In this paper, an Adaptive Type-2 Fuzzy Sliding Mode Control is designed for a class of nonlinear Multi-Input Multi-Output (MIMO) systems with unknown partially dynamics and in presence of external disturbances. To estimate the unknown functions, a Sliding Mode Control (SMC) combined with Type-2 Fuzzy Logic are developed. The discontinuous term of the classical sliding mode law is substituted with an adaptive Proportional Derivative term to reduce the chattering phenomenon. All parameters, adaptive laws and robustifying control terms are derived based on Lyapunov stability analysis, so that convergence to zero of tracking errors and boudedness of all signals in the closed-loop system are guaranteed. The proposed approach is applied to a Turbocharged Diesel Engine (TDE) and simulation results are presented to show the efficiency of the proposed method.