Good Afternoon Everyone!

I have a US model 2019 C300 4 base sedan with a code telling me to replace the coil pack/spark plug (running rough, some power loss, etc.) I have about 49k miles on the car. I know I need to replace the plugs and have bought all four of the plugs and a coil pack from Mercedes. Mercedes suggested not replacing the other packs until needed. They also didn't have 4 anyways...

What is the firing order of the engine? Gap and torque for the plugs?

Thanks everyone again!

That's the turbo four isn't it. #1 is closest to front, 4 at back. If v6 or v8 #1 is at front on passenger side.

__________________
Jim

Correct turbo 4

The gap is pre-set. The torque is 23nm and do not use anti seize on the threads.

Thanks! Have the suspected coil pack off of the plug. Cleaning around the plug before I pull it out.

My plugs might been preset at the factory but are different when using a feeler gauge. Do you now the actual gap distance?

Also, why not anti seize?


Again, I appreciate the comments and help!!!

I'm pretty sure the gap is set at .7 mm. Out of the thousands of Bosch plugs that I've done, I've never had to set the gap unless they were dropped. You don't want to used anti seize on the plugs because on these direct injection engines the plugs require indexing. They are clocked at a certain position at 23 NMs. When you're dealing with torque, you're talking about friction. Anti seize changes the friction and can affect torque values.

Uh oh….

Indexing….? How is that done? Marking the plug?

If you set at the correct torque spec, it will be in the right position. Don't over think it. If I were you, before you do much I would remove the coil from the suspected misfire cylinder and move it to another cylinder and see if the misfire follows the suspected faulty coil. I say this because the m260 and m264 engines have cylinder head failures that are pretty common. It will have a misfire that may have nothing to do with the spark plugs or coils. There's a TSB for the M260 which Mercedes extended the warranty on. The 260 is in the FWD vehicles that you probably have. The M264 that is pretty much the same engine, but for RWD is not under the extended warranty. So, if your coil doesn't solve your misfire, take it to the dealer and get a leak down done.

Thanks! Work and family are keeping me from working on the car but i'm getting ready to try and finish it up today. I have pulled the suspected cylinder 3 boot off and attempted to remove the coil but the disconnecting of it is proving to be troublesome. lol

I plan on doing the swap to see if the problem follows the swap. My engine is an M274 IIRC. don't know if this helps or not in your write up's in helping me.

Again, appreciate the help!