Drop in revs causes engine to stall (details within)

Ive been told this forum is the place to get answers - so here i go -

My wife has a 1998 Windstar 3.0

Prior to going out yesterday, I noticed that the van seemed kind of 'jumpy' when idling - the timing was a bit sticky and inconsistent and kept seeming to try and right itself. I stuck the accelerator down and it ran perfect when it was getting gas but started 'stagering' again when I took it off.

So my wife went out to walmart - a 30 min drive (we are in the country) - and all was good till she was turning the corner into the parking lot and the engine stalled. It was your standard stall - power steering went out but all other electrics kept going etc etc.

She sat there for a minute - put it in park - then fired it right back up again. After running into walmart, she just drove home as fast as possible to reduce the length of time it had to happen again.....

So while there are, Im sure, a plethora of possible issues - I was wondering about the IAC value? How could that be responsible for the parking lot though - doesn't it only act when the car is stationary?

The sort of thing was happening about 3 months ago, and I ran seafoam through the fuel - which seemed to help for a while.

Any thoughts are much appreciated - This car needs to be ready for a road trip at the end of the month so the clock is ticking.....

IAC is generally easy to check. Just remove the connector and the 2 bolts and see if the flap moves freely and that the spring is working. I suppose the electronic portion could fail as well, but this honestly wouldn't be my first guess. Is there a check engine light?

I strongly suggest checking the coil pack first and foremost. That seems to be the #1 cause of these types of failures if you read through the history of this board. Remove it and look for a hairline crack on the back. Even a tiny crack can cause some arcing and will result in frustrating symptoms like this. If it's been a while, change the wires as well (and may as well do the spark plugs if they're old, too..)

the check engine light has been on forever. I thought that was just standard with cars of this age ;) But for sure I think Im going to have a look.

The coil pack also seems a possible suspect - my we have only had this a little over a year, and judging by the state of other areas of the van, it was not the best kept. Who know how long this has been a problem.

Before doing anything, hook up a scanner and post back here all the codes. That's by far the best information available. If you don't have one, drop by any auto parts store and just ask and they'll scan it for you and tell you the codes for free.

Let us know the codes and we'll go from there.

I'm with scubacat, the check engine light is trying to tell you where to look. That information is worth a thousand posts. Stop at Autozone or another good auto-parts store who will read them for you, then post the results.

If I were to guess without information than you've posted, I'd also look at the EGR ports under the upper intake manifold. They can get clogged with condensed carbon material, and the engine will run rough at lower RPMs and lower RPM loads (like gradual acceleration or cruising). They are almost "free" to check and if they've never been cleaned they probably need it since most Windstar's see this occur after about 100k miles, then every 50k after that (depending on engine condition).

While the coil pack can cause misfire issues (just as scubacat says), the problem is that it's a fairly pricey component and there is almost no way for us average guys to check a pack for the problem that would cause this. You have to replace it and hope that it cures the problem. One symptom that will help know if this the problem is that you should see misfires on the two cylinders that are run from one of the coils (there are three coils and each one runs two cylinders, so both of the cylinders on one coil should have misfire codes, such as P030x).

I generally only replace components that I can't confirm as bad after I'm satisfied that I've eliminated the causes that I can check and confirm. Of course, that's me emphasizing the monetary costs over the time costs.

thanks guys for you help.

Ive not been able to get anywhere with the van that I can get the codes read. Its still not reliable.

Since I last posted I have changed the coil pack and cleaned out the IAC valve.

Took it for a test run yesterday and it started fine. On the way back it died on me. I got it going again eventually with foot to the floor / engine about to explode. I then had to 'fly' back to the house - the resulting wheel spin digging holes in the gravel road.

Now the thing is - I was starting to wonder about the fuel pump. The car has 200k+ miles on it, and to the best of my knowledge its still the first pump. So when it stalled I tried the old "whacking the gas tank" trick. It didnt make a difference - besides - and please tell me if this is normal - I always here the pump kick in when I turn the key. Its at least getting the pressure up in preparation? would that be normal if it was dying? surely not if it was dead?

It would appear to be a filter issue more than a pump one.

Sadly, I have a road trip to KS on Wednesday night. i was originally going to to go in my Geo Metro, but Ive driven that engine into the ground. The Windstar was my fallback plan. It looks now like Im going to have to use my E350 Bus. Yeah - 10 miles to the gallon......

The best advice I can offer, regarding the fuel pump, is the same: get the codes scanned first. The fuel pump is an annoying job, so you certainly don't want to go there unless you have some hard evidence of that problem. Heck, there could be a fuel pressure code waiting for you!

