Minor update
 

Okay, after getting back and changing out the IP on this car I finally remembered to pull the number 2 injector and check it out. The ring was perfect... Now remember that this is with a new injector installed the night before I drove home 550 miles.. The one that came out of that hole previously has been tagged for future reference.

So now I still have the slight miss but the local Independant said he gave the car a clean bill of health except it needs motor mounts. This will probably help you not feel the miss as much but it still misses...

So here's the next steps that I have already started on:

The hole and prechamber look good inside number 2 (as far as you can see with a flashlight) so I am discounting number 2 as the culprit for the moment.

This is based on the fact that it looks good in there and also on the fact that low and behold I can now loosen an injector line and guess what, the sound (nailing, clattering) that goes with the miss, disappears.

Guess which hole? #1... So I am leaning towards pulling that injector and replacing it to see if we get any improvement. I thought it really weird though that all of sudden I can loosen the injector line and although I could never isolate it before now I can.

Anyway, another trip coming up of about 300 miles. Taking along a couple of spare injectors and rings just to be sure and then will update after my return.

...hmmm, and hmmmm.

Does that help?

I went through hell like this with the car you looked at (did you find one?), and to refresh your memory it had a pocket in the cylinder wall, which caused a loss of compression. Prior to it getting worse though, it would nail at idle. Then it dropped out at idle completely, but that cylinder fired okay on the highway.

The only way I found it was by sheer circumstance.

I pulled the head to do the valves (they were perfect, which further added to the puzzle).
Now, when you pull the head, you typically put it on TDC on number one, right? Of course on a four this has #1 and #4 at the top. I marveled at the smoothness of #3 and#2 cylinder walls.
I don't remember why I turned the engine, but shore nuff, under the top of #1, there was this weird pocket burned into the cylinder wall, roughly a half inch down from the top (?).
This eventually uncovered a spot on the compression ring and I lost compression at idle. #4 was starting to do the same thing!

Now i hear that Mercedes cylinder walls are known to retain their honing marks for an impossible amount of mileage, so it should have tipped me off that I saw a shiny cylinder wall, would mean high mileage.
Gosh...

I don't think a flashlight look into the prechamber is enough to check its condition...
There are several ( seven ?) tiny holes which need to be clean..so I hope you check that also at some time.... pulling them is about the only way to inspect them.

There is supposed to be a ball in the middle of the prechamber that blocks any real view of the tiny holes Greg mentioned. They also generally point out from the bottom of the prechamber in a radial direction, making them very hard to see even if there were no ball in the way. This ball is supposed to be without visible pitting or burning damage. Any such damage is an indication something in this critical area has gone awry. Good luck, Jim

I too do not believe that you can fully assess the codition of a prechamber via the holes either injector or GP but it is a start to look through and look for obvious problems. The ballis still intact and appears to have no damage but of course you can't see the whole thing.

I find it extremely odd that it now can be isolated in number 1 but hey that's better than guessing.

I contacted Perf Prods adn they do rent a prechambe remover for 21 days for 30.00.
I also noticed though that someone has an idea for a puller that sounded relatively inexpensive.
In the meantime I am going to drive it for a bit and see if I cna rotate injectors on number one to find one that runs smooth with the rest.