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A car mileage is only 900km, equipped with 1.8L engines, AT transmission 2013 Chevrolet Cruz. Users reflect: the car is just less than half a month's new car, in recent days when driving feel the power down, the second morning suddenly failed to get a car. Fault diagnosis: the site rescue found that the starting machine runs normally, but can not start, and after dragging back to the service station, the 2, 4 cylinder cylinder pressure is 1100 ~ 1200kPa, normal, but the cylinder pressure of the 1, 3 cylinder is 0, the pressure gauge needle is not moving. Through the spark plug hole injection of a small amount of oil, the cylinder pressure is not changed; through the spark plug hole, there are no cracks, collision marks and other abnormal phenomena; through the 1 cylinder spark plug holes into the 1 cylinder combustor into the compressed air, the result found that the throttle body and 3 cylinder spark plug holes outward gas, 2 cylinder and 4 cylinders do not gas; remove the valve chamber cover Inspection, undetected camshaft abnormal; check oil and coolant no abnormal; other unchecked, analysis may be the cylinder head or valve mechanical failure, resulting in the 1, 3 cylinder pressure is insufficient. When the owner agrees to further dismantle the cylinder cover, it is found that the connecting bolt of the pulley of the exhaust camshaft is broken, which leads to the transfer of the belt and the exhaust camshaft, the phase of the whole gas distribution system is disorderly, the exhaust valve of the 1 cylinder and the 3 cylinder is just in the open state, and the 2 cylinder and the 4 cylinder are in the closed position, and the exhaust valves of each cylinder are always in the above mentioned above. The position is not moving, and the inlet valve matching gas phase is normal, so the 1 cylinder and 3 cylinder cylinder pressure is zero, and the 2, 4 cylinder pressure is normal; and the current state is the 1 cylinder in the air suction close to the end, the 3 cylinder is near the end of the exhaust, the 4 cylinder is close to the end, the 2 cylinder is close to the end, the intake door is only 1 and 3 cylinders in the opening position, so appear to 1. Cylinder blow 3 cylinder outgassing phenomenon; check cylinder piston collision free trace; check exhaust camshaft bearing no wear phenomenon. Because the connecting bolts between the camshaft pulley and the camshaft are assembled by the manipulator, the torque will not have a problem, the possibility of the tensile strength of the bolt not to reach the standard is not very likely. The analysis of the bolt fracture is likely to be that the camshaft running resistance is too large and the camshaft pulley bolts are broken. After dismantling the bearing cover of the exhaust camshaft, there is no obvious wear mark on the bearing friction pair, but there is a dark brown adhesive material on the surface, which can not be erased by cloth. So the analysis is likely to be inferior fuel. It is too much gelatin after burning, causing the valve to adhere to the valve tube, the tappet and the cylinder head, and the movement resistance is too large. Sometimes the movement resistance is too large, sometimes the resistance is too large. In the hot car, the valve can not be shut down immediately, causing the power to drop. After a night, the engine temperature drops, the valve and valve tube or tappet and cylinder head are completely stuck to death, when the engine is started, the camshaft cannot be rotated, and the pulley turns under the action of the timing belt and finally the bolt is broken. It was found that the tappet of the 3 cylinder exhaust door could not be pulled out from the cylinder head, and the other exhaust tappet could be pulled out, but the tappet also had brown adhesive on the tappet. Troubleshooting: replace cylinder head assembly, replace all oil and fuel after troubleshooting.