I had a thread started over a year ago when I had trouble with this car.
Updated (and asked for more help) that and thought I would start this one since different question(s) now.
I am just about stumped.
Not just about, stumped.
Had alternator trouble yesterday morning.
It must have went over voltage and LOTs of warning lights lit up.
But as I drove to pick up a new alternator (warranty) everything was fine.
No more flashing lights for ABS, check brake system, battery, and/or traction control.
Volt meter on battery when running was back around 14.2-14.4.
BUT
cannot get misfire/coil trouble figured out and fixed since.
P0306 (cylinder 6 misfire)was showing at first.
Once I tried another plug and coil P0356 (Power train Ignition coil "F" Primary/Secondary Circuit) shows and won't go away.
Tried a few different plugs in #6 (drivers side- closest to flywheel front bank).
Have tried 5 different coils now.
All same results P0356 and it is missing-only running on 5 cylinders.
Saw that coils could be checked with an ohm meter, so tried that and a brand new coil.
The coils are two wire versions and I have been trying to figure out how to check the power/signal to the coil.
When I check each wire going to the coil one is battery voltage and other ground with key one or running.
Compared to cylinder #5 seems same.
I spent as much time as I could in the freezing cold looking over all the wiring and connectors.
Did not see anything that looked bad.
Jiggled and moved anything I could that I thought might help show a short or bad connection.
Seeing the power/ground at #6 connector kept me from tearing up too much or stripping too much wire wrapping.
Thought it much be connected since I saw power and ground.
Thought I better search for wiring diagram and follow what feeds #6, but thought it must be connected.
Any ideas??
I am at the end of my limited knowledge.
Appreciate any help or direction.

 

Forgot , its a 2009 Lincoln MKX AWD 3.5 v6

 

I "updated" my old/earlier thread too.
I will have to just stay here, but not confident the alternator isn't going to rear it's ugly head again too

Still just don't know....
Thought overnight that maybe the weather pack connector at the coil was a missing link that I hadn't verified.
Took some test probes and alligator clips to make sure there was connection.
Then I even clipped the 2 wires so I could get better look at the connector.
Swapped more plugs and coils after that.
Started wondering if maybe the OBD or code was telling me wrong cylinder.
Everything I been doing and still no fix.
Then I remembered that I did put a "spark tester" light between that coil and plug yesterday.
Nothing lit when it was running.
So there went that theory.
Without knowing how to verify what is supposed to be "signaling" that coil, really do not know what this could be.
I had thoughts/fear that the alternator overcharging may have cooked part of the computer (PCM/ECM).
But as far as I can tell what I see at #6 is same as 4 and 5 and they seem OK.
Just DO NOT KNOW [img alt=""]data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7[/img]

 

With that many miles, I'd check compression and then diagnose the injector.

 

Replied with below on my "other" thread...

Appreciate that.
It is undoubtedly prone to MANY issues as old and worn out as it is.
But scanning shows that coil circuit out, and trying to check spark with a tester/light shows nothing also.
It sure seems like no spark at #6.
Just can't figure out why.
Tried multiple coils, multiple plugs, have power and ground at 2 coil connections, everything I know how to check seems OK.


I did figure out how to change text font color after copying and pasting back and forth.
I highlighted what I pasted and dropped down the bold/capitol "A" from the quick reply frame.
Changed from automatic to selecting black.
Just an FYI, since I see yours grey and I was doing the same up until a couple days ago.
And I also had to format so I didn't end up with a bunch of extra spacing.
Probably more reasons I shouldn't be running multiple threads for my same question.
Appreciate the help and reply!