The electronic engine control system (ECM) consists of a control unit, a whole group of sensors and actuators. At the same time, one of the most important sensors on an injection gasoline or diesel engine is the so-called MAP sensor or DBP sensor (absolute air pressure sensor).

Specified sensor:

• controls the amount of air that enters the cylinders of the power unit; • control is carried out dynamically (taking into account constantly changing loads and engine operating conditions);

At the same time, DBP actively participates in the process of mixture formation. The control unit determines the amount of air and, based on the received data, supplies the required amount of fuel to form the optimal composition of the working mixture of fuel and air. Any failures or malfunctions of the sensor will lead to disruptions in the operation of the motor. Read more in our article.

Absolute pressure sensors: types, design and principle of operation

To understand what DBP is, you should consider the general operating principle of an injection engine. Air enters the intake manifold, after which the control unit needs to calculate how much fuel to supply through the injectors to prepare the optimal air-fuel mixture.

To determine the amount of air, a pressure sensor is installed in the intake manifold at the inlet. In fact, a DBP sensor is needed to measure the current air pressure that enters the intake manifold.

Then the sensor on the manifold transmits information to the ECU, after which the control unit adjusts the amount of fuel, injection timing, etc. In this case, absolute pressure sensors are an analogue of a mass air flow sensor (mass air flow sensor).

Purpose and principle of operation

DBP and DTV

combined in one housing, which is installed on the receiver of the intake module.

DBP output signal

is a DC voltage in the range of 0.15..4.6 V, the value of which depends on the pressure in the inlet pipe. Using this signal, the ECU calculates the amount of air sucked into the intake pipe per cycle.

If a malfunction occurs in the sensor circuit, the ECU stores its code in its memory and turns on the warning light in the instrument cluster. In this case, the control unit calculates the amount of intake air based on the crankshaft speed and the throttle opening angle.

Sensitive elements of DTV

in the inlet pipe there is a thermistor (a resistor that measures resistance depending on temperature)

The output signal of the sensor connected to the control unit is a DC voltage in the range of 0.3...4.9 V, the value of which depends on the temperature of the air passing through the sensor.

If a malfunction occurs in the sensor's electrical circuit, the ECU stores its code in its memory and turns on the warning light in the instrument cluster. In this case, the control unit will replace the sensor readings with a fixed air temperature value (32°C).

Absolute air pressure sensor device

The absolute air pressure sensor measures the absolute air pressure in the intake manifold. In this case, the pressure is measured relative to the “zero” point of low pressure or vacuum. By the way, there are also relative and differential pressure sensors that measure and then compare air pressure with atmospheric pressure.

As for cars, DBPs are actively used today, which are based on a piezoresistive sensing element MEMS (microelectromechanical sensor, MEMS). Such sensors have a sensitive electronic element mounted on a mechanical movable membrane. Thanks to this interaction of electronics and mechanics, the device effectively measures air pressure.

In general, the design of the DBP consists of: 1. a plastic housing to which is attached a pipe for connection to the intake manifold; 2. on the other side of the housing there is an electrical connector for connection to the control unit; 3. There is a sensitive element inside the housing.

In this case, DBP can have different types of sensing element. For example, strain gauges and a sensitive element on a thick-film silicon substrate, where a closed air bubble is formed. Another possible option is a membrane with piezoresistors and a closed volume (volume with reference pressure).

Advantages and disadvantages of absolute pressure and air temperature sensor

First, let's determine what advantages absolute pressure and air temperature sensors have over traditional flow meters. These advantages and disadvantages will allow you to determine what is best to install on your car and whether it makes sense.

