e320 i had to go to a cooler plug, i run the ngk range of plugs and went 1 cooler range, i went from a factory 7 to a 6 heat range which is cooler with ngks, that is the coolest you can go with a copper tip plug, without going to one of those fancy iridium or twin tip sortof plugs, which arnt ment to be as tolerant if you get a bit of pre- ignition,
u dont want to see the last plugs i pulled out, they were pritty bad,
running to lean up top, hence why i want to go larger injectors.

i looked up about the knock sensor and found it,
side note like roman said i dont think it is easy to intercept the crank signal and modify it to adjust timing easily on our early m104 models like it is on your newer model