What happened to the unstable idle speed after Volkswagen's maintenance?

The idle speed of Volkswagen after maintenance is unstable, which may be caused by the following reasons:

1, the throttle has not been re-matched;

2. The work of electronic control unit and idle speed control element is not coordinated;

3. The exhaust pipe is poorly sealed.

You can take the following steps to solve the problem:

First clean the throttle. Remove the intake hose, turn on the ignition switch (do not start the engine), and press the accelerator pedal to the bottom (keep the throttle valve fully open). Spray a little carburetor cleaner on the clean cloth and put your finger into the accelerator to wipe it. After cleaning and commissioning, the fault still exists. Use V.A.G.1552 detector to detect and read the engine fault code, which is not stored in the engine control unit. Judging from this, it may be because the throttle has not been re-matched.

Due to the cleaning of the throttle valve, the work of the electronic control unit and the idle speed control element is not coordinated, and the idle speed control will be inaccurate and unstable, such as the idle speed is high and low, and the idle speed is unstable. Although the characteristics of the throttle potentiometer have not changed after cleaning the throttle, the intake air volume has changed and its idle speed control characteristics have also changed under the same throttle opening, so it is necessary to basically set and initialize the throttle.