What happened to the loud throttle when the cold car started?

First, due to carbon deposition, the throttle is too small when starting. Because the system adaptation will increase the throttle opening, the sound of engine speed increase will appear, but the adaptive coefficient engine computer will remember it and will not appear every day; It's just possible.

Second, ECM thinks that the water temperature is too low and automatically increases the idle speed to raise the water temperature. After reaching normal temperature, the idle speed will be normal.