Spark plug OEM BMW or AC DELCO

41-156 is the new plug for the LE2 engine. Our 2016.5 got them, and they are fine. 41-123s came out of it.

Plugs need to be AC Delco 41993 (no substitution). I've had misfires with other "equivalent" plugs that went away with the correct plugs.

Only use the factory AC-Delco 41-987 plugs.

I paid $42 for the ACDelco iridium plugs, $45 for the ACDelco pro wire set.

GM products run best with AC Delco plugs, just like Ford products run best with Motorcraft or Autolite.

I did track it extensively, probably 3-4,000 km of track use. The only thing it needs is brake fluid and better pads and you're good to go. My car was flawless for the entire time I had it. It threw a CEL right before I sold it that was solved with a simple spark plug change. It never overheated at the track and it was a lot of fun there and very refined and comfortable for highway travel.

I did put ac delco factory iridium plugs from rockauto on mine at 100k.

While I had the coils out, I replaced the plugs (used ACDelco double platinum professional grade, proper gap. No NGKs were available). After I replaced the coils, the misfire code(s) went away for a few days.

Put them into a stock '87 Subarban and tore my hair out thinking I messed up the wires 'cause it idled so bad. Really, like I had two wires switched. Put the old worn regular AC's that I just took out and it idled perfect.