95 windstar 3.8 p0302 code

I just registered for the forum, but I think I found a new home.
First some history. I have a 95 windstar with 99k. Replaced head gaskets 2 yrs ago in sept. No issues since....until now. Van failed inspection this yr due to a power steering leak. Had steering rack replaced. Went to have reinspection done, washed any fluid from underneath. While leaving station cel was on and was running rough. Checked wires & vacuum lines to make sure nothing got knocked loose.
Since then, I ohmed the coils, swapped the #2 spark plug and wire, used a stethescope to confirm #2 injector operation, added injector cleaner into the tank(worth a shot, I guess) all to no avail.

When it cools down, I'm gonna pull the injector to check it for crud & swap it with another to see if the problem follows. Can anyone tell me what exactly is sensed to throw the p0302 code. I know it's a #2 cylinder misfire, but I'm not clear on what is the physical cause of the code.

Also is it normal for for the A/C to be dropped out when the CEL comes on? Seems reasonable in limp mode, But I'm not sure.

Thanks for any help
Rusty:banghead:

It could be a lower intake gasket. Disappearing coolant is a good indicator of this. Be sure to clean around the injectors before removing them, compressed air works well. When you pull the injector, blow out both ends with carb/choke cleaner. It wouldn't hurt to do all of them this way. Checking the fuel pressure might not hurt also. As for the A/C, the PCM prob. could dis-able the compressor to reduce engine load I suppose, but I'm not 100% sure...

:shakehead Update. I swapped injectors with another cylinder. Code for cylinder 2 still comes up. Injector moved-Problem stayed behind.

Possibly clogged EGR ports in the intake...check thread below...wiswind has good pics. Normally, p0301 or p0304 code, tho...those cyls are farther away from EGR valve and don't clog much....when the others clog, 1 and 4 get all the dirty EGR gasses. Worth a look when you're pulling injectors.

http://www.automotiveforums.com/vbulletin/showthread.php?t=404767&highlight=plenum

Yeah, those little EGR orifices get stopped up. So far it sounds as though fuel or spark isn't the problem. Are you loosing any coolant? A compression test may be a good idea, also..

Fortunately, it's on a more easily accessible cylinder. Check cranking compression, or better yet, cylinder leakage, on the front set of holes for comparison.

A misfire error is diagnosed primarily by the crank position sensor and the relative rates of accelleration after each cylinder's ignition event. If the accelleration of the crank (measured by the CKP) is consistently lower on one cylinder over a running sample of 200 firing cycles, the PCM will set a pending misfire code. If the problem continues for a 1,000 cycle sample at a misfire more than the PCM is programmed to allow, a hard DTC will set and the MIL should light. I believe the PCM will also try to reduce injector pulse width on that cylinder to reduce the possibility of excessive HC emissions and potential cat converter damage, but I'm not sure if all the Ford systems work that way.

As you can see, the problem has to be fairly consistent before a hard error code is stored. When the injectors were exchanged, did you inspect the inlet screens? And as corning suggested, have you tested fuel pressure? Checked the manifold? Inspected the PCV and vacuum lines? You might also try exchanging coils to see if the problem moves with them.

I did read on this forum that the '95 has only 1 EGR port.
The '95 uses a different intake manifold....does not have the IMR....and has a aluminium upper intake manifold.

Cylinder #2 is the middle cylinder on the back (firewall) side of the engine.

For the P0302, the injector causes that I would expect at this point would be electrical in nature. Possible connection issue between the injector and the PCM.....or the PCM itself. I would try these other ideas first.....as they are "normal maintenance" anyhow.

Swap the spark plug with another cylinder.....if the problem moves....the plug is defective. If it does not move.....then the plug is fine.
Hopefully, you do not have the fancy Bosch plugs.....they do not seem to do well in the windstar.....Motorcraft or Autolite DOUBLE platinum are the kind to use....available at many auto part stores.

I have been burned by not so good quality replacement wires......
A co-worker was trying to find a misfire on his car for about 6 months....started just after he installed a "premium" set of Taylor plug wires......found that it was the new wire set causing the problem.....
Looked under the hood in the dark....and it was like a city under there with all the arcing from the wires.
How old are the plug wires?.......You could replace them with a quality set. Again....the Autolite or Bosch would be fine for the plug wires...available at many auto part stores.

The coil pack is also a possible suspect....after the plug wires.
My advice on that would be to buy a new one and just replace it.........
Reason for that......doing all the work to remove it....to inspect it for cracks in the epoxy body....possibly missing a crack.....and re-installing it......might as well put a new one in....and know that you have eliminated that issue.
The coil pack has 3 coils in it.......each coil...when energized....fires 2 spark plugs at the same time. I plug fires the cylinder.....the other plug is firing into a cylinder that is not being used at the time.....often called "wasted spark system".
Anyhow.....it is known for the coil pack to develop cracks in the epoxy body around the coils......and the coil then arcs through the crack.....causing a misfire.

