Presented in this paper is an adaptive control procedure applied to the idle speed control of an internal combustion (IC) engine. Adaptive control in this investigation is used to automate the design of the engine idle speed controller. The adaptive control process begins by tuning a feedback controller such that the closed loop system is stable. Next, reference step inputs are given to the tuned closed loop system. These transients are used to obtain a model of the IC engine between the by-pass air valve and engine speed. The online modeling procedure is constructed of a filtered derivative method so that the coefficients of the continuous-time model are recovered from the closed loop response. The execution of the proposed online modeling technology is realized using a recursive least squares approach. This online model of the engine process is then used to calculate a new (adapted) feedback controller. The adaptive controller is based on matching the open loop transfer function of the idle speed feedback system to an open loop transfer function that represents the desired transient and steady state performance. To implement the adapted controller, a bumpless transfer approach is used to switch the feedback controller from the tuned controller to the adapted controller. Experimental results performed on a Ford 4.6L fuel injected engine demonstrate the automated controller design process.