Symptoms of a bad MAF sensor (how to troubleshoot)

[@Viper81766]

Danners book and premium channel are the very best investment you can EVER make in learning diagnostics and driveability . I learned 110 percent more from him than I did at college . God bless you brother .

[@movingupautodiagnostics8645]

Robert Wood And that sir is a fact.

[@SmittySmithsonite]

HEAR! HEAR!

[@ScannerDanner]

Thank you guys!

[@THERIGGEDONE]

Heck, I'll drink to that!

[@bobl78]

totally agreed... send all those dealers and experts to him that rip off people by charging days to "diagnose" or throwing in tons of parts

[@jimbuford4147]

I have never been in the automotive business other than as an insurance adjuster but with a good teacher like Paul just learning is an exciting adventure.

[@erikjohnson2889]

Man, I just discovered your channel tonight. I'm a DIYer, but I'm serious about learning more than just throwing parts at my car. You're badass, brother! Thanks a million.

[@ScannerDanner]

Thanks Erik and welcome! Look forward to hearing from you more.

[@erikjohnson2889]

Dan, I subscribed to your channel last night. So stoked. Wooooooo!

[@ScannerDanner]

Then you may as well know my name. :-) it's Paul Danner I get "Dan" all the time lol

[@erikjohnson2889]

ScannerDanner ha! Sorry about that, Paul!!!

[@smilleur]

Dude....your videos look so professional. The scan tool on the screen as opposed to pointing the camera at it is such a nice touch. Nice work.

[@tjtyler5460]

Just had a 2014 Mazda CX-5 with a p0172. Looked through everything and when I got to the MAF with the scope I noticed with KOEO signal voltage was .88 V. Service manual says it should have been around .72V. Check circuit ground and 5V REF everything was good. Replaced the brand new OEM MAF with one from autozone and bam, no longer rich! Thanks for the videos Paul

[@wjs1820]

Was about to order a new MAF sensor for cadillac xts. Watched your video and felt guilty for pre-dignosing. MAF was good and clean so wanted to look at throttle plate. Took off the snorkel when I found a split in the middle of one of the folds. Ordered a new snorkel ( the correct part) DTC cleared instantly. Thanks for your help.

[@bookreader908]

New sensor $103 or can of MAF Cleaner $8 and 5 extra minutes of time. I cleaned mine and definitely had fantastic results.

[@tammiwilliams8575]

That's awesome. Save Save Save 👍

[@ColeTanner88]

That works at times for sure. Other times, internal circuitry of the MAF is causing skewed readings. I'm sure Paul would've just cleaned it if that's all it needed. Dirty MAF won't be intermittent. There's probably a failed solder joint internally that gets a hairline crack when hot. No way to take them apart without destroying them.

[@joker90029]

This just started happening to my 08 750li. Rpms started surging, car had no acceleration , running rich, can smell it . Got various codes for throttle pedal position malfunction and limp mode.. Thought it was the pedal, replaced and still getting the surge issue. This video just confirmed my symptoms as my rpms are doing the same as this car did in the video. Got maf sensor on the way. Thank you for this video.

[@hemnaswad9177]

Master of Diagnosis, Ocean of free knowledge Scannerdanner. Iconic diagnostician. All good words fit right to him. Love you Good man.

[@vunit8213]

I guessed this one right from the get go..faulty MAF...My 99 Buick regal did the exact same thing to the T....I love watching your videos and trying to couch diagnose these problems, while your out in the cold rain! Keep em coming ScannerDanner!

[@mostlymoparih5682]

Blockage of the air flow will also give you the symptom of the MAF sensor being bad. Had a car that had not been used in awhile and chipmunks had gotten in the engine bay and had brought some of the hood insulation into the airbox. Some of that insulation got into the MAF sensor. I blew out the sensor and cleaned it and the problem was resolved. Great vid.

[@ScannerDanner]

Yes it would but not a 0 volt signal. Low of course, just not zero. Thanks for the comment. It will help others.

[@mostlymoparih5682]

Thanks for helping us with your great diag vids.

[@ScannerDanner]

For sure and thanks for the comments!

