I am trying to diagnose a recent issue. My n18 R56 has developed a hiccup (one quick stutter) but only under a specific set of conditions:

A. Must be WOT
B. Must be over 4k RPM (can go higher if not WOT)
C. Must be under load (wont do it while flooring it in neutral)

I currently have a JB+ (had a few weeks but never driven hard with it), Alta intake, Forge FMIC and DV, straight pipe exhaust and a Pedal Commander. No CEL is thrown and no warning lights and I have the Torque app which shows nothing. It was recently at a Mini dealer who went over everything (like all dealers do) when they had to do several grand in tranny work last month..

 

That sounds like a superknock. It wont throw a check engine unless it does it a lot.
Grab a different app that will scan for the bmw specific codes that torque does not.
I found my superknock with Carly.

Switched gas stations and it hasn't come back so far in a month.
more or likely I'll need to walnut blast the valves, but going to try seafoam before my next few oil changes as I had good luck with that in my mazdaspeed.

 

If you have never changed your spark plugs or coil packs, I'd probably start there.

I also had a JB+ that started giving me trouble due to corroding connections on the JB+ itself, throwing weird readings to my MAF. Worth checking / cleaning those connections.