Diagnosis and Understanding: MAF Sensor Pt3 - Diagnostic Procedures

[@williamhinton5906]

I spent 35 years in the nuclear industry. Your instruction is on par with my training. I am impressed with your instruction and clear explinations. Thank you.

[@SchrodingersBox]

Good to know! I like being fact checked- keeps me honest!!

[@TheGeno2001h]

Every minute watching your videos worth it thousand of dollars thank you for your time

[@tinsnips28]

Found your video while browsing as I am an auto diagnostic technician and have paid much money on courses to learn what I do now I found I learnt more from your video than the courses. You should teach this to techs in the workshop you would earn a fortune. Thank so much for such a brilliant informative video lessons totally brilliant 👍👍👍👍👍👍👍

[@jamesmurphy3347]

So true

[@benjass8552]

Man, solid series here. Clear, clear, clear info. Not many youtubers take the moment to review, do a case study, etc. Genius. Just a young backyard mechanic here. Working on turning vehicles around. I've definitely read my fair share of books on other subjects, but the fact that you learned all of this out of a service manual and simply are translating this into more universal techniques for all vehicles. I thank you. Btw, I'm starting to feel a little cocky now that I've been getting all these multiple choice questions right. I'm just waiting until I make a stupid, jumping-the-gun kind of answer. Because after you correct me you'll say something along the lines of, "If you didn't get that, this is the wrong channel, go back to 4th grade geometry" LOL

[@SchrodingersBox]

Lol- my recommendation is to be confident but not cocky.... but act cocky if you want to quickly grow a KZbin channel ;-)

[@StefanPettersson]

How did I miss this channel? I don't fix cars but belong to the 2 percent that want to understand how it works. Getting 1.337 on the MAF test made me subscribe. It was a sign.

[@messer7bc]

Here I am. I am sick of diagnosing silly, vibrating 4cyl engine (no success yet) but even now I've enjoyed your video. For me it is kind of relax to be here watching you moving the wires LOL Great, complete story. All about content!

[@jamesdean5087]

Thanks for the videos it really helps me a lot. Sometimes I watch the same video multiple time to make sure I get it right. The knowledge is actually sinking in! Thanks again.

[@mathewmathers7342]

Your videos are great , even years later they still help out .

[@gimmick1974]

Excellent series here! I have Paul Danner's book and have worked my way through it while watching his paid channel. However, I must admit it has been your approach and your videos that have "connected the dots" with my understanding of these systems. I am just a DIY'er, with a passion for auto repair and, thanks to you, I am gaining a much stronger understanding of how to narrow down the list of possible component failures when diagnosing vehicle problems. Thank you!

[@Super-650]

Just checked an online VW manual, I too have probably been cleaning the I.A.T not the maf wire or vice versa. No codes but sometimes the high idle stays high for an extended period. No vacuum leaks and the temp sensor is fine. Cheers. Always learn something here.

[@DJDevon3]

13:00 Great point! Note worthy. When people try to modify their cars they often end up making things worse for years prior to learning enough to make it better. The fact that you know this should be reason enough alone for everyone in the automotive world to subscribe to your channel. Schrodingers Box is the real deal. If you aren't subscribed to this channel you're an idiot.

[@SchrodingersBox]

Yeah its hilarious what people on those forums do with the narrow-minded limited comprehension of "more air=power", "colder air =power" and "more fuel=power". Having spent time in those breeding pits of ignorance, it's actually the main reason I gave up on those places and started my own channel. You couldn't fund a single person who didn't chop the MAF, bypass their TB coolant, and relocate their IAT to outside the car.

[@DJDevon3]

Schrodingers Box In my circles there are people that delete the IAC, coolant bypass, and put a resistor on the IAT. Yuuuup, check please.

[@SchrodingersBox]

***** last night I saw a video of a guy indexing plugs on a stock civic lol.

[@jarinwilson9539]

Schrodingers Box LMFAO, come on now...

[@DENicholsAutoBravado]

Schrodingers Box Apparently indexing spark plugs is bad...don't know what that would have to do with them being in a car.

[@ngl-kd7tn]

I had to post a comment to show my appreciation for your in depth and well explained series in these videos. Some great contributions from your followers too. Keep up the videos. I am really enjoying what I am learning from them. Thanks again.

[@SchrodingersBox]

ngl777777 Thanks man,especially on your view of the contributers on this channel. I couldnt agree more- I also learn a ton from the comments as well. In fact one of the best parts of the whole channel is there is very, very minimal "flak" to sift through to see good comments. Most all of them either ask great questions or provide great accuirate information.

[@timothyjones8753]

Thank you so much for all the awesome work you do. I actually did have a bad MAF. I got a cheap scan tool (Bluedriver) which does surprisingly well. Took a look at fuel trims, mass air flow rate, etc. Found that the fuel pressure regulator had to be replaced (diagnosed because I had a little bit of gas leak out of the vacuum port). But still had high fuel trim and my rpms randomly revved up and down. The MAF is a digital not analog and I don't have a scope (too expensive for a beginner). I eliminated everything else that it could have been, went down to the junkyard and tried a maf sensor, worked like a charm. I know it's pretty rare but it does happen. FYI, I had cleaned the maf sensor very very well to rule that out to.

[@SchrodingersBox]

Good work- sounds like a valid scientific process!

[@roncarne206]

Your videos are amazing and I am a subscribed user. One comment you said you have almost never found a defective MAF, well I have. I was suspicious of my MAF, before I studied your series, and made the mistake of installing a Chinese made MAF. Gigantic mistake. After watching your series, I reinstall the original MAF, after clean it carefully and all problems disappeared. Great videos, I am a dedicated fan

[@SchrodingersBox]

Thanks for the info!

[@AndreSilva-gm4lt]

Sir, thank you very much! This video helped me troubleshoot a very challenging lean condition on 2011 4banger Camry, airflow sensor literally was intermittent to the point even the dealership was 100% sure the part was fine, and then it finally completely failed!

[@SchrodingersBox]

Oh wow sounds like a good case!!

