Help me pin point this rought idle...!

A couple a weeks ago my 2000 Windstar 3.8L started having a slight rought idle at around 51K miles and now it has progressed to a bad engine shake like a plug is missing. Weird thing is that it doesn't feel like the engine is loosing power.
The trembling feels the strongest from idle to about 1500RPMs and it almost dissapears after RPMs go higher. When I let go off the gas pedal it coasts down normally but then wobbles the engine when it goes thru the same RPM range (1500 and lower).

I've been using Berrymans B12 on the tank regularly, bout every 6mos.
Had the IAC cleaned and sprayed the inside of the plenum thru the PCV and Fuel Pressure Regulator openings 2 week ago.
Replaced the Air & Fuel Filters, cleaned the MAF & TPS Sensors and the TB and sprayed the inside of the plenum thru the TB a little more today.
I looked over the wires and vacuum hoses and didn't see anything wrong.

Nothing seemed to work...:frown:
What else do you guys suggest?

I would think that you would get a CEL...which would get you a code to help you pinpoint the cylinder.

It could be a spark plug, spark plug wire, or coil pack.

A IMRC problem should light a CEL also....but give them a look to see if they are actually connected.
I seem to remember that your 2000 will have electrically actuated ones.......and they may be a bit different than my vaccum ones.
A broken "clip" may have one or both sides not following the actuator.....and cause a problem.

Thanks wiswind...
I knew I was forgeting something! There's no CEL, intermitent or constant, the IMRC are connected and yes, they're electric. Also, when I did the Isolator Bolt fix last summer I also cleaned the EGR Ports real good and put new AutoLite Plats.

You could sill have a coil pack or plug wire issue.
The other thing that seems to have come up a few times is fuel delivery issues.
There is no sensor for fuel pressure or fuel flow....so there will not be a code to indicate a problem there.....just symptoms......an maybe a code indicating the symptom.
From reading posts, there are a couple of relays in the power distribution box in the engine compartment that can cause fuel pump issues.
Also, more difficult to track down......there have been a few problems posted that ended up being a failing fuel pump.....good pressure at idle...but cannot keep up under load.
The only way to really troubleshoot that would be to use a remote fuel pressure gauge, and take it for a drive.
That is something that I would go to my mechanic for.....as I am sure that a quality fuel pressure gauge for this would cost at least as much as paying for a couple hours of qualified labor.

I sure hope is not the fuel pump...! One thing to note tho the roughness as stated in the original post is worst from idle to about 1500 RPM and almost clears at anything above 1500 RPM. The engine doesn't starve for fuel or hesitates under load.
I'll see what I can do with the plug wires and coil first

this is just a shot as you've really covered things well but on my 2000 the upside down "U" vacuum tube that's at the front of the plenum (can't recall the name -(coffee kick in!)) had a very loose fitting. I think the rubber over time just simply expands. Coupled with this at 1000 to 1.5k rpm was a high pitched whine. Anyway, in getting a new vacuum line that fit snug as it should the stall, roughness went away. This never coughed up a CEL for me but at low rpm it would act as you've said.

FWIW, my :2cents:

Piper

That was the first thing I checked as at one time it had come undone on it's own as it was too loose and gave me a lot of trouble. It gets soaked with the oil from the PCV and cannot hold it self in place.
I clean it periodically to avoid trouble so right now it's holding on real good!
Thank for helping out.

Listen for hissing noises while the engine is running. I've found several vacuum leaks using that time tested method. Don't let you long hair (or your clothes) fall into any moving parts.

One of the leaks I found was a split rubber fitting on the PCV breather pipe. The rubber was extreemly soft and gummy, but it was also making noise. Another one that I found was due to a plastic vacuum line rubbing against a metal AC pipe, back along the firewall. I just let my ears do the looking.

Update:

I just got done putting a new Ignition Coil and AutoLite Wire Set (black box) and the problem was still the same, no change whatsoever with the original problem. I removed the Cowl for better clearance and checked vacuum lines and electrical connections from problem and could find anything wrong. I numbered the wires to avoid crossing them over and marked the plugs orientatin on the coil.
But, now i get this new problem.

When I went to crank the engine it started turning really slow and then the starter motor started skipping, like it does when the battery dies. I plugged the voltmeter and the battery was holding 12.29 volts, at cranking went down to 7.99volts and after the engine started it went up to 13.85volts... revving the engine to 2500 wnet up to 14.09. Those numbers look fine to me, not sure why it's acting up.

Any way, I cleaned the battery contacts and put everything back together and same thing, it tries to crank then skips, then cranks and the engine starts running. After the engine starts there's a faint smell of raw fuel coming off the engine and the tail pipe, but it doesn't blow black smoke off the pipe. I disconnected the "U" line from the Fuel Pressure Regulator and didn't notice much difference (I was expecting the engine to stall), plugged it back in and the vacuum sucked it right in. Disconnected the EGR and plugged the line, sucked on the EGR thru a straw at idle and engine RPM went up a bit. So those look fine!

