EGR mystery

Hi all,
I have been battling 401/402 codes for a good while and need some help. Recent (1500 miles) the 2002 winnie van exhibits slight to moderate bucking at around 1500-2000 rpm. Sometimes worse when cold, sometimes worse when hot. It threw out the 401/402 codes a while back but I had already replaced EGR, DPFE, and done the P0174 Leckemby repair last year. From what I gather from searching this great forum, there is a vacuum issue somewhere. I have searched around for leaks but have not found anything obvious. I checked the voltage at the DPFE sensor and the Haynes book says it should have 5 v at igniton on (it does) and no voltage when started and still cold (voltage stays same) then kick to 5 v when hot (still 5v). Now wondering if DPFE is working properly, just getting bad info from PCM. Is it too far of a reach to suspect the coolant temperature sensor as a possible culprit?

Hi all,
I have been battling 401/402 codes for a good while and need some help. Recent (1500 miles) the 2002 winnie van exhibits slight to moderate bucking at around 1500-2000 rpm. Sometimes worse when cold, sometimes worse when hot. It threw out the 401/402 codes a while back but I had already replaced EGR, DPFE, and done the P0174 Leckemby repair last year. From what I gather from searching this great forum, there is a vacuum issue somewhere. I have searched around for leaks but have not found anything obvious. I checked the voltage at the DPFE sensor and the Haynes book says it should have 5 v at igniton on (it does) and no voltage when started and still cold (voltage stays same) then kick to 5 v when hot (still 5v). Now wondering if DPFE is working properly, just getting bad info from PCM. Is it too far of a reach to suspect the coolant temperature sensor as a possible culprit?
Did you install an aftermarket DPFE or a genuine part from Ford ? Having got this problem (401/402) including a bad pinking situation I have install and aftermarket DPFE and the 401/402 were back again. I have cleaned the EGR, the DPFE tube, replaced the temp sensor, and the EGR vacuum regulator but unfortunatly the code remain there until I have replaced the aftermarket (new) DPFE with a Ford unit.

catvents;
Very interesting that the last fix was motorcraft DPFE. I did indeed go the 'cheap' route and use an aftermarket DPFE. I have a very friendly Ford parts dealer who does not rack me list price for parts, so I may as well try it.
Thanks,-
Update--thebloody CEL went off today but still bucks and shudders as it has. Does the CEL normally go out on it's own???? Crazy.

Dumped $60 amerikan on a genuine Motorcraft DPFE. Will post results after drive cycle or CEL, which ever comes first.

Dumped $60 amerikan on a genuine Motorcraft DPFE. Will post results after drive cycle or CEL, which ever comes first.
If you are not using a scan tool and are unable to light off the CEL, remove the neg terminal of the battery for about 10 seconds this will clear the codes.
I do not have the book in front of me but if I remeber it needs 2 or three complete cycles ( engine heat and drive for a while) before the CEL goes on if this malfonction is still there. ( hope not for you). Let us know

I have a 2001 3.8L Sport and it is doing the EXACT same thing JDPK describes. I have not gotten a code reader yet, but I too have done the other repairs and I was good for a few months, but last week it started this bucking/hesitation at about 1800 RPM in 4th gear going to 5th under slight loading, i.e. uphill. It will not do it on the flat or downhill or under heavy load. After about a week of it doing this, the CEL came on and has been on for about a day or so. The fuel mileage is good. I will find out the codes and see what it says....hopefully someone can get to the bottom of this. I hate to just start changing parts guessing which one to change next.

Carbon buildup on the EGR ports inside of the intake plenum is often the cause of this type of hesitation on light load. I think no code are associated to that except that it is part of the po171/174 job. Take a look on that if you have not seen it:
http://leckemby.net/windstar/windstar01.html

Dirty EGR ports can cause P0303 and / or P0304 miss fire on cylinder(s) 3 and / or 4.
This is what happened when my EGR ports clogged...
This happens when the EGR system opens up...and the EGR flow is going to just 1 or 2 cylinders......causing them to not have enough oxygen.