[@arcburn3364]

Thank you for your time and willingness to share knowledge. I agree with you and some other premium channels in the effort to educate us diyers to the point of avoiding becoming parts changers. I'm retired from another profession, but my interest in automotive diagnostics really stemmed from dealing with high dollar shops who do that very thing, which is throw parts at a vehicle until maybe it runs correctly. I just finished watching this MAF series after realizing I had watched it a couple years ago, and remembered how enlightening it was. So I hope this puts me in the 1% group. P.S. don't sell your drawing abilities short. I tend to learn by visual inputs, and your whiteboard illustrations are great.

[@SchrodingersBox]

Thank you!!

[@carlosmenard3926]

Thank you so much, I'm graduated from uti, but explained way better than I ever had in the past, thanks again

[@chadcohoon8867]

I am working on a ford. I unplugged the MAF sensor and the condition did in fact get better.

[@labradormcgraw2409]

Got an issue with a MAF sensor on my Ford, so I kicked off by searching for videos on MAF sensor testing. What was I thinking? When will I learn that, for proper diagnosis of engine faults, there's really only one guy. Ok, ScannerDanner is good, but this guy takes the biscuit. It almost seems ironic that the best automotive teacher on KZbin is also the most under-rated. Forget the others, just filter your search results to include only those from Schrödinger's Box.

[@techsavantlove]

@ 12:00, "laminar flow" is the term for the "straightened air" (pretty sure you knew, just mentioning for others). The "straightened air" can be thought of as "flat layers", or "parallel layers" each riding along on their nearly microscopic individual path, thus making the measurements much more accurate than if it were just a big glob of turbulence, as you mentioned. This laminar flow is used in many, many areas of science, physics, aerodynamics, manufacturing (clean rooms), etc

[@SchrodingersBox]

douglas lee Yep- we use a "laminar flow hood" for cell culture and other sterile work- the shield of air protect the sample from outside air contamination.

[@liquiddreamification]

Ok its been 5 years from the time you made this vid. And you open with "hello fellow do it yourselfers" i was thinking another guy in his garage helping out others. You sir are FAR from just another guy in his garage, you know WAY too much for that And explain it WAY too well. (Thank you) your awesome.

[@SchrodingersBox]

Thanks man! I appreciate it!!

[@liquiddreamification]

@@SchrodingersBox may i send you my e mail. I would love to chat about a problem i have with my friends daughters car if you have time. Its drive by wire chevy malibu and me being the bright boy that i am. I cleaned the throttle body and now it wont run for shit. Can you help.?

[@SchrodingersBox]

I get hundreds of emails. Best to post it here. Give me the data and I can help.

[@liquiddreamification]

@@SchrodingersBox ok Okay Make 09 chevy malibu Motor 2.4L eco Situation Came in needed master, front callipers, strutts, rotors, And wanted me to replace both vvt soleniods. Completed. Now waiting on my innova 5610 carscan pro to auto bleed the abs. As brakes are bled but pedal still goes to the floor. So still sitting on jack stands with all 4 wheels off. Ran fine, Then y the VVT? Because my bud asked me to. Noticed the throttle body was nasty. So i cleaned it. Has an exhaust leak but ran fine because i imagine the computer helped with that. As your fuel trims vid explained. After the throttle body cleaning, it runs smooth for around 8 sec then misfires around 10 sec and dies by 15sec without feathering the throttle. Batt died, lost codes. Charged it, ran it, got em back. Codes stored: 1/6 P0300 3/6 p0300pd 2/6 P0131 pd 4/6 p0300ps 5/6 p0171ps 6/6 p0442ps Freeze data: Trouble code p0300 Fuel sys. Sta B1 CL, using H025 Calculated load 23.52% Coolant temp 69.8F STFT 32.01% LTFT 0% Intake M.A.P. 11.81 inhg Engine speed 3435.5 RPM SPEED 0 Ignition timing 38 degrees Intake air temp 46.4 F Mass air flow 2.07 lb/m Throttle position 36.07 % Running time 23 sec. Evap_pct 0% Fuel level imput 26.66% Warm ups 0 CLR_ dist 0 mile Evap_Vp -0.19inH20 barp 29.23 inhg Cat temp188.59 F And thats about it till i get my other scanner.

[@SchrodingersBox]

I need relevant data- just the extreme basics like fuel trim curved against load synchronized with MAF and MAP. Something to start with. The only thing the freeze frame shows is a lean bank but can’t tell if it’s the cause or effect.

[@AutoDiagnosticsPK]

Thanks Matt, i could refresh my knowledge after watching your this video series again. Your videos are of great help❤❤❤

[@SchrodingersBox]

Awesome, thank you!

[@sonyagaskell3648]

It is very admirable that you ate the cost of that misdiagnosis. you are a stellar human. I've gotten soaked by so many mechanics in my lifetime who made me pay for their mistakes. I'm sorry for my confusing messages yesterday. 3am..heh,heh.... Disconnecting the maf and having it run fine kinda cinched it for me. Plus the wildly erratic data I got on Torque live data. My new Maf works but is over reporting and gives me ltft of -15,which goes away when it is disconnected. Unfortunately parts for my 01 Suzuki xl7 are scarce and cheap aftermarket stuff not so "on fleek". I've ordered another and am hoping. Has it ever been tried inserting a trim pot in the signal line to trim the output voltage down a bit? High current may be an issue for the little trimpot. Thanks for all your efforts, Mat. Very helpful.

[@nandanalal5072]

I doing a small work shop in sri lanka,its very useful these videos to my works

[@SchrodingersBox]

I am glad to hear that!! It seems you are watching every single video hahaha

[@dw7475]

Matt lovely work as always! Just a wee tip. To speed up work and avoid confusion it is better to use battery ground reference on your scope / DVOM first. I noticed you use sensor ground without wiring diagrams which is fine but can confuse less experience people when they backprobe wrong wires (and get 7V as in your example). Battery ground will just give you less clean signal on some sensors due to noise. Also it is worth always checking MAF power & ground under load. You would be surprised how much current they can actually draw. Any voltage drop problem will cause inaccurate MAF reading when MAF is clean and sound. Another variable to consider during diagnostics :-)

[@apollomedia7210]

32:25 The mass air flow sensor is often hidden to prevent it from getting dirty from oil and particles. It is often in a high location, oil and debris hits and sticks to the protective wall but air travels up to MAF wire.

