Idle air control valve overview
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− | + | The idle air control valve http://www.partsamerica.com/product_images//img/nie/21757.jpg (IAC) is a stepper motor http://en.wikipedia.org/wiki/Stepper_motor http://upload.wikimedia.org/wikipedia/en/thumb/f/f8/Stepper_motor_1.png/241px-Stepper_motor_1.png which regulates the amount of air entering the engine during idle and other times during an engine's run period (such as deceleration). There are actually two idle settings on most fuel injection engines: minimum idle and running idle. Minumum idle is the idle based on the throttle blades alone with the IAC passage closed. Running (or commanded) idle is programmed in the chip. | |
A GM engine's IAC is measured in steps. For example, 0 steps is all the way closed, and 160 steps is all the way open. So, for instance, if your commanded idle is 600 rpm, and your actual idle is 500 rpm, the IAC will open a certain number of steps to obtain 600 RPM. | A GM engine's IAC is measured in steps. For example, 0 steps is all the way closed, and 160 steps is all the way open. So, for instance, if your commanded idle is 600 rpm, and your actual idle is 500 rpm, the IAC will open a certain number of steps to obtain 600 RPM. |