What is an Air Flow sensor (MAF)? What does the MAF sensor do? What are the MAF sensor malfunction codes and symptoms? How to clean MAF sensor ?….
Two types of Mass Air Flow Sensors are used in multipoint injection systems. They are hot wire and hot films. Although their designs are slightly different, both types measure the volume of air entering an engine. The on-board computer calculates the best mixture of fuel and air to optimize engine performance.
The mass flow sensor is free from moving parts. The MAF sensor measures airflow using electrical current, unlike bladed airflow sensors. The grid sensing element is either a hot wire of platinum or a foil of nickel and is heated to a specified temperature to measure the airflow mass. (Hot film sensors are up to 75 °C above ambient temperature, and hot wire sensors are up to 100 °C above ambient temperature) To keep the air warm, the resistance is increased and then cooled. The temperature, humidity, and density of the air entering an engine are directly related to the cooling of the film resistor. Its heating is directly proportional its mass. The engine’s speed will increase, so the air intake will also increase. To heat the air, more current is sent through the flow meter. The engine calculates the mass of the air entering it due to these changes.
The PCM calculates fuel amount to be sent to injectors using the engine’s air mass and adjusts timing. The injectors’ open time will increase as the intake of air increases. This calculation ensures that the engine performs better by setting the ideal fuel/air mixture.
Fault codes and symptoms of air flow sensor fault
Even if the MAF sensor goes out, the engine will continue to run. You may have difficulties stopping the engine from starting. Under excessive load, misfires and idling fluctuations may occur. The air/fuel mixture is either rich or lean, which can lead to excessive fuel consumption. When the throttle position is changed, the engine might shake.
A faulty or dirty MAF sensor can cause a fault code and the check engine lamp to go on. Airflow changes are delayed by a dirty sensor. The PCM will believe that the airflow has dropped, and shut down injectors. This causes the engine to run with a lean mixture.
OBD II vehicles have data from the MAF sensor compared with the throttle position sensor or MAP sensor. The engine speed can then be calculated. This information can be viewed using a diagnostic instrument. You can compare these values to determine if there are any problems at high and idle. There is an issue with one of the sensors if it doesn’t change or reads incorrectly.
One or more of these codes may be displayed if the MAF sensor fails to function properly.
P0100… Malfunction in the Mass Air Flow Circuit
P0101… Mass Air Flow Circuit Limit/Performance Issue
P0102… Low Input Mass Air Flow
P0103… High Input Mass Air Flow
P0104… Mass Air Flow Circuit Range
P0171… System Too Lean (Bank 1)
P0172… System Too Rich (Bank 1)
P0173… Fuel Trim Malfunction (Bank 2)
P0174… System Too Lean (Bank 2)
P0175… System Too Poor (Bank 2)
Ford Pre-OBD II: Code 26 – MAF out of range, Code 56 – MAF output too high, Code 66 – MAF output too low, and Code 76 — No MAF change during the “goose” test.
You should not ignore engine compression, vacuum fuel pressure, ignition problems. Similar symptoms may be seen in other areas.
Troubleshooting Mass Air Flow Sensor
It is not possible to determine if the MAF sensors are working properly without looking at their output or how it affects injector timing.
The output voltage can be directly read by a digital voltmeter using Bosch’s hot-wire sensors. The sensor should be replaced if it is out of range or increases in voltage when the throttle is open while the engine is running. Dirty wires may slow down the sensor’s response to changes of airflow. A damaged, burnt or crushed wire can completely disable the sensor. The MAF sensor is powered by a pair relays, one for power and the other for the combustion clean cycle. First check the relays if the MAF sensor seems to be defective.
There are a few things you can do to check for vibration-related problems with GM MAF sensor sensors. Connect an analog voltagemeter to the MAF sensor output terminal. When the engine is running, the sensor output should remain constant at 2.5 volts. Pay attention to the meter reading by tapping the sensor. The sensor should not show any change if it is properly working. The sensor must be replaced if the analog needle jumps or the engine stalls for a moment. To check for temperature-related issues, heat the sensor using a hair dryer.
A frequency-reading measuring device can also be used to perform the same test. AC Delco legacy MAF sensors (like 2.8L V6) should display steady values between 30-50 Hz at idle, 70 to 75 Hz when running at 3,500 RPM, and between 30-50 Hz and 50 Hz when it is active. The 3800 V6 and later models should display 2.9 kHz idle and 5.0 KHz at 3,500 RPM. A new MAF sensor should be installed if there is a sudden shift in frequency signal when the sensor is touched.
The MAF sensor can also be checked by looking at the effect it has on injector timing. Connect a millisecond oscilloscope, multimeter instrument to injector ground. The supply voltage is controlled by one terminal, while the timing is controlled by the other. Next, look at the duration and speed of the pulses when the engine is idle. The injector timing will vary depending on the application. The timing of the injectors will vary depending on the application. However, if the sensor does not produce a signal, the fuel mixture may become more rich and the injector timing will take approximately four times longer. You can check this by checking the millisecond values for the injectors under acceleration and deceleration. Under light load cruising, the injector timing should not exceed 2.5 to2.8 Ms.
How do you clean the MAF Sensor?
MAF sensor problems can be a problem in Ford vehicles especially if there is contamination. In certain cases, the air filter may fail to do its job properly and polluted air could clog the sensor wire. Carbon contamination can also be caused by fuel vapors. In either case, the sensor becomes dirty and the MAF sensor begins to malfunction. It typically generates a fault code of P0171 and P0174.
This problem can be corrected by cleaning the sensor with aerosol electronic cleaner sprays. The MAF sensor is located between your throttle body and the filter. Spray the electronic cleaner. Let it sit for approximately 10 minutes before you repeat. You should not use any other cleaner, as it can damage the sensor. You should not touch the sensor by wiping it with a cloth. If you do, the sensor might be damaged.