[@Chitown388]

Thanks for a highly informative video series! You emphasized that any faulty component in the ecosystem (o2 sensor, MAP, throttle, MAF, IAT) can throw a code for any other component in the ecosystem. It would be great if the video also includes more examples of such diagnostics. That said, what would say is the most likely problem when there is a combination of faults between the MAF, IAT and downstream O2 sensors as follow? - P0102: Mass or Volume Air Flow Circuit Low Input - P0113: Intake Air Temperature Circuit High Input - P0420: Catalyst System Efficiency Below Threshold (Bank 1) - O2 Bank 1 Sensor 2 FAIL , Max: 100.00641% Min: 19.99823% Test result value: 17.37656% - O2 Bank 2 Sensor 2 FAIL, Max: 100.00641% Min: 39.99799% Test result value: 35.58479% - O2 Bank 1 Sensor 2 FAIL, Max: 6,553.5S Min: 20S Test result value: 6.6S - O2 Bank 2 Sensor 2 FAIL, Max: 6,553.5S Min: 20S Test result value: 18.3S

[@timothybeavers3305]

Yet another great video my friend I have been utilizing your videos for my own knowledge and have also passed them on to some of my coworkers we work on forklifts and most of them are not aware of fuel trim and engine management issues and how to diagnose them

[@bruceshanks6883]

Hey Matt, I am new to your channel, I am ASE Master technician, and also Automotive Instructor for Antelope Valley College in Lancaster CA. I must say your scientific background and automotive experience is very impressive. Your doing a great job, I think Keep up the good work!

[@SchrodingersBox]

Bruce Shanks Thanks Bruce- it's always very good to get "validation" from the pros such as yourself to ensure the information I put out there is indeed accurate!! I take every effort to make sure I do that.

[@TTRVision]

I just want let you know that you have 100% World Wide validation! best regards from Europe

[@alpinepat2663]

Love the video and your enthusiasm - even when you've just pointed out I should go back and watch some of the more basic videos !! Lol

[@whitetiger8652]

Excellent series on the MAF sensor.

[@kongcharathpanawattanawong1976]

a best giver, a good teacher

[@bigo-b]

What he says at 34:00 was exactly what i have done and pain in the but. I have changed all coils, spark plugs, fuel injectors and even EXHAUST MANIFOLD{which was damaged from top of course } folks, but my rich condition never got solved, And as i keep to investigate more it was my Mass air signal wire which went bad, damaged /twisted and bad reading

[@Eric-dh1tq]

I love your channel! I take automotive classes, and this helps alot to better understand the electrical aspect of automotive technology.

[@SchrodingersBox]

+Pamela Reid Thanks for the comment!

[@InsideOfMyOwnMind]

At 21:29 pure solid gold info. I mean it all is but that one is a real staple.

[@facevendetta9005]

Thanks for your video. after watching, ran out removed wire from maf sensor and car running fine. After a few miles driving i thought (plug it in) while engine running . yes it kills the engine dead.will not restart until removal of wire. new maf ordered.cheers

[@SchrodingersBox]

I don't understand - why would you replace a MAF based on that? That makes no sense.

[@facevendetta9005]

I'm not too sure but it runs without it connected . so have ordered new maf..all started after refuelling.start car revs up over 2.500 and dies.short story . o2 wire burns on exhaust melts wires past connector. o2 and new loom fitted. car is the odd ball opel zafira 2000 1.8 16v. .their is power up-to maf 12v. Mind you the car runs better than it ever did with it connected .may keep it off :)the water temp gauge is working normal now ?use to be all over up down. stable now.gears smoother.ticks over @800 before was up and down 700 to 1200. test on the maf. . as i have found a ref for it. pin 4 - 12v pins 2-3 ign on 0v pins 2-3 idle 0.6v and pins 2-3 accelerate briefly 4v briefly. mine is 5-6 v on all......cranking..as it wont run when connected....so id say its shot. your videos are a great help . will let you know results if i put new maf on. thanks.

[@SchrodingersBox]

face vendetta It makes no sense to replace the MAF based on that evidence. You have no frequency or voltage measurements verifying a defect with the MAF.

[@gordonstennings7532]

your vids are very informant and well explained thank you for doing this,and yes im a hard core viewer now,

[@kerryhughes4399]

I have been watching your videos and I have learned so much . Thanks for sharing your knowledge . ...

[@faresadayleh488]

Excellent illustration ! many thanks. We don't have in mu country the MAF cleaner, what other cleaners may I use to get similar results?

[@SchrodingersBox]

Fares Adayleh I have used electrical parts cleaner with equally good results. I have also used brake cleaner despite the warnings not to. You mainly want to avoid cleaners that are non-volatile and/or leave any residue.

[@faresadayleh488]

Schrodingers Box Thank you! Do you think that Mercedes W203 MAF is cleanable?

[@SchrodingersBox]

Fares Adayleh No idea. Any hot wire MAF is cleanable, If it uses a Korman-Vortex sensor however, then I am quite sure it is not.

[@DENicholsAutoBravado]

Fares Adayleh While you may not be able to get our style of MAF cleaner, I'm sure you can read it's ingredients and buy something similar. I really wonder why I have a few of the "specialty" cleaners that I have sometimes when they're incredibly similar to each other....but then the MAF smells different, not that you should smell it, and the amount of each ingredient may be important. To me the bigger problem is have it unplugged when cleaning it and give it an excessive amount of time to dry. Looks dry in minutes, give it another 25 minutes after it looks dry anyway. Fried one trusting it looked dry once. lol It's times like that that I feel bad about a part having lifetime warranty. :/ A note from MAF cleaning directions. Never touch the components. Just spray with cleaner for short bursts. My CRC MAF had me spraying a long time repeatedly. After breaking one, I spray considerably less, allow for a little drying between shots, and will even allow a little crud to stay on the sensor over over soaking it.

