Model: a Mercedes-Benz car for the l17 type, V8 cylinder European models.
    Symptom: When the engine is running rapidly, the jitter is serious and the speed is more than 1500r / min.
    Failure analysis
    The reasons for the engine shake may be the following:
    ① poor operation of individual cylinders; ② intake and vacuum system leak phenomenon; ③ poor fuel supply system; ④ ignition timing is not correct.
    Troubleshooting
    First check the ignition system. High-voltage line, the spark plug work properly; cleaning the nozzle, atomization in good condition; view the vacuum tube, the valve is no leakage phenomenon; adjust the CO value of 1.5% after the fault remains the same.
    And then measure the cylinder pressure, found 1-4 cylinder is 11.5 × 105Pa or so, 5-8 cylinder is about 13 × 105kPa. It can be seen that the left and right side of the cylinder pressure is significantly different. According to the judge may be timely misalignment. Remove the valve chamber cover, the crankshaft clockwise to 1 cylinder top dead center position, observe the camshaft, found in the 5-8 cylinder position is correct, in the 1-4 cylinder position is not correct, ahead of a tooth. Camshaft gears for 36 teeth, ahead of a tooth is equal to 10 degrees ahead of time. This fault is a new replacement camshaft installation error.
    The correct installation method of the camshaft: the crankshaft should be clockwise to the top of the 1 cylinder straight point, the 1 side of the camshaft side of the camshaft to 4 characters and the first support seat mark alignment, the 6-cylinder side of the camshaft Go to the next character and the first support seat mark alignment. And then hang the chain, install the tight chain device, and then turn the crankshaft clockwise two weeks to determine the accuracy of the valve timing.
    Note: When cranking the crankshaft, it must be rotated clockwise. In the arrival of a cylinder when the top dead point if you shake, you must turn back 90 degrees, and then clockwise rotation, otherwise the location is not allowed to cause errors.