The 2005 Audi A6L 2.4 car with a driving mileage exceeding 224,000 km. User Response: The car accelerated slowly and could not go up at high speed.

　　故障診斷：（1）首先用VA56150檢測有故障碼，汽缸列1和2混合氣過濃。檢查燃油壓力正常，噴油嘴無滴漏現象，試更換火花塞及點火線圈無效。分析認為該車已行駛22萬公里，三元催化器堵塞的可能性較大，經檢查發現三元催化器確實已堵塞，更換左右三元催化器后試車正常，加速不暢故障排除，但在洗車過程中發現有時起步發沖，小油門加油不走車。

　　Fault diagnosis: (1) First, the fault code is detected by VA56150, and the mixture of cylinder column 1 and 2 is too thick. Check that the fuel pressure is normal and there is no drip leakage in the nozzle. The replacement of spark plug and ignition coil is invalid. The analysis shows that the vehicle has traveled 220,000 kilometers, and the possibility of blockage of the three-way catalytic converter is greater. It is found that the three-way catalytic converter has blocked. After replacing the left and right three-way catalytic converter, the test run is normal, and the trouble shooting is not smooth. However, when found in the car washing process, the car starts to rush and the small throttle refuels the car.

　　（2）再次試車確認，故障發生在低速前進或倒車且打方向時，用5052讀取數據塊發現混合器調整達25%，仍有偏濃的情況，檢查炭罐電磁閥，有關閉不嚴的跡象，更換后故障依舊。先后又嘗試更換噴油嘴、氧傳感器及燃油泵無效，替換過節氣門、發動機控制單元，故障依舊。讀取變速箱數據也未發現異常。

　　(2) Re-test confirms that when the fault occurs at low speed forward or backward and hit the direction, reads the data block with 5052 and finds that the mixer is adjusted up to 25%. There is still a dense situation. Check the solenoid valve of the carbon tank for signs of lax closure, and the fault remains after replacement. It has tried to replace the fuel injector, oxygen sensor and fuel pump ineffective, replaced the throttle, engine control unit, the failure is still. No abnormalities were found when reading the gearbox data.

　　（3）重新調整思路，因故障多發生在低速及打方向的情況下，懷疑是不是發動機功率不足導致。經測量汽缸壓力發現4缸、5缸、6缸壓力在9bar左右，而1缸、2缸、3缸汽缸壓力都在12bar左右，分析3個汽缸氣門都出現問題的可能性不大，用內窺鏡檢查也未發現汽缸有拉傷的跡象，三元催化器已更換過，難道是1列進氣有問題？嘗試更換進氣歧管故障依舊，無奈只得拆檢發動機，發現4缸、5缸、6缸活塞的環槽都存在斷裂損壞的情況，造成汽缸壓力偏低，更換活塞及環后故障排除。

　　(3) Re-adjusting the train of thought, because faults often occur at low speed and direction of attack, it is doubtful whether the engine power is insufficient. After measuring the cylinder pressure, it is found that the pressure of four, five and six cylinders is about 9bar, while that of one, two and three cylinders is about 12bar. It is not likely that the valve of three cylinders will have problems. There is no sign of cylinder pulling by endoscopy. The three-way catalytic converter has been replaced. Is there a problem with intake air? When trying to replace the intake manifold, the engine had to be disassembled and inspected. It was found that the ring grooves of 4, 5 and 6 cylinder pistons were damaged by fracture, which resulted in low cylinder pressure and troubleshooting after replacing the piston and ring.

　　故障排除：更換活塞及活塞環。

　　Troubleshooting: Replacement of piston and piston ring.

　　故障總結：起步發沖等故障也應考慮發動機功率問題。

　　Fault Summary: Engine power should also be taken into account in starting impulse and other faults.