[@charlesdowns1691]

fares adayleh. use a sprayer with rubbing alcohol. spray it clean + don't touch any wires ECT.

[@toshibahomeschool5704]

18:50 I do have a p0355 and a p0103 right now. Any idea??? OBDII real time reading 89 celsius at 8 am. In the first cold start of the engine.

[@rusco321]

In a future video, can you touch on why a lean fuel mixture is hotter than a rich mixture. It's counter intuitive and your explanation on the matter would be enlightening, considering your scientific approach.

[@DENicholsAutoBravado]

rusco321 I believe you're talking about how the MAF as is it got hotter got more inaccurate when it was dirty? Since it needed more and more air to react to incoming air, that would mean the O2 sensor would sense a lean mixture. When a sensor doesn't "see" as much air flow as there really is, the more air flow their is the more off it is. Since the MAF on my 1999 Chevy Prizm has a combined IAT or Intake Air Temperature sensor, I was able to use a laser guided thermometer to see that my IAT was causing the same problem that Matt was discussing here with the MAF.

[@justinle998]

This has to do with what is called latent heat of vaporization. When you get out of a swimming pool or shower, you feel cold. This is because the water evaporating off your skin steals your warmth as it is enduring the phase change from liquid to gas. Any time there is a phase change, there is a dramatic amount of heat required from its surroundings for it to occur. An ice cube melting(solid to liquid) will cool its environment. Condensation(gas to liquid) will warm its environment. Ice freezing(liquid to solid) will warm its environment. So believe it or not...fuel endures the phase change from liquid to gas which steals warmth from its surroundings, which is the engine. A lean condition will have more air then fuel...thus not having sufficient evaporative cooling effect it needs. Race engines sometimes have no coolant passages because the race gas burns/cools so efficiently.

[@DENicholsAutoBravado]

Justin Le That is a great explanation. I didn't know. :)

[@ravipurohit1]

Love this series! Would love a turbo electrics series. A lot of the newer cars have turbos as standard on diesels with vnts. Would love to understand how they work to your level of detail

[@SchrodingersBox]

So would I lol!! I have yet to even see a turbo. If I do believe it will be like a Guinea pig for me lol!!

[@nikoskidis3549]

Ur one of the best teachers out there 😊 thanks

[@SchrodingersBox]

Happy to help!

[@robmut1357]

Excellent video as usual! Regarding your conclusion on the first part where a guy was probing the wrong wires, if the signal voltage was changing with RPM, it would still indicate a change whether or not he was referencing +12v or ground, since either side would be constant. Think voltage divider. In fact, if you used a scope and placed the ground on the +12v (assuming isolated grounds) the signal displayed would just be a top to bottom inverted view at 7v peak to peak instead of 5 volts peak to peak. I actually thought you were going to pick number four (the digital MAF) since the signal voltage remained constant with RPM. Of course, I could be completely nuts.

[@Netherlands031]

came here to see this, on a 3-wire MAF with 12v supply, ground, and a 0-5v signal wire, you'd expect the signal to change regardless of where you're measuring.

[@734PaulS]

This may be a stupid question, but if we're running a sealed aircleaner, and it's doing a reasonable job of removing airborn junk, what is depositing on the MAF?? Seems like there shouldn't be much in the incoming airstream to contaminate it.

[@SchrodingersBox]

Paul S Thats a great question- I not sure what the actual material is- if it is air cleaner material itself, dust getting by the air cleaner, the result of dirty air filters allowing more contaminant passthrough, carbon or what. Sometimes people using K&N filters who over-oil the filters have more frequent dirty MAF problems, supposedly due to the oil getting on the sensor and further attracting and retaining contaminants.

[@734PaulS]

Thanks, I imagine it's easy to over do it with the oiled elements, never really trusted them myself.

[@ngohmartin6792]

Thanks once more sir, you are the Love of every enthursaite mechanic, we love you so so much

[@dangerdavefreestyle]

I watched all 3 videos, and utilized them to my advantage. I solved the problem properly and it felt very good. I made a video that I think knocks it out of the ballpark and can help others as well.

[@CHIBA280CRV]

Wow excellent information as always . Thank you..

[@malcolmyoung7866]

I love these videos....and your mention of 'maxing out' fuel demand at 2500RPM(for example) is a symptom of my daughters car ATM. I am now one of the 2% (hopefully) 14.7: 1..........

[@PrabhathFernando]

dear Sir matt u ar a great man, wonderful Thank u,

[@jedi-mic]

Yeah I think I got a problem with mine valve body it situated in there maf? it's a Mercedes r170 compressor 03 it looks Sooty I was wondering best way to clean it, can you use brake cleaner or contact cleaner to clean it out is it safe or what do you recommend thanks!

[@awesomeluis]

Hello sir, after watching your videos I took a closer look at my dvom and I noticed that it has frequency ranges from 320hz to 32KHz. Do you think it might be able help me diagnose my car should I have an issue? Thanks a ton! 😎

[@SchrodingersBox]

Yes, correct

[@bbmd2200]

Hey, Matt. I have been dealing with the dreaded p0101 on a 2015 Nissan Sentra for a long time. Freeze frame data shows a good calculated load value(97%). STFT and LTFT total are below 10% suggesting that the air /fuel mixture is normal and there are no intake or exhaust restrictions (97% load value), and no vacuum leak. The Maf is cleaned, but the code keeps coming back. The biggest issue is that the car has poor acceleration and takes a long time to take off. It has performance issues. Any idea? New spark plugs.

[@SchrodingersBox]

Where is your MAF sensor data. You need to show MAF sensor volume and voltage data.