[@tammiwilliams8575]

Love the videos You're so awesome ScannerDanner!!! So professional and knowledgeable!! I love the way you explain the diagnostics!! I had to watch a few for knowledge. 2004 Ford taurus wagon never had, but I've had it for 6 years $700 bucks well spent. Love working on my car. I've been working on them since I was 9 with my step dad. He was self employed. Taught me a everything! I'm 52 and widowed and doing my own work👍💪

[@ScannerDanner]

I'm sorry about your husband 😔 But I'm super glad you are here with me. May God bless you in 2021

[@johnmichaellane1]

I had a MAF fail on me like that while I was coming home from work on New Years Eve. The car was stuck on the Jamestown-Scotland ferry. I'd like to think I got the last workout of 2015 while I was pulling that Buick onto my brother's trailer with a come along... great video. I wish I had known then what I know now!

[@earlmccain7094]

Next time just unplug the plug going to MAF and the car will run just fine.

[@davidljohnson8514]

Man I am a new subscriber to scanner danner channel. I am always amazed at all the time he takes to make a video for people. Some people may not believe me but I know he is giving us thousands of dollars worth of just keep making these videos if you can they never get boring. Such well spoken great details.

[@stephenmarshall5302]

Feel like a crazy fan or something but the more I watch of Paul and his diagnosing the more I learn and actually starts to sink in. Just watching a couple parameters on the tool can tell alot more than I would ever have thought. I'm really gratefull for this. I reccomend people subscribe to the channel and buy the book. Best investment I've made I really believe that. You know the first time I use these techniques and fix something I'm going to be very satisfied 👍👍

[@redwingsgo12]

Thanks for the diagnostic tips. My Avenger is doing exactly the same jerking as that car, even stalling at idle. DTC shows too much air in engine, that narrowed it to the MAF sensor. Now I can test it for sure with a quick test drive. Thanks.

[@martinparker6536]

a guy who knows what hes doin and what hes talkin about. great video, subbed !

[@786hunzavalley]

Hi, Great video. Thanks. My golf 1.4 tsi twincharged was running fine, no problems, just had water pump leak, so replaced water pump and also did the full service including spark plugs, engine oil, filters, dsg service, drive /serpentine belts and pulley changed. When I started the car, it was idling rough, no power at all, when press acceleration nothing happens instantly, then very slowly it speed up. Check the new spark plug, which has done 1 mile hardly, they were black. All 4 got black. Few codes came up too, initially it was p000A , when I changed camshaft sensor it disappeared and 2 other codes came on, p3008 and p0341. Then I put the old sensor back, then only p3008 remained. I replaced coolant temp sensor, thrust sensor, camshaft adjuster valve, put new spark plugs, fuel filter. And also double check each & every part for compatibility, that bought from main dealer. After installing new spark plugs, I started and it was same. After 10 minutes, I again checked all plugs, they all had slightly black carbon on them, all 4 were in same condition. No oil, just black carbon. I was thinking may be I left any vacuum pipe loose or not back in? But if it was vacuum leak then the spark plugs shouldn’t be getting black carbon on their tips. More fuel coming in as compare to air, that’s why I changed coolant sensor, I thought it was causing spark plug fouled. Can faulty high pressure pump cause this condition, rough idling, misfiring (if look at exhaust), spark plug getting black with in few minutes of idling. Also can these symptoms caused by over filling of dsg oil? I put back same amount of oil (4.8 litres)which was flushed out ? Please help

[@neilray8416]

You are such a blessing for us DIY's. Thank you for sharing your talent/knowledge.

[@ScannerDanner]

Thanks Neil!

[@ericlawrence7246]

Danner how often out here in the field putting our back into our living , that we don't have access to pertinent information . You Paul have obviously changed the course of diagnostics

[@rhkips]

You'll be hard-pressed to get a Hyundai of that vintage to throw a code or fault a drivability issue with it in park. The automotive school I went to was supported by Hyundai, and we would spend hours unplugging stuff, trying to get them to set a CEL so we could play with scan tools, and they just wouldn't until you put 'em in drive and scooted around the parking lot a bit. Another awesome video, Paul! Loved that hard bucking; been a while since I've seen that!

[@reweydewy]

Brian Petterson for sure. Not bad to work on either

[@seansy59]

Thankyou thankyou thankyou. I've had my car in the shop 5 times this year for multiple things. This just started after the car was great for 2 months and I flipped thinking now what happened. My car is doing exactly this and now I know I can fix this myself within an hour. THANKYOU!!!!!!!!!

