Dtc p0302

I have a 2000 Ford Windstar 3.8L V6
For some time now have a persistent misfire
Initially two codes P0171 and P0302
Have carried out a fair amount of investigation and subsequent work as follows :-
Changed Air Filter
Cleaned Mass Airflow Sensor
Renewed Isolator Bolts although had previously been done
Renewed Upper Intake Gaskets and cleaned EGR Ports
Renewed Spark Plugs
Switched cylinders 2 and 6 at Coil Pack but still Misfire at cylinder 2
Ran double dose of Seafoam

P0171 cleared at some point
Misfire still persists in cylinder 2
Van runs rough and noisy when accelerating but can cruise relatively smoothly at 100kmh and engine light remains on with intermittent flashing
At present generally only drive locally and not on highway to any extent

I am new to Automotive Forums
I would more than welcome any input that may help to arrive at a successful conclusion
Apart from the frustration very concerned about still driving about in this condition

My Thanks

First of all welcome to the forums...
You should stop driving the van untill issue is resolved, driving with a missfire could result in a damaged catalytic converter.
Now have you checked the condition and operation of the Fuel Injector on cylinder #2? Also make sure the connector is well seated as the plastic retaining clips for the wiring plug tend to break with the heat cycles and vibration could undo them causing a break in signal input.

I would suspect the spark cable going to cyl 2. Do the lengths allow a cable swap between cyl 2 and some other cylinder ... just to see if the misfire relocates?

Many thanks ED STRONG and 12OUNCE for your responses
I intend replacing this week-end fuel injector to the misfiring cylinder number 2
Do you have any recommendations in doing so

As noted in my original post I have switched 2 and 6 at the coil pack and the misfire remained at cylinder 2
Apparently this would indicate that the coil is not at fault ?

I feel that fuel is the problem ?

Any further comments you may have would be most welcome as I am in unknown territory !!

My Thanks

maccardiy

I'm suggesting the cable, not the pack, might be the culprit.

Having interchanged the wires between 2 and 6 and the misfire remaining at cylinder 2 would that not indicate that the wires are not at fault ?

when I had your issue, it turned out to be the Fuel Injector was faulty. The worst part was doing the intake clamshell and isolator bolts all over again. But since you've tackled that job already you should have no issues. I cleaned and reused all the gaskets and had no issues...YMMV
If you can spare new ones then go ahead!

Having interchanged the wires between 2 and 6 and the misfire remaining at cylinder 2 would that not indicate that the wires are not at fault ?

If I understanding your writing, you switched the cables at the pack ... otherwise leaving the cables hooked up to the plugs. If so, that means the cable that was originally feeding cylinder two's plug is still in place ... and perhaps the culprit.

If you have the upper intake off, then while you're in there check/clean the EGR ports for clogging.

I had an issue on my '96, might not apply to your situation.....but I would get a buildup of crud on the end of the fuel injector. Local mechanic told me about Berryman's B12 Chemtool, the liquid that you pour into your tank. I had used MANY cleaners and even tried using a maintenance dose of a cleaner with every fuel fillup and still had the issue.
The Berryman's did the trick.......so I use it maybe 2 times a year.
Contrary to what I always thought......using it on a long trip is NOT the best way to use it......where it is run through the system quickly.
The BEST way is to use it where the fuel sits in the system for a period of time (vs a tank on a long trip....where it is in there for a day or less). THIS way it gets a chance to soak the system.
The Berryman's is a SOLVENT type cleaner.....but safe for the oxygen sensors.

Worth a try if you have not taken things apart yet......and a LOT cheaper vs replacing a fuel injector (was $75 for an injector.....only to look at the old one and see the crud on the end).

One trick that I used when I had the fuel rail up off the injectors......BEFORE putting the upper intake manifold back on......but after you have completed ALL the fuel connections......I would turn the key to the "RUN" position but NOT crank the engine. This would get the fuel pump to pressurize the fuel system........
THEN I would look around the fuel rail / injector connections for any signs of leakage.
Then, turn the key off and proceed to put the rest of things back together.