Mass Air Flow Sensor - Hot Wire - Explained
ฝัง
- เผยแพร่เมื่อ 6 พ.ย. 2012
- 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.
Please feel free to rate, comment, and subscribe!
And don't forget to check out my Facebook page:
/ engineeringexplained
Also check out my official website: Make suggestions, participate in forums, enter for Car of the Month, learn through logically ordered lessons, read FAQs, and plan your future!
www.howdoesacarwork.com
NEW VIDEOS EVERY WEDNESDAY! - ยานยนต์และพาหนะ
![[Eng Sub] How the Hot Wire Mass Air Flow Sensor Works](/img/n.gif)
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.
Paulinas Dzenkauskas
LAMINAR FLOW! -Destin
What he said.
Plus, the hot wire type is a sensor used to create a signal of “Grams Per Second” a more accurate version of speed density as the engine “Runs” on speed density program until the 02 sensor heat up and become active. Unplug and go drive. Runs fine, but not quit as accurate but turns on check engine light. A large number of vehicles ran on speed density only for years. CARB required a more accurate control of the A/F ratio, hence the $200 MAF sensor that cost $32.64 cents to make.
ASE Master Tech since 1978 - Retired
@@deankay4434 Speaking of that "mesh screen before the MAF sensor"- what Paul said was true- and the thing as far as I am getting it is called a Air Straightener. And is a BIG deal if you say have an upgraded AEM CAI. Without the aforementioned part sitting the PERFECT distance before your MAF sensor- you will start to see dreaded engine codes. I have been having much trouble. I am hoping installing an Air Straightener Aluminum screen will do the trick. Because I am all out of ideas other than taking a $300 god d**n hit and reverting back to my stock. Sigh... I must figure this out without giving in. And hey- doing it without having to drop BIG bucks on a tune would be nice too. You see I do not care so much about the power gains from my CAI. But THE SOUND my turbo makes every time I shift !! < 3
@@deankay4434 nice intelligent response, thank you - coming from an ole auto mechanic with an instrumentation background added in.
Check out my website listed in the description, I've got an about me page where you can learn all about me, if you so desire haha.
When the cylinders are going down during the intake stroke, they are sucking in the air. Check out my video "engines - explained" or "gasoline vs. diesel." I give a clear explanation to what your asking in these. When you first start your car, your starter motor rotates the cylinders, sucking in the air - see "Starting a car - explained."
And thanks!
I will have a video on MAP next week. O2, knock perhaps a bit further away. Glad you enjoyed it!
Yes, the temperature influences the resistance of the wires in the MAF, and also the engine will likely have an IAT sensor.
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.
Makes sense to me!
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.
Crazy that you used to be a child like the rest of us.
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.
Did you ever make it?
Could you explain it to me?
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
I have graduation tommorow (I dont know how it works in another countries, but you have final exams, and you have graduation next year, graduation is higher level, I am car mechanic already, but I want be autotronic, something like mechanic who is doing diagnoses). And I think I am damned :DD well, it isnt that this video would be bad, it is great. But I need know more electrical information, but congratulation, I just didnt study well, but atleast I have exams... I am just saying that I know that feeling too, I hope you did it well
Nice job on this - I look forward to watching more from you!
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.
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.
I've just subscribed today. I watched it. You are explaining with so easy way. Admirable bro.....Thank you. Keep it up.
One is sufficient, but they may be used in conjunction with an IAT (intake air temp) sensor.
Cooler air means the element cools more, the same effect as having more air pass by.
because the density of air increases ,, is this correct explanation ?
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.
Very clearly explained. You are good. Thank you.
Many thanks for the informative video!
I take my mileage and divide it by how many gallons I buy at the pump. :) haha, but if you were to do it by hand, you'd have to know so much about the engine, it depends on so many factors, many of which are out of our control (air temperature, what rpm range you stay in, elevation, etc..)
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.
thank you sir
I'm learning alot from u you you are actually a mechanical engineer book great job sir
keep it up
This was a really good video!!!
You should do more videos on importnat sensors in an engine
(O2, MAP, Knock.... etc etc)
Correct.
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.
Greetings! Thank you for your great videos!
Question for you: my car (2004 malibu) has both a mass airflow and manifold absolute pressure sensor - why does it need both?
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! :)
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.
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!
You can place an air filter directly on the compressor inlet, yes.
Air flow won't change much between just after the intake and just before the throttle.
Great tutorial. Current and voltage supplied to the mass airflow meter and oxygen sensor heater, generator and other components is comprised of current ON current OFF patterns the duty cycle in percentage indicates the duration of ON/OFF time in a given period The newer Mass airflow sensors measure frequency more than current or voltage and by your same reasoning when the air supply is high [ wide open throttle ] it takes more ON/ OFF impulses per second [ frequency ] to keep the hot wire at the fixed temperature you mentioned.
