Okay I have an 02 Ford Ranger 3.0 2 wheel drive 5 speed I had a cylinder 5 misfire since the day I bought it he had the engine replaced because he couldn't find out why he had a misfire the engine is 06 I swapped the coil out and it moved to Cylinder 6. Ohm tested both coils, ohm tested my injectors, compression tested 160 on all 6 cylinders, scoped cylinder 5 and 6 to check out the valves... No problem there, fuel pressure is 55psi at operating temp. New Motorcraft plugs, wires, and coil... And still have a miss on cylinder 6. Any ideas? The ECM is for the 02 with the motor being an 06 could that be a problem?

 

Welcome to the forum

Looks like you covered all 3 bases for gasoline engines
Spark
Fuel
Compression

But one of those is still the problem if there is a misfire you can feel

1986 to 2008 3.0l Vulcan engines are all interchangeable so outside of wiring issues it wouldn't be basic engine, block and heads, issue

Ford used Waste spark system and coil packs for many years
First spark system ever used on gasoline engines is Waste Spark, sparks each time crank rotates one time, so every TDC(top dead center) of a piston

The coil pack, for a V6, only has 3 coils inside
Each coil fires 2 spark plugs at the same time

A V6 engine is balanced by having 2 cylinders at TDC at the same time every 120deg of crank rotation
These are called Matched cylinders, with the 3.0l V6 they are
1 and 5
2 and 6
3 and 4

And you will see the Coil Pack spark plug wiring is the same
1 and 5 share a coil
2 and 6 share a coil
3 and 4 share a coil

So 1 and 5 spark at the same time, one is on compression stroke and the other on exhaust stroke, so exhaust spark is "wasted" hence the name Waste Spark System

So firing order on the coil pack is important, the 5 6 4 side often gets miss wired
I have done it more than a few times and would bet my life it was correct, lol, and would have been DEAD many times over, lol.

I don't think they traded up with used 2006 3.0l engine
2004 to 2006 Ranger 3.0l engines had bad exhaust valve seats, not 100% but enough for a TSB to change the heads out.
TSB here: http://ww2.justanswer.com/uploads/s4...b05-26-03.pdf/
And symptom was a misfire

Not saying thats what it is just an FYI

You should see lower compression in #6 might not be much but lower than average.

Is the misfire steady at idle?
Or just under load?

If at idle you can often spray fuel into intake to see if misfire stops momentarily, showing an injector issue, clogged a bit or missing pulses

On some engines you can unplug the Cam Sensor, used for sequential fuel injection.
When you start the engine computer should change to Batch Fire injection
On a V6 Batch Fire means computer opens 3 injectors at the same time, 2 on 1 bank, 1 on the other bank, and then rotates them every other pulse, this keeps the intake full of air/fuel mix, if misfire stops that would also show injector issue with #6

Some engines won't start with no Cam Sensor pulse, just FYI

#6 is at the rear of the engine, and thats where the oil pools under the valve covers when engine is running and driving
So a leaking valve guide seal could cause misfire on #6 if oil was leaking down intake valve stem, but spark plug would show that, tip would be darker color than others

Also don't assume new spark plug is good, swap #6 with another cylinder, I have been finding more "bad" new parts in the last 10 years or so, basically there is no quality control anymore, "you test it, if bad we will replace it free" thats what "new" means now