Flashing Cel and misfire on multiple cylinders

[jp1234]

Hi everyone! I have a 2015 mustang gt with about 64k miles, its got a tune from lund but other than that its stock. ive been chasing a misfire for a while now that mainly happens at high rpms at wot and i finally got around to pulling all the plugs (again) and doing a compression test. heres a link to the video i took of all the plugs and their respective cylinder and compression. . If anyone could help me read the plugs id be very grateful. ive tried a couple of things like swapping the coils with new ones, pulling the injectors and inspecting them, and ive also taken the car to ford. they just told me the plugs were the issue, even though i just replaced them 1000 miles prior, so i changed them again and for another 1000 miles the car ran great until it didnt and the flashing cel came back. ill get codes p0300 and random cylinder specific codes each time the specific cylinder codes are always random and on both banks. any help would be greatly appreciated.

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[Paddles]

Can you flash back to stock tune and see if it's still happening on stock tune?

 

[jp1234]

Can you flash back to stock tune and see if it's still happening on stock tune?

I've test that out and it seems to not care what tune it's on, it still flashes at higher rpm on stock aswell

 

[K4fxd]

Are you sure you have genuine NGK plugs?

 

[jp1234]

Are you sure you have genuine NGK plugs?

The original plugs that went bad after 1k miles were OEM motorcraft plugs, then I swapped to ngk, I bought the ngk ones at an O'Reilly's so i hope they are genuine lol

 

[SnowFox]

The original plugs that went bad after 1k miles were OEM motorcraft plugs, then I swapped to ngk, I bought the ngk ones at an O'Reilly's so i hope they are genuine lol

The OEM plugs went bad after 1k miles? All of them? That's weird iridium plugs last a long freaking time.

 

[K4fxd]

I got bad plugs from o'reily. I think it was a return from amazon.

 

[jp1234]

The OEM plugs went bad after 1k miles? All of them? That's weird iridium plugs last a long freaking time.

Yeah i changed them around 60k miles for the first time then the ones i just put in went bad after like 1k miles so i took it to ford and they said "needs tune up" which was just spark plugs, so i changed the plugs and went with ngks this time and then the misfire and flashing cel went away but only for 1k miles again now its back

 

[jp1234]

I got bad plugs from o'reily. I think it was a return from amazon.

its possible but it would be nuts to get two back to back bad sets of plugs imo, i just dont want to buy a third set of plugs just for the issue to come back 1k miles later

 

[K4fxd]

Pull one of the plugs and compare it with the yt video on how to spot fakes.

 

[jp1234]

The OEM plugs went bad after 1k miles? All of them? That's weird iridium plugs last a long freaking time.

yeah something has to be making the go bad i just dont know what it could be at this point. which is why i did a compression test

 

[SnowFox]

yeah something has to be making the go bad i just dont know what it could be at this point. which is why i did a compression test

So for clarification sake:

OEM plugs went bad after 1k (all plugs or just one?)

You replaced them, the issue resolved itself temporarily. And is giving you the CEL again.

You also replaced coil packs, this didn't resolve the issue?

 

[jp1234]

So for clarification sake:

OEM plugs went bad after 1k (all plugs or just one?)

You replaced them, the issue resolved itself temporarily. And is giving you the CEL again.

You also replaced coil packs, this didn't resolve the issue?

so im getting random misfire and multiple completely random individual misfires each time the falshing cel happens, ford told me the spark plugs were bad (the oem ones i put in 1k miles prior) they didnt look terrible when i pulled them but i replaced them anyways (with the ngks). the issue went away for about 1k miles and the car drove great, now the same problem is back and thats what the video shows is the current state of each plug thats in the car now (the ngks). and yeah i swapped all the coils from a friends 5.0 same year and all to my car and the issue was still there. i also pulled and inspected each injector and they looked clean as can be.

 

[DougS550]

Are you using any fuel additives? I would send a datalog to Wengerd and see what he says. Good luck

 

[jp1234]

Are you using any fuel additives? I would send a datalog to Wengerd and see what he says. Good luck

no fuel additives and i was able to capture a data log while the flashing cel happened and i sent it to lund and they told me everything looks fine and to just do a crank relearn and that should fix the problem (it did not)

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