In order to reduce oscillations in process variables of an injection molding process, a variable-gain proportional-integral-derivative (PID) controller is utilized to control one or more of the process variables. The injection molding system may also include a tuning controller to automatically tune at least one of the proportional, integral, or derivative gains within a mold cycle. The tuning controller may obtain sensor data that monitors the operation of the injection molding machine to determine an adjustment to at least one of the proportional, integral, or derivative gains. The tuning controller may adjust the gains of the variable-gain PID controller in accordance with the determined adjustment to the at least one of the proportional, integral, or derivative gains.