1998 3.8l Windstar

jwebb37 · #1 03-11-2009, 06:06 PM

My windstar, at idle, is kind of sputtery acting like it wants to cut off. It actually has cut off once when I was at an ATM. When I accelerate it does fine. I checked the ohms on the IAC and it was normal.(10.5) The check engine light is not on so I am assuming there are not any codes. Can you test the MAF or the o2 sensor like you do the IAC? Any other thoughts? TIA!

tripletdaddy · #2 03-12-2009, 02:19 AM

Just check or change the basics - plugs, wires, coil, fuel filter, air filter so that you know what you're starting with if you need to investigate deeper. Problem with these computerized ignition systems, they can compensate for conditions so bad, you wouldn't know there may be a problem starting like the old systems.

Freakzilla69 · #3 03-12-2009, 08:22 AM

You can clean the MAF sensor with non-residue electronics cleaner, there's a tutorial on here somewhere. Check the Throttle Position Sensor, too. Might also want to try spraying some intake cleaner through the throttle body.

northern piper · #4 03-12-2009, 08:49 AM

include with the basics all vac lines, particularly the fuel regulator (upside down "U" line). I had this one come loose on my van and it caused symptoms as you've described. Check out this pic http://img222.imageshack.us/img222/2957/img1414newlabkm2.jpg.

Freakzilla69 · #5 03-12-2009, 11:38 AM

Quote:

Originally Posted by northern piper

include with the basics all vac lines, particularly the fuel regulator (upside down "U" line). I had this one come loose on my van and it caused symptoms as you've described. Check out this pic http://img222.imageshack.us/img222/2...newlabkm2.jpg.

Is that a '98?

I ask because I notice a couple of differences in mine...

1. Your PCV valve is on the front valve cover? Mine is on the back. Should it be? Should I have one on both? If that has been my problem this whole time I'm going to drive it over a cliff.

2. Your upper air intake and FPR vacuum hose are different.

northern piper · #6 03-12-2009, 12:16 PM

sorry, forgot to mention the 2000 vs 1998 differences. Your van may be different yes. Point being, check all vac lines. Sorry for any confusion.

P

jwebb37 · #7 03-12-2009, 04:22 PM

Thanks, I will check those things. Also the cutting off has started to get worse.

wiswind · #8 03-12-2009, 10:57 PM

1998 has the PCV valve in the rear valve cover.
The front valve cover has the "breather" that has a hard black plastic line that goes to the back side of the big flex line that is between the air filter/MAF tube and the throttle body.

IAC has a motor in it that drives a small opening to permit more/less air into the intake......a way for the PCM to control the idle speed.
It can get dirty....and stick......so cleaing is the first step to take in fixing it.
Common failure mode for this is stalling when you have your foot off the accellerator.....like when pulling up to a stop light......in parking lots (turning steering wheel at idle makes it worse).

Fuel pressure regulator is on the passenger side of the upper motor......note was to make sure that the vaccum line to the top of it is secure.

As mentioned......make sure that all the vaccum lines are connected.

Also....double check to make sure that the IMRC is working.
On the '98, they are still vaccum driven.....they will be OPEN with no vaccum (also with motor not running) and close with vaccum (when you start the motor).
I have pictures that show these in the pictures that they link in my signature takes you to.
If these are not working correctly.......usually staying open is the failure mode on our older windstars.....you will have poor low load issues.

Of course....make sure that you are up to date on all the routine maintenance things, like fuel filter, etc.

jwebb37 · #9 03-15-2009, 08:05 AM

Thanks for the input guys. I haven't got to check anything yet because it has been raining for 3 days here. One more question. I also noticed that when the van is cold it seems to idle fine, but after it is driven for a bit and gets warmed up is when it gets worse. Does that narrow any of the culprits down?

jwebb37 · #10 03-15-2009, 05:10 PM

Here is the latest. I took off the IAC and cleaned it. It did not look that dirty. I also plugged it up while I had it off and turned the key on and off and it does not move inside. I can feel the motor part of it working but it is not moving so I am assuming that this is the problem and I need to get another. But one thing, when I tested the ohms it showed normal. Does this make sense?

