'96 3.8L Misfire / Engine Sputters when Fan Turns On

[Jon04CTSV]

Hoping someone here can help me out with my '96 Windstar 3.8L.

It just started happening a couple days ago.

With the A/C on, when the car is idling, the engine will sputter and drop below 750rpms when the fan engages. Without the A/C on, the fan doesn't turn on so I don't have this problem.

I disconnected both fans and the problem goes away. With a volt meter, I was able to see when it was trying to engage the fans. No sputtering. Plug the fans back in and right before they start the engine shakes and sputters.

I also got a P0302 - cyl 2 misfire code. Checked the battery with a volt meter and it was dropping 1 volt every time the fan was engaging. Replaced the battery and fuel filter today and the problem still exists.

Anyone have any ideas??

Thanks!

[wiswind]

One thing that works with the fans coming on....is the Idle Air Control (IAC).
The PCM (computer) should send a signal to the IAC to boost the idle a little when the fans come on.
I would expect other issues if the IAC is sticking......most common is stalling when manuvering into a parking space....as you are turning the wheels with your foot off of the accellerator...and the power steering places an additional load on the engine.....the PCM should open the IAC some.
You could try cleaning the IAC if you are also noticing the symptoms when parking......if not.....most likely not the IAC.
My '96 does slow down a little bit when the fans come on.

First thing that I would try is to visually verify that BOTH fans are actually running.
If one is not....or is turning real slow....then that fan may be defective and need replacing.
Make sure to get a replacement fan assembly....as FORD issued a TSB that they are to be replaced as an assembly.....as the assembly is ballanced.....replacing just the motor can leave you with an unballanced unit that will vibrate.....and possibly fail soon.

One other thing to try is to look at the low speed fan dropping resistor......I have this shown in a couple of the pictures that the link in my signature takes you to.
This part is a ceramic block....that you can see when you raise the hood....and look down behind the passenger side headlight......right near the plug....and look on TOP of the metal bumper.

One other thing you could try is (temporarily) unplug 1 fan......and see if the symptom changes........then plug it back in.....and unplug the other fan.
If 1 fan causes a significant load....and the other does not...then you might have a defective fan.......

Now there is the less likely situation that you have an issue with cylinder #2 that only shows up under load at low RPM (a missing cylinder is more noticable at low RPMs).

Also......if your battery is weak......then the load of charging a weak battery is also much more noticable at low RPMs.
Anything over 5 years on a battery is borrowed time.
I mention this because a weak battery places more load on the alternator (and thus the engine) and the increased workload can cause your alternator to fail.

[Jon04CTSV]

Here's what I've tried so far..

1. Replaced Battery
2. Tested Alternator, it's good
3. New Plugs
4. New Wires

It still happens... Both fans are working.

[searcherrr]

You might be my new best friend Jon.

You are the ONLY other person that I know of on here who has the same problem I do. Mine is a near stall or could be described as you put it "drops under 750rpms / sputter" - and the kicker IT GOES AWAY ONCE THE FANS ARE UNPLUGGED..... UNLESS I LET IT START DOING ITS SPUTTER THING FIRST AND THEN UNPLUG THE FANS LATER.

If I warm up the engine from full cold without the fans plugged in at all it doesn't do it. If warm and I unplug it doesn't do it as much now.

Anyway, did you resolve this yet?

I wanted to tell you something thats gonna sound misdirected, but when's the last time you replaced your fuel filter and/or checked your fuel system pressure using the test port?

Fuel pressure is supposed to be between 30 - 45psi at idle and at 2500rpms for 1 full minute. Fuel pressure regulator is supposed to increase PSI by 8 to 12 psi when you detach the vacuum line to it.

I am asking this cause you and I are having the trouble and I am on to something with the fuel pump and/or fuel filter not getting enough gas to the engine to keep it idling smoothy in park or drive. I do not have trouble on the road, but I swear on the road that it isn't as powerful as it used to be.

[Jon04CTSV]

Originally Posted by searcherrr

You might be my new best friend Jon.

You are the ONLY other person that I know of on here who has the same problem I do. Mine is a near stall or could be described as you put it "drops under 750rpms / sputter" - and the kicker IT GOES AWAY ONCE THE FANS ARE UNPLUGGED..... UNLESS I LET IT START DOING ITS SPUTTER THING FIRST AND THEN UNPLUG THE FANS LATER.