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So, let's start with the advantages:

1. The first advantage is the cost of the sensors. For example, for VAZ cars the cost of a mass flow sensor is about three thousand rubles. While DBP and DTV can be purchased in total for about 1,600 rubles.
2. Service life. Problems often occur in the operation of mass air flow sensors - the device fails due to being clogged with dirt, and the sensitive element of the regulator may also wear out. If the mechanism becomes clogged, then, in principle, it can be cleaned, but if the problem lies precisely in the sensitive component, then it is unlikely to be replaced. In any case, the service life of flow meters is always limited. If we take into account temperature and absolute pressure regulators, they are usually installed for the entire life of the vehicle.
3. Installing two regulators instead of one flow meter, as practice shows, allows for smooth idling on camshafts with the so-called “evil” phase, from 290 degrees and above.
4. Excellent responsiveness of the gas pedal when pressed. Car owners who have already switched from mass air flow sensors to regulators note that such a system works faster, without “brakes”.
5. More optimal operation of the power unit after replacement. A correctly installed system quickly calculates the required volume of air flow, accordingly, this will lead to the engine crankshaft spinning much faster. As a result, the power unit will produce higher power.
6. Many car owners, after installing DAT and DTV instead of a flow meter, note that at idle speed the power unit operates much quieter. However, this advantage should not be taken as mandatory, since it depends on the efficiency of the engine, as well as its design features.
7. Installation of such a system is possible on turbocharged engines.

Screenshot of the control unit settings during flashing
These are the main advantages of switching from flow meters to DAT and DTV.

Despite all the advantages, such systems also have certain disadvantages:

1. In cars with factory firmware it will not be possible to install such a system. To implement it you will need special sports firmware.
2. Installing such a system is quite a complicated task, and not every car enthusiast can cope with it. If you belong to the category of car owners who can only fill the expansion tank with washer fluid or change the engine oil, then it is better not to take on this task. If you make mistakes (and without knowledge you will certainly make them), this will lead to a deterioration in engine performance. You will not be able to experience all the benefits of installing DAT and DTV, plus, you will throw away money on the implementation of this scheme.
3. Another point why you shouldn’t take on this activity without specialists is the need to understand the firmware. And not just look at the main parameters or find out the version, but also work with the firmware, changing the values ​​and adjusting the system to your needs. At the very least, you will need a qualified professional to perform this task.
4. Such systems actually do not meet modern toxicity standards. With a big stretch, according to toxicity standards, they can be classified as Euro 3 (the author of the video is the Lty D channel).

Read more: Refilling cylinders with natural gas

Operating principle of the manifold air pressure sensor

Even taking into account the fact that there are certain design differences, among the existing micromechanical sensors, a general operating principle can be distinguished.

Let's look at the most common type:

• There is a sealed volume of air inside the sensor, due to which the reference pressure is formed. This pressure is low (up to 10 times lower than atmospheric pressure). This reference pressure is used to measure the air pressure in the intake manifold. • the sealed volume is closed by a membrane diaphragm on which strain gauges (semiconductor piezoresistors) are installed. As a rule, there are 4 of them, the connection is bridged; • an electrical resistance is formed on the strain gauge, which directly depends on the degree of deformation of the membrane (the resistance changes if the diaphragm is stretched or compressed).

The sensor measures the electrical resistance of piezoresistors, which changes when the diaphragm is deformed due to different pressures between the sealed (closed volume with reference pressure) and the volume with the measured pressure.

The greater the pressure difference, the greater the deformation of the membrane. In turn, the resistance of the piezoresistors changes. Such changes are recorded by the control unit (controller), while various data on current and pressure are registered in the engine operation control algorithms in the ECU.

Instructions for replacing controllers

Let's consider the replacement procedure using VAZ cars as an example. To implement this system, it is important to take into account the requirement for the control unit - it must be version January 5.1 or January 7.2. The second option is more preferable, since you can find free firmware for it, on the basis of which you can make DBP. Versions January 5, as well as Bosch ECUs, are not suitable for this, since they will not be able to function with DBP.

Required tools and materials

To make the transition from mass air flow sensor to DBP, you will need the following elements:

• directly the DBP itself, you can use Gazelevsky (45.3829) or from Volkswagen (Siemens SME 5WK96930-R);
• you will also need DTV, you can use it from Niva, Daewoo Nexia, or take DTOZH for VAZ cars (you will have to modify it a little);
• to install DBP you will need a speed sensor plug;
• To connect the DTV you will need a DTOZH plug.

