【The owner's family car knowledge】The idling value of the automobile engine is lower than or exceeding the specified range, there will be phenomena such as stage flameout and unstable speed. Today, we will introduce the common faults of engine idling.
1. What should I do if the idle speed is unstable?
Idling unstable performance is: when idling, the engine trembles and the speed is uneven. The reasons for this are: blockage of the idle air flow hole, poor operation of the idle speed device, too weak spark plugs in individual cylinders, inadequate sealing of individual valves, air leakage in the intake manifold, too early or too late ignition time, improper idle speed adjustment, etc. When the engine idle speed is unstable, the idle speed should be adjusted first. If the fault cannot be eliminated after the idle speed adjustment, check whether the idle speed measuring hole and the idle air measuring hole are blocked. If the measuring hole is blocked, it can be cleaned with gasoline or acetone and blown through with compressed air; If the measuring hole is not blocked, the engine speed should be stabilized at a certain speed, and check for air leakage in the intake manifold or carburetor, and the lower gasket. If there is air leakage, use fastening screws or add, The method of reducing the gasket can be eliminated. If the idling speed is unstable and accompanied by a drop in engine power, the working condition of the spark plug, the sealing performance of the valve and the ignition time should be further checked, and the maintenance and adjustment should be carried out if necessary.
2. How to distinguish bad idling speed?
A working engine should be able to run evenly within the speed range of 300-500r/min. If the minimum stable engine speed exceeds this speed range, or the engine stalls or the speed is unstable within this speed range, it means no idle speed or poor idle speed. When idling is poor, it can be divided into idling stall, unstable idling and excessive idling according to its fault characteristics. If the engine runs well from low speed to high speed after starting, but it turns off as soon as the accelerator pedal is released, or it runs unstable and then turns off, it is an idling stall failure. If the engine is not running smoothly at idling speed and the exhaust pipe makes a "sudden" sound, it is generally a fault of unstable idling. If the minimum stable engine speed is higher than the specified range, and the speed cannot be reduced, the idle speed is too high or there is no idle speed fault.
3. How to adjust idle speed?
Idling adjustment must be carried out under normal conditions such as normal engine temperature, proper valve clearance, normal ignition system conditions, good sealing of all pipes, full opening of the choke valve, and tight throttle closing. When adjusting, first unscrew the throttle opening adjustment screw to make the engine reach the lowest stable speed. Then use a screwdriver to screw in the idle speed adjustment screw. When the engine is about to turn off, slowly unscrew the idle speed adjustment screw to make the engine run stably and reach a high speed. Then unscrew the throttle opening adjustment screw to minimize the engine speed. Then adjust the idle speed adjustment screw to increase the engine speed. This is repeated until the throttle opening is the smallest and the engine runs at the lowest stable speed. Finally, increase the speed and close the throttle abruptly. It is advisable for the engine to rotate without stalling.
4. What should I do when idling stalls?
When the engine is idling and stalled, the idling speed must be adjusted according to the actual situation. After adjustment, if the fault disappears, it means that the idle speed screw is improperly adjusted. After adjustment, if the fault does not disappear, you can open the throttle more to keep the engine running. Use cotton gauze or paper strips to check for leaks at the carburetor and intake manifold gasket. If there is no leak, it can be removed. Check the lower idle speed measuring hole, and blow through the idle speed oil passage at the same time, and then reinstall the test. If the fault disappears at this time, it means that the idle speed measuring hole and idle speed oil passage are blocked. For the carburetor equipped with the idle speed stop valve, check whether the idle speed stop valve solenoid circuit is normal. If the idle speed fuel metering hole is blocked due to the abnormal solenoid coil circuit, the idle speed stop valve should be repaired.
5. What should I do if the idle speed is too high?
When the engine idling speed is too high, start the engine first, and then control the throttle arm by hand to close the throttle. If the idling speed is normal at this time, the throttle spring is too soft, and the spring should be replaced. If closing the throttle by hand is invalid, check whether the throttle shaft is loose or whether the throttle is closed tightly. If the throttle is not closed tightly or the throttle shaft is loose, then it should be trimmed; if the throttle is normal, it should be checked. Whether there is a slight air leak under the throttle, if so, eliminate the air leak, if not, make further adjustments to the idle speed until the idle speed is suitable.
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