96 Windstar stalls when you...

[Tim the 2Lman]

I'm nesw to this site but have been on some Diesel forums before with a lot of success with fixes. So here is my dilema.

Info. 96 Windstar 3.8 144K miles.
Also note that I've had the luxury,at least for a couple of days of having an identical twin to compare and swap parts with.

Problem goes like so. Customer complains that the van stalls when turning. Well, found out that it requires a special scenario for this to happen. She goes to the store and pulls into a parking spot. Comes back out, starts it up and backs out. As you would usually do, she turns the wheel to go forward along with changing from Reverse to Drive and if she gives it a moderate or as I would call it 'Normal' amount of acceleration, plunk it dies. Only when the van is pretty well warmed up. Also, in my testing, I've noticed that while parked, engine idling and completely warmed up, if I snap the throttle the engine stumbles. This nearly every time. The IAC seems to just slightly over compensate for load such as going from park to reverse or drive. The donar van, same year same everything, runs perfectly (199K miles).

For what I've seen and done:

When I first started, LT FTRM% on bank 1 were running about 12% while LT FTRM on bank 2 were around 0%. I trouble shot for a vacuum and coolant leak and ended up replacing lower intake manifold gaskets as well as all upper intake seals. The EGR ports had already been cleaned out as well as the IAC had been recently replaced. When I got it back together, both LT FTRM's as well as ST FTRM's run at essentially 0%, fluctuating for driving conditions.

With the donar van, I've swapped IAC, EGR, DPFE sensor, all 4 O2 sensors, MAF and IAT sensors. Fuel pressure holds 31lbs until vacuum drops then it shoots up to 40lbs. Never see less than 31lbs. Swapped throttle bodies, which seemed to make the problem a little worse. Checked PCV valve and it's open. I've strapped the IMRC valves to their closed or idle position and thought I had it whooped until a few stops later. Ive replaced the powersteering pump because of loud growling, and as some of you have guessed, it still growls. The only times that I can kill it is related to having it in a faily tight turn. I have killed it a few times while turning the wheel sharply the then punching the gas. This little smiley truely is how I feel. The IAC works seemingly well. Heavy load and snap of the throttle will shut it down. The donar van, with a lot of the old parts from this problem van will not die regardless of what I subject it to.

Sorry for the long post but I thought it might help to regurgitate all that I've done for the past 2 weeks. Please help!

Tim the toolman

[wiswind]

1 thing you might try is a can of Berryman's B-12 Chemtool (metal can) to a tank of fuel.
It is possible that there is some crud needing cleaning in the fuel injectors.
I ran into a nasty misfire code right after my lower intake manifold gasket job.....and thought the worst.....and was advised to do this by my mechanic, and it solved the issue.
The point being, a slight miss, can contribute at these low speed, high load conditions.

My alldata information talks about a power steering pressure switch to help in just the situation you mention.
It even has diagrams and instructions on replacing this switch.
I advised a member about it, and they could not find it, so I drove mine up on ramps and went under with my camera to take pictures.....and found that mine does NOT have one either......so this is a possible dead end in your situation.

Are the tune up items current?
I changed my original spark plugs out at about 135K miles, in spite of my dealership telling me that my engine checked out just fine.
While it was running just fine, I found that the rear plugs had a much wider gap than the front plugs.

It is a LONG shot, but you could try changing the CCRM (I show that in some of my pictures).
This would be relative to the fuel pump, which you indicate is working fine, but the fact that it is giving the problem after the vehicle has been run, and then re-started.....and NOT when they are first manuvering into the parking spot, leads me to think of the moisture problems that the original CCRM had with the fuel pump relay.
FORD came out with a new CCRM with better sealed relays to address that problem.

One other thing, it will take some time for the PCM to relearn the "drivability information" and as such, if this is happening soon after a repair, it may be a result of the PCM not having completed the learning process.

[Tim the 2Lman]

Wiswind, thanks for the input. There are a couple of things that I forgot to put in the orig. post.

While I had the top half of the engine out, I decided that would be the time to change the spark plugs. The first one I pulled out, engine cold, was very resistant which made be nervous. When I got it out, there was a little aluminum in the threads. This almost made me sick. Especially beings it was the firewall side. I got a thread chaser and sent it down the hole several times and was able to re-install a clean plug and tighten down with no problem. I added a little anti-seize just for good measure. I measured the gap on two plugs on opposite sides of the engine and they both looked good and measured in the correct range. No obvious wear.

The other thing I failed to mention is that there are no codes set at all. I also wrote down all the PID information that my scanner can view and compared them between the two vans. Both sets of numbers were basically the same from one to the next.

What does the pressure switch actually do? Does it kill the engine if the fluid pressure drops below a certain level? I could see this with the parking lot scenario but not with the stumbling in park just snapping the throttle open.

