What is the reason for the unstable idle speed of Audi a3?

First, the cause analysis 1, the spark plug is not easy to use; 2. Real empty pipeline leakage; 3. High-voltage line leakage; 4. Number four. PCV valve is blocked; 5. The throttle position sensor is faulty; 6. Idle stepper motor failure; 7. Idle speed control valve failure; 8. Abnormal throttle opening; 9. Air leakage in air intake system 2. What if the idle speed is unstable? Idle speed instability is characterized by engine jitter and uneven speed at idle speed. The reasons include: the idle air hole is blocked, the idle device is not easy to use, the spark plugs of individual cylinders are not firm, the seals of individual valves are not tight, the intake manifold leaks air, the ignition time is too early or too late, and the idle speed is not adjusted properly. When the engine idle speed is unstable, adjust the idle speed first. If the fault cannot be eliminated after idle speed adjustment, check whether the idle speed measuring hole and idle air circulation hole are blocked. If the measuring hole is blocked, clean it with gasoline or acetone and blow it clean with compressed air. If the measuring hole is not blocked, the engine speed should be stabilized at a certain speed, and the middle and lower gaskets of the intake manifold or carburetor should be checked for leakage. If there is air leakage, it can be eliminated by fastening screws or adding or subtracting gaskets. If the idle speed is unstable and the engine power decreases, the working condition of the spark plug, the sealing performance of the valve and the ignition time should be further checked, and maintenance and adjustment should be carried out if necessary. Third, how to distinguish the idle speed difference? The working engine should be able to run evenly in the speed range of 300-500 rpm. If the minimum stable speed of the engine exceeds this speed range, or the engine is turned off and the speed is unstable within this speed range, it means that there is no idle speed or poor idle speed. When the idle speed is poor, it can be divided into idle stall, unstable idle speed and high idle speed according to its fault characteristics. If the engine runs well from low speed to high speed after starting, but turns off as soon as the accelerator pedal is released, or turns off when it is unstable, it belongs to idle stall fault. If the engine is not running smoothly at idle speed, the exhaust pipe makes a "chug chug" sound, which is generally a fault of unstable idle speed. If the minimum stable speed of the engine is higher than the specified range and the speed cannot be reduced, it means that the idle speed is too high or there is no idle speed fault. 4. How to adjust the idle speed? Idle speed adjustment must be carried out under normal conditions such as normal engine temperature, proper valve clearance, normal ignition system, good pipeline sealing, full throttle opening and tight throttle closing. When adjusting, first loosen the throttle opening adjustment screw to make the engine reach the lowest stable speed. Then screw in the idle speed adjusting screw with a screwdriver, and then slowly screw out the idle speed adjusting screw when the engine is about to turn off, so that the engine runs smoothly and reaches high speed. Then loosen the throttle opening adjustment screw to minimize the engine speed. Then adjust the idle adjustment screw to increase the engine speed. Repeat this process until the throttle opening is minimum and the engine runs at the lowest stable speed. Finally, increase the speed and suddenly close the throttle. It is wise to keep the engine running without stalling. 5. What should I do if I stall at idle speed? When the engine turns off at idle speed, adjust the idle speed according to the actual situation. After adjustment, if the fault disappears, it means that the idle screw is not adjusted properly. After adjustment, if the fault does not disappear, open the throttle and keep the engine running. Check the carburetor and intake manifold gasket for air leakage with cotton yarn or paper strip. If there is no air leakage, remove the idle metering hole for inspection, purge the idle oil circuit at the same time, and then reinstall the test. If the fault disappears, the idle metering hole and idle oil passage are blocked. For carburetor with idle stop valve, check whether the solenoid valve circuit of idle stop valve is normal. If the idle fuel saving hole is blocked due to abnormal solenoid valve circuit, repair the idle stop valve. 6. What if the idle speed is too high? When the idle speed of the engine is too high, start the engine first, and then control the throttle arm by hand to close the throttle. When the idle speed is normal, the accelerator tension spring is too soft, so the tension spring should be replaced. If closing the throttle manually is ineffective, check whether the throttle shaft is loose or whether the throttle is closed tightly. If the throttle is not tight or the throttle shaft is loose, make fine adjustment. If the throttle valve is normal, check whether there is slight air leakage under the throttle valve. If yes, eliminate air leakage. If not, further adjust the idle speed until the idle speed is appropriate. # 160; Million car purchase subsidy