Basic test method of vacuum degree of intake pipe

(1) Start the engine to reach normal operating temperature; 

(2) then place the gear lever in neutral idle the engine. 

(3) find the vacuum test hole of the intake system specially set behind the throttle valve, connect the vacuum gauge there (if there is no such test hole, remove the vacuum pipe on the intake manifold connect the vacuum gauge with a three-way connection), then the test can be carried out.

The influence of the abnormal vacuum of the intake pipe on the automatic control system

Because the vacuum degree of the intake pipe means the speed load of the engine, the change of the vacuum degree of the intake pipe means the speed load of the engine have changed. Therefore, in the electronic control vehicle, the negative pressure is The engine intake pipe is used as power source, widely used in actuators other devices of electronic control system, such as diaphragm to pressure sensor of intake manifold, fuel pressure regulator, positive ventilation system of crankcase, fuel vapor recovery system, exhaust gas recirculation system, vacuum actuator vacuum booster of cruise control system, used in brake system. If the vacuum of the intake pipe is abnormal, the normal operation of the above system will be seriously affected.