The short version. I was pushing the truck's acceleration to the (red line) limit trying to merge on the freeway. I never push it this hard. I felt a jerk or shutter, knew something was wrong, and the check engine light blinked. The truck came back to normal, I thought, after slowing down and the light stayed constant on. The Auto Zone scan tool said it was a misfire in cylinder one misfire. I was going to just change the coils between cylinder one and another, but I took the plug out. (I changed them all with NGK Iridiums about 3-4 months ago. The spark plug matched images of ones with carbon fouling. I replaced it with a new one and switched the coils. The Auto Zone guy says that should, if it's a bad coil. The first question is about any of the logic or steps so far. The second question is how would I know if the check engine light is switching to a (theoretical) new problem at the new cylinder if the coil is bad? If the light stays one, how do I know it's not the original problem? Or if replacing the spark plug fixed the problem, although obviously something ELSE could be causing everything. One simple cause I saw suggested was the air filter, so I looked at it, and it's extremely clean. I replace those things often enough that I don't actually remember doing it.
Thanks,
Mike Todd

 

Quick note, just to be clear. The truck is driving "just fine" as far as I can tell.

 

How would you know???????????
Same way it was found the first time.
Look at the code generated again.
.
Code for cylinder issues is not the same for electrical issues with Coils.
Code for Fuel Injector electrical/performance is still different, as well.
Mass bombing with parts is not the way to fix anything unless you just get lucky.
Know where you're going, first.
Going to redline might have broken something in that cylinder. Maybe a compression test is in order.
Good luck.

 

What I mean about how would I know is this--if I reconnect the reader and have the same code, how do I know it's not the old code still sitting there? I guess it says it's the new cylinder, then easy peasy. The code is P0301, BTW. But I guess another question is whether the check engine light turns off on it's own. If it does, and it turns itself off too quickly, you might not notice it ever. (I guess it did turn itself off last time when the issue was pcv sensor.) If it stays on until someone with special equipment resets it, then I gotta take it somewhere anyway. I was going by the suggestion at Auto Zone that the most likely issue is a spark plug, and second most likely is an ignition coil. This video suggests that the same code could be the spark plug or the coil. and I was kinda going by his comments in analysis.

 

All you need to do is lift the Battery Neg Connection off for about 5 minutes, then reconnect.
Any codes will be cleared unless any appear again, or, if any fault still exists from running the engine again..
Doing this guarantees any Check Engine Light is from a repeat or/and any different code/that return.
All codes are lost if power is removed same as clearing with a tool.
You still need to know what any code is, if any return.
Good luck.

 

I have a code reader that connects to my phone. I threw an cylinder misfire on Cylinder 6. I swapped the coil to cylinder 5 and the misfire moved. Replaced the coils (at 125k on my 2015 ecoboost). No more misfires.. Recommend you get ford replacements..