[@ScannerDanner]

Awesome

[@pauljs75]

There's also a fun MAF failure mode on GM's 3.4L 60° V6 that doesn't throw codes at all. It will fail in a way that produces a value within the allowed range, but it stays stuck at a wrong value. Maybe too much soot and shmoo from the EGR gets cooked onto the hot wire in the sensor? (That hose is in a bit of an odd location.) Anyhow it produces some really weird drivability issues. Basically it interacts with the programming of the automatic transmission and it acts like it's hitting a rev limiter before it reaches the RPM needed to upshift into higher gears, mostly with the 3rd and 4th gears. And for obvious reasons, it's annoying as hell when there's no idiot light but definitely acting up with something wrong. The good news with this is that the MAF is a hell of a lot cheaper than anything to do with the transmission itself. It's just how that feedback system works with the computer.

[@pauljs75]

@taxationistheft2.0 No problem. Hopefully that fixes it. At the time, three different guys at some dealership were trying to figure it out before a guy from the next shift showed up and knew what the deal was. But it took three days after dropping it off. Hearing the explanation was amusing though, since I thought it was some kind of transmission issue too.

[@farmerjim-fat-man-do]

Another good video but one concern. I realize this is an old video and others may have commented on this already. Replacement of MAF may have not been needed. The intake hose was loose and MAF could have been dirty due to air bypassing the filter. Tapping the sensor could have knocked off a chunk of smoo allowing it to come back into proper range. Unable to repeat fault condition in driveway indicates it may have only been dirty. Once the loose hose was found, cleaning the MAF and testing to confirm condition would of have been a good course of action. If tech replaced MAF but failed to tighten the intake hose the problem will reoccur at some point . If tech replaces MAF and tightens hose problem is fixed and will not reoccur but at the expense of a new MAF sensor. For a shop they would most likely replace sensor versus taking time to clean and further troubleshoot. For home gamer that 150 bucks or so for a new unneeded MAF cuts deep into the beer budget.

[@W.Khairi]

If it was a dirty maf you'd think it will have a lower reading a cross the board but it will never fluctuate the way it did, The failure pattern seems to be electronics related

[@ashleylong8829]

My car is doing the same exact thing..been researching all day..this video just helped out big time. Thanks!

[@ashleylong8829]

That's what it was..its running great now 👍

[@johnedward8352]

Was your car stalling out? My car is stalling out and has a check engine light on

[@RAVETOR]

This is one of your best videos imo. Very informative!

[@dougsanders6034]

Thanks for your informative vidios. I have a 2003 Ford Taurus , 3.0 vulcan V6. I have no check engine or warning lights that remain on the dash while driving . They all light up while being cranked. I had changed my air filter , so I took the hose off going from my filter to my throttle. I had to unplug my MAF sensor and a PCV hose. I reinstalled my breater tube , but forgot to plug my MAF sensor back up, since it was kind of hidden on the lower side of the breather tube. I just plugged it back up while it was running , expecting that it would change the way it ran. It didn't change it at all. I unplugged it again and plugged it up again with no change. I have never experienced this before. ( weird) There are no warning lights on the dash and the motor runs and cranks good. I have an autel scanner, and it doesn't show any recorded problems or codes either. I don't claim to be smart in this line of work, but this has me stumped. Again, love your vidio's

[@sory4beinanonymous]

I watched this 20 minute video to see if you would do a voltmeter test and all you did was bang on the maf sensor. And now i’m just jealous of ur expensive scan tool

[@ScannerDanner]

i have some other MAF videos that have a glitch where I show the meter tests. But the scan data showed voltage of the MAF right? It wasn't in grams per second if I remember. So basically the voltmeter would have shown the same thing.

[@doubleedged9194]

Great vid scannerdanner what signal and voltage should a good MAF should be reading?

