Don't succumb to the pressure of "just make it run."
Process limits are normally established during the process development stages of the validation process. A majority of process limits allow for one thing and one thing only: the ability to "tweak" the process when issues arise instead of true troubleshooting to identify root cause.
Scientific injection molding does not include establishing process limits large enough to drive a truck through. The practice of using DOEs upfront to establish limits does not fall within scientific principles and should not be used for initial process development. A DOE is a problem-solving tool, why try and use it before a problem is identified?
Too often limits are established upfront using a handful of set points or generic outputs such as cycle time. The runs to determine these limits are often very short and don't allow enough time to truly prove that the process is repeatable at high limits and low limits.