Relationship between intake pressure and actual intake air volume

The intake pressure is proportional to the actual intake volume, and the greater the intake pressure, the greater the actual intake volume.

After the engine works, the intake manifold pressure (the pressure behind the throttle) will be lower than the atmospheric pressure due to the suction force generated by the downward movement of the piston in the intake stroke. Generally, the atmospheric pressure belongs to 10 1Kpa or 10 13hpa (hectopascals, indicating that BMW diagnostic system uses this unit).

The intake manifold pressure of 70Kpa actually refers to the absolute pressure, that is, it is higher than the absolute zero pressure with reference to the absolute zero pressure, so the intake manifold pressure is more accurate, that is, the intake manifold absolute pressure. The greater the intake manifold suction, the greater the vacuum, that is, the smaller the intake pipe pressure (at this time, the intake manifold suction is opposite to the suction).

Introducing intake pressure;

When the car is idling, the intake pressure is generally between 27 and 30 kPa. If the intake sensor is broken and the computer can't receive the intake air, it will cause the mixture to be too rich and too thin, which will lead to black smoke, incomplete combustion and even the explosion of the exhaust pipe.

Too thin mixture will lead to insufficient fuel, backfire, insufficient power, weak acceleration and even difficult start-up. Both wiring harness connection problems and sensor failures will lead to this failure, and only by checking the intake pressure and temperature sensors can the problem be effectively solved.