A Beijing modern 2.0L Sonata car with a mileage of over 300 thousand km in 2006. Customer response: the vehicle is insufficient in driving and discharged with blue smoke at its tail. In this vehicle, the phenomenon of "pulling cylinder" caused by the damage of the oil pump caused by the damage of the cylinder wall to the piston was found, with the death of the main bearing of the crankshaft, and the lack of power after the replacement of the piston, piston ring and other parts of the other repair plants. After overhauling, there are many problems such as poor dynamic performance, large oil consumption and poor exhaust gas quality. It is found that the connecting rod bearing and main bearing of the crankshaft are too small because the gap between the oil film is too small, so that the main bearing and the connecting rod bearing of the crankshaft are not lubricated. After decomposing the piston rod group of the engine, according to the inspection method of the maintenance manual, the clearance of the piston ring side of the engine, the clearance of the ring opening and the gap of the back of the ring are checked, which conforms to the technical standard. The oil film and thermal expansion gap between piston and cylinder wall are measured. No. 1 cylinder is 0.03mm, No. 2 cylinder is 0.02mm, No. 3 cylinder 0.04mm, No. 4 cylinder is 0.03mm, circular error of cylinder and cylinder error are 0 and 0.01 mm respectively, indicating that there is no problem between piston and cylinder wall and cylinder base hole. The cylinder cover and main oil channel of the body are checked, no cracks or obvious traces of oil leak are found, but the engine exhaust smoke indicates that the oil consumption is discharged after the combustion chamber of the cylinder inside the combustion chamber. The original piston connecting rod group and the crankshaft flywheel group were checked. It was found that the first gas ring of the piston ring was the opposite of the second gas ring installation (second gas rings processed the oil scraper, with the oil scraping function), the main bearing of the crankshaft and the gap between the shaft neck were small (the crankshaft was processed). Replace crankshaft, crankshaft bearing, piston ring, adjust installation sequence and troubleshooting. Maintenance summary: the fault of the car is mainly because in the process of installing the piston ring, the first ring and the second ring ring are installed, causing the oil ring to be distributed in the cylinder wall and the excess oil can not be scraped out and into the combustion chamber, causing the oil consumption to be too large. Because the opening gap of the second ring is larger than the opening gap of the first ring, a large amount of gas in the combustion chamber is moved into the crankcase during the work of the engine, which causes the insufficiency of the power.