[@Splashfun2000]

Hey you've been good to answer my questions and I appreciate it. Just watched this, some similar symptoms , my daughter calls me and says her car has no power, doesn't accelerate, she thinks it's the transmission, it's a 2011 Kia Sorento with the 2.4L engine, standard engine, not GDI (I own 2 Kia Optimas and a Hyundai Santa Fe, all have the 2,4L engine but they are the GDI, so I'm pretty familiar with it) , I go to her house and read the codes, it's showing P0170 Fuel Trim Malfunction (Bank 1), most often reported fixes were replace O2 sensor or check wiring, replace MAF sensor or check wiring, leak in Evap system. I take it for a drive and use the bump shift and not the full automatic, seems to shift fine, little lag with a couple of gears, she was right, not much acceleration especially on hills. I'm thinking it's some kind of fuel or emissions problem. Didn't have any tools with me so i decided to take a chance and drive it home, I live 70 miles away, I got it up to 65-70 on freeway it was slow but it got there, here's my big question, I'm watching the fuel trims on my scanner, they don't change while I'm driving, Short Term Secondary Oxygen Sensor is 0.0, Long term Secondary O2 sensor is at -18.8, the Short and long term fuel trims stayed steady also, I know that's not normal, they change briefly when I stopped but once i was moving the hit a number and never changed. I haven't had time to check compression yet, too hot outside but thats first on my list. Any suggestions ? It had similar symptoms a couple of years ago but she didn't want to bother me at the time so they took it in, ended up replacing the catalytic converter, makes me wonder about that.

[@ScannerDanner]

STFT at zero and LTFT fixed at -18 sounds like a forced open loop condition, where the O2 is being ignored. Do you have O2 codes? What is the O2 doing? What's signal voltage?

[@Splashfun2000]

@@ScannerDanner I can only monitor the fuel trims on this. I would backprobe the connector but not sure what all the wires are. It's a NTK 5 wire sensor, I know blue is +voltage but unsure of others. I cleared the codes, ran it for a bit, read the codes and took a screenshot of what it's showing. Long Term Secondary Oxygen Sensor Trim Bank 1 is 19.5% and thats the high and low. Short Term Secondary Oxygen Sensor Trim Bank 1 is 0.0% Long Term Fuel Trim Bank 1 is 0.0%, ranged from -3.9 - 0.8% Short Term Fuel Trim Bank 1 is -2.3%, ranged from -100 - 8.6%

[@ScannerDanner]

@@Splashfun2000 that's a wideband and operates on a 4 milliamp signal range that you won't be able to directly measure. You MUST have scan data to troubleshoot it. Global data should give you that signal equivalent in either voltage or amperage

[@Splashfun2000]

@@ScannerDanner Okay had to get creative with a hookup but was able to measure to measure fuel pressure, its good. Figured out how to see the wideband data on my scanner, all the "live" wideband and downstream sensor data are in normal ranges. Only thing that seems funky is the "Long Term Fuel Trim", the minute I start to accelerate it goes negative, which if I understand it is the computer is trying to lean out fuel mixture which must mean its seeing a rich condition ? But all the pid's seem normal/okay, I would expect the check engine light to come on but its not. Double checked catalytic converter (it was replaced a couple of years ago because of no power, bad acceleration) it checks out also, new spark plugs, car idles fine, sounds smooth, revs nicely in park or neutral, the minute you drive it, no power. Wouldn't think this would have anything to do with emissions but it does have one problem, will not shift when in automatic mode but manual shifts fine.

[@nicknicu1787]

Well done Mr Danner! :thumbup: I recently had a 2009 Toyota Corolla that didn't even run with the MAF unplugged.

[@ScannerDanner]

Exactly! Everyone suggesting the unplug it test needs to listen up. The test is great! Just know it doesn't work on all cars. Thanks for helping me make my point!

[@ichoozjc]

@@ScannerDanner Isn't this because of the VE tables? Technically shouldn't the engine run fine without a MAF?

[@EricChee]

thanks for another vid. love this "teacher" whenever he say Hyundai in English with really close pronounce to what actual Korean native speakers say. Not "hyoun-die" but He always say like "hyeon-dae"

[@SmittySmithsonite]

Cars never leave you for dead on a SUNNY day, do they? Seems to be the way out here too! :D At least you didn't have to hoof it back to the shop! That would've made for a bad day ... I just had a vehicle here not too long ago with the same o2 readings. I was doing mechanical work to the car (no codes) and was just curious, so I plugged in my Autel. Thought it was my scan tool misinterpreting the data. Glad I didn't have any drivability issues, since that sensor works BACKWARDS! I didn't know that then. That would've made for a looong day! I ALWAYS learn something on each one of your vids! :)

[@thebullshorns4104]

Dude I had to drive like that for about 2 miles with my 4 ways.45 minutes later and half the town mad at me, I got home.Changed plugs, wires, fuel filter , broke heater core connector (17 bucks).Come to find out its my mass air flow sensor.

