AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual - Manual (Page 306)

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© 2014 AEM Performance Electronics
Infinity User Manual
IAC (Idle Air Control)
Idle air control (IAC) systems are used to stabilize idle speed during cold engine and after warm-
up operations. The IAC system regulates the volume of air bypassed around a closed throttle
butterfly valve. The Infinity controls the IAC system by applying various input signals from the user-
programmable software file. There are two major types of IAC systems. The stepper idle air
control motor is, typically used by Toyota, Dodge, Mitsubishi, etc. The pulse width idle air control
valve is commonly used by Honda, Subaru, Ford, Nissan, Volkswagen, etc. This instruction
manual will address both types of IAC systems.
The stepper motor IAC valve (shown below) consists of a step-motor with a seat, magnetic rotor,
valve, four wires to each of the four coils and can vary bypass airflow by positioning its valve into
one of many possible steps. Basically, the higher the IAC valve step number, the larger the
airflow opening and the greater the volume of air bypassed around the closed throttle. However,
if a voltage pulse is applied backwards, the motor will step in the other direction. The motor step
will open or close, based on the number of pulses and the direction desired.