[@Eddythe_Eagle]

Thanks for the reply...Car drives ok, but does lake the power it once had and the gas mileage is poor .It would when new idled really smooth and had lots of power. I have looked at other tests with my launch 123i scan tool. I am going to test out the maf sensor next, because I see the engine timing at idle jumping , and the engine is physically shaking. When you take the foot of the brake and strart to move the engine stopd shaking, I had the engine mounts checked , and had the main one replaced. The scanner is amazing. It will record and play back live data, and you can down load it to your computer and print it. Yep a new Maf sensor is about $260.00 canadian. Next I will check the wiring to the sensor. Some times the cold start is good, ans sometimes not. i will check this out first. If a person has a multimeter you can check out the sensor or better still have a scan tool that has those capabilities.I tried a number of scan tools before I settled on this one. It is not a perfect scanner but well worth the $, if you learn how to use it to its full potential. Done the plugs, cleaned the throttle body, used lucas ... not fixed the problem. Going ahead with the next step... Blessings Ed R

[@timmorris9031]

Hi Matt my name is Tim i am a 20 year tech and i just thought i would give you a little info about a base line for all MAF cars that are not turbo or super charged. The readings on MAF should be around 1.0 to 1.2 grams per second at idle in park with all accessories off. I know this is only good for those that have scanners but thought you might want to share it anyway.

[@kenneth.dl87]

Actually, the measured value between the signal 5V wire and 12V would have to change when you engage the throttle. Because the signal wire changes, somewhere between 0 and 5V. So measuring between a fixed 12V and a variable 5V would mean a changing measured value. You would measure something between 7V(signal = 5V) and 12V (signal = 0V). I'm a software engineer for CNHind NH combines and what we typically do, is use sensors with a valid range between 0,5V and 4,5V. That way we are able to detect short to gnd when we measure < 0,5V and short to Vcc when we measure > 4,5V. That makes sensor diagnostics easier.

[@Epro95]

Just a note about removing the MAF screen. My tuner removed the MAF screen on my Camaro and it did gain 2 RWHP. But now I'm stuck wondering if my poor throttle response is from removing that screen or something else. It wasn't a good idea. Hopefully your videos will help me figure out for sure if the MAF is reporting inaccurate data.

[@SchrodingersBox]

exactly. removing the MAF screen is one of the biggest myths of performance enhancement there is. the MAF is calibrated to the airflow generated by the screen. removing the screen causes a lean condition and that’s the last thing you want in a power application. never get advice on performance mods from a chat room!!!!!

[@brunopecego5297]

hey Matt unfortunately i still have my MAF over reporting. on my 1997 4.3 s10 it is reading 9gs at idle. i cant figure out why. i couldnt find a wiring problem to the sensor so my truck is running maxed out negative trims and still runs a bit rich because my spark plugs get fouled. i even tried putting rags inside my airbox to se if the MAF reading goes down but it didnt. but it works because i get proportionate response to throttle and if i create a vacum leak it reads 4gs. my MAP sensor reads normal so i dont think its an exaust restriction or back pressure disturbing the air measurement at the MAF and the truck has good power. i also thought this reading the maf is getting might be related to the IAC valve but it closed properly and it idles around 600rpm where it should be. it runs great but its cant really drive it because of very poor gas mileage and sometimes the sparkplugs get fouled and its difficult to start when that happens. i learned so much on the past two years on your channels and your mechanics program but i cant fix this. im about to take it to a shop. if you have any ideia of what i might try to fix it my self please help. thanks

[@SchrodingersBox]

I have to see the actual MAF signal voltage at wide open throttle.

[@brunopecego5297]

right. from what i remember now that you mentioned i need to look for a current loss or high resistance in wiring to the sensor. correct? because it would make the maf hot wire not hot enough making the computer think there is air cooling it down. i think when i checked resistance i checked with engine off but definitely not at wot. ill re watch your eletrical resistance testing videos and try it. thanks you are the man@@SchrodingersBox

[@brunopecego5297]

wait... you said signal voltage... now im confused. i dont think i can check signal voltage without a scope. i only have a basic multimeter and scan tool

[@SchrodingersBox]

You can check it with the multimeter. If it’s analog you will see a voltage increase with mass and if digital a frequency increase.

[@brunopecego5297]

@@SchrodingersBox hey Matt update on my diagnosis. I checked power signal and ground and all was good. My signal voltage at idle was around 4.4v and decreased with rise in rpm. Since I didn’t see any wiring issue i got a new MAF sensor but i still get the same 8g/s at idle at op temperature. Sorry I didnt understand why you asked for wot MAF signal voltage so I didnt check. What else could be causing this high MAF reading? I really believe its reading wrong. My pcm is not storing memory so its also a suspect but i don’t understand how it could relate to this specific problem i have. If its reading correct air volume I wouldn’t get spark plugs and o2 sensors black and a little white smoke from exhaust than maybe my IAC system is suspect or engine is sucking more air than it should for some reason. Im also in scanner danner forum but nobody there can figure it out.

[@javman4socalr809]

I have been dealing with a cyl one misfire on my 4 banger Mazda B2500 SE. I get diagnostic codes P0231, p0301 and P0402 using a BlueDriver scan tool. While using Live data, I drove a long trip and noticed voltage to upstream O2 sensor would oscillate which is a good sign. However, when engine ran very rough, sluggish, I noticed o2 sensor graph would be flat or a plateau rather than "normal" oscillation. In your expert opinion, does this suggest a bad o2 sensor? I appreciate any help or suggestions. I have already replaced spark plugs, wires, ignition coil packs, fuel filter, fuel injectors, etc.

[@SchrodingersBox]

it suggest accurate reporting of the condition. i would start with what data you have that the plugs, wires, ignition coils, AND fuel filter and injectors were all bad. that seems extremely unlikely. what data showed this was both ignition and fuel related?

[@mariusgri8490]

Amazing stuff to learn. Thank you.

[@Eddythe_Eagle]

i have a 2010 elantra with a rough idle. I disconnected the MAF and the idle and power is great. Was 0 volts originally with the rough idle.. Reconnected MAF now getting a volt readings as you raise RPMs.. I have a Launch 123i scanner that does have graphing, and live data. Any further suggestions. Great Job? Wiring? Thanks EJR.

[@SchrodingersBox]

sounds like connector may have loose wire or corrosion.