The EGR ports normally clog closest to the EGR valve first......and the ports farthest from the EGR valve are the last ones open.

The pictures that the link in my signature takes you to show the EGR ports.
This is one of my first projects with my vehicle when I had a digital camera....so they are right there on the first page of the pictures.

Sadly, the only way to clean the ports is to remove the upper intake manifold and manually clean them.

Will some SeaFoam clean that? I just did the job and I am not sure if my mechanic cleaned them the right way. I heard many things about SeaFoam but I dont know if they are true or not.:cool:

I do not think that seafoam or any other product sprayed into the intake will do much at all to clean the EGR ports.
NOTHING added to the gasoline will.....as gasoline does not reach the EGR ports.

In the P0174 fix posted, he talks about using a pick to clear the ports of the carbon build up, but when I did my 2001, the ports barely had anything in them (at least at the opening). When I opend my sister's 2002, there was lots of build up. In both cases, I used a cue-tip with throttle body cleaner to wipe the build up out. Would I have to clean anymore that just the opening, i.e. further down past the hole? and if so, how?

In the P0174 fix posted, he talks about using a pick to clear the ports of the carbon build up, but when I did my 2001, the ports barely had anything in them (at least at the opening). When I opend my sister's 2002, there was lots of build up. In both cases, I used a cue-tip with throttle body cleaner to wipe the build up out. Would I have to clean anymore that just the opening, i.e. further down past the hole? and if so, how? You did the job correctly. The carbon is located just on the orifice of the EGR ports, not deeper, so if you clean what you have seen it is correct.

Mine was also just right at the opening..
Seems it forms right where the dry exhaust meets the oil vapors in the intake.

THe new DPFE seems to have little effect. The bucking actually worsened as I drove to the airport following the installation of the new motorcraft DPFE. It sat in long term parking for 6 days, lit it off to come home yesterday and the bucking remained. Mileage still looks good, 23 mpg on short (60 miles)highway drive home. I have cleaned the ports when I did the intake job last fall, there did not appear to be much crud there, but I removed what there was. Still searching for answers.
No CEL yet but the cycle maynot be done. Wife getting impatient with my lack of success-she's threatening to take it to dealer which I am dreading ($$$$$)

A good test that you can do to determine if it is the EGR system causing this bucking......
Remove and plug the vaccum line that goes to the EGR valve.
Drive the vehicle......Does it still buck?.....if so....then it is NOT the EGR system.
If it does not buck.....then it is caused by the EGR system.

I would recommend doing this......to make sure that you are not looking the wrong direction.

This is only a temporary test.....and should cause the CEL to be on indicating a lack of EGR flow......which is correct as you have disabled the EGR system.
So you are looking for the bucking to go away....or still be there.

If it is still there.....then I would look at dirty fuel injectors as a possible cause (a can of Berryman's B-12 Chemtool in each of the next 2 - 3 tanks of gasoline).
Figuring that your coil pack and spark plug wires are in good shape.

It is possible that you have several issues....and this test will help determine if the bucking and 402 codes are truely connected.

Also....give the EGR pipe (goes from the front exhaust manifold to the EGR valve) a looking at....as well as the hoses that go to the DPFE.

I had the bucking your talking about as well. I had all recalls done for the valve cover, bolts.....I have also had a pinging problem for awhile. What I found was the IMRC control rods had come apart so even though there was no actual control to the IMRC it never generated any codes. I have reinstalled the control rods, applied seafoam through the pcv hose and my pinging has diminished to almost none and the bucking has not been nearly as bad. Almost acceptable, very little compared to what it was. I wonder if I were to pull the intake and clean the ports properly if it may go away completely.

