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    Possible cause of lift failure behind small tractors

    From:Xingtai First Tractor Manufacturing Co., Ltd.Date:2019/4/27 10:54:43

    Possible cause of lift failure behind small tractors

    (1) intake supply system.

    The intake system is an important part of the electronically controlled fuel injection system. The main faults that lead to inaccurate air supply are:

    1, the intake pipe and various valve leakage, common intake manifold rupture, intake manifold seal is poor, vacuum tube off, PCV valve /EGR valve closed lax, etc.. For example, under normal circumstances, the opening of idle speed control and air intake should strictly follow a certain functional relationship, that is, idle valve open large air intake will increase. When the air supply system leaks, the inlet and idle speed control valve opening cannot follow the original function, as a result, the air flow meter can not accurately measure the true intake, leading to the engine electronic control unit (ECU) to obtain the near air signal is inaccurate and miscalculation, resulting in engine idle instability.

    2, idle air channel and throttle scaling too much, resulting in changes in the intake cross-sectional area, as well as the idle air channel control is not accurate, so that the amount of air into the cylinder deviates from the normal value, resulting in the mixture is too thick or thin, combustion is not normal, resulting in engine idle instability.

    3, control idle sensor and other circuit disorders. If the idling switch cannot be closed, the ECU error determines that the engine is under partial load, resulting in air intake control error; Idle valve due to oil, carbon and action lag or card, throttle valve closed lax will cause ECU can not be true to the engine idle regulation, in addition to the intake temperature sensor, air flow sensor, water temperature sensor and sensor circuit short circuit, open circuit will cause engine idle instability.

    Ignition system.

    Poor ignition system is mainly the weak high pressure fire or spark plug does not ignite, directly affect the cylinder combustion, resulting in different cylinder power, so that the engine idling instability. The specific performance is:

    (1) secondary voltage depression; (2) leakage of high-voltage lines; (3) short circuit or high internal resistance; (4) wrong ignition advance delivery; (5) carbon accumulation and burning loss of spark plug; (6) incorrect spark plug electrode clearance; (7) ignition coil damage or ignition control circuit fault; (8) ECU failure.

    (3) fuel system.

    Faults that may lead to inaccurate fuel supply in the fuel system include :(1) leakage or blockage of the injector; (2) electrical damage of fuel engine; (3) the filter screen of fuel pump is blocked, the safety valve spring of fuel pump is too small or the pump oil pressure is insufficient; (4) blockage of fuel filter; (5) failure of fuel pressure regulator; (6) poor oil quality; (7) fuel line deformation. For example, when the injector atomization is poor, drip leakage, the corresponding cylinder of the mixture of bad mixing, and bad combustion, the cylinder power is different, resulting in engine idling instability. In addition, the oxygen sensor will generate a low-potential signal according to which the ECU will add a concentrated mixture. Once the fuel volume increases beyond the set regulation limit, the ECU will mistake the oxygen sensor for a fault and record the fault code.

    (4) the mechanical part.

    (1) camshaft CAM wear seriously, coupled with inconsistent wear, so that the cylinder power is different;

    (2) the timing chain (belt) becomes loose or worn, leading to the misalignment of valve phase;

    (3) valve related parts are abnormal, such as valve push rod wear, bending, lock, air leakage, valve spring fracture and valve seal damage, etc.;

    (4) cylinder liner ablation or damage;

    (5) the piston ring end gap is too large, and the piston ring is opposite and fractured;

    (6) excessive cylinder wear.

    (5) other circuit faults.

    Mainly refers to the intake system, fuel system, ignition system and other related power supply circuit or control circuit contact bad fault. Usually a transient oil supply is insufficient or poor. Make the mixture in each cylinder combustion is not normal, so as to make the cylinder power is different, such as engine ECU iron bad, power supply voltage more than 9-16v, will cause engine failure.

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