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Runs rough, plug wires, coil pack help


94RoadkillRanger

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I have a 1998 Ranger v6 3.0 automatic which I bought last year. It ran rough at first with shaking and then when it warmed up, fired on all six. There was also an engine code P0302 (misfire on #2). I just replaced the plugs and wires and the old plugs looked like they had a .100 gap (all burned up). I made sure the new plugs were gapped .042-.046. The old plug wires did not look like they were installed correctly. So, I went by the book (Haynes and Chilton and the tech section on this web site). From the front of the truck (also front of engine) to the rear, the passenger cylinders are 1-2-3; driver's side 4-5-6. The coil Pack, from FRONT TO REAR on the passenger side is 1-2-3; driver's side 5-6-4. The harness connector is in the passenger side. Like cylinder numbers connect to same coil pack numbers.
It now runs real bad, worse than before.
I do not have an exact record of how it was strangely wired before.
 


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Mark_88

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Considering what you have done and the difference between before and after, I'd say just check the firing order again carefully. It is easy enough to make a mistake on these engines as I had to make three adjustments to an old 3.0 before I got it right.

Only other thing that might be a problem is the plugs are not correct type and are not sitting deep enough...or too deep...in the head...or the plug wires are not snapped over the plugs properly.

These are things that most, if not all, of us can mess up no matter how many years we've been doing it...

The coil pack I'm not sure about as the 3.0 I worked on had a distriibutor at the back of the engine (where your timing is now set) and reaching it was most of the effort...
 

94RoadkillRanger

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Thanks,
I just changed the plug wires around 180 degrees and it runs great, no CEL either. I checked the chart again and sur'nuf there is something strange with the way this is wired, almost like the timing belt was put on wrong.
 

RonD

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Fords coil packs for v6 engines have 3 coils inside not 6, Ford uses a Waste Spark system, it fires 2 spark plugs at the same time, so when 1 coil in the pack fires 2 spark plugs spark.
One spark plug will be firing on the compression stroke the other will be on an exhaust stroke, these cylinders getting spark are matched pair cylinders used to balance the crank/engine, V6 will have 3 matched pairs 120degs apart on crank to balance the crank.

Firing order of 3.0l is 1-4-2-5-3-6
If you divide any firing order in half and put one half below the other you will see the Matched Pairs of pistons/cylinders

1-4-2
5-3-6

These are the matched pairs for the 3.0l
1 and 5 pistons are at Top Dead Center at the same time
As are 3 and 4, and 2 and 6
One will be on its compression stroke the other on it's exhaust stroke because this is a 4 stroke engine.

Now look at the Waste spark V6 coil pack
[3 4]
[2 6]
[1 5]

Matched pairs

Ignition control module fires 1/5 coil every time 1/5 pair is at TDC, doesn't matter which is on the compression stroke, both get spark
Same for 2/6 coil and 3/4 coil

This is why there is the normal 1 2 3, and then the abnormal, 5 6 4, on the coil pack.

You can reverse 1 and 5 spark plug wires, and 3 and 4, and 2 and 6 on the coil pack, because both have spark at the same time.
I have seen people do this to "even the wear" on the spark plugs, read below.

These spark plug pairs are wired in series in the coil pack, this means that one spark plug will spark from center to tip and the other will spark from tip to center, not a big deal but.............
Since these spark plugs are firing every 1 RPM instead of once every 2 RPMs they wear faster and in opposite directions.
One bank will get more wear on tip, the other bank more wear on center.
You can extend spark plug life a bit by pulling out the spark plugs, regapping, and putting them back in the opposite bank.

Using single platinum plugs only helps on one bank, double platinum will last longer on either bank.
 
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94RoadkillRanger

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Thanks Ron,
I know there are three shared pairs of coils.
Essentially, for some strange reason, I have to swap the 1-3 wires and swap the 4-5 wires as if the coil pack were mounted 180 degrees around on top the intake manifold, but the harness connector is on the passenger side as it should be. It runs fine now, but it's LIKE someone set the spark at 190 BTC instead of 10. Maybe this coil pack is not original and is from another vehicle.
 


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