What is a Mass Flow Sensor?

Mass Flow Sensor:

A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow of air entering a fuel-injected combustion engine.

The atmosphere information is important for the engine control unit (ECU) to balance and deliver the right fuel mass to the engine. Air changes its density with temperature and pressure. In automotive applications, air density varies with the ambient temperature, altitude, and therefore the use of forced induction, which suggests that mass flow sensors are more appropriate than volumetric flow sensors for determining the number of intake air in each cylinder.

There are two common styles of mass airflow sensors in use on automotive engines. These are the vane meter and therefore the hot wire. Neither design employs technology that measures the atmosphere directly. However, with additional sensors and inputs, an engine’s ECU can determine the mass flow of the intake air.

Both approaches are used almost exclusively on electronic fuel injection system (EFI) engines. Both sensor designs output a 0.0–5.0 volt or pulse-width modulation (PWM) signal that’s proportional to the atmospheric state rate, and both sensors have an intake air temperature (IAT) sensor incorporated into their housings for many post-on-board diagnostics (OBDII) vehicles. Vehicles before 1996 could have MAF without an IAT. An example is the 1994 Infiniti Q45.

When a MAF sensor is employed in conjunction with an oxygen sensor, the engine’s air/fuel ratio may be controlled very accurately. The MAF sensor provides the open-loop controller predicted airflow information (the measured airflow) to the ECU, and also the oxygen sensor provides closed-loop feedback so as to create minor corrections to the expected atmospheric state. Also, see the manifold absolute pressure sensor (MAP sensor).

How to Diagnose a Bad Mass Air Flow Sensor?

Diagnose a foul Mass Air Flow Sensor:

A wide range of problems can mimic a foul MAF (Mass Air Flow) sensor, so it’s a decent idea to check a suspected sensor before you sally out and buy a brand new one.

Before getting started, however, you’ll want to possess the vehicle’s repair information handy. Manuals, like those from Chilton, are good, You’ll be able to find more information on accessing quality repair information in repair manuals.

Step 1. Check for Diagnostic Trouble Codes (DTCs):

If the check engine light is on, you’ll need to retrieve the corresponding diagnostic trouble codes employing a scan tool or code reader. These days, you’ll be able to even get a reasonable code reader for your smartphone.

Is there a MAF-related DTC stored within the PCM’s memory? Then there is also a problem with the MAF sensor or its circuit. As was mentioned, air/fuel ratio and misfire codes might also point to a problem with the MAF sensor (though, there are many other possibilities, as well).

Keep in mind: Sometimes, a nasty or bad (faulty) MAF sensor won’t set a code, especially on older vehicles with a kind of self-diagnostics called OBD-1.

Step 2. Perform a visible Inspection:

Next, you’ll be able to progress to performing a visible inspection. You’ll want to seem for issues, like damaged wires and poor connections. confirm that the MAF sensor’s electrical connector is clean and tight.

Repair any issues found in the visual inspection, clear the DTCs, and see whether the matter returns.

Step 3. Test the MAF Sensor:

Testing a MAF sensor will be tricky. Hotwire sensors output an analog voltage signal, while hot film sensors create a square wave digital frequency pattern.

It’s important to understand what kind of sensor you have⁠—and you ought to always consult the factory repair information before testing.

How to Clean a Dirty Mass Airflow Sensor?

Cleaning a Dirty Mass Airflow Sensor:

Generally, you will need to scrub your mass airflow sensor either every six months or anytime you alter your oil. Cleaning is after you change or clean your filter is going to be a great way to saving both time and money.

Remove the Sensor:

To clean your mass airflow sensor, first, you need to take it out. This can be done by opening your vehicle’s airbox and employing a flathead screwdriver to pluck it out. When removing the sensor, make certain to never touch the wires. A disconnected mass airflow sensor can’t electrocute you, but the wires are delicate and tiny. Breaking one would require a replacement, which might run upwards of $100, so it is best to take care.

Clean the Sensor:

Next, you’ve got two choices. The most affordable option would be to require your mass airflow sensor and place it during a bag crammed with the application. Take the bag and move it around, ensuring the alcohol washes all of the dirt and dirt from the sensor. An alternative choice would be to travel to your local auto parts store and buy a special mass airflow sensor cleaner and spray it onto your sensor, but as stated before, this can be costlier.

Dry and Reinstall the Sensor:

After cleaning your mass airflow sensor with either the cleaner or application, let it sit, generally for 20 minutes or more. The sensor needs to be completely dry before it is reinstalled in your car, otherwise, you will damage it. Replace it and that is all.

How to replace a faulty MAF sensor?

