GEN 2 Engine stumble under light boost on freeway - code P0301

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91Eunos

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I know there are a couple similar threads out there, but my situation is a bit odd.

Background: Truck religiously maintained, and only super unleaded/93 octane or better ever put in the tank. Have had cam phasers replaced twice, and IWE done once…all under warranty.

Situation: My wife was driving my truck down from Ft Worth a couple weeks ago and said she got a flashing check engine light, with a noticeable loss of power, then the light stopped flashing and the truck was driving normally. No codes thrown though, which I thought was odd.

Fast forward to last week, and I’m driving in to work in typical San Antonio early-morning traffic on I35…. i.e. full throttle followed by full stop, LoL. Got the flashing light and could feel the engine stumble, along with a huge power loss. First thought was an intake hose came off or collapsed, but as I was making my way over to pull off the highway, after about 30 seconds or so, it cleared up and the truck drove normally.

Later that day, I grabbed my OBD-2 reader and got a P0301 code: misfire on cylinder #1

No issues since, and I’ve intentionally gotten into the boost a few times to see if it’ll trigger again. Nothing.

It’s been almost 40K miles since the last time I changed the spark plugs, so I’ll do that today, but anything else I should be looking for?

Any easy way I can check the coils at home?

—break—

Also, I have noticed an occasional big ‘clunking’ noise that you can feel when putting the truck into gear after reversing out of a parking spot lately. Only when it’s cold. Likely nothing to worry about, but any thoughts on getting the transmission/rear diff looked at?

Will mention it if I wind up taking it into the dealer for this engine code regardless.
 
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FordTechOne

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When you’re changing plugs do a thorough visual inspection of the coils and boots. Look for cracks, corrosion, swelling, etc. Are you running a tune or stock?
 
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91Eunos

91Eunos

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Did the plugs, nothing out of the ordinary. Definitely worn, but not ridiculously so. Here’s the plug from the #1 cylinder (the one that threw the code), next to a new plug:

608E6851-4FE4-4B31-ADB6-F2BCFB2A3A9E.jpeg

I took individual pics of all the others too, but all looked about the same to me. Here’s a group pic of all six; in order from top to bottom, 1-6 :

EF0BF52A-75F9-4356-8DA4-3E0E768842DA.jpeg

Nothing unusual noted on the coils or boots, no cracks or indication of over heating, and the boots were still very supple. I also started and ran the truck for about a minute after each plug was changed, just in case I didn’t get something right.

So far, so good…. No codes and it seems to be running very smoothly. Gonna take my wife out to dinner in a bit, and will get into the boost a bit during the drive as well.


edit: back from dinner, and did several moderately hard pulls in normal and sport mode…zero issues!
 
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91Eunos

91Eunos

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Was a little concerned about the oil on #5, but now think it’s just old anti-seize. I looked down in the cylinder with a flashlight and small mirror and didn’t see anything.
 
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91Eunos

91Eunos

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Will grab some of those next time I’m at the dealer…or if I have any issues again.

Changing the plugs really isn’t difficult at all; some fiddly bits moving stuff out of the way, but pretty easy and straightforward, so going back in to replace the boots won’t be difficult.
 
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91Eunos

91Eunos

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Well, it’s back…. Did a long drive on the freeway, and on the return leg it happened again. Same thing

same code too: 0301

Off to the other side of San Antonio to grab the sole ignition coil actually in stock. More to follow.
 

ColoradoBoss

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I was told not to run anti seize on spark plugs because it can cause issues. Also mine clunks in reverse too. It stopped when I replaced the suspension in November but it's started to do it again but not as harshly.
 
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