Bogging/missing under load

[Rex2nr]

1999 ranger, 4.0, 5spd 4x4, 196,000 miles

2 weeks ago I took a vacation and painted my cap, shaved my tailgate handle and repaired up any rust. I only drove the truck to get a cup of coffee and hit the grocery store- about 3 miles total- the whole week. The next Monday morning I left for work and filled up the truck at a gas station 1.1 miles from my house. The truck was running good, and looking better too.

I stopped for a cup of coffee near work, and jumped back on the express way. The truck stumbled pretty hard on the ramp, and settled back down once at speed. It ran fine the way home, and the next day. Wednesday it started to act up quite a bit, to the point I was considering having it towed home (aaa, why not?).

I found the the 4th cylinder had no spark. I tested by pulling the plug, and holding it against the head with vice grips. I started off replacing the wires since one looked a bit corroded when checking the plugs. The plugs all are a nice grayish and clean. I swapped in a new coil (ultra power performance coil) and now have spark at all cylinders. I found the coil I got is actually for a 97-98 3.0 ranger. It has the vertical plug. My truck had the horizontal stock, so I had to adjust the plug wires location to get it to even run.

I also did a compression test. I got 127-117 on a cold engine and had to use a plug non-fouler cut down as an adapter for the tester, due to the depth of the threads in the head. Those numbers are great, for 200k.

I have also checked fuel. When trying to find the correct firing order, I took a break, and pulled the plugs to do the compression test. At this point the engine wouldn't start. All the plugs had fuel on them, and had turned a black, damp color. I. Don't want to say they were fouled, but did not look as good. I had used 6.5 gallons of the 87 octane I filled up with initially. Last night I filled up with non ethanol 91 octane to hopefully eliminate bad gas. No change, though that ethanol free stuff smells nice and potent. I dumped the gas from my filter, and that shot out nice and clean.

I have no check engine light.

The truck is running better, but still misses accelerating. Any suggestions to try next?

 

[Tedybear]

Have you hooked up a scan tool and checked for existing and pending codes? At times a problem could be bad enough to cause an issue...but not quite bad enough to trip the 'money light'.

OBD II gives a very unique way to see how the engine is running, fuel trims, data readings...

Just saying this is a starting point... Another would be fuel pressure. It could be fine at idle and off idle.. it could be buckling. Just a few ideas...

S-

 

[Rex2nr]

I haven't. I was going to order an Ultra gauge but every time I get the extra cash together something breaks lol.

I have not checked fuel pressure, but it shot three feet out of the filter when disconnected it not sure what at concerts to in psi.

 

[AllanD]

Shot three feet out of which end of the filter?

Did you replace the filter?

Replacing the filter would be my first reflex action with the described symptoms...

 

[Rex2nr]

Tank side. I did not. I replaced it in the fall not that it really means much.

 

[Rex2nr]

I picked up a fuel filter, but the quick release has frozen and I have destroyed my removal tools.

I'll post back as soon as I have more info.

 

[Rex2nr]

New filter, runs the same.

 

[RonD]

Ford uses Waste Spark system this means two spark plugs fire at the same time.
A V6 engine will have 3 "matched pairs" of pistons, each pair will be at Top Dead Center(TDC) at the same time, one at end of compression stroke and the other at the end of exhaust stroke, the exhaust stroke spark is of course "wasted" hence the name waste spark system.

Waste spark is nothing new, pretty much every 4 stoke engine made that used a magneto or single cylinder(lawn mower/motorcylcle) used Waste spark, it sparks at each TDC, compression or exhaust

The coil pack only has 3 coils inside, 2 spark plugs per coil.
For the 3.0l or 4.0l coil pack the wiring looks like this
3 4
2 6
1 5
Front

The 1, 2, 3 side is easy
The 5, 6, 4 side is the one I goof up often, and swear it is right, lol.

The firing order/match pairs are there in that wiring
3 and 4 are matched pairs, so are both at TDC at the same time
2 and 6 are matched pairs
1 and 5 are matched pairs

So even though I am sure you got it right, just follow each spark plug wire to its cylinder.
I have also reverse 4 and 5 and 5 or 6 at that end

 

[Rex2nr]

I linked the image I found for the 3.0 plug wiring, which now that I look at it, IS the same as the 4.0 plug diagram, just layed out weird. Following that diagram made it very difficult to clip the plug wires onto the coil because they cris-cross but thats how it runs best.