Went to take it for a drive and then everything went down south even farther. The engine started backfiring (sounded like it was making popcorn) and loosing power when put in gear, but it didn't stall. Drove for like 10 miles and didn't improve! I really don't know what else to do, don't understand how it got worse... Could it be the Fuel Pressure Regulator gonne bad or is it something else?
I can't believe I still don't have a CEL to track.

Hi
FWIW, to my knowledge and by personal experience, if you "suck open" the EGR at idle, the van dies. So, perhaps, just maybe your EGR is stuck shut. Now I would certainly think you would trigger a CEL if this were indeed true, but it is a thought.

With the engine off and putting "man vacuum" on and off of the EGR I usually can hear the valve opening and closing.

Good luck

hmmm interesting...

Actually the RPM went up just a bit when I applied "man vacuum" to the EGR at idle and then the RPM went back down just a bit when I stopped applying vacuum at idle. While I was doing this test I could hear the EGR making some hissing sound.

The little tube that goes connected to EGR had just a little bit of vacuum to it but it was enough to hold a cap on it. Then, as soon as shut the engine off the cap fell off. Don't know if that would be the normal amount of vacuum needed, but I found it to be somewhat too low.

But none of this would cause a backfire condition would it? I don't understand how it went from bad to worse so suddenly. Is it possible I got a bad coil? The 1st time after the coil and wire set replacement the engine started with the same old simptoms (not so severe problem) and by the 3rd time I started it and took it for a ride all went worse!

I cannot figure why.

It is normal for there to be a very slight amount of vaccum in the EGR valve's vaccum line at idle......it is not enough to open the valve though.

If you apply vaccum to the EGR valve's vaccum fitting, the valve should open.
If the valve is open at idle......the engine should die.
The EGR valve should be closed, and stay closed at idle.
It should take a fair amount of vaccum to open it.
If the valve is not fully closed when it should be......your vehicle will not run properly.
The EGR valve itself is not a high failure item.....but it can happen.
I would try working the valve manually by manually applying vaccum to it....with the engine OFF.....just in case you may have some carbon particles causing it to not seat properly.

Your slow turn over could be a weak battery or connection.
This can also cause you to have a wide variety of problems as electronic controls are sensitive to voltage issues.

As you smell fuel when trying to start......I would think that you are getting fuel......
Fuel pressure regulator is also not a high failure item.....but the vaccum line to it can have issues seating to it.
The pressure regulator will give you maximum fuel pressure with no vaccum applied, and adding vaccum reduces fuel pressure.
You can test the fuel pressure at the test point on the fuel rail......middle of the front of it.

You may need a good diagnostic at a well equiped shop that can monitor the various aspects of you engine controls.
Fuel injector firing, Camshaft position sensor, MAF, and vaccum leaks can be slight enough that the PCM does not throw a code....but is trying to compensate for a reading that is wrong, but within range.

So how about the relays? I should not worry about the relays?

When I tried cranking and it started skipping, the first thing I though of was the Starter Relay since the battery checked out good with the voltmeter.
I remember before reading about owners having weird stuff and being caused by a relay, Starter relay, Fuel Pump relay etc. I don't know where they are or what do they look like or how to test them.

OK I tried "man vacuum" on the EGR this time with engine off and the EGR operated normally, I could hear the diaphram move and it tasted awful...LOL
The Valve was able to hold vacuum pressure and stay put, altho with engine running it still revs up just a tiny bit when applying vacuum and settles down when vacuum is off but it won't stall as is supposed to. But I don't think thats the issue with the engine running rough and backfiring.

I Also unplugged the "U" shaped vacuum hose for the Fuel Pressure Regulator at the regulator and didn't notice much difference on engine rpm at idle, but when I unplugged the Plenum side (clam shell) it almost stalled. Today there was a stronger gas smell from the engine area and tail pipe fumes. Not sure if it was caused by unplugging the "U" shaped vacuum hose while the engine was running.

Another thing I didn't notice before was that when I put the tranny in gear, I hear something that sounds like when air comes off a fire extinguisher, it doesn't have the familiar hissing accompanied by a vacuum leak and it only happens when in Reverse or Drive gear, it doesn't happen in Park or Neutral. Anyone knows if that's normal behavior?

Now I have a broken Belt Idler... I guess from revving the engine yesterday doing tests, so I couldn't take it out for a drive to see if it's still backfiring.

The thing about fuel pressure / delivery, there will be NO CEL to tell you about it.
There is NO sensor for fuel flow or pressure.
There have been a few posts where people had fuel delivery issues, but backfiring was not mentioned in any of them.
The best way to troubleshoot the fuel system is to connect a fuel pressure gauge to the test point on the fuel rail.
A good shop will have a isolator......which will isolate the gauge from the fuel.
This would enable them to use a long line to the gauge.....and be able to take the vehicle for a drive, while monitoring the fuel pressure at the fuel rail.
Not having the isolator would make this a unsafe practice.

