Mass Air Flow Sensor - Hot Wire - Explained

How does a mass air flow sensor work? What is a MAF sensor? This video explains how a hot wire type mass air flow sensor helps the engine determine how much fuel to inject, by giving a proper reading of the amount of air going into the engine.

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[paulinasdzenkauskas]

The purpose of the mesh in front of the MAF is not to filter particles (air filter does that already). The mesh removes air turbulence thus straightening airflow across the wires for more accurate readings.

[zonedancecrew]

Honestly this helps me in terms of my exam as a mechanic in just a few weeks. You explain it so nicely now i just have to translate it to my own language

[masonlee]

I was going to write you and ask for a video explaining how the mass air flow sensor works. Looks like it's already done!! Thank you for posting this.

[EngineeringExplained]

Great question, and something I should have mentioned. No, carbed engines will not have MAF sensors, the carburetor is designed to create the proper air/fuel ratio. I have a video on carburetors if you're interested.

[EngineeringExplained]

You're measuring the amount of air passing through, the temperature of the air, and the position of the throttle sensor. The air's pressure is going to be relatively even throughout, so by measuring the mass flow rate (the quantity of air that goes by one point will be the same quantity at a later point) you can predict how much fuel is needed.

[EngineeringExplained]

The IAT is used in combination with the MAP sensor. With temperature and pressure, along with RPM, the ECU will know how much fuel to provide.

[EngineeringExplained]

There may be a temperature sensor, or perhaps it is compensated with algorithms defining the density of air based on the temperature of the filament.

[EngineeringExplained]

Sounds cool, good to hear about trying to figure it out on your own. Yeah you have to break down the chemistry and match air with fuel by molecular weight. Perhaps I should do a quick video on that sometime.

[prozzni]

Very nice channel!

Let me just say that the filter that prevents particles, dust, whatever to go through the intake, is the air filter. However,  that "filter" you said is not a filter actually. Its job is to conduct the air through the intake by killing the vortex effect made by the air filter.
Keep going! :)

[EngineeringExplained]

Both are not required, but it may use both to fine tune and have controls check to make sure the proper amount of fuel is injected.

[EngineeringExplained]

Yes. But warmer air would mean the heated element is cooled less, so the ECU would know there's less air, and cooler air would cool it more, so the ECU would know more oxygen is coming in. Also, it would always be possible to have an air temp sensor to verify with.

[osmanaj]

Dude! I had trouble with the MAF in the land rover discovery, i had to sell it, it kept making black smoke, Temporary solution was to reset the computer by removing the battery. Really loved the car.

[EngineeringExplained]

Cooler air means the element cools more, the same effect as having more air pass by.

[EngineeringExplained]

I will have a video on MAP next week. O2, knock perhaps a bit further away. Glad you enjoyed it!

[EngineeringExplained]

Yes, the temperature influences the resistance of the wires in the MAF, and also the engine will likely have an IAT sensor.

[incyphe]

Great job! I think we need more electric cars! these videos make me realize how complicated gas engine cars are!

[uuhamm]

Haha, nice. I had a feeling you might have a video on this. I was looking at the MAF on my car and it didn't seem to be mechanical so I was trying to think of how it would work. This is exactly what I was thinking would work for this.

[MultiJonja]

What do you do for living, what is your major? Keep the vids up pls so interesting!

[EngineeringExplained]

One is sufficient, but they may be used in conjunction with an IAT (intake air temp) sensor.

[-E]

It would be great if you did a video on individual throttle bodys (ITB's) and intake runner length and a video on exhaust and header design. Anyway keep up the good work!