Originally Posted by
5.7ute
Doesnt matter if a cam is added. It is a measurement of the effective area under the iac valve.
As for step that is how the iac valve operates. It is a stepper motor that moves by small increments in or out depending on what the pcm commands. Each step open will increase the amount of air that can bypass around the throttle blade. Since the pintle on the stepper motor is rounded & the seat is flat, greater control of the airflow is achieved at a lower step count. This is why at warm idle you should be shooting for between 40 & 80 steps. Once the pintle has moved beyond about 120 steps it has a very minimal effect on airflow per step, so it will need to make large movements to control airflow. This will make it too slow & inconsistant to correct for swings in idle speed.