A good shop will also have the equipment to connect up and monitor various engine functions......and know how to interpret them.
There are OBDII monitoring programs that you run on your laptop computer.....but those also require one to be able to interpret the data that you see.
A good diagnostic can save you money over guessing.....and a lot of frustration.

I would certainly get the battery checked out to make sure that it is not contributing to your issues.
I would expect the battery voltage to be pretty constant over various RPMs.....once it is charged up.

A starter relay could contribute to starter problems.....but not to the driveability problems.

A fuel pump relay is a higher failure item....but again....it would be throwing a part at the vehicle...
Spark plug wires and (in my opinion if still original) a coil pack are tune-up items ....that are good to do at this point anyhow.
Another good to do would be to replace the fuel filter, air filter and clean the MAF with MAF cleaner that you can buy at most auto part stores.

If you did have carbon tracking and arcing around the plugs and then changed the wires without changing the plugs the current can travel the carbon track along the plug and still cause a miss. I know its a long shot but it does happen. To make sure you don't have any arcing on the wires/plugs/coil run the engine with the cowl off in a very dark area and see if you see any arcing. If you don't then you can rule that out.

Just came back from working outside. I got the Belt Idler replaced, gave me a hard time but no biggie.
When I bought the Belt Idler, I took the battery to the Auto Parts store and had it tested. I was able to pass the first test (load test I guess) then the guy asked me if I wanted him to charge the battery, I said sure why not.
He put it to charge and 45 mins later came back to tell me the battery would not hold a charge. I brought it home put the voltmeter on it and it showed 12.54 volts... what gives?
Anyway, I went and got a new battery and replaced the old one. The van started right up and gave me no issues cranking.
But it still giving me the rough idle, and the fuel smell feels even stronger at the tailpipe. It was pretty dark outside and I look for arcing but didn't see any arcing or sparks flying (other than my brain frying). The plugs were replaced @10K miles ago with AutoLite's Double Plats by the way.

I went to take it for a ride and it started backfiring right away.

On my first post I covered what I've done before coming here for help... Air/Fuel filters, MAF cleaned, Berryman B12 in the tank, cleaned IAC/TPS sensors, etc.

The EGR behavior puzzels me....but I would expect that it would light the CEL.
Clogged EGR ports, DPFE, etc.....all should light the CEL if it was causing this extensive of a problem.
I hate to keep telling you to change this part and that.......as that adds up.
I revisited the tune-up items....as you would hate to go to a shop, just to find out that it was a simple tune-up item.
I have the AutoLite double plats in mine right now.....and they are doing just fine.

Ed_Strong
The backfiring sounds like a timing issue as the timing is controlled by the pcm that confuses things more. However as Wiswin said that a fuel delivery problem could be an issue as Im well aware of. I had kept checking my fuel pressure (purchased a fuel pressure gauge from Sears for $30.00) There seemed to be no problems. However I realized by leaving the gauge on as driving (cowl off taped guage to the windshield I could watch the pressure change. The biggest note was at cranking. When you first turn the key on you hear the fuel pump run for a second or 2. I thought that was good. When I applied the gauge the fuel pressure was 20 Llbs. If I turned the key off and then back on the fuel pump would run again and the pressure would go to 30lbs. The fuel pressure should remain about 40lbs with the key on engine off and maintain that pressure give or take. If you notice change at the given rpm of the backfire I would suspect the fuel pump or fuel regulator. My problem was similar in that I figured if the fuel pump was bad it would starve at higher rpm. Not so. I you cant figure it out in my opinion I would take it to a shop and have them diagnose it. It cost me $108. to put in on the computer and tell me exactley what was wrong. I had them do the fuel pump but i replaced all the fuel injectors as one was bad and I had so many miles. I kept throwing money at it replacing parts and could have had it diagnosed for much less. The only reason I didnt feel to bad is the age of the van and miles. Replace it now or replace it later. Preventative repairs

Today I went to start the van and it cranked slow again after 2 days with the new battery. Could this be related to the problem?

I had a suspision that something could be draining the old battery and I checked at night for anything that might be staying on and there are no lights staying on inside or outside, or anything making sounds.

Anyone have any clues...?

Just about anything can cause a silent drain. If you think your battery prematurely needed to be replaced, I'd be suspicious of the alternator. Make sure everything is turned off. Disconnect your battery pos cable. Try tapping it on the battery post to see if it sparks any. Big sparks for big draws, little for little. If it is big, you can't use a normal multimeter to test the current draw. You will have to use a clamp meter or the voltage setting on your multimeter. Put your multi meter between the battery and the cable to measure current draw or voltage(current is better). Start pulling fuses to see if a major change occurrs, drop. Check the fuses underhood if no luck with inside fuses. To check the alternator, pull all the connectors off of it and see what the meter does. You might do that first, then the underhood, then the inside fuses last. I wouldn't expect much more than 0.05 amps draw normally with it off as there is the computer, radio, alarm, remote entry etc, that draw current even with the van off.

a little while ago on this board someone was complaining of a mystery battery drain and it was traced to a bad rear windshield wiper. Seemed that it was the intermittant part that caused the problem. Just an "off the top of my head" thing.

