Seems odd there is no check engine light and the scanner shows no codes for a misfire but #3 plug wire is dead.

I replaced the wires, plugs and the coil pack still nothing.

Anyone Ideas

 

It cannot be as you posted.
The reason why is as follows; cylinder performance is measured by crank rotation time as measured by the crank sensor.
If any cylinder is actually missing or down on power for any reason it will be detected as a slower rotation time when compaired to the average as stored in the program table for the engine.
The program table is updated over the long term and can actually account for engine wear over time..
The ignition on a V6 is actually a wasted spark system where one coil winding sparks two cylinders.
This means two cylinders are paired in 3 pairs.
for the 6 cylinders.
Your missing something in the way your looking at it if there is no codes set and engine shows no rough running as displayed on a Scanner.
Good luck

 

Thank You Bluegrass 7.
To follow up on your advice. I checked all the wires again. They are brand new. They all fire but #3. I switched #3 and #4 at the coil as 3 &4 fire at the same time. Now the wire to #4 is dead. No check engine light on and there are no DTC's logged. This is a new coil pack also

 

Something is missing here besides the spark.
The coil is likely faulty for one.
Second, with no spark to a cylinder, the cylinder has to be detected as a misfire because there is no combustion to turn the crank with any torque so the rotation has to be much slower, as detected by the crank sensor.
Of course the rotation is carried through cylinder to cylinder by the inertia of the crank and it's rotating mass of the crank assembly.
If there is no code, there has to be a 'second' problem causing the confusion.
With no spark to one cylinder, you have to feel and see the results of the misfire just in engine idle.
Misfire codes are 30x. A rotation time code.
Faulty coil primary or coil driver is a 35x code, an electrical failure detected..
Yes or no!
Sorry to insist but this is the way the system is designed and works.
Can't be any other way.
See if your check engine light comes on when you turn the key on 'before' cranking.
.
This checks out all the dash functions prior to cranking.
Also check to see if a PCM fuse is blown that powers the keep alive data and memory.
If yes, this is why you see no code stored when you take a look because it can't be stores with no memory power present.
The motor will still start and run without this fuse but has no memory functions. This also restarts the diagnostic program all over again each time the key is turned on..
The answer is here some where.
Good luck.

 

How are you determining that cyl #3 was "dead"?


And if you switched #3 and #4 wires ONLY at the coil, since they are companion cylinders (i.e., fire together) that would only change direction of electron flow in the secondary of those two cylinders.


And a question for bluegrass:
In a waste spark ignition system, if you pull a sparkplug wire off, that cylinder can't fire, but can its companion cylinder still generate a spark?


And a second question:
With all the voltage these ignition systems can generate, if there is no secondary connection, will that cook a coil in a short time?


So if the OP say had a dead sparkplug in #3 hole, and he switched the wires for #3 and #4 at the coil, would #4 appear to be dead, since that is the companion cylinder?


Thanks in advance for any insight..........

 

In a paired cylinder ignition, the coil secondary is not grounded.
At time of firing the cylinder, the mate cylinder is in it's exhaust cycle by intent and it's plug gap appears as a near short to the high voltage due to the ease of breaking down the exhaust components in the mate plug's gap.
The other mate cylinder is under compression so sets combustion in progress for that cylinder.
If one side is open, the high voltage will likely find a way to ground at the coil tower. The other cylinder may still fire but misfire under other conditions as they change under load.
This results in a conductive carbon burn path to ground and becomes permeant damage to the coil and misfire results.
Normal voltage levels in a good system vary from about 7000 to 15000 volts because at the time the plug gap breaks down the air/fuel mixture under compression, this puts a limit on how high the voltage can rise at that moment.
Even though the coil is capable of as high as 40,000 volts open circuited.
This is why the voltage will find a way to ground in a faulted system and cause damage at the easiest point it finds to go there.
The reason it goes to ground is at that point in time, the other side is going to ground so it becomes a complete circuit with some resistance from the plug gap plasma on one side and the breakdown on the other flowing though the engine's iron work.
Just like Lightening does when it strikes.
The polarity of the spark remains fixed such that in this type system, half the plugs could be specified as a different number due to different metals used in the center electrode to reduce erosion from the reverse polarity that cylinder is forced to use.
And ya all thought it was just a 'simple' ignition system.
Good luck.

 

Thanks for the education bluegrass.


To the original poster (Bashkoff):


If the #3 hole in that new coil has gone bad, when you switched the #3 and #4 wires at the coil ONLY, you said #4 then went dead. It appears to me that at that point cyl #4 was being feed by the #3 hole in the coil pack and therefor it would go dead if the #3 hole in the new coil pack was bad.


So my question is, how are you determining that the cylinder has gone dead?

 

Update
I do all my testing using a power probe, not a test light. All the fuses are good. Power at the coil pack same
The only engine light is service engine soon. It works. And I see no other CEL even examining the dash with a flashlight. No codes show up on my scanner with the truck KOEO OR KOER. I don't have the manual for the truck so it makes things difficult but I have access to Mitchell Pro for info I need.
I ohm out both coil packs and they show ohms between the coil towers and from each tower to power and ground pins.
The wires from the ECU to coil pack 2.1-2.5 ohms so that's ggod
I check for spark using an inductive timing light. It flashes on all but #3. If I switch #3 and #4, #3 flashes and #4 doesn't. The new coil pack was installed after the new plugs and wires so I doubt its burned out but I guess its time to try another coil pack and its time to get the grandkids. Back at it tomorrow
Thanks to all for your input. Greatly appreciated

 

Problem Solved!!
Of course overlooking the obvious because I had just put a new coil pack only to find out it was bad just like the old one.
I choose and unorthodox route so I didn't have spend money on another coil pack that no one wants to take back
I took and reversed the switching wires from the ECU so now the front coil towers became the rear ones. Reversed the plugs wires and bingo the right rear tower still did not fire. My thought was if the problem followed the wire to the front towers the problem was definitely not the coil pack. Went over to NAPA and picked up a new one and she purrs like a kitten
This still don't explain the lack of the CEL being on.
Oh yeah the defective coil pack, cheapie from Rock Auto.
Thanks again for all the help

 

And we worked as hard as you did to solve the issue.
Glad my fingers did the walking across the keyboard to help explain it.
Good work.

 

Thank YOU for reporting back!