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A journey mileage of about 59 thousand km, equipped with manual transmission of the Volkswagen 1. 8TSI car. User response: the engine of the vehicle is not well accelerated and the fuel consumption is high. The maximum speed can only reach 140km/h, when the automatic transmission is always shifting between 5 and 6 gears. Fault diagnosis: the fault code is read by the fault detector. The fault code is 00665/Pa299, which means the supercharger booster sensor A circuit control limit is not reached. The fault code can be cleared, the fault is reproduced after trial run, and the supercharger booster sensor A is replaced. The dynamic data flow is read by the fault detector. 1) air fuel ratio data: the change of oxygen sensor value indicates that the concentration of gas mixture varies between Dense dilute, but the adjustment value is + 8.2%, and the instruction is thickened all the time, and the air fuel ratio is modified by long effect. The main reason for this failure mode is that the air quality is relatively small. 2) air relative quality data: the relative quality of air is the engine load value calculated by ECU, and it is also the reaction parameter of turbocharging, variable timing adjustment, variable intake pipe and other air filling control effects. The relative mass of the air is 15%, and the relative mass of the normal car is less than the air relative quality of the normal vehicle (40.6%). It indicates that the system's air filling control effect is poor, such as turbocharging, variable timing adjustment, variable intake pipe and so on. 3) turbocharging group data: under normal circumstances, the turbocharging value of idle speed is 1.01 x 108 MPa, the maximum turbocharging value is about 1.8 x 108 MPa when the original land is speeded up; the air flow is 2.3 to 2.5g/s at normal idle speed, and the air flow in the place of rapid acceleration is up to about 65g/s. The actual value of the boost pressure is 1 x 10 8MPa, and the maximum value is 1.2 x 108 MPa, which indicates that the actual supercharging value is low. The air flow rate is 2 ~ 2.1g/s at idle speed, and the maximum air flow rate is about 50g/s in situ, which indicates that the signal of the air flow sensor is small. The main reason for the poor control effect of the air filling is the bypass of turbocharger system turbocharger. Perform the component test. The turbocharger bypass bypass pressure regulator solenoid valve N75 works normally. The bypass opening of the supercharger is regulated by the self inlet pressurization, and the actual value of the boost pressure is smaller (1 * 108 MPa), so that the bypass of the supercharger under the idle speed condition is larger. According to the comprehensive analysis, the fault of the vehicle is the blockage of the exhaust system, and the kinetic energy of the impeller driven by the exhaust gas is insufficient, resulting in the insufficient kinetic energy of the turbine and the smaller actual value of the boosting pressure. To disintegrate the exhaust pipe, it is found that the three element catalyst is seriously blocked, the color of the surface is reddish brown, which is caused by too much sulfur in the fuel oil, and the bottom color is gray white, which is caused by excessive lead in the fuel. The cause of the trouble is that the blockage of the exhaust pipe is caused by poor fuel quality. The user ignores the fact that the fuel quality is poor, only 3 times specified fuel additives are added to the vehicle maintenance, and it is acknowledged that there is no quality No. 97 oil at the gas station and 4 cases 93 inferior gasoline when driving on the long distance highway. Troubleshooting: after removing the blockage, the three element catalytic converter is dry cleaned with high pressure wind, and the acceleration is good, the speed can reach 220km/h, but the idle speed data flow and the lower value are deviant. Then replace the exhaust manifold assembly, the idle data flow is normal, the oil consumption is normal, the trial run is normal.