Freakzilla69 · #11 03-15-2009, 07:55 PM

Quote:

Originally Posted by jwebb37

Here is the latest. I took off the IAC and cleaned it. It did not look that dirty. I also plugged it up while I had it off and turned the key on and off and it does not move inside. I can feel the motor part of it working but it is not moving so I am assuming that this is the problem and I need to get another. But one thing, when I tested the ohms it showed normal. Does this make sense?

Maybe the problem is mechanical and the electric motor is working?

I don't think they're very expensive.

My van is idling a little rough, I think I should check mine, too.

What should my vacuum pressure be?

tripletdaddy · #12 03-16-2009, 12:48 AM

The IAC pretty much is only used when the engine is at idle and a load is put on it. So since you have proven that it ohms out correctly, the best thing to do is to see if it actually is working. The easiest test is to turn the steering wheel from stop to stop while in park, then while in gear with foot on brake pedal and see if the engine can keep idle or struggles. If the latter, then bad IAC. You can also test it with the ac, turn wheel, high beams, rear defrost, wipers and foot on brake all at the same time to really load up the engine to see if the IAC can compensate for the load.

You said the idle seems to get worse after it warms up? If you cooling system is full with no air trapped inside, your heater works, etc., then your Engine Coolant Temperature sensor may not be working correctly. The PCM uses the temp info to determine what the fuel to air ratio should be. Do the fans come on as expected when the van gets hot? If so, the ECT is probably fine. It is located just over the thermostat housing that connects to the upper radiator hose. You can check the ohms on it cold and hot to be sure it's ok.

tripletdaddy · #13 03-16-2009, 12:58 AM

Now on this business of intake vacuum, I refer to Ford's TSP. It's for 95 models, but since it's for the same engine, I expect it to be the same or close enough. I won't post the whole section as it is quite large and probably goes beyond what you need, but if you want all of it, then PM me and I'll try to get it to you that way.

Intake Manifold Vacuum Test

Bring the engine to normal operating temperature. Connect Rotunda Vacuum/Pressure Tester 059-00008 or equivalent to the intake manifold (9424). Run the engine at the specified idle speed.

The vacuum gauge should read between 51-74 kPa (15-22 in-Hg) depending upon the engine condition and the altitude at which the test is performed. SUBTRACT 4.0193 kPa (1 in-Hg) FROM THE SPECIFIED READING FOR EVERY 304.8 m (1,000 FEET) OF ELEVATION ABOVE SEA LEVEL.

Hope this helps.

jwebb37 · #14 03-17-2009, 07:45 AM

Well, I replaced the IAC and it is still doing the same thing. Of course it starts up fine and isn't rough until it warms up. I guess my next thing is the ECT but I don't see how you get to it.

tripletdaddy · #15 03-17-2009, 09:49 PM

Hmm, since you say it runs fine when you give it the gas, I kind of doubt the ECT is your problem. Never-the-less, first of all, you should be sure you don't have any trapped air in the cooling system, as that will give incorrect readings. Second, typically, a problem with the ECT circuit will produce a trouble code. Third, you can test it while in the engine with your ohm meter. With the wiring to it disconnected, you can expect around 40.5 k-ohms at 65 deg F., and with the engine at operating temp., 180 to 220 deg F., 3800 ohms down to 1840 ohms. You should also check to see if you have around 4.5 to 5.5 volts at the connector to the ECT while disconnected. You can check this if you want with just the key on but engine off, I'm pretty sure.

The ECT should be screwed into the top of the intake manifold just beyond the thermostat housing in a straight line from the upper radiator hose. The ECT has a TWO wire connector to it, not one. The temp sending unit for the dash temp gauge has a single wire to it. The ECT also has a gray plastic body with a brass base. All of this may be buried under the coil and throttle body/snorkel, so you may have to trace your upper rad hose to it. The thermostat housing is also to the right of the egr valve when looking at the back end of the engine. Autozone.com may have some good pix if you need it. Wiswind has a link to pix in his signature area that may be of this too. His 96 should be the same as your 98.

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