Abstract: This paper attempts to tune any controller without the knowledge of mathematical model for the system to be controlled. For that purpose, the optimization algorithm of MATLAB / Nonlinear Control Design Blockset (NCD) is adapted for On-line tuning for controller parameters. To present the methodology, a PID controller is verified with the physical plant using the engine speed control System where the problem of maintaining the engine idle speed at a reference value with the applied load is studied. A Proportional Integral Derivative (PID) Controller is used to solve this problem, but to get the best controller parameters the (NCD) Blockset is used for tuning the PID parameters. Simulation shows promising results in the idle speed response by comparing NCD tuning results with the trial and error results. The analytical results are carried out MATLAB / SIMULINK.