Piper

Hi
I had posted earlier on another thread about the rear wiper. A friend with a 2000 has now had the problem twice - mystery battery drain. In both cases on closer inspection the rear wiper was out of place, both times too low on the window partially onto the body. Apparently, the system continues to try and "park" the wiper. I don't know why it does not blow a fuse, nor why a GEM does not shut off the power after a period of time (like it would a dome light). But in any case, twice dealing with the rear wiper corrected the problem.

Good Luck

While it may not explain the original rough idle condition, from your posts it
sounds like the backfire/fuel smell issue started after replacement of the ignition coil and plug wires. You mentioned that you replaced only one wire at a time but it sounds like a wire might have been crossed. Was the layout of the coil the same? Or if the rear plug wires were replaced somewhat blind by feel maybe the boot end was inserted over an exhaust manifold stud. Misfiring would allow unburned fuel into the exhaust. To check your alternator for a draw, with engine off, remove the heavy red output wire and install an ammmeter in series, I had one that had a 4.5amp draw. Just another thought, maybe the rough idle and now backfiring are the result of a broken intake valve spring.

I must admit, the rough idle started when the coil & wire set were replaced, but... the engine will not backfire or run worse than before while in nuetral. It runs worse and backfires while in gear and backfires when you give it gas while driving, once you lift off the gas it stops backfiring.
Im thinking of putting the old coil back on it tomorrow and see if it stops backfiring.

Today I managed to get a Snap-On OBDII diagnostic machine to test and at the KOEO Self Diag Test it didn't find anything wrong. The I ran the KOER Self Diag Test and it came out with.

P1000 OBDII System Checks Incomplete
P1127 HO2S Downstream Sensor Not Tested

I checked all the sensors readings and everything seemed fine. Then ran the KOER Self Test Diag again and it posted:

P1000 OBDII System Checks Incomplete
P1127 HO2S Downstream Sensor Not Tested
P1151 HO2S21 Snsr Indicates Lean

Not sure about this results but I would really like to fix it my self if you guys could help me!

It might be time to go back to basics, meaning ye ol' timing light and vacuum gage. You can tell a lot from these tests. If the backfire is coming from timing or a mechanical problem, or a vacuum leak, you'll see it with these checks.

Pulled the old timming light out and checked the front three plug wires and they all have electricity flowing. Couldn't check the back three because of clearance and fear of getting burned, but I'm sure they also have power flowing. Still smells like raw fuel in the engine bay and out the tail pipe.

I'm gonna throw the old coil back on it and see if the backfiring goes away. With the cowl removed I'll check the back plug wires with the timming light and I'll remove the plugs to see if they're flooded.

Out of curiosity I disconnected the alternator and cranked it up to see if there was any difference to no avail... I left it unplugged overnight to see if the battery drains again while it sits thru the night.

I really cannot see, hear or feel any vacuum leaks! Now, what kind of connections do we have on the lower back of the engine? Like below the plugs if there's any?
I smell a hint of burning rubber or plastic and wonder if there's a loose wire making contact with the manifold or converters, but can't see anything back there.

Interesting that one of the O2 sensors was throwing a lean code. Possible that sensor is bad stuck on lean, the PCM trying to compensate could be making the engine run in an overly rich condition, thus the fuel smell. Other senario could be that it is actually running lean and not burning fuel. I don't know how one would actually test the timing on the 2000 3.8l without use of a mirror or making your own timing marks. A professional scan tool can be used to check ign timing, even that would give false results if the harmonic balancer/trigger wheel on crank had rotated out of proper position due to a sheared key.

I have noticed that none of the aftermarket coils (that I have used) had the diagram on top that shows which coil section fires which plug/cyl pair. In fact, one of the aftermarkets (AdvanceAuto) replacement had a whole different order of coil-sctions ... not the same as the original ... was very tough to fiqure out. The Ford replacement has the drawing glued in place and, of course, has the same original coil-section order.

(Edited, ... thanks, Ed): IIRC, the rear-most section (closest to firewall) fires the 1&5 pair, the center section the 2&6 pair, and the front section the 3&4 pair.

I have noticed that none of the aftermarket coils (that I have used) had the diagram on top that shows which coil section fires which plug/cyl pair. In fact, one of the aftermarkets (AdvanceAuto) replacement had a whole different order of coil-sctions ... not the same as the original ... was very tough to fiqure out. The Ford replacement has the drawing glued in place and, of course, has the same original coil-section order.

IIRC, the rear-most section (closest to firewall) fires the 1&4 pair, the center section the 2&6 pair, and the front section the 3&5 pair.

