发动机在运转过程中,进气歧管内会产生一定的真空度,如果该数值符合标准且比较稳定,反映到发动机工作中就是平稳、有力及加速性良好。当气缸的密封性能下降,进、排气管路泄漏或堵塞,点火性能不良,空燃比控制失常等原因引起发动机工作性能下降时,进气歧管内的真空度就会发生变化。在发动机运转过程中对进气歧管内的真空度进行准确 Engine during operation, the intake manifold will produce a certain degree of vacuum, if the value of the standard and relatively stable, reflected in the engine work is smooth, powerful and acceleration is good. When the sealing performance of the cylinder is decreased, the intake and exhaust lines are leaking or clogged, the ignition performance is poor, and the air-fuel ratio control is abnormal, the performance of the engine is degraded, the degree of vacuum in the intake manifold changes. During the operation of the engine, the degree of vacuum in the intake manifold is accurate