01 Winstar with studder at idle

Hi,

This is my first posting at this forum. I wanted to run something past you and let you know what brought me to this site.
First thanks for all the information so far that I have been able to learn about Windstars. We have 3 Windstars. A 2003 SE with 60K miles, a recently purchases '01 LX with 87K miles, and a '00 LX with 147K miles. The '00 LX we have had over 3 years and runs good for its age and miles but it is showing it age.
What brings me here though is our recently purchased '01 LX. The dealer let me bring it home before we bought it and I drove about 70 miles. It drove, ran, and shifted great. The best part is the body has almost no rust which is one the big problems with the '00 LX. So we went ahead and purchased the '01. It had about half a tank of fuel when we first brought it home so we kept driving it until we used up that tank of gas. The problems started when we filled up with the new tank of 87 octane gasohol. We put a couple of gallons in because it was below "E" but we need to get somewhere. After that I noticed a little studder at idle if we sat at a stoplight for more than a few seconds. So later that day we bought a bottle of Slick 50 fuel injector cleaner and filled the tank. We if anything it got worse. The engine has good power at highway speeds, probably more power than the other 2 Windstars, but at idle no matter if it is cold or warmed up it wants to studder ever few seconds. It isn't a steady pattern but it is persistent. Now I have been able to drive it enough to get that tank of fuel used up so I don't know what would happen if I filled up at a different station. I am hoping that will help since it was doing so well when we bought it.

So I wanted to run a couple of possibilities by you.

1. We just got some bad gas and things will clear up with good fuel.
2 We sucked the fuel filter full of junk by letting the tank get so low and then putting fuel injector cleaner in the tank.
3. We have a vacuum leak somewhere that is confusing the computer since the MAF sensor isn't registering all the air that is going into the engine.

I did try cleaning the IAC and it looked fine, probably too clean. Like maybe someone else had already tried that.

Here is the biggie. I noticed if I pulled the wire off the IAC that the idle speed dropped but the engine kept running. I tried that same thing on the '00 LX and I couldn't plug the IAC back in quick enough to keep it from dying. That tells me the '01 is getting almost enough air at idle to keep it running even without the IAC open. That smells of vacuum leak!

I replaced the PCV valve too but that didn't help. I also found the vacuum hose that goes to the EVAP is very soft and could be sucking itself shut. My local dealer should have one for me tomorrow.
Another item I learned here is that we do have the older metal DPFE. I may endup replacing that too.
I did take the EGR valve loose to look inside too see how much carbon was in it. It didn't look too bad. I didn't take it completely loose because I ran out of time. I should probably go back and revisit this. I keep remembering my 83 T-Bird with a 302 that I had to take the EGR valve off of about ever 5,000 miles because carbon would get it stuck open. The problem is it has been 20 years since I had that car and I don't remember if the symptom was rough idle....

I guess what's throwing me is my gut tells me there is a vacuum leak but how did we drive it 150 miles on that first tank of fuel without a hint of a problem and now it studders every time it is idling? Should I try some Seafoam in the next tank full? Should I switch to a brand name station like "BP". I also saw the suggestion to spray something carb cleaner around and find where any areas that cause the RPMs to change, but doesn't this kind of make a mess?

The last thing I just thought of, could it be something like the vacuum booster for the brakes? The brakes work fine but that is a large vacuum line going to it so plenty of opportunity for lots of air.

Thanks in advance,
Bob

At the top of the forum page is a sticky post about a TSB (Technical Service Bulletin) that talks about a problem with 1999 and newer windstars with the isolator bolts having the "isolator" break down from exposure to oil.
This causes a problem with vaccum leaks....and can cause problems.
The TSB also talks about the DPFE.

The EGR valve is pretty reliable on the windstar.

The IAC is a mini accellerator.......controlled by the PCM.
This is how the PCM maintains the idle speed under varying loads when your foot is not on the accellerator.
This can stick.....and cause stalling issues when turning the steering wheel during parking manuvers....and such.
So...I do not think that this is your problem.

Another thing to look at is the IMRC ( Intake Manifold Runner Control).
This will be on the passenger end of the lower intake manifold.
There will be a acctuator that connects to 2 shafts......1 shaft in each bank of the lower intake manifold.
On this shaft are plates or "butterflies"....that open and close a 2nd port for each cylinder.
On the newer windstars (1999 and newer) these are electrically driven.....and the problem that comes up is that the nylon clips that connect the shafts to the actuator break....fall off...or otherwise become disconnected.
Sometimes one side is connected and the other side is not....which will cause a imballance condition between the front and rear banks of 3 cylinders.
Unfortunately all my pictures are of my '96....which has the older vaccum actuated version.....

For a fuel system cleaner....I have tried MANY and the one that works best for me is Berryman's B-12 Chemtool in the metal can.

There are numerous things to check out for sure. I will throw in my two bits as well. Although I have heard numerous times that the EGR valves are reliable, it doesn't men that you don't have a problem so you may have the EGR valve stuck open a little which would cause rough idle, but if open enough, you will stall so this is a bit of a long shot. I would test the DPFE. Check the REF voltage out from the sensor and see what you get at idle. It should stay constant. Not sure what the Ford sensor will register, but it should be similar to after market units. On my 01 I have the older style DPFE which does NOT mount on the manifold, but right on top of the exhaust line connection with short rubber hoses. WhenI am at idle with a new aftermarket unit, I get 1.0 volts. If you can get another vacuum line from the manifold temporarily over to the EGR valve, connect it while idling and you SHOULD stall. While connecting it, keep testing the voltage on the DPFE, it should vary up as the vacuum is applied. If it is stuck at any fixed amount, the DPFE is bad. This may or may not be the issue, but at least you can eliminate it as being the problem. I agree with WISWIND about the injector cleaner. Put a few bottle through. Maybe afterwards if nothing has improved, you want to pull and test them to confirm they are spraying correctly? Also, if you haven't completed the EGR manifold gasket repair (P0174 code) you should and when you are in there, you can clean the ports out. If you do have a significant leak, then it would seem to me that you would idle rough. When I did the repair, I had no idication of any running problem except the the CEL came on and my brother-in-law told me about the fix from this web page. After the repair, the van ran smoother, the fuel mileage went way up and I learned a whole bunch about how to fix my van myself! Good luck.

If you need instructions on how to take stuff apart, just ask. Lots of us have pictures from taking things apart and lots of us have the Ford manuals. I have it on DVD and can send out things electronically if need be....

Well I am about 2/3 of the way through a new tank of gas with Berryman's B-12 Chemtool. The studder is getting much less noticable. Sometimes when I stop at a stop sign or traffic light it doesn't studder at all. I may go for a second can if it is still doing it when this tank of gas is gone. So maybe there is hope that I won't have to do a major intake teardown, at least not right away.

I did get the bad vacuum hose that goes to the EVAP replaced. It didn't seem to make much difference but it wasn't helping any either.

Thanks for your help!!

Don't you have a 30 day lemon law your way? I thought it might be Federal. If so, you should be able to take it back within 30 days of buying it if it is having problems. Unfortunately, since you fiddled with it, and if the dealer figures that out, they may be unwilling to take much time fixing it. Good luck.