You're right 12Ounce... the aftermarket coil (AdvanceAuto) don't have the diagram on top that shows which coil section fires which plug/cyl pair.
What I had to do was draw the engine on a piece of paper with the firing order and then copy my own diagram from the top of the original Motorcraft coil on the same paper.
For reference the actual 3.8L firing order on the coil is the rear-most section (closest to firewall) fires the 5&1 pair, the center section the 6&2 pair, and the front section the 4&3 pair.
Looking at it from the top will look like this...

rear (closest to firewall)

|5&1|
|.....|
|6&2""|
|.....|
|4&3|

front (closest to TB)

Thanks, Ed ... I edited my goof!

Update:
I'm also a goof! I re-traced the plug wires and saw I had crossed plugs 4 with 5... what a dork, LOL (with all the precautionary measures I took)
Anyway, switched them back and it started ok and runs better, no backfiring, didn't smell raw gas. but there's still a hit of burnt plastic or rubber and the old idle issue is still present but not as bad as when the original post, maybe the PCM need to learn?

Also the alternator is still disconnected and the vans started good, no weak start at all!

Glad you found that problem.

Have you tried gobbing up all the vacuum hose-ends and vacuum tube ends with petroleum jelly for a really good seal?

Will a DPFE sensor go bad without throwing a code? All the posts I've read have had a CEL code set announcing it's demise. To this day I have not got a CEL code of any kind, (the CEL lights up at KOEO by the way). I should be getting an EGR code, right?

The Ford CD lists the DPFE as the first item to check for a rough idle condition. From what I understand the reading value should be between 45-55volts, is that a fact?. The manual says to check with scan tool for DPFEGR (hot idle value within 0.15v of KOEO value)

At KOEO I get a value of 1.21volts, and at idle it jumps to 1.24volts. If my numbers are right, that should indicate a faulty DPFE sensor. What do you think?

A DPFE will only give you a rough idle by opening the EGR valve at idle ... which should never happen.

So if you determine that the EGR valve fully closes off flow (most of them do) and is not stuck partially open .... and if you then remove and plug the EGR valve vacuum control line ... you have taken the EGR system totally out of the picture. (I think.)

Does the engine still idle rough??? ... if so, it ain't because of the EGR. There's gotta be something else ... such as a intake vacuum leak ...or an unhappy idle air control valve ... or, etc, etc.

Do you know what the scanner value should be for the IAC Valve? I cleaned it really good and TPS and TB as per first post, so I automatically ruled it off.

I applied man vacuum to the EGR valve and now the engine stalls as it should! Both lines for the DPFE hold vacuum when applied, but the voltage still roams between 1.19 - 1.24v, not sure if that where it should be...

I took the van for a ride with the scan tool connected and it took a good reading of the (%) value for the IAC, it changed accordingly to foot pedal poosition. Not sure what oder tests to perform on it.
But for some reason it won't read voltage values of the IAC to see if theres any fluctuations.
The DPFE on the other hand was jumping all over from 1.19v - 3.04v at different driving scenarios. Is that normal behavior for the DPFE?

Hi
I don't know the exact values you should be seeing on the DPFE, but it would seem it should fluctuate based on differential pressure across the unit. I sense you know this but just to be certain: the DPFE is only a "passive" device measuring the EGR open/closed condition by differential pressure. The device that "controls" the EGR as commanded by the PCM is the EGR control solenoid on the back of the plenum :
http://info.rockauto.com/Airtex/Detail.html?2F1128.jpg

I would think that if the solenoid is commanding an open position when it should not that the DPFE should sense this and you would pop a code (P0402 perhaps). Anyway, keep looking for a vacuum leak - try vacuum testing the solenoid and the vacuum line(s) to and from it.

Good Luck

I believe in 03 I had a pair of problems. First the cat element rattled around till it turned sideways and plugged itself. Unfortunately on the same side as the egr tube. So, I had straight full blast exhaust backflowing up into the engine compartment through the two ports of the dpfe. It was a nightmare as I was taking my family on a summer trip to the lake on a hot day and I couldn't get it fixed well under the hood so it wouldn't melt any more than it did. I'm not sure if that caused my dpfe to go bad or just accelrated it going back. It did code a couple of times I think after I fixed the cat, I can't recall if it did on the trip or not, though I thought it should as is was measuring no pressure difference as the hoses were burned off. Anyway, cleaning the dpfe inlets didn't get it to work. It was an aluminum casting that was breaking down. Interestingly enough, I tested it according to my manual and decided it wasn't right so I replaced it but tested the new one too. The new one had identical results!?! D*mn manual!?! New dpfe is black polycarbonate, so hopefully won't crumble from the heat. Took apart the old one. Only problem with it was it was plugged up deep inside it that drilling is out wouldn't have worked, but electronically it still was functional.

Ok, enough chatter.

To make these measurements, the dpfe has a three pin wire connector. For orientation looking at the inside of the connector, the holding clip is on the right and a groove for mating with a ridge on the dpfe is on the left. The signal pin is next to the groove at the top, the middle pin is ground, and the bottom pin is the reference.

