96 Winstar, 3 & 4 missfire

My 96 Winstar with 160k miles has codes, PO304 & 303. The gas mileage has been poor 15-16 mpg in town and all the "get up and go" has "got up and went". No power. So, I "SeaFoamed" via brake booster vac line. Like a dummy, I couldn't pour at this location, so I stuck the vac hose in the can. Needless to say too much product too quick. After this the van started to idle rough. Seemed ok at hyway speeds. Engine light came on and flashed, had codes read, PO304 cylinder missfire. Checked plugs, wires, injectors, everthing seemed ok. Then off to the mechanic. By this time engine was idling rougher. He said codes 304 & 303 were detected. Thought is was coil, replaced and did not work, Replaced control modual with out success. He has had it now for 5 days. Still has'nt figured it out. Said he would be easy on me, but I can't afford this much longer as this is my service vehicle and need to work. Any one have suggestion????? I need my van back! I keep up on maintence and have never had any major problems.:screwy: :screwy:

Sounds like you are having a very similar problem to the one that I have (see my 95 windstar P0305 cylinder 5 misfire thread). I can see why he is focusing on the ignition system. After all, cylinder 3 and 4 are paired. I am no expert, but I would say that if they are getting spark, they are okay. If not, and you've replaced the spark plugs, wiring, coil pack and ignition control module, then if the '96 is like the '95, all that is left is the Powertrain Control Module (PCM) that tells the Ignition Control Module (ICM) when to fire the coil for 3 and 4. I've been pricing them, your looking at a $250-350 part.

Now remember, I'm not an expert, so this is all conjecture (although I am debugging a similar issue). However, if the wiring is producing spark, your problem is probably not with the ignition system, but lies in the fuel system. Previous threads about similar issues have pointed to clogged or damaged fuel injectors. I have also been told that the head gasket can also be to blame.

At this point in my troubleshooting, I am looking at probably taking the fuel system apart, looking at the fuel injectors, cleaning them if needed, and swapping them around to see if the problem continues after cleaning and if it moves around. Despite the labor involved, I'm kind of hoping its just a clogged fuel injector because I don't want to pay the cost of a PCM or wait for it to arrive (I live in Germany, the part has to be shipped overseas).

Hope this helps, sorry I couldn't be of more help.

I remember a guy on the cartrackers.com forum had a problem after the Seafoam treatment and it was simply that some of the gunk that was getting cleaned out of the intake ended up fouling a plug. You may just need to remove the plugs and clean them.

That would be similar to the current diagnosis concerning my vehicle - foreign matter in the intake manifold, ruptured gasket = right into the cylinders causing misfire. We'll see how it pans out. I want my vehicle back too, its all we've got for our little family.

Up Date, I had my van at the mechanic for a week. He switched out plugs, wires, injectors, coil pack, and control modual. None of which helped. Compression check was ok. Checked EGR by disconnecting and pluging, OK. This is a great mechanic, but he has thrown his hands up and reccomended a mechanic on Gasoline Alley (I live in Indy near the Track). Problem is, I plan on taking this van to FLorida with in a week. Would like to figure out ASAP. Also it is a 3.0L. I see most have the 3.8L. Any suggestions would be appreceiated.

A independant mechanic told me that what I experienced with my '96 3.8L having a misfire this past spring is very common with FORD due to the fuel injectors.
He gave me a can of Berryman's Chemtool B-12 and told me to run it through.
It actually took 3 tanks of gasoline (1 can in each) to totally clear it up.
He told me that Chevron Techron, and most fuel system cleaners are detergent based....and are great for keeping things clean.
The Berryman's B-12 in the metal can is a solvent based cleaner.....stronger.
You can buy this at Autozone, and many other auto part stores.
I would try this treatment.

Problem solved!!! I took the van to a second mechanic ( a female), who discovered it was a bad plug. About a month ago I replaced the plugs with Bosch Platnimum. Bought them at Advanced Auto. Bottom line only Motorcraft plugs work on Fords. Plug in cyclinder #3 was destroyed, shorting out and robbing the current for 3 & 4. Since #3 is the hardest plug to get to, no one removed it to check it. #4 looked ok, but missfire went away with a AC Delco replacment in shop. Replaced plugs and wires with Motorcraft and the van runs great, even transmission shifts more responsive on hyway. Good lesson to learn but costly. So don't skimp on parts.

If you have trouble locating the Motorcraft brand......Autolite double platinumn will also work fine.
It is understandable that people get the Bosch plugs.....those displays at the auto part stores really get your attention....but Bosch is not the correct plug for the windstar.

....but Bosch is not the correct plug for the windstar.

Uh oh... I guess that's the reason I'm getting a random missfire now and then.

Looks like I have more work to do, this has become a great hobby car!

Could that have something to do with my 0171/0174 codes?

What about the Bosch wires? Duralast?

Problem solved!!! I took the van to a second mechanic ( a female), who discovered it was a bad plug. About a month ago I replaced the plugs with Bosch Platnimum. Bought them at Advanced Auto. Bottom line only Motorcraft plugs work on Fords. Plug in cyclinder #3 was destroyed, shorting out and robbing the current for 3 & 4. Since #3 is the hardest plug to get to, no one removed it to check it. #4 looked ok, but missfire went away with a AC Delco replacment in shop. Replaced plugs and wires with Motorcraft and the van runs great, even transmission shifts more responsive on hyway. Good lesson to learn but costly. So don't skimp on parts.

Well give the female credit.
She was smart to check the plugs.
Yes Bosch belongs in the trash can.
Like I keep saying OEM type parts only hurt one time.
And if it is a 3.8 the EGR valve ports being stopped up in the intake will cause a miss fire to.

I am not an authority on spark plug wires.....I have autolite "professional" wires on right now.
I also was careful in the routing of them....and put more of the nylon "dress up" covering on them where they were against anything....like the engine....or any sharp edges.

I do have a friend who put Taylor brand wires on his Cavalier.....and had problems with misfire right away......6 month later......he found out that it was caused by the wires......
I lifted the hood at night in a dark garage with the engine running.....looked like a city in there with all the sparks coming off the wires....
They were advertised as a high performance wire, with thicker than stock insulation.

At Autozone......Duralast is their good line......Valuecraft is there "budget" line.

Over the years I have gotten less than expected parts from dealerships and from auto part stores.....so you have to monitor what is going on carefully.

As a percentage, the parts from the dealership should be the best....
An example.....oxygen sensors......I understand that the Motorcraft brand are made by Bosch, however, they are made to Motorcraft specifications, which very likely are a tighter specification than the Bosch brand......it was only a couple of dollars more for the Motorcraft brand at Rockauto.

Dealerships seem to be so difficult to deal with......
I really think they miss the boat on a great business opportunity by not having the parts department set up to look like a store within the dealership.....with informative displays......and helpful clerks.....that know what they are talking about......and would be a great lead into the service department for more difficult repairs.
Reasonable prices......made up for by higher volume.....and a loyal customer base....and more customers for full service.

At Autozone......Duralast is their good line......Valuecraft is there "budget" line.

Thanks, I'll try the Duralast wires. I'm affraid to look at mine in the dark, I think they're factory original.

I agree with you for the most part on the dealer parts store. However I've found the clerks at my local Ford dealer to be very helpfull, it's just the prices that scare me.

BTW, I have bosch O2 sensors in my van to the tune of $50 a peice from AZ (maybe from Advanced, I can't remember) might that have something to do with my 0171/0174 codes?

I doult that the oxygen sensors are causing the lean codes....most likely a vaccum leak or a fuel delivery issue (dirty fuel injectors).