This paper proposes a LQR control algorithm and a robustness stability analysis to the model parameter uncertainties so that the mass air flow and the manifold absolute pressure of an experimental Diesel engine can be performed. The corresponding weight matrices of the LQR control are chosen based on the maximum admissible deviation values of the state matrices and command vector from the state-space system representation. This approach leads to finding the maximum upper bounds of the model parameter uncertainties so that the closed-loop system preserves its stability.