[@Eddythe_Eagle]

@@SchrodingersBox Thanks It may be just that. I will retry with the scanner and try playing with the connector to the MAF sensor or the wires. Seems strange car runs better without the MAF sensor plugged in. But I am wondering why the check engine light did not come on. I tried for 2 years to get someone to diagnose the problem. The problem has been getting worse over the last 2 years. It use to idle so smooth that you did not know the engine was running. I did get a check engine light to come on, and I did reset the DTC.when I detached the MAF Sensor. But it looks like that the ECU is resetting itself back the way it was before I detached the MAF sensor. Any other I will rerun the MAF sensor test with the Launch 123i and also read the 02 sensors and fuel trims when I can. As the problem got worse. It would taking the car driving for a long time before it would idle better? Any other suggestions? Thanks

[@SchrodingersBox]

I have also seen a loose hotwire cause this. If you graph the MAF output and gently tap on the MAF with a screwdriver and the signal drops out, that may be the problem and MAF needs replaced. I actually have 2 videos where I show this happen!

[@Eddythe_Eagle]

@@SchrodingersBox Thanks for the reply. I was wondering , I think there is a OB2 port under the hood by the firewall. If so i could plug in the 123i and set it ti the MAF sensor and record the data stream while I try what you are saying. I noticed before I started looking into a MAF sensor issue that the O2 sensor B1, and B2 are normal,, and that the fuel trims were in normal range but what I did notice was that the advance #1 cylinder timing was was not smooth at idle? but jerky? Not sure if there is more than one issue. i had the timing belt and waterpump replaced because the car was 10 years old. It made no difference on the rough idle issue. But I still wonder why the scanner did not turn on the check engine light until I disconnected it? Hot wire possible, since perhaps maybe that's why the engine idle's better after I drive a long time? Does that make sense. I also a misfire in cold starts but check engine light does not come on either. I go out each morning when it is cold and start the car and see how it starts and runs, and how is it idling. Seems like every cold restart the ECM is reprogramming itself, but not for the better. The idle seems rougher when I am at stand still, and stopped with the transmission in drive, and the engine is runnubg. I also noticed that the engine is noisier when the transmission in drive and I am stopped ? I will check out these issues . Meanwhile should I NEED a new MAF sensor should I use a genuine OE Hyundai part? Around $260.00 cdn? Thanks again Ed R

[@SchrodingersBox]

that’s correct.

[@Plazmattack]

Big thumbs up and subscribe, loving your work man. Extremely helpful for me.

[@SchrodingersBox]

Glad to hear it!

[@ELNENOMELGO-bk2xs]

thank you sir. you are a brilliant technician

[@SchrodingersBox]

Thanks and welcome!

[@edwaggonersr.7446]

This an excellent series. I will watch it over and over again. By the way my Klein MM2300 measures up to 500K Hz. auto range. Like you say, when I bought the meter I though, what the hell am I going to do with a Hz. measurement.

[@SchrodingersBox]

+Ed Waggoner Sr. (Papatch) Yes that meter will be ideal for MAF measurements. Also some MAP sensors use frequency as well.

[@nandanalal5072]

Matt I have a problem to solve ,when vehicle is going on a hill road throttle ful open time map is comes to the atmosphere pressure at that time what will be the maf sensor reading because air flow is allready finished

[@SchrodingersBox]

In general the MAF sensor at wide open throttle matches the engine displacement. So a 2L engine will usually read close to 2lbs/min.

[@flightmaster178]

Thank you for the videos and taking the time to share your knowledge. I appreciate it, and love the videos!

[@SchrodingersBox]

+Brenndon McGill You're welcome!

[@davidesquerra5244]

I pulled the engine on my car and now it idles at 3000 rpm's and will sometimes drop too 1000 and go back to 3000 could that be a maf sensor? Usually the car will turn itself off but when I remove my tps it'll run that way without dying.

[@SchrodingersBox]

You obviously reinstalled engine incorrectly. Why do you suspect MAF? What dat do you have?

[@allankorekop9508]

Excellent explanations.

[@dcbigsky]

Great info .......waiting for next video

[@83bebo1]

Hello my best teacher, can the MAF power feed be a 5 volt?. I have toyota corolla 2019 with MAF 4 wire (MAF + IAT). The car is running perfect. The only proplem for me is there is not 12v power feed (5v instead). The maf signal is perfect square wave. Is it 5v power feed. Or karman vortex type. The vehicle owner (friend) didnt allow to take off the screws beacause of the warranty :-)

[@SchrodingersBox]

hmmmmm I have not seen one with a 5V ever before. 2019 is really new- way newer than what I typically see because most people go to the dealer for warranty repairs. I suppose if could be some kind of potentiometer technology but I would be very surprised. interesting for sure but I wonder if you are seeing 5V with it unplugged or are you backprobing it?

[@83bebo1]

@@SchrodingersBox hello teacher, I do the measurement both ways (connector unplugged, backprobing) and its always constant 5 volt. Another thing that I have noticed that the MAF signal is still square wave even when the engine is not running (KOEO). Could the hot wire be a very low resistance that the 5v can heat it?

[@SchrodingersBox]

man I gotta tell you- I don’t know. that’s really interesting. I am not sure what the mechanism is for that design!!! I will try to find a wiring diagram for it and see how it works!!

[@salahkebi05]

Hi there, i have 4 wires maf sensor GND, 12V and two(2) 5volts ref wires, whar would be the second 5volts wire, for the IAT may be...thankful.

[@SchrodingersBox]

Correct.

[@salahkebi05]

@@SchrodingersBox thanks a lot appreciate it...

[@jayframes4967]

@@SchrodingersBox Hey Matt, great video's man. Wishing I was brighter so I could grasp more info from them:-) Hoping you could help me! I have a chevy 4.8L kicking the p0102 code (mass low frequency) it's got the 5 wire sensor(so I believe it's the maf/iat combo) checked wires at connector, have good ground, 12v on 1 wire, 5v on 2 wire's, and 30mv on 1wire. I get a 0.00lb/min maf reading on the scanner.I checked wiring diagram for this and 1 wire is labeled as low frequency, so I'm assuming that's the 30mv wire. Is there any advice you could give me on this please?

