Idle Problems At My Wits End

Been working on a car from a used car lot it's a 99 Windstar 3.8L So FAR I have done the upgrade on the lower intake insultators, the new valve cover, new vaccum lines, cleaned the IAC, and in other, I think, unrelated problems, I have replaced the power steering pump, brake booster and master Cylinder. Although oil contamination of the brake system did cross my mind? Now When I pull up to a stop light the van stops as it should and then the idle begins to bounce and drop down to like 400-500 range. At this point I usually throw it into Neutral and it levels right back off and is fine again? Once when idling and checking fluids the van did stall out completely in park. But it fired right back up and has not done it again. I am not sure what else could be causing this. I do have a check engine light back on but have not pulled the codes yet. The only other thing I have on my list is the IMRC is missing one of the metal rods. I have the clips just need to get to a bone yard and grab the rods. Are they the same front and back or different? The front rod is hoooked up and the rear is not, would that make a difference?

Thanks in Advance for any help or suggestions!!! Rich

The first thing that I would do is get the IMRC situation corrected.
The IMRC on your 1999 is driven by a electrical unit....on my '96 each bank has its own vaccum actuator.....so I am not experienced with your setup.
However, when 1 bank is open and the other bank is closed......it leaves you with a imballance between the front and rear banks......which the PCM has to struggle to deal with.

Other things to look for would be any disconnected or damaged vaccum lines.
As you know, there are a number of vaccum lines that connect to the back side of the upper intake manifold.....and then various "T" connections here and there.
A vaccum leak is likely to show up more at idle....as the vaccum is higher (more flow through a leak) and the RPMs are lower (so any roughness is more noticable).

Lower down on the list would be the IAC (that you already cleaned) and the DPFE (measures the EGR flow).
The DPFE would be low unless you get a P040x code (a code indicating a EGR flow problem).

But, as I said....correct what you know is wrong, and see what you have from there.
I would correct the IMRC problem.....see if the problem is solved......
If you still have a problem, clear the code(s) and drive......seeing if the Check Engine Light comes back on.....and then get the code(s) read again.
Point being.....you want to view only codes that happen after your IMRC repair (codes are stored for a while after the problem is solved).

Took the van to the Ford Dealer and they told me and I quote Don't worry about the IMRC they are not fixing them anymore either, they are simply zip tying them open to the holes in the gaskets. They diagnosed it as the intake gaskets all the way down at the heads. So I pulled it all apart and did the new gaskets, as well as replaced all the stuff that I had just done with the new stuff that came in the set. I was amazed that the new PCV valve is still allowing oil to come through into the intake and the van was only driven 65 miles since it was all done? I took apart the PVC hose and put in a old style chevy PCV Valve and chrome breather, and then attached the hose to the intake thinking it would help out but it did not do anything to stop the flow?

Anyway all said and done the power steering is getting quieter, and the van all back together with all new gaskets from the heads up went only 13 miles before tossing up the same codes. I am thinking now that it has to be a vacuum line and I guess my question would be is it possible that the leak is inside the van???

Customer is getting pissy now and wants the van back. Inspection in PA doesn't allow for an OBD2 to pass with any emissions related codes, normally. We are looking into getting a WAIVER for this year since we have more than surpassed the threshold for trying to get it too pass. But I still think it is something small and stupid and would be an easy fix.

Just for kicks why don't you plugged off all vacuum going to the car ... the firewall vacuum manifold and the brake booster ... and see what happens. Don't forget that you won't have much braking during this test .... ??

I agree with the dealer on the IMRC ... tho I don't know if I would use that particular "solution". BTW, the link rods (front and rear) are quite different in shape.

Why are you concerned about oil from the crankcase? It normal ... tho folks don't want to believe it. Its just a shame the intake manifold does such a poor job of passing this oil on into the combustion chamber. ( I redesigned mine so that it does just that! But that's another story ... and won't be understood by many.)

Anyway all said and done the power steering is getting quieter, and the van all back together with all new gaskets from the heads up went only 13 miles before tossing up the same codes. I am thinking now that it has to be a vacuum line and I guess my question would be is it possible that the leak is inside the van???

Customer is getting pissy now and wants the van back. Inspection in PA doesn't allow for an OBD2 to pass with any emissions related codes, normally. We are looking into getting a WAIVER for this year since we have more than surpassed the threshold for trying to get it too pass. But I still think it is something small and stupid and would be an easy fix.

Originally you posted that you hadn't pulled the codes yet and now you state that the same code came up again. I am confused. If you have the IMRC rod still missing, you will definitely set a CEL code, mine was P1518 but I had the front rod of the IMRC dangling loose and yours is the rear one. I replaced the white nylon bushing, snapped the rod back in and drove the car for about 25 miles before the CEL went out and has stayed out for a week now. As a note, I had no driveability issues or idle problems while the IMRC rod was unhooked.

The only codes this thing have ever thrown out are P0171 and P0174, lean codes. Last I pulled other plugs off just to see if I got any other codes? It did seem to idle better with the fuel pressure vacuum line plugged with my finger?

If it's lean then too much air or not enough fuel.

Fuel pressure?

I have a vague recollection that I once (about 6 years ago) had to replace a runner control motor due to those codes, but I don't remember now.

You had the upper manifold off, so I would assume you checked and cleaned the EGR ports. This probably wouldn't throw a lean code anyway, but it's a common "maintainance" issue that I address once every two or three years.