Good introduction to flow meters for fuel injectors
Thanks! I really enjoy that kind of stuff and clearly you know far more about it than I do! haha but yeah i would love to see a video, if its not too much trouble or too far-fetched for you.
I just replaced one of these in my car. Good to know how it works now! Thanks
thanks for the reply and ill be sure to check it out
Good Info, You may want to add possible problems with MAFs, symptoms and the fixes
Thx
Interesting question, probably so. But it would want to take the reading from inside the intake.
I know, I need to join. One day! haha
Thks,keep up the good work.
Great job! I think we need more electric cars! these videos make me realize how complicated gas engine cars are!
well done, you have explained this better than my university has
hey im loving the vids and watch every one but does fuel injection and carburated engines have a mass air flow sensor or only fuel injection? thanks
Could you not just clean the MAF? Was it vane or hot wire?
What do you do for living, what is your major? Keep the vids up pls so interesting!
I think it's been said, but the screen on the front is to try and smooth the airflow into a laminar flow, as hot wire resistance changes are only really accurate if you're given laminar flow.
nice video, man.. and how about if I would like to turbo my car? could the stock maf still handle the air flow from the turbo?
nice illustration
Checked the service manual before filming..
:O ...... i didnt know there was such a thing. Ill have to get one, thanks!
The mesh in the front of the mass air flow body is also to smooth out the air across the element and not let the air act in a turbulent manner . If it does the car can run like it has a idle issue...thanks
Summer means warmer roads and better traction, so... summer. As far as this device it will work well regardless.
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.
Very nice. It took me from zero knowledge to a very narrow ballpark.
thank you
What do you use as a current source..do you use a constant current source or a constant voltage sourse
@EngineeringExplained Would you mind giving me a quick explanation on what a wideband o2 sensor is regarding performance vehicles. Thanks a lot for your response.
Hello, i would like to ask you. You said that you will make a video about how o2 (oxygen) sensor works and so on. I can't find it on youtube or maybe you haven't created that yet?
A quick question, assuming you are quite familiar with Subaru FA20DIT engine (on my 2017 Subaru forester XT), is it safe to run the engine for a while (for example, engine in idle for 5 minutes) when MAF sensor unplugged?
Ive been watching you for a while and figure you are the best chance I have to try and solve my problem in my 2012 ram 1500 r/t. So evrything seems to work fine until I mash the gas. Then it boggs down / seams to be suffocating. I say this because it stutters and then eventually gives full smooth power. I cleaned the mass air flow sensor and checked the air filter but still happens fairly often. It feels like only some of the cylinders are getting the right air fuel mixture because of the spirty nature of the acceleration. Like some of thecylinders are giving great power but the others , not so much....then they all work. Maybe someone here has had this problem and knows a quick fix. I feel like it has to be something easy beacause of how well the engine functions at any time other than hard acceleration. Please help and thanks in advance
Very true, unless i wanna become an engine ECU ill have to stick with the trusty 'miles driven/fuel used' technique, i was just curious if there was another way, thanks for the replies!!
Jason, can you please make a video on IAT Resistor mods? or at least I would like to know your 0.02 here.. thanks.
Nicely explained, but I genuinely wonder if the resistance of the wire is maintained at a constant value? This would require the system to control the current across the wire proportional to the voltage across it. It would be simpler to keep either the current or the voltage constant and to measure the voltage or current repectively? I'm probably wrong, but I'd welcome further clarification.
do we require both MAF and MAP in a car to measure the air flow or only one of them is sufficient..?
The MAF on my 87 Chevy Sprint Turbo has gone bad and the part is discontinued and I cannot ind an What is my best option if I want to continue driving the car? Think I can steal one from another vehicle or use an aftermarket one? If its got the same reference voltage and same diameter, I should be able to wire in a different setup right?
Hi, would a dirty or faulty MAF sensor cause my car to have a rough idle at a normal operating temperature? Jumps between 600-1000rpm when I'm in neutral. Thanks mate great videos
Thanks for another great video! Just one question. How does this device handle the fact that the car will be driven in different ambient temperatures?
Some MAF have an internal air temp (AT) sensor.
hi! hello from panama city centro america
its possible you get a better idea how its works
but i try tu install a AFC neo on my subaru impreza GC3 1996, everything its fine except for the MAF when i plugin the maf to the afc my engine go to rich mixture (8afr) i think its possible i put a wrong info because the afc ask fot the numbers of sensors IN & out the question is the maf sensor have more than 1 sensor inside of them
if you have a better idea please i going to appreciate that
i got an f-150 3.7L v 6 2011 truck that i need to wire a new pigtail plug to. how do i know which wires go where on this truck as the wires coming from the harness dont match the wires on the new pigtail?
