I have 2004 ford taurus that has a #4 misfire I have changed plugs and wires also changed injector checked compression. changed coil and fuel filter and tried a cam sensor... THE PLUG IS VERY WET whats next?

i think its the ecu, i had misfire codes come up in my 06 explorer, changed everything like you did, it was the ecu, i got one on ebay with keys for 150, it worked, also ford systems require a fully charged battery

Possible causes - Faulty spark plug 5
- Clogged or faulty fuel injector 5
- Faulty ignition coil 5
- Fuel injector 5 harness is open or shorted
- Fuel injector 5 circuit poor electrical connection
- Ignition coil 5 harness is open or shorted
- Ignition coil 5 circuit poor electrical connection
- Insufficient cylinder 5 compression
- Incorrect fuel pressure
- Intake air leak

The P0305 code means that the cylinder 5 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 5. If the problem persist more tests needs to be done to diagnose problem, see "Possible Causes



When is the code detected? Engine Cylinder 5 is Misfiring.


When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.

Yes.
You could have a leaking head gasket or a crack in the cylinder head.
After driving the car for a few days the spark plug should show signs of coolant on the tip.
You may want to do a compression test to see if that cylinder is low on compression too.

Change nothing till you get the compression check,guessing will cost a lot of money,and still not be fixed.It may be best to go to the Ford dealer and get it repaired.They have a scan tool that will pinpoint the problem and cost less,here's a link to Code P0301. P0301 OBD II Trouble Code

Crank Position sensor then the timing belt are the next two steps in the sequence.

Have you had it scanned anywhere. If its misfiring, the computer will read it as a misfire. if it is misfiring, the probable cause is the fuel injector. have you changed the plug wires with the plugs?

Do you have spark at the number four cylinder? Check that if spark is present , then you should swap the injector from four to five and see if the miss goes with the injector. If not then you will need to test the engine compression .

If the plugs, wires, and coil are all good then it can be a partially clogged injector, or low compression on that cylinder. It can also be a bad ECU. My cousin had a 99 Taurus with the exact same problem and it turned out to be the ECU which he had to replace. The ECU is very expensive so make darn sure everything else is good before you replace the ECU. It could be the coil has an intermittent problem and may show good especially when cool. You might try putting that coil on a different plug position, resetting the ECU, and see if you get the same code PO301. Run a compression test on all cylinders to see if you have good compression. Add a can of Seafoam Fuel Treatment to a full tank of fuel to make sure the injectors are clean. Check all wiring closely for frayed wires or loose connections. Eliminate all other possibilities before looking at the ECU itself.

coil pack if has weak spark

Sounds like either a bad plug wire, or coil pack. This is about all that would cause the misfire.