Originally Posted by
Weston@HPTuners
Assuming the OBD-II adapter and vehicle ECU are reporting properly, this is likely the actual throttle plate position, rather than your throttle pedal input. This was simpler with the old cable throttles that were a direct relationship to your throttle pedal input, but in many modern vehicles, it can have a mind of its own... the engine computer is using your throttle pedal input to determine how much engine torque output it thinks you want, applying various other adjustments to that, and then commanding the engine controls accordingly.
The best way to overcome this is to change the OBD channel selection to one of the Throttle Pedal options, assuming that your vehicle offers this. What's available for this varies widely between different cars, so that's why we don't have it selected by default.