I've got a 2011 JCW R56. I know the prior owner drove it on the track, but I know nothing more than that. He had a higher performance turbo which I've replaced to stock as well. I use the car as a daily driver and do not drive it hard. The fuel pump died and I had it rebuilt and ultimately I blew two pistons many months later. I rebuilt the engine and bought a brand new fuel pump - I suspect the rebuild fuel pump was failing. Now, to be cautious, I question if the prior owner could have tuned the ECU for tracking days. Is it possible that a tune could result in or contribute to blown pistons? Is there any way to know if it's got a modified tune?

Should I reset the ECU? If so, how?

 

Yes, a bad tune can cause blown pistons. By going back to stock turbo, it seems like you aren't interested in a hi-performance car. If you can't find a shop familiar with Mini's, try a Mini dealer --- either one can point out after-market parts. Dealer can always re-map the ECU to the latest software for your year/model. Probably at less cost than a basic stage 1 tune. Suspension, intercooler, pre and post turbo air flow hose mods (stage 1) will all work fine on OEM ECU maps. If interested in "slight" performance, consider a stage 1 or 2 tune.

Terminology --- I "reset" my ECU often, to clear codes or to "unlearn" recent driving habits / conditions. Re-mapping the ECU changes engine operating characteristics to take advantage of aftermarket parts. Many scanners have the reset feature, but not all can read Mini codes and faults. Changing the ECU map requires special equipment --- costly and not useable without training.

 

I have blown piston 4 in two minis. Its not uncommon