If I warm up the engine from full cold without the fans plugged in at all it doesn't do it. If warm and I unplug it doesn't do it as much now.

Anyway, did you resolve this yet?

I wanted to tell you something thats gonna sound misdirected, but when's the last time you replaced your fuel filter and/or checked your fuel system pressure using the test port?

Fuel pressure is supposed to be between 30 - 45psi at idle and at 2500rpms for 1 full minute. Fuel pressure regulator is supposed to increase PSI by 8 to 12 psi when you detach the vacuum line to it.

I am asking this cause you and I are having the trouble and I am on to something with the fuel pump and/or fuel filter not getting enough gas to the engine to keep it idling smoothy in park or drive. I do not have trouble on the road, but I swear on the road that it isn't as powerful as it used to be.

The fuel filter was replaced either last year or the year before. I don't think I've ever replaced the pump, nor have I tested the pressure.

In other news, I replaced the coil packs last week. It has improved a lot. The problem is still there but barely noticeable. It doesn't sputter (misfire) as bad now. I'm guessing this is because the new coilpack provides more voltage than my old one did.

So it still seems like an electrical problem to me. Something is drawing too much power. I've unplugged the 2 fans 1 by 1 and it happens regardless of which fan is plugged in, so that basically rules out bad fans.

[searcherrr]

See I thought it was electrical too at first as did a lot of other people (and still do): http://www.automotiveforums.com/vbul...d.php?t=900206

Thats a really long one. Maybe I am wrong in this assessment, but the problem is GONE when I am cruising to where the RPMs are above 750. To me if it was electrical it would happen regardless of RPMs/Speed.

This is what got me into looking at the fuel pressure, though I have my original coil pack too. It is on my list of "maybes", though I don't like replacing things I can't discern to be bad first.

Does anyone know what the coil resistance is supposed to be for our Windstars? A quick test with the multimeter would show whether its good or not.

I am (been being lazy about it) about to go outside and do my last 2 final fuel pump related tests and possible a 3rd test (fuel psi just before fuel filter), but if either of the 1st two tests fail I really won't need to check PSI at the fuel filter. In any case mine is LOWER than spec PSI anyway.

[Jon04CTSV]

Originally Posted by searcherrr

See I thought it was electrical too at first as did a lot of other people (and still do): http://www.automotiveforums.com/vbul...d.php?t=900206

Thats a really long one. Maybe I am wrong in this assessment, but the problem is GONE when I am cruising to where the RPMs are above 750. To me if it was electrical it would happen regardless of RPMs/Speed.

This is what got me into looking at the fuel pressure, though I have my original coil pack too. It is on my list of "maybes", though I don't like replacing things I can't discern to be bad first.

Does anyone know what the coil resistance is supposed to be for our Windstars? A quick test with the multimeter would show whether its good or not.

I am (been being lazy about it) about to go outside and do my last 2 final fuel pump related tests and possible a 3rd test (fuel psi just before fuel filter), but if either of the 1st two tests fail I really won't need to check PSI at the fuel filter. In any case mine is LOWER than spec PSI anyway.

I had the same thing. If it was sputtering at a stop light, once I took off it was ok. However, sometimes, when it was really bad, it would sputter even when I was taking off. There was 1 hot and humid day where I'm pretty sure I was running on 5 cylinders for a bit.

When you say that the problem is gone after you take-off, do you know if your fans are still on? It's possible they've turned off since airflow is cooling the engine...

[Jon04CTSV]

I just went through some of your posts on the other thread...

Are you saying that you only have that problem when the fan turns OFF? Mine happens when it turns ON.

[wiswind]

Searcherr's problem when the fans turn OFF is truely strange.....
My '96 DOES slow down a bit at idle as the fans turn ON....as the additional electrical load is a increase load on the motor through the work that the alternator has to do to provide the extra power.

Under these conditions.....lower RPM and higher load....even the slightest missfire is going to be really noticable.

Now....with cooler weather, we are running our defrost....which causes the A/C compressor to engage...another load that cycles ON/OFF........and when the A/C is active.....the radiator fans come ON......

[searcherrr]

Originally Posted by Jon04CTSV

I just went through some of your posts on the other thread...

Are you saying that you only have that problem when the fan turns OFF? Mine happens when it turns ON.

