06-05-2026, 06:15 AM
I'm kinda scratching my head here. I've got a 2018 330i and about 20,000 km ago I replaced the spark plugs myself. It ran great for a while but now the rough idle is creeping back, especially when the AC is on at a stoplight. I used NGK and gapped them correctly from what I remember, but maybe I rushed it or didn't torque them properly? I'm thinking of just taking it somewhere that does a lot of these engines because I don't want to chase my tail buying parts that aren't the issue. I've been looking at a Meticulous Spark Plugs Replacement service where they actually check coil condition at the same time and use a torque wrench instead of the "good and tight" method. Does anyone know if these engines are picky about plug brand? I've seen some people swear by Bosch only for the B48. Also could old coils cause the new plugs to foul faster? Trying to figure out if I should just redo everything properly or if something else like injectors might be the real problem. Really don't wanna spend a fortune on guesswork.