Measuring the correct dose of fuel delivered by the controller is conditioned by the proper operation of the flow meter (MAF). The latter, more precisely, its sensor, however, is damaged as a result of the impact of pollution, as well as mechanical factors such as vibrations or sudden impact, e.g. during a collision.
MAF – how does it work?
As has already been said, the task of flow meters, which have been used in cars for almost half a century, is to measure the mass of air supplied to the engine intake duct, and then transfer this result of the bus, within which the engine controller (ECU) operates. This is very important, because thanks to the work of the flow meter (specifically its sensor) it is possible to precisely measure the dose of injected fuel, and thus to create conditions for optimal combustion of the fuel-air mixture. Consequently, the emission of exhaust gases into the atmosphere is reduced, as well as the amount of fuel burned.
What breaks down and how to notice it?
According to experts, the most common cause of flowmeter damage are various types of pollution sucked in with the air inside and deposited on the sensors. Mechanical failures, such as excessive engine vibration or sudden events associated with strong impacts, e.g. during a collision or accident, are often responsible for the failures. Potential damage to the flowmeter sensor may be manifested in the form of uneven operation of the drive unit at idle or its sudden stalling. The resulting failure is also evidenced by the ignition of the engine control light, a decrease in power during acceleration, excessive vibration during standstill or automatic changes in engine revolutions (from high to low, sometimes vice versa). To get 100% certainty that the flowmeter sensor has just been damaged, you should perform its detailed diagnostics using a diagnostic tester that detects an error recorded by the engine controller. With its help, among others, sensor connector, supply voltage with the ignition on (the correct voltage should be between 7.5 and 14 V) and the output voltage with its frequency during engine operation. In this case, the correct voltage is 0-5 V, and the frequency is 0-12000 Hz. It is also important to check the wires between the controller connector and the sensor connector. Correct resistance is … no resistance, i.e. 0 ohms.
Which flow meters should be used?
Experts advise to choose devices from reputable brands. In their opinion, we will then receive a guarantee of their correct and trouble-free operation. What should we pay attention to when buying a flow meter? First of all, we must determine whether to buy a complete flowmeter with the sensor or just the sensor itself. A good flow meter should meet the requirements of the OE specification for resistance to interference, ensure precise measurement of the temperature of the mass of flowing air (in the range from – 30 to + 70 ° C). We should also pay attention to whether the flow meter recommended to us has a double heating element. This is important because this solution allows it to work much more efficiently, and thus reduces fuel consumption and harmful emissions. A good flow meter should also have a quick response to changing engine operating conditions, and also have advanced diagnostics, including with direct reading of real data from the device and its re-adaptation. Generally, the new flowmeter should provide comparable (or identical) readings and output signal to the factory-fitted device. Only then will an adequate dose of air supplied to the engine intake duct be ensured, and consequently the fuel fed, which will translate into proper operation of the power unit.