I have a 240D with 215K. I have turned up the pump quite a bit. I suspect has at least one bad prechamber. I am taking a look today to see. If I have a bad one I am going to replace them all. Has anyone ever opened up the orifices in the end of the PC? People have posted that they were going to try it but never posted the results.

I have seen picks of PCs with holes blown in them and the engine was ok. It smoked but the piston didn’t melt. I can imagine that the small orifices are acting like nozzles that create high speed jets inside the PC for better atomization and to mix in fresh air, but are a choke point for the expanding gasses to get to the cylinder to push the piston down. I also imagine that if one opened up the orifices that the gasses would expand the combustion chamber faster but the PC preinjection high pressure jet effect would be reduced. Plus if one went too far there might be structural problems as there has to be a tremendous amount of pressure in the PC during ignition.

I am just thinking “since I have them out” if there is an improvement to be had sort of thing.