My E39 520i (M54B22) has now 425 000 km and runs smoother than ever, mostly on LPG btw. One issue with these engines which is VERY often overlooked and therefore rarely mentioned: 🤓 On the M54 and M52, the hydraulic lifters OFTEN clog due to heat and cause all kinds of engine issues and fault codes, incl. misfires (!) but NONE of these codes actually mention to check the hydraulic lifters - they always "blame" another part. Hence you end up replacing alot of parts which might still be good without getting to the root cause. Try HYDRAULIC LIFTER CLEANING FLUID first, this stuff is meant to do just that, and it often really works! This is the simplest fix for your M54 and M52 engine, and you can't really hurt the engine with cleaner lifters, even if there is another fault as well. Think of it as Vitamins for your engine! And please: Try it first, comment and thank me later 😉
The dielectric grease is non-conductive, don’t use it on the actual metal connector but lightly between the boot and ceramic on spark plugs. The grease in the injector connector seems problematic.
