I’m looking at two MINI Cooper S here in France and would appreciate some opinions from people who know these cars well.

R53 Cooper S

2005
W11 supercharged
185k km
Manual
€4,000
Clutch done at 142k
Supercharger serviced
General service history
Timing chain not replaced
Slight oil sweat
Very clean underneath

R56 Cooper S

2008
N14 turbo
186k km
Manual
€4,300
Timing chain, HPFP, water pump, thermostat, head gasket/head work done around 160k
Valve cover done later
Original turbo + clutch
Slight oil consumption, she told me a cup
Gutted cat

I’m a mechanic, so DIY repairs are fine. I mainly want to avoid a (unwilling) money pit.

Valuation still sucks. $4k.

I'm back again, with my issue of bogging when pressing the throttle when cold still very present. If you blip the throttle it bogs, and will staying bogging as long as you have the throttle open.

I have so far replaced all vacuum lines, coil, wires, plugs, vacuum ports, all seals, BPV, etc. I have also had Adrian check the tune multiple times, and there's no issues showing up electronically when it's running.

This last time around, we decided to pull the 30 mile old plugs. It appears cylinder 3 is running much richer than the others, as the plug is black and covered in soot and smells of gas. The remaining plugs are gray/brownish.

Any ideas? I'm thinking injector gone bad?

Mods: 469 Cat Cam, JCW head, .5 over pistons, 15% pulley, 550 injectors.

Edit: Compression test shows 151-154 psi across all 4 cylinders.

Apres avoir suspecté une fuite de vide j’ai achete une machine à détecteur de fuite.
Lors du test une fuite de fumée est apparu derrière la boîte à air mais à aucun autre endroit à ma grande surprise.

Je vais démonter prochainement pour regarder d’où cela peut venir.

Des idées du problème ?