Neighbour just bought P38 Diesel, compared to mine it is very sluggish,push the throttle and revs climb to 2500 then it starts to pull.
It has a Rimers tunning box fitted, Nanocom tell me fuel metering out of range. Could this box be causing the problem, how does it connect into the system all the wires are black and I have no paperwork for it.
Thanks Richard

Yeah the diesel is a bit…. Relaxed when it comes to performance.
I have PSI box fitted… same fitting as this video https://youtu.be/K4_mvsCWwmA?si=YPlIFQbOmLTCE4PQ

If it has an EGR valve, get it blanked off. Made a big difference on mine.
You can also look at a performance air filter and a bigger Intercooler should you wish.

There's a thin tube, same size as the leak offs, connected to the egr, pull it off and the egr valve can't open to allow oil fumes into the inlet. That's it!.
If the mot is a worry, stuff something up the tube to block it and refit it.