I'm kind of thinking out loud here, but what do you think the chances are that the Cat's or one of them is partially plugged, due to long term consumption of antifreeze, creating excessive back-pressure once the engine and the converters are up to operating temp. I was planning on, this morning, heating the van up, duplicating the problem and then, diconnecting the exhaust pipes from the manifolds and retesting. I'll post my findings.

Also, Did I mention that I disconnected all 4 O2 sensors and the problem persisted once the engine was hot? This is telling me something but I haven't put my finger on what yet. This thing has been .

[wiswind]

The power steering pressure switch...which I'll bet you do not have either....maybe it was on some year(s), was to provide input to the computer when the pressure in the power steering system was high.....in the situation of turning the steering wheel in low speed, low idle conditions......just as one does in a parking lot.
The PCM could then bump up the idle speed to prevent the stalling.
Pretty much how the engine behaves when the A/C compressor kicks in.

I don't know about the catalytic converters being clogged.
The test you do with them might help there.
Take the extra step to use a wire to support the flex pipe that is just behind the "Y" pipe assembly so that it is not damaged by hanging all the way down.

Also, it is gonna be real noisey with the cat's off.

[Tim the 2Lman]

Well, I could only get one front-side nut off of the exhaust pipe and only loosen the other. It did allow a pretty good gap between pipe and manifold. The back-side nuts wouldn't budge. They acted like they would twist in two before backing off and I sure don't want that. Of course, I probably could have pulled the O2 sensors off and accomplish the same thing. Miight try that next.

If this van should be equiped with a pressure switch on the PS, do you know approximately where it would be?

The one test I've been using, as to a fix or not, is to start the engine, let it idle down completely and then snap the throttle. The result is a pause or as I characterize it, a stumble or drop in RPM's. The other van, no matter how hard I tried, would not pause or stumble. It did seem to react to the snap more slowly that this one does. But still, it never even remotely paused, the rpm's never dropped as a result of the snap test, nothing. It just raised the rpm's somewhat. When I say I snap the throttle, I only open it about 25% and is open less than a half second. I do know this. The RPM's have to be low around the 700 rpm level for this to happen. If the IAC is compensating at all, it never stumbles.

[12Ounce]

If neither vehicle has codes ... I'd be temped to change controllers. An easy job on my '99, but I don't know about your model.

I suspect donor vehicle controller to have a dealer installed change.

[wiswind]

The alldata manual for the '96 windstar shows the power steering switch to be on the steering rack, right where the high pressure line goes in.
I only mentioned it because, if you are using the same documentation, or if it is mentioned in your documentation, it could send you on a search for something that is not there.

Much of the response to the quick press and release of the throttle will be control by the PCM, and the drivability information that I mentioned will be a factor in this response.
You are also correct in that the IAC will be operating here to control the idle speed.......in response to control from the PCM.

As a long shot, you might try taking some voltage measurements, comparing what you get from problem vehicle with what you get on the good one, just in case there is a poor electrical connection in the mix.
Measure at the battery, under a few operating conditions, and do the same at some other "hot" point in the electrical system.
Also check the battery voltage, with the engine OFF.....as a battery that is charging will place an additional load on the engine.

If you have a fuel pressure gauge, you could try measuring the fuel pressure at the fuel rail, and see how that compares with the known good vehicle.

[Tim the 2Lman]

Wiswind,

Both vans run 32lbs at idle and 40lbs with a vacuum drop like snapping the throttle or pulling the vacuum line to the regulator.

This van has had some battery and alternator probs. in the not so distant past. I took care of these as well. The battery would intermittantly short internally and then would normalize. I finally caught it in the act and replaced it. However, the overload on the alternator caused it to fail within a couple weeks after that. It has been fine since that with the exception of the problem described in this post.

As to whether or not this problem pre-existed the battery/alternator failures, I don't know......yet. I'm having to give it a couple day break so as to generate some real revenue but will get back on it as soon as I get the donor van back.

PCM was a question in my mind too. It almost acts like the timing is way out of whack when the throttle is snapped. I'll try that in a couple days also.

Thanks for your input and keep'er comin'.

[Tim the 2Lman]

I took the intake plenum off and rechecked the EGR ports. They are wide open. I also took out the temp sensors and cleaned them thoroughly.

Bottom line... No change. Oh my head.

[wiswind]

It is so hard when there is no CEL / Codes.
Do check to see if the CEL comes on when you first turn the key to the ON position, but have not started the engine.....just in case it is burned out.


The other thing that I would recommend, as it seems from your description that the van runs OK.....take it for a nice drive......
If you can do a nice long drive, say in a circle, so you are not far from home if something should go wrong...... I think it would be a help.
I am talking about AT LEAST 30 minutes.
Even longer would be good.
Interstate driving would be best....

