2000 Ford Ranger 3.0 Engine Issues

[Grandpa_truck]

Hello All,

First post / new member. Thanks for this forum!
I need some help with my Ranger.

Vehicle:
2000 Ford Ranger
RWD
Automatic Transmission
3.0 Flex Fuel
202,700 miles
Coolant leak at timing cover
Slight rear main leak

Story:

Yesterday, my truck started running rough after coming to a stoplight. The idle dropped and acted like the engine would die. This has happened before, but it would be minor (slight miss could be felt in the seat, but no check engine light and the idle would smooth out).
Let the truck sit overnight and this morning had the misfire as soon as it was started. The check engine light then came on. Drove to Oriely and borrowed the scanner to find code P0304. While driving, I could feel the miss but the engine still had good power.

Bought plugs (Motorcraft SP-500) and wires, if I needed them. Drove home and pulled the number 4 plug to find the tip was worn flat. I thought bingo, problem solved.

So then I proceeded to change all spark plugs. The wires were replaced 2 years ago and looked to be in good condition. I changed all the plugs and noticed cylinder 5 plug was worn nearly flat as well (think this is due to the waste spark system I read about).

I was so happy I thought I fixed the problem to find the truck to still have a rough idle after changing all plugs. The engine sounded good when revving it, but the engine was shaking and missing when idling.

I then read this thread about the firing order (https://www.therangerstation.com/fo...anger-three-point-oh-3-0-firing-order.185020/).

It states that the plugs can be swapped (in their associated pairs) as copied:
3 4
2 6
1 5

OR

1 5
2 6
3 4

I then tried swapping wires from the first orientation stated above:
3 4
2 6
1 5

To

1 5
2 6
3 4

I tried to start the truck at it barely idled then died after a second. I then swapped the wires back to:
3 4
2 6
1 5

This was the orientation when I changed the plugs (did not touch the wires on the coil pack) and had the miss.
Trying to start the truck, the engine behaves the same as the swapped wire orientation:
1 5
2 6
3 4

Any ideas what could be wrong now? Clearly I have the miss for some reason and I just created another problem. I have read if the coil is wired incorrectly it will work, but not properly.

I'm stumped!

 

[2011Supercab]

It states that the plugs can be swapped (in their associated pairs) as copied:
3 4
2 6
1 5

OR

1 5
2 6
3 4

I then tried swapping wires from the first orientation stated above:
3 4
2 6
1 5

To

1 5
2 6
3 4

3 4
2 6
1 5

can be switched to

4 3
6 2
1 5

You can switch side to side, NOT front to back.


A misfire can also be an injector problem or a compression problem.

 

[Grandpa_truck]

Thanks for the reply.
Well I hooked it up backwards and swapped the pair front to back

What happens if the coil pack is wired backwards?

My fear is the camshaft position sensor is now out of sync and even with the wires in the correct orientation, the engine will not run.

 

[Grandpa_truck]

Following up on this.
What happens if the spark plug wires are connected wrong on the coil? I know the engine will not run but does anything get damaged?

 

[Grandpa_truck]

Following up.

I let the truck sit overnight and corrected the routing of the spark plug wires. The truck started and ran, but still had the misfire.

I ended up going to a shop and they said they believe there was carbon build up under one of the valves in cylinder 4 causing the misfire. They cleaned the throttle body and performed a compression check too. Can't remember the number off the top of my head but it was within spec.
Misfire is now gone and engine is running well.

Guess I'm driving too much like a grandpa after all.

 

[superj]

Following up on this.
What happens if the spark plug wires are connected wrong on the coil? I know the engine will not run but does anything get damaged?

as long as you don't drive it around forever, it won't hurt it. it probably won't hurt it anyways, even driving for a long time, but it would suck driving it like that for a long time