Your Mercedes-AMG's engine tune is only half the equation. The Transmission Control Unit (TCU) decides how that power reaches the wheels — and the factory calibration leaves a lot on the table. This guide explains what TCU tuning is, how it works, and why every tuned AMG needs one.What Is the TCU (Transmission Control Unit)?The TCU is the computer that controls your automatic transmission. It manages: Shift timing — when to upshift and downshift Shift speed — how quickly the clutch packs engage during a gear change Torque converter lockup — when and how firmly the torque converter locks (on...