the vehicle fail to start. (4) Trouble diagnosis: The electronic injection system will carry out trouble diagnosis for the driving stage of the fuel injector. When the driving stage of the injector is short or overloaded to the battery voltage, as well as short and open to the ground, the trouble mark level will be positioned. At this moment, the closed loop control and the self-learning pre-control of the oxygen sensor will be closed, while the self-learning data last time will be effective. The trouble mark level will be repositioned after the trouble being removed. 9. Idle speed actuator stepper motor (Fig. 1-15) Fig1-15 (1) Function:
A by-pass air intake passage will be provided by the idle speed actuator with stepper motor. When the throttle is closed, air will enter into the engine through this by-pass passage. With a stepper motor, the ECU can adjust the size of the passage, and then confirm the air volume into the engine. At the same time, the ECU can also adjust the fuel injection volume on the basis of the air volume. With the stepper motor, the ECU can change the working condition for the engine according to actual situations. (2) Structure and principle: As a mini-size motor, the stepper motor consists of several steel stators in a circle and one rotator. Every stator is winded with a coil.
The rotator is a permanent magnet, and at the center of the magnet, there is a nut. All the coils of the stators are connected with the power supply constantly. As long as the current direction of one of the coils changes, the rotator will turn for an angle. When the current direction of the coil of each stator changes in a certain proper sequence, a rotary magnetic field will be formed, and the rotator of the permanent magnet will rotate in a certain direction. 34