My 2013 5.0 (90k miles) is giving me a P0308 with absolutely zero drivability issues. I swapped the #8 coil pack with #7, cleared the code, and it came back a couple days later, on cylinder 8 still. I then changed the spark plugs (was pushing 45k on them anyway) and didn't notice anything suspicious about the #8 plug at all..... cleared code and it was back the next day. Any ideas? Any common stupid issues that cause this? I'll do a compression test next time I get a chance, but given the lack of drivability problems, I'm doubting it'll have anything to tell me. Just figured I'd ask about common issues before I pull the fuel rail and replace an injector for possibly no reason. Thanks

 

Double check the code and verify which is the correct cylinder.
swapping coils sounds like good trouble shooting. Maybe the ignition wire to that coil has a problem? Check the wiring there (ignition wire to harness) for continuity, make sure somehow it is still intact?

 

Yea, didn't even think about the primary harness at the coil.... definitely still cylinder 8, cause I reverse installed the coils on all the cylinders when I re-instslled them after changing out the plugs. Took them off 1-2-3-4 and 5-6-7-8, switched them and installed them 4-3-2-1 and 8-7-6-5.....

 

What I meant was did you assume the bank you swapped coils on was 5678 or could you really have been on the opposite bank (1234)? I’m not trying to insult you, but if you never looked it up it could be reasonable to think 1234 is the driver side bank and 5678 is the passenger side bank.

According to a quick google search 1234 is the passenger side and 5678 is driver side, with low numbers (1,5) at the front of the vehicle.

 

No, I got ya..... it's bass ackwards! I did look it up though

 

At this point I’d start with checking the ignition wiring. After that, hopefully someone has some fresh ideas for trouble shooting.

 

RFI could be an issue. Install any new electronics in the truck lately? Perhaps have a phone charger? Dash cam etc.....
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Maybe injector?