O2 sensors read the absence of oxygen compared to the outside air. Lean indicates too much oxygen in the exhaust, so bad O2 sensor (with low voltage output) could be the cause. I'd pull and clean the upstream sensors. The outside needs to be clear of any grime, because air needs to get inside the sensor for an accurate measurement. The inside can get coated with combustion deposits. I've cleaned them with a propane torch on the business end until they are red hot to burn off any deposits. You can also check for basic operation with a voltmeter on the sensor wires at the same time.

Of course, as mentioned, any vacuum leak (gaskets and lines) will lead to lean codes. It sounds like you've done a lot to try to get any vacuum problems, but it's still a possiblity.

I recently replaced my idle air control due to high idle and erratic idle-I also had been having a problem with the engine racing when you turned the steering wheel, I thought I needed a power steering pressure switch to cure that. long story short I cleaned the iac several times with no result-changed the iac and all the problems went away. No more racing when turning, no more erratic idle, and as a bonus almost 500 miles on the last full tank.(used to barely get 400 miles to a tank)
you might want to give it a try
best of luck,
Don

well...if one is going to fasten the IMRC in one position....I would fasten it CLOSED, not open.
Open is to give you a boost (more power) under hard accelleration.
Stuck open will give you low RPM issues.....and pinging.
FORD issued a TSB about the broken IMRC links causing pinging.

I may be wrong, but I think that you can disconnect them, fasten them closed....and the electric actuator will move back and forth.......and the PCM will think that they are opening and closing......when they are not.
This would work for 1999 and newer.
My 1996 has the vaccum actuators.....1 per bank.....and the sensor is inside the actuator unit......springs in the IMRC pull and hold them open....and the actuator pulls and holds them closed.....so it is harder to fool the PCM.

Wisconsin is the same with the OBDII inspection......I used to live in PA, and prefer having the safety inspection.....here in Wisconsin....the wheels can practically be falling off the car.....but all that is inspected is the emission.....fuel cap, OBDII, and a mirror under the vehicle to see if you have removed the Catalytic converters.

It is a real pain when you get the P0171 / 174 codes.....as there are so many possible causes.....the most common is a vaccum leak.
The oxygen sensor almost never cause this code on the Windstar.
The PCM monitors the oxygen sensor closely....and there are a lot of codes to cover the various ways that a oxygen sensor can fail.
So.....the oxygen sensor is almost CERTAINLY reporting the correct information....that there is truely a lean condition.

As far as the PCV, it is NORMAL for some oil vapor to be drawn into the intake.
The upper intake manifold seems to have a lot of little places for this oil vapor to condense.....and pool.
You don't want to reduce the amount of air being drawn out of the crankcase....as a healthy draw (but not more than FORD designed) is critical to drawing off contaminates in the crankcase.....preventing oil break down....and sludge....among other bad things.
I DO recommend that a Genuine FORD/Motorcraft PCV valve be used, as the PCV valve is more than just a check valve (as I used to believe), it actually meters the flow.....
The PCV valve has a spring inside.....and when the vaccum increases (at idle) the opening is made smaller.....and at less vaccum, the opening is bigger....providing a even flow out of the crankcase.
I added a Greddy Catch can to my windstar....shown in the pictures that the link in my signature takes you to.
I get a LOT of fluid in the cold winter.....not very much in the hot summer.
It has a big "dead air" space....which provides opportunity for the vapor to settle out into liquid......and stay in the container.
I am hoping that this will keep my EGR ports and fuel injector ends cleaner for longer.

For the Breather end.....on your 1999 in the rear valve cover.....make sure that the air that goes into this is through the tube from the big flex hose that is in between the air filter and throttle body.
With this setup...the air that enters the crankcase to replace the air that has come out through the PCV line.....has already passed through the MAF.....so the PCM has a measurement of this air.
If you draw the air from another source......then this would be air entering the system that the PCM does not know about....which is the same as a vaccum leak.

The TSB for the 1999 and some newer years....where you replace the isolator bolts for the upper intake manifold mentions something about that vaccum line to the fuel pressure regulator.......in short....make sure that that line is not cracked.....broken....and that it fits tightly onto the pressure regulator.
If it fits on real loose....you have found a vaccum leak.

Ok. An update on the whole deal!

We have takent the van back to the dealer to have it reflashed. And at the time, the SAME guy then tells us that we really should replace all the IMRC stuff? After telling us not to worry about it a week before.

So I cut off the bands I had holding IMRC open and shut them. Ford reflashed the van and told us that they took the time to download the newest version of the reflash which appearantly was just issued late last week???

The van seems to run much better now, but is still not perfect. Still idles rough when stopped in gear. Clears right up as soon as you put it in park or neutral? The van did manage this time to make it 35 miles without blowing an codes which should be enough for the state required drive cycle.

The "drive cycle" is required by the vehicle ... to do the necessary "relearning". 35 miles may be enough ... if everything is near perfect on the vehicle ... and the 35 miles includes all the drive conditions necessary for testing. I allow 150+ miles of all around driving to make sure all conditions are met.

I agree with having the IMRC shut ... that's the way they are by design until the engine passes 2500rpm, or so, .... how often does that happen? Just leave the links off the motor and you will be just fine. Just make sure you know which way "shut" is.

Up until the vehicle has run the required "full test" cycle, you will have a code stored....I think it is P1000.
That tells them that the full test cycle has not run.....the vehicle has to go through a variety of different situations........so the time will vary......a few hours sitting at idle in the driveway most likely will not do it....driving down the road.......stop and go lights, etc is what is needed.
From what I read.....the test that takes the longest is the downstream oxygen sensors (catalyst monitor).
I understand that it can be frustrating trying to track down a problem......and it certainly does not help to get conflicting information from the same expert.