SweetAlpaca

I have been having an issue with ignition coil 6. I have changed it 4 times now and it keeps going bad after a few hundred miles. The spark plugs are practically new (only 1000 miles on them). I changed all the plugs the 2nd time I had the issue with the coil. It's only the same coil that goes bad (from cylinder 6). At this point the only thing I can think about is an issue with the power harness that connects to the coil. Has any of you ever experienced an issue like this?

////AMG_C43

Sounds like an intermittent harness issue. Swap that #6 coil with another cylinder position and see if the problem moves with it. Bet it will be ok when moved and the replacement will then show bad over time. Simple and cheap way to troubleshoot it.

SweetAlpaca

Update:

Swapped another good coil into cylinder #6, changed the spark plug, and misfire continues to happen in cylinder 6. I have noticed that it mostly happens when I'm driving steady without breaking for a long time (like in the highway) and then come to a stop. Using an icarsoft, I got the code P2315 and reads "the actuation of ignition coil 6 has a short circuit to ground". The ground for the coil was cleaned, but this did not fix the issue either. I have not seen anyone on this platform with this issue, but I can't believe I'm the only one out there. If anyone has any idea of what it could be or has gone through something similar, please help!

////AMG_C43

So you have confirmed its not a coil\plug issue.The message "the actuation of ignition coil 6 has a short circuit to ground" probably indicates that your coil trigger wire is being shorted to ground somewhere. Follow along the harness and look for any places where it may be abraded and rubbing against grounded metal. Also, clean the coil terminal on the harness and ensure there are no frayed wires anywhere. Never looked at my coil connections, but this is just basic electrical troubleshooting. Good luck.

MatthewJ

This might sound trivial but are you certain you are working on cyl #6 and not #3? They are not labeled and ive not seen much as far as engine diagrams for the M276 Dela30. LHD and RHD may also change what the ECU calls cylinder #6.
Aside from confirming that, what others have said is where i would start...tracing the connector at the coil back through the harness looking for rub/chewed spots.

SweetAlpaca

yeah, it's a little hard to actually trace it because of the way the the cables all go into one bigger cable and through the middle of the engine. I did checked and clean the coil terminal

Unfortunately yeah, I'm sure. I even changed all the plugs and coils around, but the misfire continues in cylinder 6. I took it to a shop, they did pretty much the same thing I did as well as clean the ground where the coil sits, but the misfire continues to take place. I tried taking it to the Benz dealer, but they wanted an arm and a leg jus to run some tests. For a C class, it's just not worth it regardless of how much I actually like the car.

////AMG_C43

I would at least consider replacing the harness connector at the ignition coil. Second, a faulty injector can also be a source for misfire codes. Doing nothing will eventually lead to catalytic converter issues. Good luck.

SweetAlpaca

Sensors for injectors do not show any issues and the way the harness is, you pretty much need to replace the entire harness (Mercedes making **** hard for people to work with). I'm trying to avoid messing up my catalytic converters as much as I can.

////AMG_C43

Pull all of the relevant numbers off of your connector and then Google them. You never know; a possible solution or replacement may turn-up. I am confident there is a simpler fix than a complete harness replacement.

White One

I know you probably have worked this in, but are the plugs properly gapped, and what do they look like?..Just wondering..Also are any different sounds coming from the are Ala lifter, rocker noises that may be off a bit?.

SweetAlpaca

I think I will

Yes, all the plus are gapped correctly and have less than 2k miles. They are all in perfect conditions. No different sound coming from the air intake. or air box. The only issue currently is the misfires.

////AMG_C43

https://connectorexperts.com/c-12616...ctors-all.html

AMGiggity

If it is telling you you have a ground fault in cylinder #6 ignition circuit and you know both coil are spark plug are good, then you need to replace the wire harness powering cylinder #6 coil, no way around it. Somewhere along the cable powering cylinder #6 coil, the positive lead is touching the frame of your car, so the current goes through your car frame instead of going across the spark plug tip.