What is the working principle of the idle speed motor?
2 Answers
Here is the working principle of the idle speed motor: 1. The idle speed motor itself has 4 working states, which are stator coil AB energized (CD de-energized), stator coil CD energized (AB de-energized), stator coil AB energized (CD de-energized), and stator coil CD energized (AB de-energized) in sequence. 2. Under the control of the engine ECU, the idle speed motor cycles through the above working states repeatedly, driving the rotor of the idle speed motor to rotate continuously in a clockwise direction. Through the screw mechanism, the valve core is gradually pushed out, reducing the engine's air intake. 3. Similarly, to lower the engine speed, if the pulse signal sequence sent by the engine ECU is reversed, the valve core of the idle speed motor is retracted, thereby increasing the engine idle speed.
This thing is actually quite interesting! The idle speed control valve is a compact electric valve hidden next to the throttle body. When I press the clutch or turn on the AC, the ECU instantly calculates how much air the engine needs to maintain stable RPM. That's when the stepper motor kicks in—it rotates precise angles like clockwork, pushing the valve core in or out. The valve opens just a crack to let air sneak into the intake manifold, perfectly compensating the airflow. The whole process is silent and ultra-precise. If it gets stuck, your car will shake like a rocking horse at red lights. I've seen people DIY clean the valve core, but always use specialized cleaner to avoid damaging those delicate internal gears.