[@stevescott8758]

1st time I've seen you break down on a road test. GG 👍

[@WILSON.1]

Excellent video and explanation as always, man. I'm not sure if I missed it (watched the whole video), but how do you know if a cars O2s are opposite like in this case (i.e. low voltage/rich, high voltage/lean)? Is that because of the make and model or a result of the problem happening in the car?

[@ScannerDanner]

First, make sure it can respond to ratio changes. (snap throttle testing works well for this) Second, a decel event will always cut injection pulse. So you can always verify the lean side of these O2 sensors during that condition. Hope that makes sense. Thanks!

[@WILSON.1]

I think I get it, thanks man!

[@ericlawrence7246]

Thanks Danner . In all honesty Paul you single handedly changed my career , thank you my friend . Top Drawer

[@jimlong2755]

Eric Lawrence k mmm j

[@abzbrk490]

Hi Paul I had the same problem with a KIA optima 2004 and the problem was the crank sensor under the exhaust manifold was melted with the heat and shorting. changed it and that fixed my problem.

[@Gagik5779]

Hello again Danner wonderfull video ,many times when maf sensors was built in a not very small componetns I had change in it comparator or shunt resistor on the same issue now opening MAF sensors we can see very small things and we must throw it in the gasket

[@Travelingman-1980]

The North Koreans hacked this one at the South Korean factory Paul. Lol. You are always teaching something new, ie: reverse voltage O2 sensors, thanks.

[@ralfsautomotive]

Looks to me this was a NO power diagnostic rather than a low power. 😁 Wished I was closer to you I would have the perfect case study for you. No Start, no CAN, NATS tripped and intermittent driveability when it was running 3 years ago LOL. I was thinking of making a video on how I will go about fixing it but I'm just not a Camera person. 👍

[@josepeixoto3715]

Well, there is ALWAYS another way other thanthan wigling the connector and stressing the pins,when you have readings that jump around; i'll tell you the way i do it: (this has saved countless hours and money!!!): 1- you *MUST* measure thickness of the terminal male blade connectors on the MAF itself (remove it,if you do not have another one ); i eyeball that with a caliper (i am always within .003" that way),if i don´t have another of the same,broken, maf around 2- cut 3 to 6 inches of solid copper wire,around 1mm2 3- grab a hammer and hammer down the tip of the copper wire to the thickness needed (most times around .025) you will be amazed at how EASY it is to PERFECTLY turn the copper round wire into the BLADE you need 4- grind the blade to the width needed ; the one i have in my hand right now,i hammered and ground both ends ; to .060 and .100 and thickness .025 5-- use the blade to TEST EACH female receptacle in the harness connetor ( maf,or anything else); The materials they use for the spring female connetors are sometimes not springy enough, cheap, (should be berillium copper,tinned) and after a lot of shops attacked them,they no longer make a positive contact; then i pull the plastic "finisher" on the plug and with a tool (i use a small screwdriver,specially groung for that) i re-bend the receptacles,test again with the copper blade (tight means VICTORY!!)and re-assemble; never fails.

[@quisqueyatvw.5174]

Hi there! I was having almost that same problem but not as rough like that... the maf sensor was the issue and still is since I have not been able to get the me maf sensor for my Hyundai Santa Fe 2005 2.7L, what I did was to disconnect the sensor and the runs ok but when I reduce almost to cero it looses power or the car is not getting enough gas...

[@thinman8621]

Makes rocket science understandable. Thank you.

[@Warren1814]

I have a 2000 ford e150 van and they can't seem to find what is wrong with it. the codes are P0171 and P0174. Change the MAF sensor on it 2 times. And then thing is. It runs good... but the service engine soon light is on. I keep trying to tell them to watch your youtube channel and they could learn something.. After watching this video of yours.. I am pretty sure i am not having a MAF sensor problem (maybe). Like your channel very much!!! Keep up the good work.

