In this paper, a method is presented for modifying the truncation error of a given finite difference scheme approximating the family of third-order KdV equations such as KdV, generalized KdV and KdV Burgers equations by using their steady state. At the small times, it is shown that the new scheme has several advantages over the original. It is higher order without widening the spatial stencil, in the absence of time derivatives, it is not less accurate than the original scheme, has the same time-step requirements and although the same stability condition and it is often stable for more time.