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Failure phenomenon: a golden cup SY6480A2E bus (with 491 -E engine, engine using a single point fuel injection system Motorola), the engine idle running smoothly, but when the air conditioning is serious, sometimes even flameout, fast acceleration, slow speed, enjoy the front and back. Failure analysis: according to fault symptom analysis, it is suspected that fuel pressure is caused by problems, so the fuel pressure gauge is connected to measure the pressure of fuel system. When the engine starts to start the engine, the fuel pressure gauge is shown to be 100 kPa at idle speed, and the pressure can be maintained at the speed of rapid acceleration, but the fuel pressure slowly descends to about 10 kPa when the accelerator pedal is trampled to the end, and the fuel pressure can rise to about 80 kPa as the engine speed falls down. The fuel pressure has fluctuated along with the fluctuation of engine speed. Obviously, the fuel supply is insufficient. Check the fuel filter. No problem. Remove the fuel tank and remove the fuel pump for inspection. It is found that the fuel pump screen has been smeared with muddy dirt. Thoroughly clean the fuel pump filter and fuel tank after the retest car, the car is rapidly speeding up the normal speed, but the engine in idle speed will occasionally flameout, especially when the air conditioning is more obvious. Check the throttle body, found dirty, so prepare to remove the throttle body disassembly to clean, but in the process of detection, the intake manifold absolute pressure sensor (MAP) wire side connector has no trumpet, but on the side, then the MAP wire side connector is inserted after the test, and the engine idle speed is found black smoke, Rapid acceleration of weakness. Evacuate the vacuum tube on the MAP, without a vacuum; put the intake manifold on the intake manifold in a mechanical way and clean it clean and connect to the vacuum camp. It is found that the engine is still smoked at idle speed, and the engine will occasionally flameout and the acceleration is still weak. The signal voltage of MAP is measured at idle speed of 0.35 V, and it can rise to about 3.5 V when speeded up, which is up to the standard. The signal voltage of the throttle position sensor is sometimes 0.5V, and sometimes it will suddenly drop to about OV. The power supply voltage of the throttle position sensor is 5V, and there is no problem to check the throttle position sensor line. It appears that the throttle position sensor itself is faulty. Elimination method: replace the throttle position sensor.