The book says with key on engine off, backprobe the wiring harness while connected (it says the dpfe should have the reference voltage for it printed on it):

VREF 4.0 to 6.0 volts

However, mine was backwards, I got on both dpfe units:
VSIG 5.0 to 6.0 volts (maybe ford has mine backwards?)

The book had no value for this, but I measured this
VREF 0.66 volts
Vgrd 0.05 volts
Looking at this with fresh eyes, I wonder if Haynes labeled their diagram wrong

With engine on, book says:
Cold (no egr)Vsig 0.20 to 0.70 volts
Warm (egr on)Vsig 4.0 to 6.0

EGR vacuum regulator
30 to 70 ohms

Turn key on, pull egr vac reg connector
should get battery voltage at connector
It appears the battery pin is next to the bump on side of the connector.

Well, I went to my van to check things out this morning at about 20 degF. I think that would constitute a cold engine. I tested for the spec voltage and also verified wiring etc, to settle the proper pin connections.

First off, Haynes is wrong, it's backwards, so I will give it by wire color to straighten things out. I did also checked Haynes wiring diag and that agreed with what Ford has.

KOnEOff
BAT 12.15v

FWIW with the harness off the dpfe:
Vsig 5.08 - Brown/Lt Green
Vgrd 0.11 - Gray/Red
Vref 5.08 - Brown/White, by bump on side

Harness connected, backprobed measurements:
Vsig 0.59 BR/GN on mine was top
Vgrd 0.11 GR/RD middle
Vref 5.07 BR/WT by bump on side, bottom

Eng on
Vsig 0.75 @cold idle - 1.0 @ high rpm
Vgrd 0.3
Vref 5.25
Note: Coiuld not get hot eng meas as van was leaving.;(

Maybe try running engine, go for drive without dpfe connected and see what happens. I think, with it disconnected it will get worse if it is ok and no change if it is bad, but you need to be sure the egr and egr solenoid are ok first. If the dpfe is ok and you disconnect it, I would expect a cel for that. Good luck. Let us know what happens. Thanks

I pulled, checked and tested every vacuum hose and they all check out good. Also I put the old spark plugs back on the engine to no avail. Still No CEL to track and scanner checks out all Injectors working "A" ok. Unplugged the IAC Valve with engine running and idle slows down to a stall.

I tried testing the DPFE Sensor with the harness OFF and Key On and got:
Vsig 4.99
Vref 4.99
didn't do the ground testing (forgot that one)

Couldn't do the back probe with engine running since my meter probes are too big to fit the back of the harness.

Do you have the specs to test the EGR Vacuum Regulator? How does one applies that one?

When I can't get to a metal contact, I learned to insert a sharp sewing pin through the wire insulation or in your case, a pin or other slender metal piece like a stiff wire into the back of the wire connector alongside the wire. I don't think the ground measurement is particularly important, but I like to see if it is close to 0 volts. I certainly would think there is a problem if it is high.

Maybe you didn't catch it earlier, but I'll elaborate more now. To test the egr vacuum regulator, pull the wiring harness off. Then measure its resistance across its two terminals. Normal range is 30 to 70 ohms. Outside that I would assume it is no good. Now you should also check to be sure it is getting proper voltage. So, with key on, engine off, check for full battery voltage inside connector.
It appears the battery pin is next to the bump on side of the connector. The other contact is the signal receiving wire to the computer, so it shouldn't be much if any.

<<Saga continues>>
Friend of mine (a Ford Tech) stopped by today:

Plugged his scanner to the van, no codes and no issues with engine systems. He couldn't find anything to indicate an electronic component malfunction. He feels that the rought idle is that the engine is off balance.

He took of the accessory belt off and ran the engine without it while inspecting the damper for out of balance rotation and nothing, same rough idle problem. He then sprayed the intake and plenum with some fluid and nothing, same idle problem. He went underneath with a big craw bar and wedged it on the back of the engine to lift the engine while in idle, I guess to rule out the possibility of a engine mount gone bad to no avail.

He left with the VIN No. to check the OASIS system to see if there's any other similar incidents and what's the outcome. He feels strongly about the off balance issue. Next step would be to disconnect the Torque Converter from the engine to see if idle returns to normal, but he wants to be sure before we start taking things apart.

This is getting ugly, we'll have to wait and see!

Wow! You've got a real mystery going on. There's not many things that would give a low rpm out-of-balance that wouldn't be even worse at a higher speed.

Bad tensioner resulting in loose cam chain? Something loose on the crank?

??

Good luck.

The engine isn't that bad to rebuild ... then you know for sure. But there are a 1000 other things to do first ....

I've reread this whole thread ... your problem seems to have started when you changed spark cables. I have two suggestions:

1. Again replace your plugs. I'm going to update my tranny/engine thread with what I happened, by chance, to "learn". Read the latest there.

2. Disassemble and inspect the whole upper (and spacer) area of the air intake. Maybe some plastic plenum got cracked, or something, when you were reaching the rear plugs ????

