dobrosun писал(а):
После замены ДХХ и регулировки ДПДЗ и положения самой заслонки расход стал на трассе 10,0 а раньше был 7,95 летом. Город по зиме также пугает - 15-16 литров на 100 км.
Правда умельцы мне почистили форсунки, может быть из-за этого произошло увеличение расхода.
Кстати заехал на диагностику, проверили двигатель. Сказали все ОК, кроме состояния ДМРВ, и рекомендуют или заменить или хотя бы промыть спиртом. Утверждают, что именно этот датчик влияет на расход.
Профессионалы, что посоветуете насчёт промывания спиртом ДМРВ? Насколько это криминально?
Я не профессионал, но ДМРВ мыл. Изопропилом. Никакого изменения не произошло. Мыть надо аккуратно. Если у тебя не сетка а нити, то мыть вроде и не надо - там в момент запуска двигателя на нить продаётся высокое и всё гуано сгорает
The Mass Air Flow Sensor is probably the best way to measure the amount of air an engine takes in (engine load). This sensor not only measures the volume of air but also compensates for its density as well. Ford, GM, and many imports are using engine control systems based around this sensor.
There are two common designs of MAF sensors used in today's vehicles. One produces a variable voltage output (analog) and the other produces a frequency output (digital). In either case their operation is similar. Both outputs can be measured by a scanner or a digital volt/ohm meter (dvom) that can measure frequency.
Both designs work on the "hot wire" principle. Here's how they work. A constant voltage is applied to the heated film or heated wire. This film or wire is positioned in the air stream or in an air flow sampling channel and is heated by the electrical current that the voltage produces. As air flows across it, it cools down. The heated wire or film is a positive temperature coefficient (ptc) resistor. This means that it's resistance drops when it's temperature drops. The drop in resistance allows more current to flow through it in order to maintain the programmed temperature. This current is changed to a frequency or a voltage which is sent to the computer and interpreted as air flow. Adjustments for air temperature and humidity are taken into consideration since they also affect the temperature of the heated wire or film.
GM (Bosch) Hot Wire MAF Sensor
Humidity always affects the density of air since humid air is denser than dry air. No other compensation is therefore needed for this factor. Air temperature affects density since colder air is more dense than warmer air. Many systems use an air temperature sensor to compensate for this factor since similar amounts of air can enter an engine at different temperatures. Some MAF sensors use an internal "cold" wire to send ambient temperature information to the computer. Some use an intake air temperature sensor in the manifold or the intake piping. This sensor is almost always ntc in design (negative temperature coefficient). That is, it's resistance goes up as air temperature goes down. This "thermistor" works just like a coolant temperature sensor and usually has identical resistance to temperature values. By the way, these values are very different from manufacturer to manufacturer and are available in most repair manuals. They are also programmed into scanner software.
In a hot-wire MAF, a platinum wire is heated 212 degrees F above the incoming air temperature. In a hot-film MAF, a foil grid is heated 167 degrees F above ambient air temperature.
The output signal produced by the MAF sensor varies according to the application. The hot-wire Bosch MAF sensors, which are found on some import cars with LHJetronic fuel injection dating back to 1979
as well as 1985-89 GM 5.0L and 5.7L Tuned Port Injection (TPI) engines,
generate an analog voltage signal that varies from 0 to 5 volts. Output at idle is usually 0.4 to 0.8 volts increasing up to 4.5 to 5.0 volts at wide-open throttle.
The hot-film MAFs, which AC Rochester introduced in 1984 on the Buick turbo 3.8L V6 and were also used on Chevrolet 2.8L
engines and GM 3.0L and 3.8L V6 engines, produce a square-wave variable frequency output. The frequency range varies from 32
to 150 Hz, with 32 Hz being average for idle and 150 Hz for wide-open throttle. In 1990, GM switched most of its engines back to
speed-density fuel injection systems, except for the Buick 3.3L and 3.8L which changed to a Hitachi MAF sensor.
Another difference between the hot-wire and hot-film sensors is that the Bosch hot-wire units have a self-cleaning cycle where the
platinum wire is heated to 1,000 degrees C (1,832 F) for one second after the engine is shut down. The momentary surge in current is controlled by the onboard computer through a relay to burn off contaminants
that might otherwise foul the wire and interfere with the sensor’s ability to read incoming air mass accurately.
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