I am looking at possibly picking up a 2012 JCW with the n14. I have owned a 2012 MCS with an n18 for 3+ years so I know a fair bit about these cars so far.

My questions are around that specific n14 engine that seems very one off. Same goes for the wiring harness in this car. Does the ECU on this match what the other LCI cars run for ECU or is this the same ECU as the older n14 chassis cars? Can an n18 be placed into this 2012 chassis if this very rare n14 JCW block / head have issues.

I ask as the car I am looking at is very rough, interior is clean but the engine was misfiring on all 4 at idle and did have a bit of a vac leak sound from the rear of the motor. While it does seem to idle okish and drive ok it is down on power and surely feels like it is misfiring very lightly. While that could just be garbage fuel or worn plugs I am trying to think long term as this is a 170k engine that the current owner has been beating on as a flipper of this car. I did also notice that even tho this n14 is using the same style HPFP as my n18 the idle pressure was down to 770psi vs the 1000+ mine is at idle.

While the JCW brakes are still there any other suspension goodness is missing as it is slammed on raceland coilovers so I know more than enough about replacing those right away

So big questions around that engine and wiring, how special is that wiring harness for the n14 in the LCI chassis that should have an n18. Has anyone done the n18 engine swap in place of a 2012 n14?

Thank you for your time.