After washing the accelerator, the idle speed becomes higher. What is the reason?

In the intake process of the engine, impurities will enter the throttle valve together with air, and these impurities will accumulate on the throttle plate for a long time, and the carbon deposition of impurities will be more and more. When the throttle valve reciprocates, it will be resisted. If this situation persists for a long time, the engine computer will adjust the position of the accelerator pedal. That is to say, the position of carbon deposition is regarded as the throttle body, which means that the throttle is not in place at all but close to the position of carbon deposition.

Due to the influence of dirt on the throttle body, sludge keeps accumulating on the edge of the throttle. Under the idle condition, the idle intake of the straight-through idle control system is obtained by the motor pushing the throttle opening, and the throttle opening is very small at idle. Due to the sludge jam at the edge of the throttle valve, the intake air is insufficient, which makes the engine speed decrease.

When it deviates from the standard speed, the electronic control unit outputs a larger signal, instructing the motor to continue to increase the opening to maintain the target speed. This new opening data (motor position sensor signal) replaces the old opening data again, and at the same time, it is stored in the memory of the electronic control unit as the new optimal data for controlling the motor. With the passage of time, sludge accumulates, and the motor on signal is constantly updated and stored. At this time, the opening is just suitable for the air inlet blocked by sludge, thus ensuring the current idle speed.

What is the reason why the engine idle speed will increase after cleaning the throttle?

After the vehicle cleaned the intake valve, the flap still moved in the original formation, which showed that it was not in place, but the carbon deposit was cleaned. So the air intake will be a little more than usual. This will lead to high idle speed. In this case, computer programming is required. If you don't do it, the engine computer will take a long time to adjust and recover.

Once the sludge in the throttle body is removed, the ECU still controls the throttle opening according to the memory, and at this time, the air intake will inevitably increase accordingly, resulting in an increase in idle speed. It takes time and repeated learning and memory to get it back to the optimal idle speed.

Solution of high idle speed after cleaning throttle valve

If you use the diagnostic instrument for setting, the optimal idle speed data will immediately replace the data before cleaning, so that the engine speed will immediately return to the optimal target speed.

If there is no diagnostic instrument setting, you need to repeat the relearning process 1 time, constantly refresh the old data and store new data, and you can also return to the optimal idle speed. The duration of this process depends on different vehicle control systems.

Some manufacturers' products, such as Toyota, can clear the learning value as long as ECU and electronic throttle are powered off for 30s; Some manufacturers' products, such as Lu Zun, need the original diagnostic instrument to refresh the control program (also called programming).

Therefore, it is best for the owner not to wash the throttle himself. After washing the throttle, it is recommended to make a throttle match. Or some cars can break the battery head, erase the memory of the computer and restore the original throttle position.