Hello Everyone and Welcome in This Video: Explanation of Mass Airflow Sensor (Vein Type)

I'm going to be explaining another type of mass airflow sensor, which is actually more of a mechanical system rather than the hot wire. If you haven't already watched my video on the hot wire mass airflow sensor, I would recommend watching that first because this is a bit older technology and I don't believe it's used much anymore. However, I'll still explain why it was phased out.

Mass Airflow Sensor Vein Type: A Mechanical System

The main difference between this vein type mass airflow sensor and the hot wire type is that it's actually more of a mechanical system. This means that there are no wires to heat up or cool down when air passes through them, which makes it less reliable than the hot wire system.

The Vein Type Sensor: How It Works

So, what's happening is that as you open up your throttle, this mass airflow sensor will be right behind your air filter and ahead of the throttle body in the order of operations. As you open up the throttle, more air will come in, and that air will push on this flap and open it up. If you can't really visualize this, just think of a box with a flap in it – as the air goes in, it pushes that flap up.

The Flap: A Position Sensor

This flap is connected to a position sensor, which is actually a potentiometer. When the flap moves up, the potentiometer changes its resistance, and this change in resistance is what the ECU (Engine Control Unit) uses to determine how much air is coming into the engine. The ECU will take the altered resistance and turn it into a voltage reading.

The Voltage Reading: How It's Used

Using the voltage reading, the ECU can then determine that this is how much air is coming into the engine – and therefore how much fuel needs to be injected. There's one small problem with this system, however: if you just base it on cold air having more oxygen in it (which it does), then the mass airflow sensor will give a false reading. This means that another thing has to be added to the system as an air temperature sensor.

The Air Temperature Sensor

To fix this issue, an air temperature sensor is needed to measure the actual air temperature and adjust the readings accordingly. By using the voltage change from the position sensor in combination with the air temperature sensor, you can get a more accurate reading of how much air is coming into the engine – and therefore how much fuel needs to be injected.

The Check: The O2 Sensor

As an additional check, there's also an oxygen sensor (O2 sensor) located in the exhaust system. This sensor will back up the ECU's readings and ensure that the engine isn't burning lean or rich. By using all of these sensors together, you can get a very accurate reading of how much air is coming into the engine.

Why the Vein Type Mass Airflow Sensor Isn't Recommended

There are several reasons why this mass airflow sensor type isn't recommended. First and foremost, it's a mechanical system – which means that there are moving parts and potential for wear and tear. Accelerated acceleration forces can also affect this flat, causing it to rotate up when you slam on the brakes. This is what makes the ECU think there's more air coming into the engine when really there isn't.

Gravity Also Affects It

Gravity will also always be pulling down on this flap, which means that even if you calibrate the system to make up for it, there may still be inaccuracies in the readings. This is why this type of mass airflow sensor has largely been phased out – it's just not reliable enough.

The Dampening Flap: A Smoother Motion

One thing I didn't mention earlier is the dampening flap. This little chamber is located right next to the flap, and there's a small gap between them. As the flap rotates, air will be squeezed into this chamber, which in turn will want to come out of that small gap. What this does is slow down the movement of the flap – it doesn't just sit there and go real quickly anymore; instead, it provides a smoother motion.

Location: Where It Will Be Located

Finally, I'll show you where this mass airflow sensor would be located on my car. As with the hot wire type sensor, it will be directly behind the air filter and ahead of the throttle body in the order of operations.

