Symptom: a 2006 annual production FAW - Volkswagen Bora 1.6L sedan, equipped with BJH engine, mileage of 33,000 km. According to the user to reflect a month ago when the car appeared in the hot car occasionally bad car accident, the recent hot car every time the start will be bad, but cold all normal, that is, put a few days can also be a smooth start The car.
    Check the analysis: because this car has been repaired in a number of repair shops, the author considered in addition to the original failure, but also increased the human failure. First, the basic inspection, check the ignition high voltage and measurement of fuel pressure are normal, the use of fault diagnosis instrument to retrieve the fault code, there is a mixture of over-thick fault code, start the car, the engine data stream shows the oxygen sensor in the -10 % ~ -20% between the regulation, indicating that the mixture is too thick. For the hot car when the mixture is too thick lead to failure of the car, there are many possible causes of failure, but according to maintenance experience, common causes include fuel injector drip fuel, cylinder coke too much and with gas timing Errors, etc., following a targeted one by one investigation.
    Because before the measurement of fuel pressure, the pressure after the pressure is normal, so you can rule out the possibility of injector drip. This car has been demolished and cleaned, and the mileage is shorter, so you can also rule out the possibility of excessive carbon deposition within the cylinder. Maintenance personnel observed that the hot car starts, each time with a car and then turn off, so decided to check the cylinder pressure in the construction phase is a problem. Measuring the starting cylinder pressure, when the measurement of 3 cylinder and found no cylinder pressure, cylinder pressure table is not a problem? Measuring the cylinder pressure of other cylinders normal, and re-measured the 3-cylinder cylinder pressure, cylinder pressure is normal, to achieve the highest cylinder pressure time is also normal. But the author found that the results of multiple measurements of 3-cylinder cylinder pressure are different, it seems that the problem lies in the 3-cylinder.
    Troubleshooting: Remove the valve compartment cover and observe the 3-cylinder valve without finding the problem. When the camshaft was removed and the problem was found, the 3-cylinder inlet valve was broken and the spring was underneath the valve spring.
    Review: Because this car has been repaired in other repair shop, so I think this spring seat may be installed before the maintenance staff, the purpose is to change the length of the broken valve spring expansion, this maintenance method is not desirable. The valve door valve after the break, affecting the valve stroke, resulting in mixed too thick, resulting in a bad hot car failure.