I replaced the spark plugs in my 2015 2.7L for the first time using NGK Ruthenium 95605 plugs. After taking the truck for a test drive, I noticed it would shutter when hard accelerating. The Check Engine Light flashed briefly and I was able to get a code P0305 meaning 5th cylinder is misfiring. I checked the spark plug #5, it looked OK, reinstalled it and swapped ignition coils #4 & #5 and started up the truck again. With wide open throttle, in park, more shuttering occurred and I received code P0304. I purchased a new ignition coil and placed it in cylinder #5. I then went for another test drive. Under light load & easy throttle - even up to 70 mph, it runs fine. It is when I accelerate hard that it will still shutter for a few seconds but this time there was no check engine lights. I am not sure what went wrong and what I need to check or do next. I also noticed that while in park I can not get rpms higher than 4000. I don't know if this is normal or not as I have never tried that before. Does anyone have any idea on what could be going wrong? Any help would be appreciated.

 

If you had no issue before the plug change, it sounds like the plug gap is out of spec.
Under load and a misfire occurs, the Turbo is pumping a higher pressure and possibly blowing the spark out.
Recheck your work and the plug gaps for all the cylinders.
Could try two of the old plugs in cylinders 4 and 5 to see what happens.
Good luck.

 

Use OEM plugs---get one step colder, it will run great!!! OEM are very good plugs!!

 

Here the list of compatible NGK spark plugs for the 2015
Laser Iridium
ILTR7N8
95822

Laser Iridium
ILTR6S8
95927

Ruthenium HX
LTR6BHX
90495

Iridium IX
LTR6IX
94374

Pregapped at 0.032”
Recommeded gap 0.028” - 0.031”

OEM Part Motorcraft SP594

Replace coils with OEM Motorcraft. Do not use non-OEM coils they will cause misfires and performance problems.

 

You say that you got a new coil and put it on 5 when the code came back for the misfire on 4...sounds like you put the coil on the wrong cylinder.

 

looks like you got the wrong plugs. TL tech below states 90496. also just because it is new does not mean it is good

 

"blowing the spark out" is a myth:

https://www.ipdusa.com/Articles/512/...it-My-Birthday

 

So it turns out I bought the wrong spark plugs. The lesson I learned is even though RockAuto says they are compatible, it doesn't make them compatible!. I swapped them out with Motorcraft SP594 and now it works fine.

Now, since I had the issue a few days ago, I did some research and learned that Forscan can tell you misfire data. With these new plugs installed, I checked the Mode 6 data and under "Misfire counts for last/current driving cycle (calculated)" I will occasionally get 1 or 2 counts on random cylinders. There does not seem to be any rhyme or reason. These zero out after the truck is turned off and there are no numbers under "EWMA misfire counts for last 10 drive cycles". Is this normal? The truck feels fine, no jerking or shuttering under any speed.

 

Thank you for the video link, I appreciate you.

 

You're welcome, and thank you! Welcome to the Ford F150 Forums!