"WEBVTTKind: captionsLanguage: enhello everyone and welcome in this video i'm going to be explaining another type of mass airflow sensor so if you haven't already watched my video on the hot wire mass airflow sensor i would recommend watching that first that's a little bit later technology than this this is a bit older i don't believe this is used much anymore but anyways mass airflow sensor vein type so the difference with this is it's actually more of a mechanical system rather than the hot wire and i'll explain why that's a disadvantage and why it was phased out so what's happening is as you open up your throttle this is going to be right behind your air filter so it's going to be ahead of the throttle body in the order of operations here so as you open up the throttle which will be downstream more air will come in and as that air comes in it's going to push on this flap and open it up so if you can't really visualize this just think of like a box with a flap in it and as the air goes in it pushes that flap up so as that flat moves up this flap is connected to a position sensor so that position sensor is a potentiometer which changes its resistance while this flap opens so with a different position so since you have a different resistance what's what the ecu is going to do with that is going to see okay the flat moved and it altered the resistance so it's going to take that altered resistance and turn that into a voltage reading and using a voltage reading it can then determine okay this is how much air is coming in i need to inject this much fuel now there's a small problem that if you just uh base it on this cold air has more oxygen in it it's denser than hot air so another thing you have to add on to this as an air temperature sensor so these you can use this in combination with the voltage change to know the right amount of air to put into the engine or i'm sorry fuel to put into the engine to have a good ratio of air and fuel now as a check you've got the o2 sensor which is in the exhaust and so that will back up the ecu's reading and make sure okay there isn't uh there is too much oxygen or it's burning lean or uh burning rich so that'll be the check and i can explain an o2 sensor in a future video now why would this mass airflow sensor not be a good idea to use well there's a big disadvantage of it and the fact that it's a mechanical system accelerated acceleration forces affect this flat so say this is oriented so that the front of your car is here and the back of your car is here well if you slam on the brakes this flap is going to want to rotate up now when that flap rotates up your ecu is thinking okay there's more air going into the engine when really you're braking so then it'll inject more fuel you don't want that to happen also gravity is going to affect this so there's always going to be gravity pulling down on this flap now of course you're going to calibrate it to make up for that but think about it when you're on a banked uh curve i mean gravity is going to be slightly less in the direction that you calibrated it for so it can affect the readings and that's why this has been phased out really one thing i didn't mention this dampening flap so what this does is you've got this little chamber in here and there's a small gap between this flap and this wall here so as this flap rotates you've got air in here and that air is going to be squeezed and it's going to want to come out of this small flap so basically what it does is it slows down the movement of the flap so it doesn't just kind of sit there and go real quickly instead it's going to be a more smoother motion because it's going to have this regulating how fast it can move so that's the damping flap and that's a vein type mass airflow sensor i'm going to show you real quick where this will be located on my car so just like the hot wire type mass airflow sensor um a vein type mass airflow sensor would also be located directly behind the air filter so it'd be right here on this vehicle if it were to have that as a feature to measure airflowhello everyone and welcome in this video i'm going to be explaining another type of mass airflow sensor so if you haven't already watched my video on the hot wire mass airflow sensor i would recommend watching that first that's a little bit later technology than this this is a bit older i don't believe this is used much anymore but anyways mass airflow sensor vein type so the difference with this is it's actually more of a mechanical system rather than the hot wire and i'll explain why that's a disadvantage and why it was phased out so what's happening is as you open up your throttle this is going to be right behind your air filter so it's going to be ahead of the throttle body in the order of operations here so as you open up the throttle which will be downstream more air will come in and as that air comes in it's going to push on this flap and open it up so if you can't really visualize this just think of like a box with a flap in it and as the air goes in it pushes that flap up so as that flat moves up this flap is connected to a position sensor so that position sensor is a potentiometer which changes its resistance while this flap opens so with a different position so since you have a different resistance what's what the ecu is going to do with that is going to see okay the flat moved and it altered the resistance so it's going to take that altered resistance and turn that into a voltage reading and using a voltage reading it can then determine okay this is how much air is coming in i need to inject this much fuel now there's a small problem that if you just uh base it on this cold air has more oxygen in it it's denser than hot air so another thing you have to add on to this as an air temperature sensor so these you can use this in combination with the voltage change to know the right amount of air to put into the engine or i'm sorry fuel to put into the engine to have a good ratio of air and fuel now as a check you've got the o2 sensor which is in the exhaust and so that will back up the ecu's reading and make sure okay there isn't uh there is too much oxygen or it's burning lean or uh burning rich so that'll be the check and i can explain an o2 sensor in a future video now why would this mass airflow sensor not be a good idea to use well there's a big disadvantage of it and the fact that it's a mechanical system accelerated acceleration forces affect this flat so say this is oriented so that the front of your car is here and the back of your car is here well if you slam on the brakes this flap is going to want to rotate up now when that flap rotates up your ecu is thinking okay there's more air going into the engine when really you're braking so then it'll inject more fuel you don't want that to happen also gravity is going to affect this so there's always going to be gravity pulling down on this flap now of course you're going to calibrate it to make up for that but think about it when you're on a banked uh curve i mean gravity is going to be slightly less in the direction that you calibrated it for so it can affect the readings and that's why this has been phased out really one thing i didn't mention this dampening flap so what this does is you've got this little chamber in here and there's a small gap between this flap and this wall here so as this flap rotates you've got air in here and that air is going to be squeezed and it's going to want to come out of this small flap so basically what it does is it slows down the movement of the flap so it doesn't just kind of sit there and go real quickly instead it's going to be a more smoother motion because it's going to have this regulating how fast it can move so that's the damping flap and that's a vein type mass airflow sensor i'm going to show you real quick where this will be located on my car so just like the hot wire type mass airflow sensor um a vein type mass airflow sensor would also be located directly behind the air filter so it'd be right here on this vehicle if it were to have that as a feature to measure airflow\n"