The second image I am linking shows there apparently is a difference in how the coil is wired- coils 1 and 2 are reversed between the horizontal and vertical coil plugs.The other shows the two plug types- my original was the oem in the pic- horizontal, the aftermarket I received is like the screemin demon.

I also checked timing with a timing light. It seemed to be ok. If I used cylinder 4 (I chose that because that was the initial dead cylinder) and the light fired very intermittently. My plugs started to wet foul from trying to find the proper plug wiring. My Dad was telling me that a fouled plug can do that, just happened with his bike.

I can not remember if the crank position sensor works optically or magnetically? I replaced one in my long gone 95 3.0. Mine was coated in grime, so I cleaned that. Then i confirmed the plus were tight on the coil. With them crossing over each other, I believe one may have been loose. It then idled better than it ever has, so I took it out for a drive. It was still stumbling under load, but got better as I drove. I put about 2 miles on it and called it a night.

 

[Rex2nr]

Couldnt add more than 2 attachments. Sorry to post whore lol

This is "image #1" in the post above.

 

[RonD]

Firing order for 3.0l and 4.0l is 1-4-2-5-3-6 which also tells you the matched pairs for the waste spark

1-4-2-------5-3-6

1-4-2
5-3-6

1-5
4-3
2-6

Only wiring that matters is that the pairs stay together
And the computer knows which coil is for which pair

Terminal 3 (coil 1)-spark plugs 1 and 5

Terminal 2 (coil 3)-spark plugs 2 and 6

Terminal 1 (coil 2)-spark plugs 3 and 4

Can be 5-1 or 1-5, makes no difference at all, both spark
But they must be on coil 1

3.0l coils are mounted on divers side and backwards, coil #1 in back, on 4.0l, its passenger side coil #1 in front


And just as a heads up, with Waste spark you never use single platinum spark plugs, it is a waste of money, because 3 of the spark plugs(V6) will wear out just as fast as regular copper spark plugs.
So used regular copper or Double platinum.

 

[Rex2nr]

Firing order for 3.0l and 4.0l is 1-4-2-5-3-6 which also tells you the matched pairs for the waste spark

1-4-2-------5-3-6

1-4-2
5-3-6

1-5
4-3
2-6

Only wiring that matters is that the pairs stay together
And the computer knows which coil is for which pair

Terminal 3 (coil 1)-spark plugs 1 and 5

Terminal 2 (coil 3)-spark plugs 2 and 6

Terminal 1 (coil 2)-spark plugs 3 and 4

Can be 5-1 or 1-5, makes no difference at all, both spark
But they must be on coil 1

I got it.

I can clean up the coil so the wires are a bit neater. I'll also recheck the positioning. It is running better, but still missing between 2500 and 3000 RPMS. I replaced the TPS and IACV last fall, Cam syncronizer/sensor also.

3.0l coils are mounted on divers side and backwards, coil #1 in back, on 4.0l, its passenger side coil #1 in front

That explains the diagram I posted.

And just as a heads up, with Waste spark you never use single platinum spark plugs, it is a waste of money, because 3 of the spark plugs(V6) will wear out just as fast as regular copper spark plugs.
So used regular copper or Double platinum.

I've always used NGK standard plugs with my Hondas, any preferred brands for Fords? It has Motorcrafts in it now.

 

[Rex2nr]

For whatever reason, the truck only runs with the wires on the coil like this:

1-5
2-6
3-4
Front of engine.

Essentially this coil is wired backwards from the original OEM.

It is still missing and bogging. When the plugs were in the factory position, it would just crank and dump fuel. If they were in any other combination it seemed to want to vapor lock.

I am going to replace the plugs tomorrow after work.

 

[RonD]

If the 4 wire connector is on the passenger side then it would be opposite of the way you have it.
But if connector is on drivers side then that way would be correct, coil pack is just rotated 180degrees
1 5
2 6
3 4
front

rotate 180
3 4
2 6
1 5
front

 

[Rex2nr]

The connection is on the passenger side, same location as the original. I am really lost now, but this is the only way the truck will start, but it still misses. Still no CEL either.