1. A method for predicting intake manifold pressure, said method comprising the steps of: obtaining a difference of values of intake manifold pressure and a difference of values of throttle opening; obtaining a predicted difference of values of intake manifold pressure, through an algorithm of estimation with fuzzy reasoning, including fuzzy rules determined based on an amount of a difference of values of intake manifold pressure and an amount of a difference of values of throttle opening; and adding the predicted difference of values of intake manifold pressure, to a value of intake manifold pressure, to obtain a predicted value of intake manifold pressure.