1. It gets the vehicle up to temps and works pockets of moisture, and cleaner.....etc out of the system.

2. It will give the PCM the chance to learn the "drivability" information.

3. It will give the opportunity for the vehicle to be under actual operating conditions for a while.....which will activate systems that are not operating at idle.....such as the EGR system.....
As such....you may get a CEL that will help you troubleshoot to the actual cause of the problem.......or...maybe, it will simply go away with the combination of all 3 reasons.

[busboy4]

Hi Tim

Just joining you on "thinking out loud". The only item in fuel/air delivery I have not heard you talk about is the throttle position sensor. I realize it can throw check engine codes, and has not. But, since you are swapping out parts with your "donor", why not?

Good luck

[Tim the 2Lman]

Thanks, guys. That's good input. Unfortunately, that has all been addressed. I took it on a 3 hour drive. No change. If anything stumbling was a little bit worse although I could have been imagining it. As far as the TPS, that was swapped out between donor van and this one when I did the throttle body. I've watched both of them pretty closely with the scanner for sudden jumps but there were none.

Hopefully, I can get the donor van back again today and compare a few other things. Thanks again. If you think of anything else, please don't hesitate to ask. It seems when I start with the KISS principle it ends up being complicated. Or even worse, and this just happened this past fall, it's more simple than I could have imagined. I'm trying not to assume anything, but check and recheck everything.

[Ian Szgatti]

have you installed a new fuel filter? your van really should have thrown some kind of code because I'm sure you have had it through at least 20 drive cycles... and intermitten codes would by now surely have shown up as hard codes if the problem has been persistant.
just as a though here... fuel pumps don't alway just die when they're done, they do loose efficiancy...

you know though, the symptoms you described are really a lot like that DPFE problem... I can see the other posters concerns about PCM re-learn, but it bothers me again that you have no MIL.

I also see the validity of the power-steering switch idea, if that is, you have one... a fault like that may not throw a MIL...

As far as you back-pressure, it's entirely possible that you contaminated and destroyed the catalyst and melted the thing causing a blockage... but if you have pre and post cat O2 sensors, you again would have a MIL. Keep us posted. I think you have a fuel delivery problem caused by either an old fuel filter or a worn out fuel pump/pick-up screen...

[Tim the 2Lman]

Well, here is a long awaited update. Still no fix and it will probably go home to the owner today or tomorrow. I got donor van back, spent a 10 hour day with it last Friday and here's what I did:

New fuel filter- no change.
Did find that CAM PS was out of time compared to donor - still no fix

Swapped the following with no change what-so-ever:

Upper intake w/ throttle body and MAF and filter.
Fuel rail w/ regulator and injectors
Engine wiring harness
EECM
All spark plugs and wires
Coil pack
Cam PS
Crank PS
All four O2 sensors

Check fuel pressure and tested the throttle snap with max pressure. (40psi) and still no affect after filter replacement. Bottom line is this. Someone correct me if I'm wrong, but, if the fuel pump had flow problems, it would most definitely show up in the fuel pressure readings. If the pump couldn't muster the flow, the pressure would never come up or at least drop off when throttle is snapped. However, the pressure snaps up from 30psi to 40psi on throttle snap test. Compared timing between donor and problem van. They are running the same. Checked the timing ring on the harmonic balancer, they are both the same. Ran it with out the belt to eliminate AC noise from the alternator and reduce load on the engine. It still hesitates. Put most everything from the bad van on the donor van and it works perfectly. Pulled both O2 sensors just out of the manifold to relieve back-pressure in the exhaust, no change. Pulled each vacuum line from the each port and plugged it with no change. My gut tells me that when I find it, I'll know immediately because the hesitation is present at cold startup, hot run and everywhere in between, whether EECM is re-training or not. The rpm's have to be completely settled out at around 700 to reproduce the problem. The donor van works perfectly with in re-train mode or not and even with the EECM from the problem van, it works perfectly. The airflow out of the exhaust seems to be the same as well. Ran compression tests on both vans and the bad van actually tested a little better but basically the same. All cyl's were between 200psi and 210psi. I don't know what else to do. Dare I pay a dealer to fully test this thing out?

Ps- To add insult to injury, when I was swapping the crank sensors around I found out that the bad van's engine front cover is leaking as well. My gut tells me to replace the entire engine but I know the owners are not going to want to do that. They will probably replace the thing. Probably the best choice from what I can see. Any thoughts?

[12Ounce]

I agree with Ian's thought path. "Snapping" the throttle at idle does not equate to a loaded engine.

Fuel pump and fuel filter (including the one on the pump itself) would be my guess.

Reading fuel pressure can lead to "analysis paralysis" ... unless you can hook up the guage in such a fashion so that you read pressure while actually driving and accelerating.