Hey again 12Ounce:
To clear some confusion I'll add that the rough idle started about 1½ months ago, started as a slight engine tremmble and in about a period of 3 weeks progressed to what I could describe best as a bad engine shake/woble. It's also been affected by a shudder or surge (not sure if engine or tranny) at a slight gas pedal depression while cruising.

I immediately thought of a injector plugged or spark plug missing.
Reading so many other posters issues with idle being caused by a bad coil I figured I must had the same problem, so I went ahead and replaced the coil, I figured I should throw the wire set sincew I'll be working around them anyway and it's gatting close to the 60k mark. But the wires and coil didn't fix the problem instead I ended up with a backfire and poor engine performance caused by my own mistake, after taking so many precautions I still ended up crossing 2 wires causing the missfire/backfire which was eventually corrected and bringging me back to square one with the initiall rough idle problem. So again to clear things, the spark cables replacement didn't changed a thing.

Thanks for your suggestions, as I almost did take the whole upper intake out to make sure nothing got screwed, but after putting the old spark plug back on the engine I did inspected all vacuum hoses wire connections and components to be sure I could rule out a leak or a wire fault.

The fact that I never got a CEL, found the engine at a loss of performance and fuel consumption still normal has me confused and at a loss, making me think the engine might not be the culprit here. But then again, I can't be 100% sure!

In another thread, the crank key sheared allowing the crank pulley/balancer to rotate out of proper position. If you ever had the alternator, idler pulley,
or other accessory seize up on you this may have happened. Scan tool will probably not detect, as it senses that timing is correct. While looking at some photo's of 3.8's, it appears that there is a counter balance driven by the camshaft. If the timing chain jumped as was previously suggested, that would also throw the whole works off, including the synchronizer. Maybe 12 ounce could confirm the presence of a counter balance. You would think any out of balance issue would effect the engine at high speeds also.

I do feel it at engine high speed, but not as strong as in the idle to 1500 RPM level, at high speed the engine vibrates as similar as when a tire is off the floor in a jack or something... hard to explain! Something like when you drive over a draw bridge (the kind that you can see thru when looking down), or like a rear wheel drive car with a bad driveshaft joint.

My Tech guy checked the crank pulley balancer last nite and he did mention the possibility of the camshaft counter balance along with a bad torque converter theory.
But as I mentioned before the engine performs as normal, there's no loss of power, no bogging down, tranny shifts as it should and fuel comsumption is average. I would assume a bad timming would throw all kinds of weird behavior, maybe a DTC code as one sensors won't be able to keep up with the other. Well I really don't know what to think anymore, I'll have to wait for his diagnose, I just want to get to the bottom of this!

While I'm throwing some wild guesses out here consider this. On a early 90's Ford Escort a relative owned, the outer pulley of the crank pulley assembly migrated off of its inner hub that was connected to the crankshaft. When looking at a photo of 12ounce's dampner assy, the trigger wheel appears to be attached to the inner hub, the dampner rides on a rubber bushing. If the dampner had some how rotated, this cound throw the engine out of balance. You mentioned pulling the serp belt to rule out any accessories and I assume to check the crank pulley for a wobble. While I don't want to create any unneccesary work on a wild guess, it might be worth pulling the dampner assy and inspecting. Hope you get this one solved soon.

As Cnlk points out, the timing ring is rigidly mounted to the hub so it's not apt to get out of place. But if the belt pulley portion of the balancer slips on its rubber bushing ... will that cause an out-of-balance situation? I don't think so ... the belt pulley portion looks pretty symmetric and balanced to me.

Noticing the rubber was a bit cracked on my unit, I did the following check: After the balancer/pulley was mounted on the crank, but before the heads were mounted; piston #1 was brought to exact top dead center ... and then the marking on the pulley was checked and found to be exactly aligned with the front cover indicator. So that pretty well proves my balancer/pulley has not slipped. Now looking at the photo, one can count 8 teeth from the centermark to the tooth gap. This can be a reference for anyone to use to see if their pulley has slipped or not.

Sounds interesting... but from looking at the picture, isn't the center mark section and the tooth ring screwed together? That would tell me that for the two parts to shift, the screws would either have to break off or come loose.

What I need to figure out is if the center mark and the crank pulley actually shifted from each other, but I don't see anything I could use as a reference point to verify correct allignment.

12Ounce, is there a counter balance of some sort mounted on the damper pulley? If there isn't any, then I would agree with you in not thinking that it will that cause an out-of-balance situation. Also I would assume that for the crank pulley to cause such a wobble/shake/vibration it would be visible if the damper is out of balance, which the Ford tech already checked for.
I'll still run it over my tech guy when he stops again, I havent heard from him

No, the toothed ring is bolted to the hub ... but the massive belt pulley is rubber mounted to the hub .. the two (toothed ring and pulley) are not hard attached to each other. I don't know of any "counter balance" section of the belt pulley ... wish I had another chance to look at one. I may pick up one at a parts counter and take some more photos. I think the idea is to use the rubber mount to isolate the serpertine belt and its loads from the small irregularities of crankshaft rotation ... and vice versa ...helping to smooth out both in the process

There is a counterbalance shaft that is above and driven by the camshaft.

