What is the intake pressure range of a general automobile engine?

The normal value of engine intake manifold vacuum is between 64-7 1 kPa.

If a cylinder is not working properly, it can be diagnosed by single cylinder flameout. After the single cylinder is turned off, the greater the drop value of Px, the better. This is an index to judge the quality of each cylinder (ignition, fuel injection and sealing). Quickly open and close the throttle. If the pointer swings sensitively between 6.7-84.6 kPa, it shows that Px has good following performance to the change of throttle opening, that is to say, the sealing performance of all parts is good under all working conditions.

If the seal is not good, Px is lower than normal at idle speed, which is obviously unstable. When the throttle is opened quickly, the pointer will drop to zero, and the pointer will not return to 84.6kPa after the throttle is closed. In order to verify the tightness of each cylinder, the vacuum gauge should be replaced at the hole of the dipstick, and the pressure measured in the crankcase should be negative pressure; If it is positive, it means that the sealing is not good, or the PVC is not well ventilated.

Extended data

Among the structural parameters of intake manifold, the length of intake manifold is the main structural parameter that determines the influence of fluctuation effect on intake. In order to ensure the use of fluctuation effect, the volume of the pressure stabilizing cavity should be as large as possible. The influence of the main parameters of the intake pipe on the intake performance of the engine can be summarized as follows:

1, intake pipe diameter, determines the total intake volume, according to the throttle diameter.

2. The diameter of the intake manifold determines the air intake of each cylinder, and the air intake is determined according to the air intake diameter of the intake port.

3. The length of the intake manifold affects the dynamic effect. In the optimization calculation of intake pipe, it is optimized as a target parameter.

4. The volume of the voltage stabilizing cavity affects the wave (resonance) effect. Proper volume of the pressure stabilizing cavity can not only improve the charging efficiency by using the fluctuation effect, but also make the pressure environment in the pressure stabilizing cavity relatively stable, which provides a good condition for using the dynamic effect, eliminates the mutual interference of the intake of each cylinder and improves the intake uniformity.

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