Evening... so long story short, no matter what I change/fix right now, nothing seems to sort out the P129D code from coming back and the JCW (R56 2009) from creating cannon fire and flames on up/downshifts and sluggish performance.

As much as I love the action from the exhaust, I would really rather it didn't feel like I'm driving a Cooper rather than a JCW.

It's stock, the engine has a clean bill of health, recently passed smog in Cali, timing chain issues dealt with, great compression on all cylinders and it just had a decoke. The issue also seems really prevalent the minute I hit the sport button.

Any help would be great fully appreciated.

 

Check this thread:
https://www.northamericanmotoring.co...plausible.html

 

I searched and didn't find this! Thanks for then link

 

Turns out I'd already replaced the TMAP sensor so it's not that, still throwing P129D code so the hunt goes on.

 

What sensors have you replaced with new ones? Other then the sensors, what else have you replaced?