1. The intake manifold works
In naturally aspirated engine, since the intake manifold after the throttle valve is located, so when engine throttle opening hours, a sufficient amount of air can not be sucked into the cylinder will cause the manifold vacuum is high; and when the engine throttle opening degree is large, the degree of vacuum in the intake manifold becomes small. Thus, the injection engines will supply a pressure gauge mounted on the intake manifold, the engine ECU determines that the load is supplied, and the fuel injection amount administered.