the vr advance 4000, is an assist in syncing the timing of the engine to the fitech. Various signals can cause distortion, so they have you do the static check with the base timing at 4000 rpm. if the timing is wavering at 4000, and doesn't match the same value as base...then you adjust this value to get it to match. http://fitechefi.com/fitech-uploads/2016/07/HandheldcontrollerfeatureDefinitions.pdf