A 2000 TOYOTA Camry equipped with 2AZ-FE engine. User response: the engine accelerates badly at high speed. After the engine failed to replace the engine cylinder (overhaul engine), after driving 3000km, it felt more difficult to accelerate 120km/h and the engine had a larger voice. Failure analysis: the customer will drive the car into the shop, and the technician will have difficulty in speeding up the test after 120km/h is confirmed. The technician first carried out the stall test: the stall speed of the vehicle at D and R bits was 2100r/min, and the normal value was about 2350r/min, which could be judged to be the engine power shortage. Check no fault code, check the relevant data list: IGNADVANCE No. 1 cylinder ignition timing is advanced, idle speed at BTDC 5~15 degrees, is within the normal range. Active test of VVTCTRL B1 system, engine stall at ON, normal speed at OFF. The measured fuel pressure is 310kPa, between 304 and 343kPa of normal value. The pressure of the cylinder was measured above lOkPa. The above check can eliminate the mechanical fault of the engine. At this point the fault point is doubted on the exhaust system. Connect the exhaust pressure gauge, the pressure at idle speed is 90kPa, the normal value is 80kPa. When the engine is 3000r/min, the pressure is 300kPa and the normal value is 150kPa, which indicates that the exhaust system (exhaust manifold) is blocked and the exhaust is not smooth and affects engine power, especially at high speed. Solution: replace exhaust manifold (three way catalytic converter), measure exhaust pressure, test run, everything is normal. Fault revelation: special measuring instrument is the key to eliminate this fault. The use of special measuring instruments can reduce unnecessary replacement links, save time, improve work efficiency, and become more professional. Troubleshooting: maintenance personnel are more accurate in judging faults. Through stall test, the power shortage of the engine was judged, and then a series of tests were carried out to determine the failure of the three element catalytic converter. All this shows that our technicians are very mature when judging such faults. Of course, use the equipment reasonably, find out the fault point accurately, this shows the importance of the related equipment, if there is no exhaust back pressure meter, I want to judge the cause of the failure, it is bound to take a certain curve, at least when dealing with the customers, it will not be good. Another point is, in the inspection, the reasonable use of the detector, read the short-term fuel correction value, can also indirectly help us to judge the failure of the exhaust. When the engine speed is kept at 3000r/min for a period of time, the acceleration pedal is suddenly loosened and the value of the short-term fuel correction value is observed. If the value is above - 15%, the failure of the exhaust blockage can be judged.