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Fault phenomenon, a SAAB car, the cumulative mileage of about 50 thousand km, after the hot car engine failure, it can no longer start the failure of the machine. Inspection and analysis showed that the starter could operate normally, and the engine appeared to have signs of engine when it started. The connection fault detector detects that there is no fault code stored in the engine control system. The spark plug is checked. The spark plug is full of gasoline, indicating that the spark plug is "drowned", and the spark plugs are re baked and the engine is tried to start the engine. The failure is still. According to the fault phenomenon and the absence of fault code storage in the engine control system, the electric control system of the vehicle should have no problem. Next, starting from the gas path, oil circuit, ignition circuit, cylinder pressure, valve timing and ignition timing, the engine is basically checked. According to the results of the previous inspection, the gas path, the oil circuit and the ignition should be all right, leaving only the timing and cylinder pressure. As the calibration time needed to remove many parts, it was decided to check the cylinder pressure first. When the cylinder pressure meter is connected to the starting engine, the first cylinder pressure meter reads about 1MPa. When the colleague in the car is ready to stop running the engine, the second compression stroke finds the cylinder pressure meter reading maximum to 1.2 Mpa, when the difference of the cylinder pressure feels as if it is larger than the normal car, so it is allowed to start. The motive forces the engine to run a little longer, and find the maximum readings of the cylinder pressure meter reading can reach 1.6 Mpa, and the normal cylinder pressure of the army should be 0.9 MPa-1.2 MPa according to the standard. According to the maintenance experience of the author, I feel that the muffler is blocked by foreign matter. So let colleagues start the engine again, I check the exhaust pipe in the back of the exhaust, but there is no sense of anger. The 2 oxygen sensors in the front are removed from the starter engine, and the engine starts smoothly, and it works normally after running. The muffler was removed and examined. It was found that the rear part was very heavy and was blocked by endoscope. It turned out to be only about 20 km a day, and a very long time without high speed, causing the water in the rear of the silencer can not be discharged, and then these days are very cold, the water inside the silencer is frozen into ice, blocking the silencer. The elimination method eliminates the accumulated water and ice in the muffler, and ensures that the vehicle is driven at high speed.