Photo gallery “Getting ready for installation”

Installation and connection

For the system to work well, you need to install all the elements correctly:

1. The DAT is mounted on the engine panel, since it is very sensitive to vibrations. The controller should be installed with the plug down, this will prevent the accumulation of moisture and condensation inside. The device is connected to the gasoline pressure regulator pipe through a special tee; alternatively, it can be connected to the receiver.
2. The DTV can be installed in the housing of the air filter element, in the pipe next to it, or in the flow meter housing. Securely fix the sensor so that it does not become loose due to engine vibrations.
3. To connect the devices, you will need to run wires from the electronic control unit to the controllers; the wires themselves can be laid through a special hole next to the vacuum brake booster. As for the connection order, for DTV it is not particularly important, but in the case of DAT it is necessary to take into account the pinout, it is marked on the body of the device.
4. Once the devices are installed and connected, it is necessary to flash the control unit, since different parameters will be used to operate these sensors. In the case of VAZ cars, you can use firmware J5LS (J5 Light Sport), J5SPT0005. As stated above, the flashing procedure is a rather difficult and responsible task, so you need to be prepared for this step. If you have doubts that you can do everything correctly, then it is better to entrust this task to specialists.

Read more: Replacing the cabin filter for Skoda Octavia 2013

Sensor on the intake manifold: types and features

Among the existing types of pressure sensors for cars, we can distinguish devices that differ: • in the type of output signal; • compatibility with engine type (atmospheric and turbo engine).

Like many other sensors, DBP comes in analog and digital types. 1. In the case of an analog device, an analog signal is generated from strain gauges, then transmitted to the computer and processed. Such sensors are almost never found on cars due to the fact that a special control unit is required to work with an analog device. 2. Digital DBP has become widespread. The main difference from the analog solution is that a circuit is integrated into the sensor design that independently converts the analog signal into a digital one, after which the finished signal is transmitted to the ECU. Moreover, sensors of this type are compatible with the vast majority of car ECUs.

We also recommend reading the article about what a phase sensor is. From this article you will learn what it is needed for, as well as how the camshaft sensor is designed and works.

T-MAP sensors are also considered a separate option. Such a sensor is a combined solution when a pressure and temperature sensor (thermistor) are combined in one device.

This type of sensor measures not only pressure, but also air temperature, which allows for more accurate measurements and influences the operation of vehicle systems (for example, controlling the intercooler on turbo engines). Let us also add that pressure sensors in a car can be located not only on the engine, but also in other systems (for example, air suspension).

Other Lada Vesta

Products from the Dustershop77 range on the topic of the article:

Faulty manifold sensor: signs

Considering that the intake manifold pressure sensor plays an important role in the operation of the vehicle's ECM, sensor malfunctions lead to serious engine malfunctions in all modes.

As a rule, if the DBP fails, the following signs and symptoms can be identified:

• idle speed is high or floating; • under load the speed “jumps”; • the engine is noisy and smokes; • increased level of vibrations; • there is a smell of fuel in the exhaust; • power decreases and consumption increases.

The appearance of these signs clearly indicates the need to check DBP. If the diagnosis reveals a sensor malfunction, the problem is solved by replacing the absolute pressure sensor.

Video “Visual instructions for installing and connecting DBP and DTV”

The video below provides more detailed and visual instructions for installing and connecting absolute pressure and air temperature sensors using the example of a VAZ 2114 car (the author of the video is Kostay Yakovlev).

The engine does not start the first time; it stalls not only at idle, but also when revving up. The reason is that the mass air flow sensor does not correctly read the amount of air entering the engine and transmits the wrong voltage to the ECU, which, in turn, generates a distorted cyclic voltage to the injectors. The cylinder will receive a rich or lean mixture. The engine will begin to puff, explode, stall, etc. due to overeating or undereating fuel. If the engine actually consumes 50 kg. air per hour, and a faulty mass air flow sensor shows a flow rate of 40 kg/hour, then the ECU calculates the amount of fuel per 40 kg. air, resulting in a lack of fuel. The mixture is poor, the car does not pull, the driver presses on the trigger, and the result is increased fuel consumption.