[@SchrodingersBox]

@@jayframes4967 Sounds like you have a digital MAF so the best you can really do is check your power and ground and then for the the reference you should see the AVERAGE voltage change with frequency. If you have power and ground and continuity with signal to PCM but no signal change it is lost likely you have and open hotwire.

[@jayframes4967]

@@SchrodingersBox Hey Matt, thanks man, it was a break in the 12v wire going to maf sensor. Found it and reattached, maf is now working:-) took it for road test, still running like shot and kicked on 3 new codes:-(

[@disarm2k10]

With the example of the fuel trim and rpm with a dirty maf, wouldnt the ltft stay at 10 (réferenced on a base idle triming needed) and the stft adjusting when more than 10 is needed (ie: raising the rpm)?

[@GRowe1978]

I have heard another bone-headed theory on the MAF sensor screen. Someone once told me that it's only there to keep you from touching the delicate wires. LOL! Like you can't reach in there from the other side and jam your fingers into them. Gotta love those highly informative forums... Oh yeah, I almost forgot, replace your MAF!

[@oggonzalez9291]

I have 2006 WV Pointer. I belive this has a MAP/IAT 4 wire combination. The condition is surging idle. Do you have a video explaining anything similar?

[@oroscriss1608]

took you awhile to get this out, rough times at work? I'll just put it to watch later cause i'm rushing to work too. Glat to see part 3 out. Have a nice day, keep going Matt!

[@richardpowers2106]

Hey Matt Thx for the videos. I have 07 Ford Freestar. Showing codes p2295, 2197. Extreme trouble at idol but ran rather well at high RPMs. Between these and the Taurus series, I checked O2 MAF and fuel trims. Sensors showed they ocellated. LTFT both rails 0.0. STFT pegged at 49. You know where I’m going. Exha

[@richardpowers2106]

Exhaust leak or dirty MAF easiest to check MAF. I cleaned it. It runs actually better than it has in two years. I like your approach. At least I can scientifically mark items off the list BEFORE I touch a wrench. Thx again

[@SchrodingersBox]

How do you explain STFT pegged at 49 but LTFT at 0?

[@Epro95]

I have a service manual for my LT1 Camaro, could I expect more than the WOT value in the book if my car is cammed? I'm 99.9% sure it would show a higher value.

[@SchrodingersBox]

Make it 100% then because you are correct. An aggressive campaign profile absolutely increases induction and thus increases efficiency of breathing. But also keep in mind you need to make exhaust is high flow to maximize that!

[@marksloan2323]

I have a 2018 GT Mustang when testing the wires going to the MAF sensor I have two wires with 5 volts 1 good ground haven't checked the second ground. Should I have two 5 volt wires running to the MAF. Im getting a PO 103 high input code. And now a PO 61C. Any help would be appreciated thanks

[@SchrodingersBox]

It depends. Is it pulsewidth modulated or analog?

[@equsnarnd]

In diagnosing a P0172 code, a faulty MAF sensor is suggested as the problem. What confuses me about that is that the MAF sensor is reading air flow to the engine and not to just one bank. How could it be that it effects only one bank? I'm totally ignorant about engines so I'm just guessing but if I'm wrong I'd like to know how so I can change this assumption in my thinking.

[@SchrodingersBox]

it’s can’t. a MAF affects both banks. what data do you have indicating the MAF is the problem?

[@thomastormaschy3835]

In Intelligent diagnostics a 172 which is bank 1 lean I believe, would suggest MAF sensor because it is often found in conjunction with other bank lean code

[@hollow82]

Hi, Matt! Thanks for your videos! I have a question: I looked on a MAF data On my 4.3 vortec v6, using scanner , noticed that with ignition on but the engine not running, scanner shows me like 2.5 - 2.8 grams of air flow, is it supposed to be like this, or is MAF faulty? Thank you

[@rimka11]

Do you have a dyno results with screen removed and not? Is there some actual data ?

[@SchrodingersBox]

I am actually planning on making a video showing this but basic, fundamental operational knowledge obviously indicates the screen's absence would have to cause a lean condition.

[@SchrodingersBox]

How is it possible removing the screen could cause a NEGATIVE fuel trim? That makes no sense at all to me. Please explain what I am missing. How would removal of the screen possibly cause this? I can't think of one possibility.

[@rimka11]

It would be more easy for me to talk about fluid dynamics in my native language, but I will try to make sense. The hot wire is very sensitive to where it is located. For example, if maf is located somewhere after a bend, there can be areas of different gas pressures and speeds. And the areas can move a little on different gas flow rates. There is no simple answer without CFD computation.

[@musaalgheriany8917]

Thank you so much indeed. What a great video

[@ericgale2695]

I have an issue with my son's car. Starts fine, rpm go up to 1200 then they drop to stall level. Codes P0171/74, P0300, P0303, P0305, P0102. Cleaned maf, IACV, throttle body. Fuel pressure is 50psi. I don't want to just start throwing parts at it. Ideas?

[@SchrodingersBox]

What data do you have? I have nothing useful to go one here

[@windimuhsin6439]

I have a civic ek4 b16a, the rpm of my car sometimes drops and when the gas pedal is pressed it doesn't respond, what do you think is the cause ... ??

[@SchrodingersBox]

could be anything. what data do you have?

[@besofacacia6103]

man thank you for great work ! your videos are the best... i almost find an answer watching your videos. cold start misire m54b22 engine. have done and tested everything written on internet + ecu + lifters. when i unplug maf it starts x3 time better on cold, almost perfectly. when engine is 45+ degree i plug it back and it runs - 1 + 1 fuel trims. changed mafs 3 times, bought oem but used ones. reading are 98% perfect. 3.0-3.1 grams per second... it is perfect reading for my engine. have any ideas ? compared iat readings with 3 new one with multimeter in room temperatures - they were the same. 2 mafs i used before were leaning mixture to 10% . this one sets on 0. now after 6 months i beleave its overeading a little. could this be a bad timing ? old bmw scan tool inpa does not show any timing problem.

