A diesel fuel, diesel fuel additive concentrate and method for improving the performance of fuel injectors for a diesel engine are provided. The diesel fuel includes a major amount of middle distillate fuel having a sulfur content of 15 ppm by weight or less; and a reaction product of (a) a hydrocarbyl substituted dicarboxylic acid or anhydride, and (b) an amine compound or salt thereof of the formula wherein R is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms, wherein the reaction product contains less than one equivalent of an amino triazole group per molecule of reaction product, and wherein the reaction product is present in an amount sufficient to improve the performance of diesel direct and/or indirect fuel injectors.