OFF - yes.

The reason I'm attaching myself to you here though is because its a start; thinking that since you've noticed it happening during the fans cycling on could somehow indirectly be related to when mine turn off and the fact that your stuff happens at idle.

My tech is thinking the cam synchronizer is not set right, causing timing to be off, causing horrible gas mileage and possible engine damage. Thread on "bad fuel pump?" here if ya wanna check it out:
http://www.automotiveforums.com/vbul...37#post5862737

Cam timing is extremely important to proper fuel mixture. To me I could see where it could possibly affect fuel PSI too, but maybe I'm off on that thought.

Ever had your cps or cam synchronizer messed with?

[Jon04CTSV]

Originally Posted by searcherrr

OFF - yes.

The reason I'm attaching myself to you here though is because its a start; thinking that since you've noticed it happening during the fans cycling on could somehow indirectly be related to when mine turn off and the fact that your stuff happens at idle.

My tech is thinking the cam synchronizer is not set right, causing timing to be off, causing horrible gas mileage and possible engine damage. Thread on "bad fuel pump?" here if ya wanna check it out:
http://www.automotiveforums.com/vbul...37#post5862737

Cam timing is extremely important to proper fuel mixture. To me I could see where it could possibly affect fuel PSI too, but maybe I'm off on that thought.

Ever had your cps or cam synchronizer messed with?

Nope, although I had the engine replaced 3 years ago. This problem only started a month or 2 ago though.

[searcherrr]

Sorry, I missed your question a few days ago. Yes, I have confirmed that while giving it gas with the fans still on that it does not give me the problem. I'm sure they were still on when I gave it gas. They weren't on for long, but they were on and I notice too that it is definitely worse in hot weather and/or after a long drive (excess of 100 miles).

Do you hear any whining/squealing like air being let out of a balloon with the lips of it squeezed? Mine does this from time to time immediately after I shut the engine off. People say they hear this when their cam synchronizer has gone bad, though I don't know if they heard it when the engine is on or off. I also have a hard starting a/c clutch too so I've been wondering if its the a/c high pressure switch that I'm hearing too. A/C high pressure switch would make more sense since I would doubt the synchronizer would be "spinning down" after I shut off the engine. If I understand it right that should come to a halt as soon as the crankshaft does.

In any case I bet you that cam synchronizer is toast by now man. These are known failure items and its just too old. It got transferred to your new engine like mine did and is no longer good. From what I am reading up on these do not get oiled well cause they have to draw the oil upwards and people have started to remove the CPS and drop some oil in there from time to time to prevent it from going bad.

Other than that what Wiswind said:
IAC - I would no doubt think needs cleaning or replacement if its never been done.

Does your voltage still drop 1 volt when the fans kick on since the new alternator? See in troubleshooting my issue the voltage regulator is very steady and it doesn't variate more than maybe .1-.2 volts during fan or other load operation. Thats how it should be too. If it drops a whole volt I would suspect electrical issues or bad ground connections.

Dropping resistor is most definitely toast. After all these years these things do not last long. I just replaced mine like 4 or so months ago and the new one already has hairline cracks in it from absorbing electricity. I wish there was a better alternative to this thing that is exposed to the elements.

Cylinder 2 misfire - Did the code go away when you replaced the coil pack? If not and you still have the problem I would pull the plug from cylinder 2 and look at it for signs of abnormal burn (IE: coloring tinted green or other color) from coolant. If your head gasket has never been replaced the misfire could be due to a leak in the cylinder through the old defective head gaskets Ford put on originally. Also, you should thoroughly inspect Cylinder 2 spark plug wire for damage/burning - Mine was burnt a while back and it was replaced with the new engine I got.

[searcherrr]

Did you ever get to the bottom of this? Important.

[Jon04CTSV]

Originally Posted by searcherrr

Did you ever get to the bottom of this? Important.

Nothing new to report. Still ocassionally happens. Always cylinder 2... Only thing I can think of now is the injector... That's all that's left, right? I've replaced coil packs, plugs, wires..

Also get the occasional P0171

[wiswind]

On my '96 3.8L the fuel injectors tend to get dirty at the spray end.
I have had this cause misfire AND P0171 and/or P0174.
The lean codes are from the PCM trying to compensate for the "misfire" that it has detected.