[@Eddythe_Eagle]

I was wondering the car I have has a rough idle issue. But when I disconnect the MAF it runs almost like new I wonder if there is a wiring issue like my car . Check out this site on how to check for this problem . Not sure if this would help! I am going about the same issue! i have a Launch 123i scanner, that works really well. If you have a scan tool that you can use try it? Hope that helps!

[@besofacacia6103]

@@Eddythe_Eagle All this time I have been fighting this problem, fixed it with tuning manipulations.

[@AdrianPoroch]

tkx for the video and advice ... mine hade 3 cold solder connections 12v gnd and iac send ... resolderd them and good to go!

[@sortemout6]

Verry Verry good, I got a lot from this, thanks V much

[@zannehaynes7279]

I love your videos and I always like how you look for evidence for your conclusions, I always do the same. I had a problem on a BMW e46 with a mass air flow which reads sometimes on the scan tool. Tested the signal wire with it unplugged and ignation on and got 0 volts but when its plugged into the sensor it reads a voltage from about 0.9 to 2 volts when the rpm is from idle to 3000 rpm. At first I was thinking a broken signal wire but when I got a reading when plugged in it had me questioning myself. Any Suggestions? Was thinking maybe its a digital signal and my multimeter is averaging 0.

[@randyingrao2445]

just found your site today, you mentioned self cleaning elements for as MAS, would this be the reason for a burn off relay?

[@speakbigtruth9383]

How does the computer know the temperature of the wire?

[@SchrodingersBox]

It knows based on the resistance that is present causing fluctuation in the amperage baseline.

[@barrycoogan8412]

hi i have a problem with MAF sensor vw 1.9 tdi using vcds reading used to be around 230 now reading is approx 430 jumps to 475 its all over the place if i disconnect it it goes to 550 it has been changed with another MAF sensor no change i have 12 v 5v feed and ground is good testing signal wire at idle it reads 1.9 v the problem started with white smoke from exhaust and is more under load. its driving me crazy need a new set of eyes to see what i cannot anyone any ideas thanks.

[@MrYaatri]

The resistance of an MAF, a negative temperature gradient thermistor, whose resistance is quite high at low temperature and it decreases with rising temperature.

[@techsavantlove]

Another excellent series. Thanks. I hope you DO do one on MAP only engines, as that is what I have on my Sebring. Separately, yes, disconnecting the MAF can help identify a bad MAF. A friend had a late 80's or early 90's GM, 3800 I believe, that used a digital MAF. To my recollection (this was a few years ago), the hz did not change much, or it was in too small a range. When I disconnected the MAF, the car idled better AND drove better on the road. Not great, but much better. More drivable. He drove it like that for a couple months until he sold it.

[@SchrodingersBox]

***** It is not that MAF's fail- it's that they get dirty- I have seldom seen a MAF actually fail. And actually I have seen a MAP fail as result of backfire in the intake- it happened on my own car. But one of the main advantages (at least as far as I'm concerned) with MAF vs MAP only- which I will discuss later, is the ability to modify an engine without re-programming.

[@Atjavs]

Thank you for all your videos👍🏼

[@SchrodingersBox]

So nice of you

[@alfacor27]

hi sir i have a problem with my suzuki wagon r 1000cc efi gasoline engine turbo intercooler , during warm up idle is ok but until it reaches the normal operating temp the idle turns rough and it fluctuates eventually but when you rev it up in almost 1500 of the rpm it will gone and if you depressed it again it will come back can you give me an advise? thanks..

[@SchrodingersBox]

What data do you have? There is nothing but description of symptoms here.

[@Sloppyjalopy123]

Hey Matt, quick question for you. My Mitsubishi has one of those Karmon vortex maf sensors (which aren't the best). So I'm wondering, how do you go about cleaning these? I've considered spraying the honeycombs out with maf cleaner, but wasn't sure about harming it? Obviously there way different than the hot wire setup. It's no wonder many people switch to the LS maf, like yours.

[@charlesdowns1691]

never remove screen. too lean will result.

[@ziggyboggs5485]

You recommend a certain manufacturer for map sensors.

[@davoinshowerhandle3302]

That maf looks similar to my saab 9-5 maf delphi brand 3 wires. Im here to get some ideas, PO102 keeps popping up this guy mentions that MAF is also interconnected with IAT need to check it on my day off.

[@SchrodingersBox]

If you have a 3 wire MAF it will not be interconnected with an IAT. You would at least a 4 wire design for that.

[@confidential8738]

I have an 03 impala and bench tested the 12v and ground and reads nothing. Tested one at autozone and that one the same thing... Am i missing something?

[@SchrodingersBox]

Well of course it would read that. You are bench testing it. what was the resistance between the ground and signal?

[@confidential8738]

@@SchrodingersBox the reading stayed on 1 with no response. Maybe im not sure what bench testing is then lol. I did what u did in the video with the red going on 12v and the black going on ground and yours had a reading. I maybe doing something wrong.

[@confidential8738]

Thank u for the response btw

[@SchrodingersBox]

Are you reading voltage or resistance?

[@confidential8738]

@@SchrodingersBox resistance. 200 on the upside down horseshoe.

[@AdrianPoroch]

if I have a 10 Mhz bandwidth millimeter is that good to use?

[@SchrodingersBox]

+Adrian Poroch Sure, if you signals are up to 10MHz

[@AdrianPoroch]

I tested my sensor but I can't understand why my car sometimes runs great and sometimes it struggles no power and sometimes the engine stops (this all after the car worms up to 90 degrees Celsius) .... Air Mass / Air Flow Sensor (G70)/(G19) ... 31-10 - Open or Short to Ground - Intermittent

[@SchrodingersBox]

Adrian Poroch if you have intermittent signal loss the signal, when present, is probably normal. You need to detect the source of intermittent loss.

[@AdrianPoroch]

I suspect te 12v power for the sonzor ... my senzor contains the intake air tepm senzor (ptc type to ground) and an analog maf ... probing the senzor at idle 1,18 v and as I crank the engine it rises so logical for me the problem should be the 12v power line ... maybe I'm mistaking