Has anyone experienced issues with this vehicle like this. Engine light came on a week after purchase. Been back 4 times to reset light and continue diagnosing since Nov 2012. Case has been raised with merc Germany but apparently not another vehicle in the world has had this issue and last time it was in for three weeks with still no resolution. Except we have had it back a week and no light this time but missing worse than ever. I suspect they have increased the misfire counter as they are trying to tell me it starts ok and they do misfire cause they are a high performance engine. Ahhh, don't think so.......It's embarrassing to start this thing up. Shocking miss at high idle when cold. Puffs of un burnt fuel. Perfect running though after 20 seconds. They have replaced spark plugs, swapped number 8 injector to another cylinder, re-soldered a wiring harness that apparently has caused similar issues on a different model merc sedan. All with no luck. They have said that the spark plugs on the right bank line up perfectly with injectors straight up and down however the whole left hand bank is 1/4 of a degree out. But with flat washers this is not something they can change and they have to follow Germany advise on next steps to take. I'm in Perth in Australia and I don't know anyone else with one of these cars I can compare whether this is just how they run at start. I would have thought not.

 

Never had any problems so fare and did a 3000 miles in 1 month...

Please register on the AMG private lounge forum and ask them.
I hope this gets resolved asap Sir

 

We have had a problem on two of our AMG's and the cause of those mis-firing problems was the plug itself. I forget what cylinders they were but it will give you a specific misfire code for that cylinder. What happened with the plug is that the porcelain part of the plug actually broke and it was moving around. When it separated it would start to misfire and when it was back in place it would stop so it was intermittent but the problem was found very fast. I know that you said you changed the plugs so I am not helping you here, I just thought I would share the experience that we have had.

As for the plugs not lining up, that is very weird that they would not line up on one side of the engine. The factory Mercedes plug is indexed and if you look at every plug from Mercedes for this car you will notice that the threads are always the same length and always start in the same spot. The reason for this is so that the plug ends up pointing the same direction when it bottoms out in the cylinder. This probably has something to do with getting the most efficiency from the combustion chamber with the direct fuel injection. Indexing plugs has been around for a long time in racing but this is the first time I can recall a manufacturer building their cars to utilize this.

The fact that you said that the dealer says that one side does not line up correctly is what raises a caution flag as to why that is. I really do not have any expertise on the subject but I would think if Mercedes designed the plugs to fit this way and you have 1/2 of your engine with the plugs not fitting correctly, then that would indicate a problem with the manufacturing of the cylinder head.

Now, before you go calling anyone about this I would ask you if you know how the dealer checked that the plugs are not lining up correctly when installed. Did the dealership actually remove a cylinder head to check this? I doubt that they would do that much work at this point. Did they just mark the plugs and try to visually see where they stop when installed by looking in the spark plug hole with a flashlight? There are a lot more questions that need to be asked before jumping to any conclusions.

On top of all of that, I do not really think in my own mind, that it is that critical for the plugs to be installed facing a certain direction so I would not attribute that to my problem. What would worry me more is, if Mercedes really did build the cylinder head and spark plugs to line up a certain way, what is causing that to not happen. The only thing that I could think of is that the machining on the cylinder head is wrong when it comes to the spark plug hole. If it is wrong there, is it wrong anywhere else on the cylinder head.

 

Sorry about that, I've not had this happen. Just a brief 1-2 second diesel rattle then the normal V8 idle beat. Hopefully they will sort you out soon.

 

The .55 biturbos are having all sorts of issues, other problems have been biturbos die after cold start. My service rep told me to stick with the 6,3 bc of its bulletproof reliability until they sort out the issues. Tell shop to do an ECU reflash to see of that helps.

 

Bad coil pack? When its isolated to an individual cylinder surely it can't be too far away from being found.