Troubleshooting methods for idle speed faults such

2022-08-24
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Troubleshooting methods for idle speed faults such as uneven engine speed and flameout

different models of automobile engines have different idle speed ratings. If the idle speed of the engine is lower than or exceeds the specified range, flameout, uneven speed or high speed will occur. When these phenomena occur, the symptoms should be judged, checked and eliminated in time

I. idling and flameout

the most typical ones when idling and stalling, such as cantilever impact tester, electronic tensile tester, Mooney viscosity tester and various measuring instruments, also fall into this category. The idling speed should be adjusted according to the actual situation first (if the cause of the fault is clear, it can also be repaired directly). After adjustment, if the fault disappears, the idle screw is improperly adjusted; If the fault cannot disappear after adjustment, open the throttle wider to keep the engine running, and check whether there is air leakage at the carburetor and intake pipe gasket with cotton yarn or paper strip; Its predecessor is DSM composite resin group. If there is no air leakage, the idle measuring hole can be removed for inspection, and at the same time, the idle oil passage can be blown through, and then it can be reinstalled for test; If the fault disappears, it indicates that the idle measuring hole and idle oil passage are blocked. For carburetors equipped with idle stop valve, check whether the cut-off solenoid circuit is normal. If the idle fuel saving orifice is blocked due to abnormal coil circuit, the stop solenoid valve should be repaired

second, the idle speed is unstable. The engine runs unsteadily at idle speed, and the exhaust pipe makes a loud noise, which is generally the fault of unstable idle speed

stabilize the engine at a certain speed and listen for air leakage. If it is difficult to find out the air leakage part, apply a little oil on the middle and lower gaskets of the carburetor. The place where the oil is sucked in is the air leakage part, which can be eliminated by fastening screws or adding or subtracting gaskets. Then screw in the throttle adjusting screw to increase the engine speed, then tighten the idle speed adjusting screw and gradually loosen it to see whether the speed is stable; Then loosen the throttle adjusting screw a little, slowly reduce the engine speed, and operate smoothly, that is, the fan blades rotate evenly, and the blade contour (400r/min) can be distinguished. If the adjustment is invalid, check the oil level from the inspection hole on the carburetor. If the oil level is too low, adjust it to solve the above problems. If they are all in good condition, continue to check the wiper tube and intake and exhaust manifold for cracks and air leakage. The rubber tensile testing machine adopts the integrated structure of DC servo electromechanical and speed regulation system to drive the synchronous belt deceleration mechanism, disassemble the carburetor, blow through the idle air measuring hole and the idle air measuring hole with compressed air, and if it works well after reinstallation, it indicates that the measuring hole is blocked

if the idle speed is still not improved after the above maintenance, the fault may be the engine, usually caused by the excessive gap between the engine inlet valve rod and the guide pipe, or the engine is approaching overhaul and the technical performance is reduced. Therefore, the cylinder head should be removed for maintenance

III. the idle speed is too high. When the engine is idling, the speed is higher than the normal range and cannot be reduced by adjustment, which is the fault of high idle speed

when the engine idle speed is too high, stop the car on a flat ground and push the choke button and the manual acceleration button to the bottom for inspection. Press the throttle rocker arm by hand to close the throttle valve. If the idle speed is normal, it indicates that the carburetor control lever spring is too soft. If it is invalid to press the throttle rocker arm, check whether the throttle shaft is loose or whether the throttle is closed tightly. If the throttle valve is normal, adjust the idle speed with the idle speed adjusting screw. If it can be adjusted well, it means that it is caused by the original adjustment. When the idle speed adjustment is invalid, remove the inspection hole plug on the carburetor to keep the engine running at idle speed. If gasoline can flow out of the inspection hole, it indicates that the oil level is too high, and the fault is eliminated

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