An off-line procedure is described for obtaining optimal control calibrations for an engine during warm-up operation. Mathematical models are obtained for fuel and emission flow rates, and for important temperatures. The optimal control problem is formulated with these models, and is solved using a method of feasible directions. The resulting cold control laws are given as modifications to the warmed-up engine calibrations found by a separate procedure. The cold optimization procedures have been applied to a 5.7L fuel-injected engine equipped with an oxidizing catalyst.