2017 3.5L V6 - Misfires While Accelerating

[chrono]

I got this truck 2 months ago with 50k miles on it. About 3k miles later, I started noticing misfires or "pinging" in two situations: (a) when accelerating at highway speeds, like while passing, and (b) when climbing hills. Eventually I had enough misfires to trigger a persistent Check Engine Light, so I brought it in to find that I had a P0302. They replaced the the coil and the plug on cylinder 2, and it drove fine after that.

Now, 7k miles later, I'm noticing the same thing. I have a code scanner, but it hasn't happened enough to trigger the DTC, so I don't know which cylinder it is yet. But I imagine this will happen soon enough.

What's up with these coils/plugs? Should I just replace them all now? I'm at 60k miles - the manual recommends replacing the plugs at 100k, says nothing about the coils..

 

[07navi]

I got this truck 2 months ago with 50k miles on it. About 3k miles later, I started noticing misfires or "pinging" in two situations: (a) when accelerating at highway speeds, like while passing, and (b) when climbing hills. Eventually I had enough misfires to trigger a persistent Check Engine Light, so I brought it in to find that I had a P0302. They replaced the the coil and the plug on cylinder 2, and it drove fine after that.

Now, 7k miles later, I'm noticing the same thing. I have a code scanner, but it hasn't happened enough to trigger the DTC, so I don't know which cylinder it is yet. But I imagine this will happen soon enough.

What's up with these coils/plugs? Should I just replace them all now? I'm at 60k miles - the manual recommends replacing the plugs at 100k, says nothing about the coils..

If it ain't broke don't fix it. My coils were at over 200k when I sold it. 100k is too long for the plugs though.

 

[mquick5]

Yeah start with a set of plugs. And you may want to add a oil separator, or catch can.

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[LokiWolf]

Don’t need to have CEL to have a code. Especially if you have more than a basic scanner or FORSCAN.


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[07navi]

Don’t need to have CEL to have a code. Especially if you have more than a basic scanner or FORSCAN.


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will forscan work on 2007 5.4? Some sellers say it won't.

 

[LokiWolf]

will forscan work on 2007 5.4? Some sellers say it won't.

Yes, but limited functions. You can see codes, and do some of the maintenance functions, but not many changes.


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[3tonsoffun]

I got this truck 2 months ago with 50k miles on it. About 3k miles later, I started noticing misfires or "pinging" in two situations: (a) when accelerating at highway speeds, like while passing, and (b) when climbing hills. Eventually I had enough misfires to trigger a persistent Check Engine Light, so I brought it in to find that I had a P0302. They replaced the the coil and the plug on cylinder 2, and it drove fine after that.

Now, 7k miles later, I'm noticing the same thing. I have a code scanner, but it hasn't happened enough to trigger the DTC, so I don't know which cylinder it is yet. But I imagine this will happen soon enough.

What's up with these coils/plugs? Should I just replace them all now? I'm at 60k miles - the manual recommends replacing the plugs at 100k, says nothing about the coils..

I change plugs every 35k on my 16 (tuned, step colder 542s gapped at 0.028”) and 50k on my wife’s 16 (stock, step colder 542s gapped at 0.030) if you have a buddy that has a tuning device, I would recommend booking to up and seeing what kind of knock values you are getting. Could be a little more serious than just plugs/coils

 

[chaos254]

Replace all of the plugs

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[chrono]

thanks everyone for your advice and experience - it's given me some things to look into / think about.

so it sounds like the majority of expi drivers are doing fine with their stock coils, then?

by the way, here's a photo of the coil+plug that came out of cylinder 2 after the misfires at 53k. the mechanic said the discoloration was a sign of coil failure.

View media item 7056

 

[John D]

I had exact same symptoms as you in my 2016. I was given the advice to swap the coil from the misfiring cyclinder to another and see if the misfire followed it, but to go ahead and replace all the plugs and boots. I did this and no more issues. I had replaced plugs at 45k simply for maintenance and then one of the "new ones" cracked at 85k.