What is a stepper motor?
The stepper is an important part of the car engine that is installed on the gas valve of the car. When the gas pedal is not pressed, the stepper, which is a mechanical electronic part, is responsible for regulating the amount of air entering the gas valve and also keeping the car on. The stepper, together with the throttle sensor, by receiving and sending information to the ECU, prevents the car from shutting down at low engine speeds.
Due to the presence of this part in the inlet part of the gas valve, there is a possibility of getting it dirty with suspended particles and oil soot. Contamination of the stepper causes its malfunction and it is necessary to clean this part so as not to cause serious damage to the engine.
Stepper motor components
This part, like any other electronic part, is made up of various components, the coordination of each of these parts together makes this part work flawlessly. Among the most important components of the stepper motor, we can mention the electric motor, holding spring, separating bush, stepper shaft and cap.
How the stepper motor works
As mentioned, this part is installed on the throttle and is controlled by the car’s computer or ECU. The stepper controls the amount of air intake by moving forward and backward, which is controlled by 4 transistors.
By receiving the engine temperature and other vehicle conditions, the ECU sends the necessary command to the transistors, and as a result, the stepper valve opens and closes. In fact, as the engine temperature increases, its valve opens and after the engine temperature decreases and reaches normal, the valve is closed again. Also, if the gas pedal is not pressed, due to the engine’s need for air, the valve will open to supply the air required by the engine.
The most important task of this part is to keep the car running at low speeds; But the stepper has other duties, which we will discuss further among the tasks of the car stepper motor, the following can be mentioned:
- When the engine is cold, the stepper plays the role of throttle; That is, when the engine is cold, by adjusting the needle, the car starts with the first start.
- This part adjusts the engine speed when taking an extra load; For example, when you turn on the air conditioner in hot weather, you are actually imposing an additional load on the engine; At this time, the engine speed must be increased to respond to this additional load, which is the responsibility of the stepper.
- Another function of the stopper is to regulate fuel and air at low revs. The meaning of low revolutions in the car is usually between 900 and 1100 revolutions per minute. When the car is parked and the car engine is working normally, fuel and air intake adjustment is done by the stepper.
- When changing gears, this part adjusts the speed of the car. When the driver takes his foot off the gas pedal during a gear shift, the stepper adjusts the speed by preventing the air path from closing too quickly. It is worth noting that this issue also occurs when the driver suddenly takes his foot off the brake pedal.
Symptoms of stepper motor failure
Now it’s time to look at the symptoms of stepper failure. The most important task of the stepper is to prevent the car from turning off at low speeds; In other words, the engine speed at low revs is regulated by this part; Therefore, its failure can be detected at low speeds, and often when the engine is running, the engine speed is not stable and changes constantly. Diagnosing stepper motor failure is accompanied by other symptoms, which we will mention below:
- Increasing the engine speed immediately after starting the car
- Turning off the car by releasing the gas pedal
- Reducing the engine speed in additional loads such as turning on the cooler
- Unstable engine speed while working
- Car gassing for no reason after starting the car
- Increasing engine speed with increasing engine temperature
All the signs of stepper motor failure are related to the way the stepper itself works; Because its valve does not open and close properly and as a result, the amount of air entering the engine is disturbed and the above cases will appear.
Washing the stepper motor
Some of the symptoms mentioned above are caused by dirty stepper parts, which you can clean without going to a mechanic. Next, we will mention how to wash the stepper motor.
- Turn off the vehicle and allow the engine to cool down sufficiently.
- Identify the location of the stepper. For this, get help from the car guide.
- Unscrew the relevant screws and disconnect the wires and other connections from the motor.
- Wash the stepper piece carefully. For this, you can use diesel or injector spray.
- Dry it using compressed air.
- Check the stepper valve and make sure it is closed.
- Put it back in place, connect the wires and tighten the screws.
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