It is known for the PCM to develop a failure in the injector drive circuit.....requireing replacement of the PCM....after one verified that the injector is connected to the PCM...(PCM provides a momentary ground to fire the injector)....
But...as I said...best to try the other....more likely things first.

Welcome Rusty!

I'll go along with the crowd here, ignition. I'm betting that your coil pack is bad.

To test.

0. Find an old spark plug.
1. Turn off the fuel, by pulling off the fuel pump wire harness wire (just above the jack).
2. "carefully" pull the wire off of #4 cylinder. (Frontmost, passengermost, (LHD) )
3. Plug in the "spare" plug and ground it.
4. Have a partner throw the ingition.
5. Steady spark is OK, no spark = bad wire or coil pack.
6. Repeat for #5 wire and #6 wire.
7. If you find "no spark" swap a wire.
a. no spark = bad coil pack
b. spark = bad wire

Note: Because the coil pack (should) fire two cylinders at a time, testing the front three cylinders is a pretty good indication as to whether the pack is good.

Karl

Got home late today, but checked the coil for leakage in the dark. Nothing obvious at least. I haven't taken it off yet, but do the 3 coils come apart or are they molded as one? If they come apart, can I swap them to see if the misfire moves?
If I had a bad coil, wouldn't I get the misfire code for that partner cylinder as well?
BTW, I plugged off the vacuum hose to the EGR and the misfire doesn't go away.
Also I have noticed no loss of coolant, and the coolant is clean & green, and no coolant/water is noted in the oil.
I appreciate all the help so far. Thank you all.

It will be 1 molded assembly....so swapping of individual coils is not an option.

Sorry I haven't gotten back. Working ALOT. Further checking finds no spark at the plug for cyl 2, but good spark at cyl 6 (the partner cylinder) I'll get a new coil pack tomorrow even though primary and secondary resistances are perfect.
Any other reason for this to happen? I read something about the voltage from the coil being higher in the compression cylinder than the waste cylinder. What determines this, crankshaft position, or....?
I'm just trying to think of anything else that would cause this issue.

Oh, and 1 other question... Can I swap the wires for cylinders 2 & 6 since they fire together? I would assume the misfire would then appear at cyl 6 instead.

PS I hereby promise to post the resolution to my problem, whatever the outcome. (Nothing worse than never knowing)

Sorry I haven't gotten back. Working ALOT. Further checking finds no spark at the plug for cyl 2, but good spark at cyl 6 (the partner cylinder) I'll get a new coil pack tomorrow even though primary and secondary resistances are perfect.
Any other reason for this to happen? I read something about the voltage from the coil being higher in the compression cylinder than the waste cylinder. What determines this, crankshaft position, or....?
I'm just trying to think of anything else that would cause this issue.

Oh, and 1 other question... Can I swap the wires for cylinders 2 & 6 since they fire together? I would assume the misfire would then appear at cyl 6 instead.

PS I hereby promise to post the resolution to my problem, whatever the outcome. (Nothing worse than never knowing)

Well go figure. Got a new coil pack from a junkyard & installed it. Spark at cyl 2 plug! Started it & drove arouond for a few minutes. No misfire and no CEL.
I'm still confused as to why, with all readings ok, but no sense overthinking things.
Thaks to all for your help. I think I'll bookmark & keep track of the posts. Much to be learned from some very sharp people.
Thanks again.

Glad you fixed the problem.

But for the question you asked earlier, you could have swapped the #2 and #6 cables at the coil pack ... and the misfire would have likely moved to #6. It's possible for one end of a coil go get "grounded" and the other end still function.

Those coils can develop a crack in the molded epoxy body, through which it can arc, which can account for your measurements being good.....as you will not measure any lower resistance through the air gap......but the voltage will jump it.

Many thanks to those who contributed to this thread, especially wiswind and CoachKarl! Thanks to Rrey199 for posting his solution also. Thanks for the recommendations on replacement plugs and wires to use.

The information was invaluable to me in working through a serious runnability problem with my 2002 Ford Windstar 3.8 p0302 code. Sure enough - the coil pack was bad. Visible cracks in the bottom.

For me one symptom that the coil pack was bad was the the car abruptly went from running well to running awful. I'm not much of a mechanic, but I suspect if it was a spark plug or spark plug wire issue the car would gradually start to run worse - like maybe intermittently, or runs poorly when cold, or some such thing.

I'll post some other comments on the work I did in another thread.