02 ranger 3.0 cylinder misfires

[cherokeejeeper76]

ok fellas, I have so far replaced all 6 fuel injectors, new plugs and wires, upper plenum gaskets. I also doused the motor down with brake cleaner while it was running to track down vacuum leaks, none found. It's missing on cylinder 2 and 6 and has a really rough idle. Kinda stumped here. Ideas???

 

[RonD]

Welcome to TRS

2 and 6 share a coil in the coil pack, so I would start there, its possible you have burnt exhaust valves but 2 and 6 do have the coil in common

Coil pack only has 3 coils inside, each coil sparks 2 cylinders when they are both at TDC(top dead center), called a Waste Spark system, uses Crank timing unlike a distributor that used Cam timing

Coil wiring looks like this
[3 4]
[2 6]
[1 5]

So 1 2 3 side and then 5 6 4 side, 1/5, 2/6, 3/4 these Pairs spark at the same time
Those are the Match Pairs of how the V6 engine is balanced, 2 cylinders at TDC every 120deg of rotation, balanced rotation
It can go this way as well, don't get hung up on direction its the Matched Pairs that matter
[1 5]
[2 6]
[3 4]


If you have a 12v test light you can test if computer is "sparking" all 3 coils

Unplug the 4 wire connector on coil pack
One wire will be red/green, that wire has 12volts with key on, powers all 3 coils in the pack
The other 3 wires go to the computer
Tan/and different color stripe for each

Test light goes to red and one of the tan wires
Crank engine over, test light should flash on and off, if so computer is working on that one tan wire
Test the next tan wire
No flashing means that tan wire is disconnected OR computer transistor(circuit) is bad

Pins 26, 52 and 78 are the 3 tan wires on computer connector

 

[wyatthansen]

I had the same problem with my 2000 3.0 ranger. Went through everything and couldn't find the problem. I don't know if my original problem manifested to this but I finally got to the point it was running so bad that I took it to the dealership and I had a bad intake valve, exhaust valve and leakage past the piston rings on one cylinder. Had the same misfire codes for 13,000 miles and replaced a whole bunch of parts to no success. That engine is now toast so its currently getting a 5.0 from a 2000 exploder.

I guess what I would do in your situation if you went through everything but still have those codes is a compression/leakdown test.