Does adding a k&n filter performance cat-back exhaust to my 2020 Ford Ranger mess up my sensor and ecu? Does it have to be retuned.
wont it be affected by ambient air temp?
Would it make more sense to have the MAF sensor just before the intake manifold due to the possible changes to the density from heating and cooling? Especially from a turbocharged engine?
Is it accurate to compute the instant fuel consumption just by knowing the air mass and the A/F ratio?
When upgrading my MAP Sensor from 3 bar to 4 bar will I have issues with the car or will the car adapt
if it is posible eliminate the flow meter? n do something to trick ecu? in going to convert my fuel system whit separeted or multi trottle bodys
Correction to what you said about your manifold absolute pressure sensor (MAP) it does not replace a Mass air flow sensor (MAF)
MAP sensor reads manifold pressure... or "Reduced" pressure (Vac) It's used commonly for "Altitude readings" and or Engine load
as i believe, the IAT sensor replaces the MAF sensor on your vehicle.
If the wire is cooled (by relatively more air passing over it) it will inject relatively more fuel.
Hye to Engineering Explained,
For the N/A car that already done Bolt On Turbo, if using a piggyback management as the ecu management, where is the specified location of Mass Air Flow sensor, is it:
1. After Air Intake Filter & Before The Turbo
2. Before Throttle Body & After Blow Off Valve
You may drop your opinion either 1 or 2, and justify the opinion.
The goal of these sensors (vane/MAP/MAF) is to get engine load. MAP (manifold air pressure) aka air density based systems needs additional sensor information (IAT or intake air temp) to get calculate load or VE (volumetric efficiency e.g. how much your air is getting pumped / maximum). MAF sensors are great because they are inherently temperature compensated. To measure a volume of air using MAP, you need temperature and pressure. Remember PV=nRT? Also, MAF will react faster to changes than MAP.
That's surely not a big deal :) Thank you for replying me.
Hi dear my mad sensor is 4,2 volts at idle and when increase the rpm it the maf signal voltage goes down actually .like 4.3 4.1 3.90 how cud u explain that a vacuum leak ?
What if you have 115 air temp plus engine heat. ?
Could you explain the computer input/output to the MAF? Is this 5V input? Does the output ride on top of this voltage? OBD shows Grams per sec and Freq, Does this only output Frequency and the scanner generators Grams number?
Its this a 4 wire system? 12 V Gnd 5V, Temp wire 5V?
Hi , i have a problem and maybe u can help me. So , i have a honda accord or acura tsx 2009 2.2 i-dtec (diesel) and i made a custom cold intake , the problem is that i reduce da maf sensor pipe from 80mm to 76mm using a maf adaptor. Now the engine throw the p1103 code i tried fitting the honey comb straightener but still doesn't work. Is it because i reduced the pipe size and fit the same maf ? Thanks
How does it account for air temperature? Cold winter air should cool the hot wire more that the air on a hot summer day in Arizona.
Years ago I had a Toyota Tacoma 3.4 l.. I made a HHO generator and for weeks I was getting 34 to 36 miles per gallon.. when the vehicle average was 18 this really surprised me.. The map sensor burned out and the vehicle ended up at the garage being fixed so I never experimented again.. but maybe you can shine some light on this.. is there a way just to merely bypass or eliminate the map sensor??
So I got a question, what happens when hot air enters the MAF sensor? Air that has higher temperature than the hot wire element? Does it tell the ECU to spray less fuel?
Great video. but I don't understand how voltage changs. only current changes due to resistance drop. voltage should always 12v or 5v from ecu.
I did thesis on hot wire anemometer
How does this work? Can you explain?
Does a Mass Airflow Sensor only work with Fuel Injectors? If not how can a MAF sensor also work work with a carburetor, like does the ECU adjust the mixture control in the Carb somehow?
I suppose it could, yes.
Cabuertor engine will not need this type of sensor right?
So which is better driving in winter or driving in summer?
Haha yes, electric cars are definitely more simple (though I understand them much less). The downside is charge time, and batteries, of course. But I think the industry will be getting more and more electric as time goes by.
Can you explain how in the ECU, the increased current caused by the increased airflow is "translated into a voltage change" ? What exactly does this mean?
The airflow changes the resistance of the element which current is passing through. When the resistance changes, due to a change in temperature, the voltage changes. Ultimately it comes down to the material properties of the element which the air passes over.
is your integra b18 vtec or non vtec?
very great
CARS LOV
ER
Is that a wheatstone bridge setup?
Hi
I am trying to develop something to capture aerosol produced in dentistry. This is to fight the Covid pandemic.
Currently my approach is to use high flow and volume of air.
To test effectiveness, I need an air flow meter of sort. How can I re-purpose a MAF to read air flow rate?