I definitely do not understand everything I know about the IMRC system other than now I realize what thsoe things were when I had the intake torn down.;-)
As a test, I moved the IMRC arm one way then had another start the engine-it moved back so I assume the arms are connected up properly since they moved back on ignition??
Bucking has now reduced to almost tolerable but I am still going to try the vacuum trick with the egr and drive it when I get a chance. Human powered vacuum applied to EGR makes it almost stall so I assumed the plumbing past the EGR valve is working.
One can of B-12 in today for good measure to completely confuse myself should it begin to work right.:runaround:

Update--
-Plugged the hose coming from the EGR solenoid today after the main driver (wife) said it was bucking like crazy. I drove it only briefly and it did not seem too bad.
How long can I leave the line plugged to determine if it has helped?
I will be able to put some miles on it myself in two days......

I don't think that 2 days will hurt.
However, if it does not improve greatly with this disconnected, then you are looking at problem other than the EGR.

There is a very slight chance that the EGR valve is sticking....maybe a grain of carbon on the valve seat....but this is NOT common on the windstar from the posts that I have read.

jdpk, last night I tied a zap strap around the rubber elbow vaccuum connection to the top of the EGR valve. I made sure I had a snug fit, by removing the elbow and pulling the strap a little tighter and then pushed it back on. I took the van for a 20 minute drive and no bucking! I reset the engine light and will wait and see if it all stays running well. I will let you know if I have anymore problems, but you should investigate that connection. Takes longer to open the hood than to fix it! Hopefully you have the same issue. The conenction should be snug. On mine and my sisters it was loose and took very little effort to pull it off, plus there was oil residue all over the top of the EGR valve that appeared to be coming from the vacuum connection (even though it didn't make much sense to me how a vaccuum leak could leak out?, but we both had the same thing).

If you do not have a loose conenction there, try checking the hose back to the EGR for a leak or plug and the connection at the EGR end. If that valve doesn't move like it should, you get a lot of bucking! I also tested the hose by removing the EGR valve end, with the engine running and put my thumb over the end and revved the engine. I could feel the vaccuum amount changing as I revved it up, so I was fairly sure the solenoid was working and there was no major leak since the vaccuum was present and changing with the engine.

My 2000 3.8l would buck and stall occasionally. In my case the MAF sensor was at fault, never set any codes or CEL.

OK, as usual, I was wrong. I still am getting the odd small buck and CEL came back on. Pain in the ass is that I do not have a code reader and I am in Canada so can't go to one of the stores, but I will probably buy one now as I am getting anoyed. Seems I have made progress as the bucking is significantly reduced in size and amount. I will report back when I get the code again; maybe it is something different this time?

Well......with the line to the EGR plugged off it runs pretty well, not perfect, but much better than the extreme bucking with the EGR system hooked up. I know the EGR will hold vacuum so I will try to see if I can detect the solenoid producing any vacuum. I was unable (not enough talent, tools, or patience) to remove the metal pipe from EGR to exhaust manifold for inspection although I stuck a small wire tie down the two ports and beleive they are not obstructed.

PS-Should I be able to feel vacuum on the line to the EGR when increasing RPMs? There's nothing there but I don't know if there is some threshold RPM when the solenoid sends vacuum.

The EGR system should not be working when you are sitting in your driveway.
It is not unusual for a small amount of vaccum to be present at idle....but it is not enough to open the EGR valve.
The PCM uses a variety of factors to decide when to send a signal to the EGR vaccum solenoid to open vaccum to the EGR valve.

In your case, I would buy a new DPFE sensor......(If I remember correctly, you already cleaned the EGR ports recently...and it takes a while for them to clog up).

WSWIND--Running with a new Motorcraft DPFE now. I am still concerned that the voltage to the DPFE at cold start is 5v. Voltage to DPFE when engine is hot- 5v. Shouldnt this be different? I would also like to check the voltage at the electronic vacuum regulator too but the van is hot, it's late, and I already scraped up my knuckles enough today. ....
Getting discouraged

I have not a code over the last few days other than the intentional ones when I plugged the vacuum line. Plugging the egr line obviously generates one. Should I be looking at the coil since the slight bucking persists? The car runs fine when you put the hammer down, (other than persistent pinging) still shudders and bucks at 1500-1800 rpm when cruising

Seems that the coil can cause the missing that you are having.
I hate to tell you to just throw another $75 or so at it.
I would keep up with the Berryman's B-12 Chemtool.....treat a total of 3 tanks of fuel with a can each.
This dirty fuel injector thing is a really common issue with these windstars....and the solution is cheap and easy.

