Mini Cooper S - Diagnosis and Performance Refinement
We’ve been busy in the workshop lately, and one recent project stood out, a Mini Cooper S that arrived with a challenging issue. The car had been fitted with an aftermarket downpipe, but the O₂ sensors had been incorrectly placed, shorting the circuits and causing a constant check-engine light, unstable fuelling trims, and poor overall performance.
Diagnosing the Problem
Our first step was a full diagnostic assessment. The O₂ sensors were relocated to optimal positions in the exhaust flow to restore accurate readings and proper closed-loop operation. Once the electrical faults were resolved and the ECU was reading clean, valid data, we moved on to what the Mini does best; performance refinement. 
Calibration and Performance Tuning
Using our OEM-level calibration tools, we refined fuelling, ignition timing, and throttle mapping to take full advantage of the turbocharged engine’s potential. The goal was to retain the Mini’s playful, go-kart-like character while making it sharper, faster, and more responsive through the rev range.
The difference was immediate. Boost control and fuelling consistency improved dramatically, throttle response felt more precise, and mid-range torque arrived with far greater urgency. The result is a Mini that drives exactly as it should; energetic, balanced, and smooth, with reliability restored and performance fully unlocked.
Engineered with Care
At AutoUpgrades, every project begins with proper diagnosis and ends with precise calibration. We combine engineering discipline with development-grade tooling to ensure every tune integrates seamlessly with factory protection systems delivering performance that’s sharper, stronger, and every bit as dependable.
Click here to check out the Mini Tune and see how proper calibration turns small-car character into serious performance.