Have you run the engine with the belt off?

I know this thread is getting pretty long quickly, but a few posts back I stated that the Ford Tech friend took the belt off and checked the damper turning and also tried prying the mounts to move the engine from idle to 2000 RPMs to rule out a bad engine mount.
He then took my VIN No to check at the dealer and run an OASIS report to check for other repair with the same problems.

Yep, I have now reread that post.

The only counterbalance shaft I know of is the one I've already mentioned. Lengthwise ... just over the camshaft and revolves the opposite direction.

I continue to recommend opening up the intake and closely inspecting all plastic parts ... holding them up to the Sun, checking for hairline cracks, ... fit of internal horn-manifold ... air flow blockages .... etc. No telling what you might find. After that, I would drop the oil pan for a look-see. After that, the big one ... heads, etc.. ... ... but hopefully you wont get that far before discovering something simple and easy.

I realize that a slipped hub on the crank pulley is unlikely, I thought that the
dampner part of the pulley was constructed in a way as to give some counter balance. I felt the pulley on my 3.8 and it is constructed that way, it is not symetrical. A sheared key is also unlikely but can happen. About the only way to confirm would be to get #1piston at TDC and check alignment of timing mark with pointer that is part of the timing chain cover. Getting the #1 piston at TDC can be a little tricky as the crank will turn of few degrees before and after without the piston moving. I've attempted this by inserting a rod in #1 cyl while turning the crank back and forth and watching the timing marks, not easy to do by yourself. If by chance the key was sheared, then ignition timing would certainly be off. If the dampner portion just rotated, then a possible out of balance condition could be present. In a previous post you mentioned replacing the idler pulley, was the bearing seized? That could possibly have caused something to slip. Seems like you definetly have a unique problem.

The idler pulley felt too loose and wobbly when I did my own pulley check, it didn't seize up on me. But still I decided to replace it, at $15 it wasn't a costly choice and it made me feel better.
So how about the tranny sugestions by my friend? You guys don't think it could be the tranny causing all this? Again fluid is at level and looks/smells good, tranny shifts normal, there's no slippage or hesitation which makes thing harder to diagnose.
Before all this the van used to surge or shudder with a light gas pedal aplied while cruising as posted here many times in other threads. But since I replaced the battery it has not happened again! Other than that and the groanning sound I never was able to fix/get corrected (see thread here) (http://www.automotiveforums.com/vbulletin/showthread.php?t=716386&highlight=ed_strong) everything seems and feels normal with the tranny.

I have a bit more info:

My friend took the van again to look it over and discovered that when he tried to verify if the crankshaft pulley bolt was secured by tightening it, the whole pulley assembly moved so slighly and led him to believe that the pulley has shifted off balance.
He assures to me that the pulley/damper has a counter balance, which could confirm the out of balance vibration if it's shifted out of place.

Problem #1
This darn pulley is $250 at the online Ford Parts (Genuine Ford Parts, Y2K Ford, etc.), Rock Auto doesn't even lists it on their onlie catalog.
He suggest buying one from a junkyard for a fraction of the price, but who knows what I could end up with!

Problem #2
When looking for the price at Team Ford Parts they offer an exploded view of the engine components <<check here>> (http://www.teamfordparts.com/partlocator/index.cfm?action=getJointLocator&siteid=214270&chapter=&Sectionids=10,0&groupid=10012&subgroupid=62097&componentid=0&make=10&model=Windstar&year=2000&graphicID=T027040&callout=29&catalogid=1&displayCatalogid=0) (hope linky works) and it shows the damper pulley as a two piece -Item #30 Pulley and Item #29 Vibration Damper it would be nice if I could just get the Vibration Damper by itself but the online catalog doesn't list it.
On the other hand the exploded view on my Service Information Manual shows it as one whole piece, so I'm not sure what I'm looking at.

Mr. Strong, you might be able to get by without installing a new assy. Pull the old one, maybe the bolt loosened and the key sheared allowing the whole assy to shift out of proper position. If so you could reuse if the bore is still in good condition. While the assy is off compare it to another one (if available) to see if just the dampner portion rotated, in which case a replacement would be necessary.

Last Update:

Just got the van back tonight from the shop. New Crankshaft Pulley/Damper installed, problem solved! No more idle issues... purrrs like a kitten. Wife is happy, and that's all that matters.

Thanks to all that contributed to this thread. I really appreciate all your attention, patience and helpfull suggestions. I hope this can help someone else avoid all the headaches I had to go thru!

I am delighted that your engine runs better, but totally surprised that the crank pulley was the problem ... especially at the relatively low mileage of your vehicle. Thanks for the feedback.

Do you have any suspicions as to what may have caused the pulley to fail? A lot of exposure to oil perhaps? ... road salt? ??? Was the pulley loose on the hub, or had it just slipped?

I am going to be more critical of mine (230kmiles) now, and closely compare it to a new one.