You might consider getting a cheap code scanner of your own, especially with multiple older vehicles. Any OBD-II scanner will read codes from vehicles 1996 and newer. I have a couple, myself, and they're endlessly useful.

https://www.amazon.com/Autel-MaxiScan-MS309-OBD-II-Reader/dp/B007JSGR9Y/ref=as_sl_pc_ss_til?tag=scubacat-20
(https://www.amazon.com/Autel-MaxiScan-MS309-OBD-II-Reader/dp/B007JSGR9Y/ref=as_sl_pc_ss_til?tag=scubacat-20)

The low RPM & stalling is most often caused by the IAC....(Idle Air Control) valve.....
Use some lubricant like SeaFoam Deep Creep.....sold and many auto part stores.
The IAC is controlled by the computer (PCM). When your foot is not on the accelerator and your RPMs drop below a certain level....the computer will drive the IAC to open a air passage to maintain the correct RPMS, preventing the engine from stalling.
Inside the IAC assembly is a small motor that drives a "worm gear" which is like a screw.......onto which is mounted a sleeve that moves back and forth as the motor turns the screw back and forth.......THIS sleeve is connected to the little "throttle plate" inside the IAC assembly that opens and closes as the sleeve moves back and forth.
Dirt builds up on the threads of that screw.....and you need to clean (as you have) and lubricate this.

If this does not work.......the IAC will need to be replaced.

Again, I have babbled on about this because it is a very common issue (my Toyota Sienna has the same issue.....and I have to spray the SeaFoam Deep Creep into mine...from time to time.....just like I did on my Windstar).

The advice on getting the codes read is spot on.
Most auto part stores will do this for you for FREE.
Make SURE to ask them for the actual codes.......not just "misfire" but the P030x code.
With the code(s), you will be able to diagnose the issue.

Please note.....you mention that you have a 3.0L engine.......MOST Windstars were built with the 3.8L engine....and you do NOT have many of the issues that the 3.8L engine had.

The Upper manifold bolt issues that have many posts on here do NOT apply to you for 2 reasons.....
First.....that issue was with 1999 and NEWER ONLY.
Second....You don't have the same type of upper intake manifold with your 3.0L as the 3.8L had (you don't have the IMRC plates, actuators, etc associated with the dual intake ports that were NOT on the 3.0L engine.)


Getting a OBDII reader is a very good idea.
I have one of the original ScanGauge brand readers......the newer ScanGauge unit is much better vs my old one.
Recently, I bought a "OBDLINK" unit on Amazon (regular price is $99).
This unit connects to Android and Windows devices via Blue Tooth and gives me MANY more options for data.
Both of these units get good reviews and are not expensive.
However......the auto part store reading is available in most places in the USA for FREE.

Getting the code(s) will help get you to the issue without throwing parts (and $$$) at the situation.
Take note that 1 simple problem can cause MANY failure codes to show up....so don't panic if you see multiple codes.

Fuel Filter......This should be located under the vehicle....just forward of the rear, driver's side, wheel.
The 1998 Windstar does NOT have sensors that monitor the fuel pressure or fuel flow.
Some OBDII devices will give a fuel flow value, but that is a calculated value based upon other data......primarily the air flow through the intake.

you guys are all so helpful!

Well, I changed the fuel filter. No difference really. If anything it might be worse?!
I left it running - struggling more like - for about 10 mins - then tried to drive it. I could not get it to accelerate unless I floored it. At this point I really dont think I can 'call' it without the codes. Seems to me it could just as easily be bad leads or plugs....

Yes, a code reader is not too expensive, <$50, and worth every penny.

Regarding the fuel pump... if you have a bad fuel pump (which located in the fuel tank), you'll probably won't have a directly related code b/c the Windstar PCM doesn't monitor fuel pressure. The first thing to check is fuel pressure when it stalls. I had a bad fuel pump last year and found that there was almost no pressure on the fuel rail when it wouldn't start, and it never came back once I bled off the pressure. You might get misfire codes for a bad fuel pump.. I've seen that when I've run the van low on fuel, so I think you'd get the same thing. I had no codes when my fuel pump when bad. In my case, the failure was in the electric motor... when the van was running everything was fine, but when it was stopped then it would have trouble getting restarted. If the pump was bumped then the motor would start to run and everything was fine until the van was shut down again. You might have a different failure mechanism than this, so your symptoms could be different, but all fuel pump problem result in low fuel pressure at the engine.