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Fault diagnosis and troubleshooting of car electronics EFI car to start the difficult process
Nov 23, 2012 | Views: 188
Difficulties cold start and hot start the difficulties influencing factors and check in much the same terms of the concentration of the gas mixture, the mixture too lean and rich mixture both cases. Affect oil supply failure may occur in the fuel quality, fuel pump, fuel filter, fuel pressure regulator, cold start system, fuel injector, and the water temperature sensor; affect intake fault symptoms clogged air filter intake system leak and idle control fault. Personal/Office Electronics
??1.car electronics faulty fuel pressure regulator failure Reasons
??Hydraulic fuel system has a direct impact on the mixed gas concentration, and therefore should first check the fuel pressure. The method is: first the access fuel line of the fuel pressure gauge, and then start the engine, measure fuel pressure. If the fuel pressure is too high, the pressure regulator should be replaced; pressure is too low, the hose can be pinched back the damage to the fuel pressure regulator, fuel pressure rises to normal, otherwise check the fuel pump and fuel filter . Check the fuel pressure after shutdown should be maintained at the specified value 5min otherwise injector leakage, the mixture is too thick.
??2. Car electronics failure of the fuel pump and fuel filter failure Reasons
??Difficulty in starting, fuel pump to work properly, the problem of multi-pump filter is clogged causing pump not sufficient amount of suction fuel or fuel filter caused by lack of oil supply system pressure is not smooth.
??Reasons 3. Car electronics failure cold start system failure
??In some models has a cold start injector, gas mixture enriched in the cold start to improve cold start performance. Cold start injector is controlled by the start switch and the thermal switch control, fuel injection duration depends on the thermal-controlled switch when the heating coil current and the temperature of cooling water.
??Cold start system failure symptoms: cold start injector is clogged by the gelatinous material, the impact of the fuel injector atomization quality, cold start problems; cold start injector failure does not work properly; thermal controlled switch when short circuit (contact normally closed) or open circuit (normally open), if the contact is normally closed, the hot car is still in control of the cold start injector too much fuel injected into the hot start difficulties, short circuit when the control switch, cold start injector always does not work and causes cold start problems.
??Car electronics fault injector failure Reasons
??The general performance of the injector failure: the injector orifice glial OBSTRUCT carbon deposition or cause drip Mifengbuyan, leading to the concentration of the gas mixture is too small or too large. The detection method is: First, start the engine, check the operation of the sound of each injector with a stethoscope can not hear the sound, you should check the wiring connector, injector or injection signal from the ECU; then measured with a multimeter the resistance between the terminals of the injector, such as the resistance value with a predetermined value does not match, then replace the injector; Finally, checking the fuel injection quantity of the injector, its value should be within the normal range and the difference of the amount of each cylinder injector is less than 5cm3.
??Reasons 5. Car electronics failure of the water temperature sensor failure
??The water temperature sensor is used to detect the temperature of cooling water, and converted to the temperature-related voltage signal input ECU to correct the fuel injection quantity on the basis of, as an ECU. If the water temperature sensor failure or with the ECU wiring between open circuit, short-circuit surface furring serious, will cause the output signal larger deviations, and ultimately the injector can not be timely to increase or reduce the amount of fuel injection, resulting in difficulty in starting. If the water temperature sensor is open, the start of a hot car to the ECU input low temperature signal, the ECU will control the supply of fuel injector mixture too thick, causing hot start difficulties; water temperature sensor failure or short circuit, the cold start hot car signal will cause the mixture is too thin, cold start problems. Usually, by detecting the resistance between terminals of the water temperature sensor is within the normal range, may determine whether the failure.
??Reasons 6. Car electronics failure idle speed control valve (ISC) failure
??Most EFI engine stepper motor idle speed control valve, the ECU based on the engine operating conditions, adjusting the order in which the stepping motor energization of the solenoid coil, so that the stepper motor shaft a tapered valve body screwed into or screwed out, adjusting bypass the degree of opening of the air passage, to achieve the adjustment of the bypass intake air quantity.
??If the engine start difficult but a little step on the gas was able to start, idle speed control valve failure. The dismantling ISC valve will find more coke, glial viscous oil accumulation in the valve cone, results reduced the range of adjustable conical valve, causing the cold start, the feed rate is reduced, the gas mixture too thick and difficult to start.
Material Handling & Construction Machinery
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