P0305 Code 2003 Ford Windstar 3.8

[lboynton]

I have a 2003 Ford Windstar witht the 3.8 V6 giving me a P0305 (Misfire on 5). I have replaced the Coil, Wires, and Plugs. The engine still misses. A diagnostic found no compression problems. Before I replaced the coil, it was sending P0303 (Misfire on 3) After the coil was replaced, the code cleared and the engine ran well for about 300 miles. It started misfiring again and now is giving the P0305. I don't know how to diagnose what to try next. Reading online makes me wonder about injectors and oxegen sensors. I don't know how to diagnose what to replace next.

[wiswind]

It is very unlikely that the problem is due to an oxygen sensor.
I could be a dirty fuel injector.
The BEST over the counter cleaner for this that I have found is Berryman's B12 Chemtool in the metal can.
Treat a tank of gasoline with the correct amount (if the can says it is for a 10 gallon tank.....you will need 2 cans for a 20 gallon tank).

Another fuel related problem could be (less likely) low fuel pressure.
The computer does not monitor fuel flow or fuel pressure, so it will not give any code(s) for any issues with that.....

Another possibility is that a spark plug wire got damaged in the change process.

The "Check Engine Light" (CEL) will flash when the misfire is taking place.
If they CEL is on but not flashing and has the misfire code stored....it means that it detected the misfire, but it is not happening right now.
This hint is to help you to determine if this is happening all the time or just sometime.

A flashing CEL is an indication of a problem that can damage the catalytic converter.

If the misfire is due to lack of spark....it can cause raw fuel to pass from the cylinder into the catalytic converter.
If this is a persistent problem....it can burn out the catalytic converter.

If the misfire is due to lack of fuel, then there is no fuel to pass on through into the catalytic converter.

The PCM (computer) does not know the cause of the misfire so it will flash the CEL on and off.

[scubacat]

What brand of wires and more importantly spark plugs did you use?

[12Ounce]

Did you do the work yourself?

[Windstartled]

Originally Posted by lboynton

I don't know how to diagnose what to try next. Reading online makes me wonder about injectors and oxegen sensors. I don't know how to diagnose what to replace next.

The most efficient way to tackle this is to begin the diagnosis process starting with the easiest and/or less costly suspects.

You will need a few items from an auto parts store: fuel injector cleaner, plastic spark plug boot puller, 2 basic ignition cables with boots attached, 2 new spark plugs, fuel filter. Total cost should come under $50

Begin by replacing the fuel filter, a 10-minute job. This by itself will likely not fix the issue but it will ensure that clean fuel (and the injector cleaner mixed in it) will reach the injectors under adequate pressure. Once this is done add the injector cleaner according to manufacturer instructions. It takes a little time for the injector cleaner to work (usually a few days) so don't expect instantaneous improvement.

In the meantime you may as well check ignition cables. Even without visible damage they could be faulty. With engine running and using the plastic boot pullers carefully pull the boot on each spark plug, one at a time. If the engine begins to run rough when the boot is pulled it means you have spark and cable is probably ok. Put boot back on plug and proceed to the next one. If pulling one of the boots has no effect on engine rpm replace the cable. Still no effect? Replace the spark plug. If that doesn't work then the coil pack will likely need to be replaced

One cause of coil failure is coolant leaking on it, fix any leaks you may spot before installing a new pack.

If all the cables and plugs work correctly the next logical cause is clogged EGR ports. Some say you can test for this by disconnecting the PCV vacuum line and see if misfiring stops but I think this would only work if the misfiring is constant at idle. If it's intermittent a visual inspection of the EGR ports is required. This obviously requires the removal of the intake manifold, which is not a complex procedure but can be very tedious... as would be my instructions on how to proceed if I was to post them here. Luckily there are plenty of sources online that will tell you how to proceed, as well as the Haynes manual which, for this specific procedure at least, is a lot clearer than the Ford shop manual.