Another thing to look over....which I think you already did is a vaccum leak.

If the PCV line is not seating firmly.....I would replace it.

The voltages at the DPFE should be staying pretty steady.....at all temperatures.
The only thing that should change is the voltage out....which would change as the flow through the EGR pipe changes.
As you have a new DPFE, I would look elsewhere for the issue....and the dirty fuel injectors, coil pack, and spark plug wires all become suspects.

I think that you already verified that both of the IMRC linkages are intact and that the actual shafts are turning.
There is a TSB for this relative to pinging.....and the links being broken.....missing, etc causing one or both IMRC shafts to not turn is known to cause the pinging.

If the vehicle has higher mileage on it before having the TSB for the front valve cover done.....the long term extra oil into the intake could have caused carbon build up inside the cylinders.
This would increase compression and cause pinging.
Getting the carbon out of the cylinders is not a pretty thing....and FORD's solution was to reprogram (reflash) the PCM to delay the timing slightly to reduce the pinging.
OF COURSE, the EGR system not working (as with the line disconnected) will also likely cause pinging.....so that could be the cause right now.

That's a wealth of information--the TSB WAS done (by yours truly) with 120K+ miles on the engine. I don't suppose the Stealership would re-program my PCM for free eh? What's the normal fee for this and is it a special set of code for the post-TSB 3.8 motors? The B-12 treatments will continue since the bucking continues. Idling is doing fine so the wife isn't scared it will stall but the bucking is still definitely there.
PS, the other day I figured out a way to get the intake plenum off without removing the cowling if anyone is interested, PM me.

B-12 treatments continue. Main driver of van says it's 'okay'. I got to put a few miles on it last week and the bucking was still there. No codes yet, I guess we will stick with the fuel treatment for a while.

jdpk,

The bucking on mine has been eliminated about 99% from fixing the minor vaccuum leak I had at the EGR valve connection. I say there is 1% left because I have had one or two minor incidents since I fixed the leak, but otherwise it is now gone. I still have the P0401 code up, but the van is running completely fine. I have not found the reason yet for P0401, but I haven't had time to look either. I suggest you check all those vacuum connections very closely. If anything is loose, then do what you can to tighten it. My problem was the rubber elbow on the EGR valve would spin freely and easily slide of the valve connector. It would stay on without coming off on it's own, but just being loose enough to turn was all it took. I only knew that it was supposed to be tight because when I grabbed the elbow on my sister's van, it was tight at first, but then it became loose after I removed it once for inspection so we replace the elbow and now it is difficult to remove let alone turn. Mine was loose to begin with so I knew I had to do something. Check that vacuum line really closely from one end to the other for any kind of a leak. You can remove all the components and blow into them with one end sealed to check for cracks and if anything is loose, try tying a zap strap around it or temporarly tape it to see if it helps.

Found some good stuff on EGR valve, DPFE and testing. A bit vague, but it really helps when you better understand how it all works when you are troubleshooting.

http://autorepair.about.com/library/faqs/bl656h.htm

http://car.justanswer.com/car/1i9x-2001-windstar

These last three are fantastic explanations and troubleshooting information. If you want to learn about EGR systems, then read these links...

http://en.wikipedia.org/wiki/Egr

http://www.asashop.org/autoinc/nov97/gas.htm

http://www.asashop.org/autoinc/dec97/egr.htm

Last night I cleaned the vent on the solenoid, which really wasn't plugged and I tested the EGR valve (proved it works) and tested the DPFE sensor and proved that it didn't work. Replaced it and reset the CEL. Seems better, but I hate to say I fixed it until a while has passed. I will report back. Then I may post some pictures and details on what I did...

Case closed. Number 3 plug fouled badly. Changed the whole set and wires and she runs (almost) like new. 147K and still chugging. Think the DPFE (motorcraft) and vacuum solenoid fixed the codes.