Problem: I have a big problem my pcmtuner interface often disconnects and I’m afraid that it happens during a write you already have a problem I changed my usb cable still the same.
Solution:
It will do this if using some OBD modules if you are not using scanmatik interface, you need to cycle ignition between ID and Write routines
and never while using OBD in car, connect external power to pcmtuner.
It’s an obd module in car, car battery is power source you DONT use a power supply connected to pcm tuner NEVER.