One less common source of misfiring is water contamination of the combustion chamber. This can happen through the gas having water in it from tank or line condensation, or the presence of above normal condensation in exhaust components. The former happens mostly when fuel tank is punctured or if you consistently drive the van with less than half a tankful. The latter occurs when upstream exhaust components are not airtight (faulty exhaust manifold gaskets, cats, worn flex pipe flange, punctured muffler, etc.) and let water in near the engine. Telltale sign is abnormal amount of steam exiting the tailpipe after starting the engine even in warm weather.

[Windstartled]

Originally Posted by wiswind

The "Check Engine Light" (CEL) will flash when the misfire is taking place.

Don't always count on it, mine flashes only when misfiring occurs in in cyl #4, 5 or 6 but not 1, 2 or 3. In other words only the front cylinders. According to what I read online I am not alone. Had an interesting exchange with a '01 Mustang owner about it, his car has the same Essex Windsor engine as my van and it's the same for him. He thinks it could be due to misfiring detection being linked with coil polarity, but I lean more towards a PCM bug.

Single cylinder misfiring appears to trigger CEL regardless though, but not flashing. For example I drove the van without even the wire to #3 being plugged at either end and got no flash but when #4 started misfiring at random (still with #3 unplugged) I got the flash immediately each time it happened. I didn't want to drive the van in this state for long so I didn't test for the remaining cylinders.

[lboynton]

Motorcraft.

[lboynton]

I found my problem! The plug in #5 is all corroded. It looks like I might be burning coolant buy the buildup. These plugs were new in April. The P0303 went away after the coil was replaced but then the P0305 started. I am not sure what is happening, since a compression test looks good and the van doesn't use much in the way of coolant. With a new plug in #5 it runs great. I'll have to check it in a month and see if it is building up again. Thanks for all the suggestions.

[lboynton]

Some. I paid for the plugs and wires in April and the Coil in November. I replaced the wires with a new set and plug #5 myself trying to eliminate the problem.

[JosieChapman]

I have a 2002 Ford Windstar LX. I have had P0171 and P0174 trouble codes for 12 months now. I have since then had to replace a fuel pump at 155,000 miles. My wife went to Kansas this past Thanksgiving and on her return trip back to Colorado the engine started sputtering. I had her take it to the nearest Parts store to read the codes.
They came up with P0305, misfire in cylinder #5. The CEL was also flashing. I have changed the spark plug's and wires apx 11 months ago, 10 months ago I changed all four oxygen sensors, cleaned the Manifold sensor, checked for vacuum leaks (None found).
Starting about 10 months ago it started burning oil, no black or blue smoke, but it uses about 2 to 3 quarts a month. There has been no evidence of oil in the coolant and vice versus. Before the fuel pump replacement it died on her twice. Since the pump change it has not stalled on her.

Today I went to the store to read the codes and it came up with 14 codes. UGH. B1185, 1198, 1194, 1254, 1246, 1250, 1242, 1214, 1210, 1420, 1404 and P0171, P174, P0305. Of all the codes I can not find the following: B1185, B1198, B1194. Any suggestions?

I am going to follow your advice fore-mentioned. As soon as it stops snowing! It now has 157,800 miles registered.

Do you think it is worth salvaging or trading it in? I also forgot to mention that every now and then it will light up various warning lamps all at once, light the brake, abs, traction lamps and sometimes various others.

Thanks,

[12Ounce]

I would first try this ... lift a battery cable for five minutes and reconnect. As soon as the engine check light comes on, have the codes read to see which ones are first to show. If you have to drive a long way to get to parts store ... you may have to do this all in their parking lot, or down the street.

Of course we can't always get to things as we should, but codes should be dealth with as soon as possible ... or they will lead to other codes and bad conditions. It is likely that you have a vacuum leak ... it could be associated with the intake manifold and the famous isolator bolts. I don't know if your year model has this issue or not.

As far as whether you should repair or not ... that answer depends on you more than the vehicle. If you have the time, skills, tools, and work space ... the Windstar is very fixable and can be made to run "forever". But if car repair is not "your thing" ... need very repairable transportation, "right now' ....and you have to depend on paying others to repair for you, I would be inclined to let it go. Also depends on how deep your pockets are.