Misfire Service Mode
 

I got a check engine light tonight. Stuttering anytime I went into boost. r56 s n18. First code was misfire on 4. If firing order is 1342 starting at passenger side then I swapped coils 4 and 2 on the interstate (could hear worsening of idle when unplugged coil 4) then cut car off. Car still stutters if go into boost then limp mode but code is now for..... cylinder 3... will test more today after work just wondering if anyone understands that oddity.

misfire is NOT related to firing order but rather the position of that cylinder. so, the order of cylinders is 1 2 3 4 from passenger to driver side. that's why you got misfire on cyl 3 after the swap. the good news the code moved which means you need a new coil pack.

Yup, I made all those logic connections pissed off on the side of the interstate. Thank you for setting me straight!