Replacing a Faulty MAF Sensor:

If you’ve identified that the MAF sensor is faulty and needs to be replaced, it’s best practice to follow these simple steps:

1. To begin, connect a diagnostic tool to your vehicle. Select the right make, model, year, and engine code of the vehicle you’re acting on. Record the fault codes, and check the live data parameters for the MAF sensor. Then exit the diagnostic software and flip the ignition.
2. You’ll also have to check the feeds, ground, and wiring. Connect the oscilloscope. Ideally, an occasion out lead should be wont to prevent puncturing the wiring’s insulation and causing a future wiring issue. To induce a reading, snap the throttle open, and observe the pattern.
3. Once it’s determined that the MAF sensor is faulty, you’ll have to replace it. Remove the connector and so the fastening screws. Next, remove the sensor from its housing.
4. Inspect the flow tube to make sure there are not any cracks within the plastic housing. If there are, you’ll have to replace the whole unit – not just the probe. If the flow tube is crack-free, then you’re alright to replace the sensor probe only.
5. Remember it’s important to handle the sensor connector only. Never touch the electronics as this could damage the sensor probe.
6. Carefully slide the new sensor probe into the flow tube, then tighten the fasteners and replace the connector.
7. Reconnect the diagnostic kit and delete any fault code(s). Run the engine, and recheck for any new fault codes. Exit the diagnostic software and cut the ignition. Finally, make certain the check engine light has been extinguished, then perform a test.

Why do MAF Sensors Fail?

Reason Why MAF Sensors Fail:

Since the MAF sensor is liable for measuring airflow into the engine, they need plenty of air passing through it. In fact, quite 9000 liters of air can flow through the engine for each liter of fuel used. That’s plenty of air! And thereupon comes the potential for plenty of contamination. Dust, dirt, and other debris can all get into the sensor and are one of all the first causes of MAF failure.

Such contamination could occur as early as 18,000-25,000 miles, counting on the vehicle model. On small or compact cars, for instance, the MAF sensor can clog quicker, because it is situated during a smaller engine bay subjected to more risk in critical areas (oil vapor flows and combustion debris). During this case, a replacement becomes the equivalent of a protracted drain oil service… it almost becomes a service-style repair.

Other common failure problems include:

1. A contact fault at the electrical connections
2. Damaged measuring elements
3. Mechanical damage from vibrations or an accident
4. Measuring element drift (exceeding the measuring framework)

Look out for these in a failing MAF sensor:

When a MAF sensor fails, the engine won’t know the correct amount of fuel to feature, causing several common signs:

1. Check engine light: like most engine management components, a controversy with the MAF sensor often causes the check engine light to return on.
2. Engine runs rich at idle or lean under load: this is typically pointing towards a contaminated hot wire.
3. Engine runs rich or lean: caused by the MAF continuously misreporting airflow into the engine – a process is required to substantiate this.
4. Rough idle or stalls: a failed MAF sensor won’t send any airflow information to the ECU preventing it from accurately controlling fuel.
5. Excessive vibrations when stationary.
6. RPMs changing noticeably without driver input.

What is VAF?

Volume Air Flow:

The VAF (volume airflow) sensor measures the airflow into the engine with a spring-loaded air vane (flap/door) attached to a rheostat (potentiometer). The vane moves in proportion to the airflow. A voltage is applied to the potentiometer and a voltage appears on the output terminal of the potentiometer proportional to the angle the vane rotates, or the movement of the vane may directly regulate the number of fuel injected, as within the K-Jetronic system. Many VAF sensors have an air-fuel adjustment screw, which opens or closes a little duct on the side of the VAF sensor. This screw controls the air-fuel mixture by letting a metered amount of airflow past the air flap, thereby leaning or richening the mixture. By turning the screw clockwise the mixture is enriched and counterclockwise the mixture is leaned. The vane moves thanks to the drag force of the airflow against it; it doesn’t measure volume or mass directly. The drag force depends on air density (air density, in turn, depends on air temperature), air velocity, and also the shape of the vane, see drag equation. Some VAF sensors include a further intake air temperature sensor (IAT sensor) to permit the engine’s ECU to calculate the density of the air, and also the fuel delivery accordingly. The vane meter approach has some drawbacks:

1. it restricts airflow which limits engine output
2. its moving electrical or mechanical contacts can wear
3. finding an acceptable mounting location within a confined engine compartment is problematic
4. the vane has got to be oriented with relation to gravity.
5. in some manufacturers, fuel pump control was also a part of the VAF internal wiring

If you are looking to buy Used Cars, Machinery, Bus, Trucks, Parts from Japan. We provide high-quality used vehicles directly from Japan.
Please visit our website: www.japanesecartrade.com
Check more useful blog pages: blog.japanesecartrade.com/blog