P0308 Code

[21 Blue Ram]

Hi,
I have a 2021 Ram 1500 with the Hemi, that I bought used about 1.5 years ago. It had 26k on it when I bought it. Has just under 40k now. Have noticed a few times upon starting a loud tapping noise, that quiets down after about 10 seconds. Today when I started it, it was running a bit rough. Started to drive down street and got start/stop system shut off message and then check engine light came on, so I went back home. Check engine light was flashing. I have a basic code reader and it came up with P0308 code- misfire in cylinder 8. Going to call tomorrow and try to get it into a shop. Hoping it’s something minor like plug, coil, or injector, but worried it could be the lifter issue. I did purchase an extended warranty, not a Mopar one. Just looking for input as to what others have run into. I run 5W20 Royal Purple full synthetic oil in it. Thanks.

 

[Fatherof3]

I’m not an expert but I don’t think it’s a lifter issue . The tapping noise wouldn’t go away if it was .

 

[21 Blue Ram]

Thanks. Was able to bring it to my mechanic today. Fingers crossed nothing major.

 

[John Kloehr]

Agree "the tick" would not stop after a few seconds. And it is at a mechanic so the rest will not help you.

With the low years and miles, not anywhere needing plugs. Could be a failed coil. Swapping it with another coil to see if the problem moves would be an easy diagnostic.

First I would hook up my handy-dandy OBD diagnostic tool and look at the fuel trims for that bank. If it is a failed coil, then there will be too much fuel in that bank and I would expect the PCM to reduce fuel to bring the A/F ratio back in line. Would also listen to the injector with an automotive stethoscope to see if it is activating. And if it is not or if it is clogged, then the PCM would add fuel to compensate.

Another possible problem accounting for the tick at startup would be a broken exhaust manifold stud or cracked manifold, kind of common on these trucks. The leak may tighten up as the manifold heats which would account for it fading after start. A leak here would dilute the exhaust gasses and the O2 sensors would see this as a lean condition. The PCM would add fuel. This would make the cats happier but the engine would actually be rich. This could foul a plugs (or more than one). Visual inspection and the previously mentioned automotive stethoscope can help with finding the source, and removing the plugs to inspect them for soot would be part of the diagnostic procedure (along with looking at the fuel trim). If they are heavily sooted, then they might need early replacement; I have had mixed results cleaning these modern plugs.

There are a few other things it could be (massive intake leak at #8, ...), I tried to hit the common and straightforward likely suspects. I would have still expected at least pending codes for rich or lean conditions in addition to the misfire on 8 so scratching my head a bit on the one. Please post up what your mechanic finds.

In any event, a flashing CEL is a stop-driving signal as there could be expensive damage soon. It this case, it would probably be damaging a catalytic converter. So getting it to a mechanic quickly is a correct action.

 

[1791]

same issue lifter noise for about 3 seconds i'm told it's normal and it won't hurt anything. still the sound is troubling