The mass air flow sensor can be of various types. The most popular include ultrasound, mechanical (weathervane type), hot-wire and others.
The VAZ mass air flow sensor (hot-wire type) includes a sensing element. It is presented in the form of a thin film. On it are temperature sensors, a resistor (heating). In the center of the film is a heating section, the temperature level of which is controlled by a temperature device. From the side of the air flow and symmetrically from the opposite side, 2 more temperature sensors are located on the film surface. They in the absence of flow show the same temperature. When air appears, the first sensor cools. In this case, the temperature of the second device is practically unchanged. This is due to the heating of the flow in the heating zone. A differential signal is supplied from the sensors, which is proportional to the mass of the passing air stream. According to the electronic circuit, the signal is converted to direct voltage. It is proportional to the mass of air. This design is called Hot Film. The advantages of this device are the ability to accurately measure air flow, as well as register the reverse flow. Among the shortcomings, experts note low reliability in case of moisture or contamination of the device.
In previously used systems, the mass air flow sensor included a sensing element made in the form of a thread. The output signal had a certain frequency. In other words, when the air flow rate, the pulse frequency changed, not the voltage. Such a mass air flow sensor was not very accurate, and it was not possible to register the reverse air flow. However, these shortcomings were offset by its high reliability.
The mass air flow sensor is a very important part of any control system. The incoming signal from it starts the process of calculating the cyclic filling of the cylinder, which is eventually converted to the pulse duration when the nozzles are opened.
It should be said that various types of sensors were installed on VAZ cars: SIEMENS, BOSCH, Russian-made and GM. From 1999 to 2004, two types of devices were installed on conveyors - 004 and 037. They show different indicators of output voltage (calibration) at the same flow rate. Replacing the first with the second is possible only when replacing the calibration tables in the firmware. The same applies to the new 116 sensor, which was installed in 2005 in series. According to the current documentation, three modifications are allowed on the conveyor.
The first (historically) sensor 004 was used in projects with four calibrations. The first 2 projects can be easily determined by external parameters, since they are not equipped with a neutralizer and they use a resonant detonation device. From a certain moment, the first two projects ceased to be carried out, and the projects with the other two calibrations were equipped with 037 sensors. This modification differs from the first by a modified internal channel. This refinement made it possible to eliminate the pulsations of the air flow, which were formed earlier with a laminar flow in the intake manifold.
Since 2005, the serial use of sensor 116 has begun. The modification was intended for projects with the latest generation Bosch and January controllers (Russian counterparts).
The sensor is supplied exclusively assembled with a code. There is a green circle marking. The design of the element itself, compared with previous modifications, has been changed. Unidirectional bolts are used to secure the sensor in the housing.