[CarWiz]

If your PID has the Auto-Tune feature, run that from an ambient temp oven. That will set stored parameters based on your oven characteristics. Once set, it should tighten the heat range up a lot on succeeding runs. The parameters are stored even when powered off afterward so you need only to run Auto once unless you change something in the oven.

It's important to check that your PID is registering the correct PV (Present Value) temperature before the Auto-Tune. You'll need an accurate thermometer to compare the PV display to ambient temperature. If the PID is off, you can set a temperature off-set to correct the thermocouple sensing. Also, make sure the thermocouple is not in direct contact with a wall and that the tip is in free-air.

Once you run the auto cycle, let the oven cool to ambient temperature then run another cycle for a test. It should stay within a few degrees of your SV (Selected Value) temperature. If not, report back.