Big Jimbo

In my previous posts about an elusive misfire problem on my 2012 C63 I have changed plugs, cleaned injectors, replaced O2 sensors, Replaced a coil pack, checked all grounds and fuses, and yet the problem returned a couple of weeks ago. Because I had totally exhausted my ideas I took the car over to our newest MB dealer in Gilbert AZ and the only official AMG in town. Their AMG tech spent several hours with their diagnostic equipment and came to the conclusion that it looked like a wiring harness issue. He was also puzzled by what appeared to be "adapters" between the wiring harness and the coil packs. He said he has never seen them before on a any 6.3 car. He checked with all his sources and said that there is no documentation to indicate my car should have them so he removed them and that fixed the problem!
The interesting part of the story is that these are factory parts but the part numbers don't show up anywhere. And they are not really "adapters" because the have the exact same plugs as the wiring harness and the coil packs. So I cut one apart and they have a small diode on one of the wires. Why would they add a diode to the coil pack as an add-on with an adapter? Well it sure runs like a scalded cat without the diode! I will attach the picture and wonder if anyone out there has ever seen this or had experience with these and misfire issues.

Funkwagen

How strange, looks like the purpose is to add resistance between the harness and coil/spark. As far as I know circuit resistance is a factor in ignition timing, so these look like something to modify that? Seems like a crude way to do so..

edit: part number isn't found in EPC, either

Big Jimbo

Thanks for that information. It is certainly odd that even Google comes up with nothing on a Mercedes part number! It sure runs great now and I want to thank the AMG mechanic Josh at Gilbert Mercedes for not giving up on my misfire until he actually found the cause for the problem! If anyone in AZ has a difficult AMG problem I would recommend taking your car to Josh.

Savage-wp

That is such a strange problem. You have to wonder where this mysterious part was installed.
Glad that you got it sorted, and you can enjoy the AMG thunder.

FactoryFast

Ive seen/installed that on cars that used to be boosted. Maybe it used to have a supercharger kit on it.... Its to fool something constantly by adding resistance. The stuff i did back in the day was fooling the MAF sensor on my VR6 engines to think the car is richer than it is so you always run a little lean which is hotter which ultimately makes power...or something like that, i installed em, didnt engineer them. Now that im re reading, they were on the injectors....maybe an E85 tune?

Either way, its a solid mystery!

Big Jimbo

I did some research and the label says it is made by CTC Cartech Company which is a German company that does R&D and manufacturing for auto companies. The label say Adapter Zundspule which translates to Ignition Coil Adapter which is exactly what this part does while adding the diode. Maybe the diode was supposed to lengthen the duration of the spark or something like that. But whatever it was the ECU didn't like it and was causing misfire. Maybe some of the diodes were going bad. I look up the part number on the diode and you can buy them for about $1 on the internet.

roadkillrob

That is super interesting, seems like they are an company that provides services to Mercedes in design and testing of electronic and ignition components. What is the history of your car - you the first owner? any chance it some type of demo test car, either at the mercedes track school or press car or mercedes executive driven car? Seems someone was testing something on that car at one point and it was sold without being removed - quite a mystery!

Big Jimbo

I am the second owner of the car and the first owner was not what you would call a car guy. He was a property manager and just had the car maintained at the dealer. It had the factory filters, wheels, tires, and was never flasher.
The interesting part of my misfire issue was that when it would start missing it would miss for as long as I drove the car but if I would stop and turn it off and restart it 2 seconds later the miss would be gone. I have seen a couple of posts from other members who had similar issues and it would be interesting to know if they might have these "adapters" too.
I received my ESS Supercharger last week and now feel it is safe to install it as after the install the dealer might have just blamed the misfire on that. The install will start next week! I had my pre-installation dyno after the adapters were removed and it did 400.37 HP and 342.28 Torque so can't wait to see what the New Gen Whipple will do. I am going to use the 6# pulley for 91 octane fuel.