I have a 99 ranger 3.0 V6 flex. Code 305 came up.I know this is a misfire in cycle. #5 . I found a tan burn and a split in the wire. I replace all plug wires and the spark plug. The code is still coming up. I switched #1 and #5 on the ignition coil. The code still came up 305. I listen to the injectors with a screwdriver their all firing. Is there anything else this burnt wire could have caused to keep the code coming up. I'm in need of help , I love my truck don't want to get rid of it. Thanks.

 

To take it off the table test for fuel in #5
Unplug the 4 wire connector on the coil pack, so no spark
Crank the engine a few times
Pull out #5 and another spark plug for comparison

Both tips should be equally wet with fuel

Injector could be working but clogged


Next would be compression test
Shops can do electronic compression tests now, takes about 10seconds once computer is hooked up so shouldn't be an expensive test

If you do a mechanical compression test remove ALL spark plugs first then test all 6 cylinders.
3.0l runs 9.3:1 ratio so you should expect 165psi or higher depending on battery/starter motor speed and test gauge

If it is a compression issue then #5 should start working at higher RPMs, so if misfire goes away as engine warms up or at higher RPMs then could be compression issue

P0305 or any misfire code can be caused by 2 things
#1 is an actual misfire at the cylinder, computer uses Crank sensor for this, every time a cylinder fires it adds speed to rotating crank, a misfire doesn't, computer times crank so can tell down to the millisecond what is happening.
This can be caused by spark, fuel or compression

#2 is coil pack feedback, when computer unGrounds a coil and Grounds it again it will get a feedback pulse from that coil, if there was a problem this would generally cause a different code but computers are not smart.
This can be wiring problem or Coil Pack problem
You can test coil packs with OHM meter
Google: How to Check an Ignition Coil Pack the easy way
Watch the video, it is short

Now this doesn't tell you the coil pack is GOOD, just tells you if it is obviously BAD

Because Ford use Waste Spark, swapping plug wires can not always tell you if it is a coil problem or wire/spark plug problem, it is a good test to do though