no doubt I didn't leave it off long enough.

It's a 2003 with 120k and I believe it was the 401 code. I foolishly didn't pay attention to what specific code the NAPA guy pulled and he just told me it was the DPFE sensor. The other flag for me was that when I looked at my DPFE one of the hoses was completely destroyed on the inside (with a small hole leading to the outside) and it had melted half of the stem off the original sensor.

On my 2000 expy also with a 5.4 I had could for high DPFE Flow(I don't remember the number) it was one of the hoses going to the sensor it had hole burned in it both hoses were very brittle so I replaced both of them. if that is the problem need to get the hoses from ford dealer not they are not just vacuum hoses.

When I was doing an engine change in my Navigator I found that the OEM hoses were disintigrating from the outside as the rubber was flakeing off on my hands by just touching them. The hoses seemed to still be good and firm otherwise but, I replaced them with high pressure fuel hose and 3 years later they are still doing fine. I check them whenever I'm under the hood just to be sure. Better safe than sorry!

Okay so I let the truck sit for a long time due to an overwhelming schedule and what not. Finally got around to it today and first off the battery was dead from me letting it sit forever. I jumped it and was surprised to see that the idle was normal. I let it warm up and the idle stayed fine. Then I decided to take it for a trip around the block. Everything is fine at light pedal pressure or at idle but once I need to accelerate, she falls flat on her face.

I'm about to rip her apart right now to clean the IACV but just wanted to get an update out now.

Cleaned out the IAC...did some more experiments. The issue is only when given a large amount of throttle at once. If slowly added there are no issues, if added in one big chunk, like trying to accelerate quickly to join traffic, she gets all lumpy and nasty, then settles back to a smooth idle.

Are you getting any codes now?

Hey Mel,

No codes since I replaced the DPFE. Just cleaned the MAF and waiting for it to dry before testing.

Well that pissed her off..rough idle has returned, almost like she's missing....trying to unplug the COPs one at a time to see if there's a point where nothing changes....damn it's hot in there. :)

Still no codes.

Unplugged the #6 COP and conditions did not change. Game on.

Hrm....I wonder if this could be a problem?

http://sphotos-b.xx.fbcdn.net/hphoto...65559815_n.jpg

GAH!!! Replaced the plug and cleaned the junk of the COP of #6 and now #3 is the PITA...pulled that COP and the same issue, it's sitting in a puddle of water and the plug is corroded. Needless to say time for a full plug replacement.

You must have a source for water to drip onto the plugs to cause that much rust. I suggest that you close the hood and spray a lot of water in the area of the cowl and hood and then check inside to see if there is a trail showing where the leak is. Then you can seal that area or find a way to divert the water away from the cops.

Yeah odd thing is we haven't had any rain for weeks now and everything looks fine hood wise...one would think it would have evaporated. Coolant level looks fine so I'm not worried it's coming from the other direction.

EDIT: There was a small puddle in the #6 surrounding the plug and the #3 coil came out wet. There's also about 1/2" of built up dirt surrounding each COP.

There's a heater hose in the area of cylinders 3 & 4 that has been know to drip coolant into these two spark plug wells.

Thanks I'll check that guy out. But it doesn't explain the water in #6. I'm wondering if its stuff that might have been there from the winter (before the problem started) when I might have goofed off in some big puddles.

Just got #3 out and it had a lot more rust on the tip than #6 did. So I think I my adventure has been a collection of problems.

....and #7. I'm replacing the rest this morning but it seems as though my problems have been fluid and corrosion on top of the DPFE failing. There is no vacuum leaks..yet. :D

OH! One fun thing, when you pull the big vacuum hoses to work on the #6 or #7 (in my case), make sure you plug them back in before you test to see if everything is working. :D My reaction when the engine would just die was "great, what'd I screw up while fixing this thing!?!" then I saw I left them loose. HA!

Been there, done that! Didn't like it.

If you have the vacuum lines crossed going from the exhaust manifold to the EGR sensor you will get some strange codes and the CEL will come on.

Yeah I'll bet! :D

So the problem surfaced again and my new plugs are corroded as all heck. I finally thought things through. It's not water in the plug wells...it's coolant. Intake manifold gaskets are leaking.

New weekend project.

Sorry to hear that! Good luck with it.

I'm taking my time, 6.5 hours and it's all apart. Inspecting the crossover and intake manifold. The seals were toast. I will go at the intake tonight/tomorrow and see if I can get away with just cleaning/new gaskets.

Nope, cracked at the crossover on the passenger side. Dorman IM ordered and expected tomorrow for installation. It will be nice to have this thing usable again. :)

Well that was no joy. Dorman came and was broken on one of the fuel rail towers. Had to order a replacement. Took my time putting it all back together and she's happy for now but only about 100 miles on it since the install.

It's quite nice to feel normal acceleration again.