Air flow sensor shall determine the amount of air consumed by the engine.Based on the data obtained from the device, the engine control unit calculates the amount of fuel injected into the cylinders.
Possible "symptoms" malfunctioning of the flowmeter:
- engine "does not hold" idle speed.
- increases fuel consumption.
- turbine connected untimely or not connected at all.
- engine speed can be limited to 3000 per minute.
- possible speed limit.For example, the machine may be more or less active gain speed to 100 km / h, after which the acceleration stops or becomes very slow.
- machine significantly loses power.
Check the air flow sensor is made by means of special equipment - compressor and an oscilloscope.There is a forced flow of the air flow sensor and the tracking signal range.It is also determined by the time during which the heating foil warms up on the sensor.
When checking the output in the first measured time it takes to transition process at the time of switching on the ignition.In the case where the air flow sensor is serviceable, the resulting value will not exceed a few milliseconds.To increase the heating time of the sensor can cause pollution, which are deposited on the sensor.In this case, the transition process may take tens or hundreds of milliseconds.Further
measured voltage value when an air flow equal to zero.To test requires that the engine has been stopped, but the ignition must be included.Average value of the output voltage in the presence of a zero air flow may be different and depends on the air flow sensor which model set.
Then measured maximum voltage during sudden peregazovki.The motor of the machine should be at operating temperature and the transmission is in neutral.While checking the throttle is opened sharply at a time that does not exceed a second.This check is possible only for atmospheric engines (without the compressor and the turbine) and, if the accelerator pedal is mechanically coupled to the throttle valve (via levers or cable).
When the engine is running at no load at idle, the air in the intake manifold, is weak.If the air flow sensor is normal, the voltage should in the short term to exceed the mark of 4V.If the sensor is very dirty, the sensor can react more.This ostsilogrammy "smoothed".Due to contamination and reduced heating current signal of the sensor, which leads to a decrease in supply of fuel to the cylinders.Therefore, when a sharp peregazovke voltage sensor signal does not have time to reach the maximum.
If you were diagnosed with a serious malfunction of the device, you should replace it.Repair the MAF sensor is not done.