[@UNKLELUKE86]

I really enjoyed the suspense and car stall was nice . I feel like just replacing mine just because I have 230000miles. 2000 Nissan i30 . I bought a bluedriver scanner.

[@VladGoro25]

The best test for MAF sensors yet for me: wiggle it or hit it with a wrench. If it fails - it's bad :) p.s. Watched the whole video, glad we have same methods :)))

[@wjs1820]

Thanks again, you're videos are very helpful.

[@jimcook8933]

I sure do miss the old days when Bob would come over with a dozen stubby Molsons. We'd sit on the porch for an hour looking at the darn thing, finally he'd look at me and say, shoot some carb cleaner into that Holly double pumper and throw on a new oil filter, and you should be good to go!!!! Great vid by they way, had to get out and beat my maf sensor as well, got me to where I wanted to be, now looking maybe to clean It! .

[@harrisdarryl6]

I've learned more from watching him also i spent a lot of time in community college and learned more about this from watching his videos coinciding with my books and jobs that have been brought to me. Hopefully one day i can get premium 😄but the few free videos are priceless we need more geniuses like him and all of us abundant.... On cars for 17 years loving it

[@Ashroyer86]

I just got an Escape. At idle the load shows 29% with Bank 1 and 2 trims being around -10%. Ocassionally the vehicle will stall at idle. I'm leaning towards MAF sensor. The trims read normal under light load, haven't road tested it yet. The G/s are reading about 3.5 at idle so I thought that was normal but then again my $20 bidirectional tool im sure is only showing averages.

[@zurn56]

My jeep was having issues stalling & the idol doing what that car did. I cleaned the throttle body, replaced the IACV, o2 sensor, & PCVs. They helped but didn't fix it. I watched this video & borrowed a buddies scan tool. Yup, my MAS was done for. 25 year old Heep is dubbed the Struggle Bus.

[@johneric3886]

Another good video scannerdanner. Hope you're well. I just finished a bicycle trip from Cleveland Ohio down to Cincinnati and back. Took the Ohio Erie Trail. Just mention that to you because I know you live somewhere in Pennsylvania in case you ever had any interest in riding it.

[@victorvillasana3409]

Before you buy a new maf sensor, check the air filter box for a mouse nest. Will choke the air flow. Typically cars that sit long periods especially in the winter.

[@ScannerDanner]

That is a good tip but will NOT cause the MAF signal to drop or glitch to 0 volts

[@jonathankilmer8949]

Good morning Dan, I have a situation with my 98 blazer. Obviously 4.3, I'm 2nd owner 96k miles. However I can't seem to figure out the problem with it. Bottom line is a fuel delivery issue. I have completed a pressure test and test came out around 50. Before the blazer completely broke down ( crank no start) I had to use starting fluid to start it. All my needles in dash are moving to full or high when I turn key on ( sometimes even stays when I turn off). I understand that could be unrelated I'm just trying to give you related symptoms. Personally I think I have a bad full pump so I jumped relay to send a decent current to pump for a charge and like I said the pressure is staying around 50. Still doesn't start. FYI the pass lock doesn't look like it's been activated.

[@ScannerDanner]

Your system will NOT start under 50 psi! It needs to be 62+ during cranking. I agree with you, it sounds like a low fuel psi issue

[@vizualizeit08]

One of his best videos ✌️

[@master1235534able]

I have a BlueDriver, and it’s reading MAF using units lb/min. Is that the same as looking at your graph that reads in volts? In other words, will I see a big peak in lb/min as your saw when using volts if I should try to accelerate hard?

[@derrickrobertson3334]

My little 01 frontier XE is doing basically the same thing.. it's a 5dpeed. Was just driving along and it starts like jerking spuddering. My first thought was fuel pump and filter. Thing starts up and sits idling fine. I start out, and anytime I get around 2000rpm... It starts spuddering. Like it's running too rich I gotta figure this out.. ran codes at advance, popped up MAF SENSOR. So I gotta decide, I'm digging the info, thanks

[@ismaelcarrillo3956]

If you get stranded you can also disconnect MAF sensor and drive on limp mode.

[@alvinlawanto]

5:56 i need more of this simple yet clear theory

[@blueridgeburnouts8265]

Are there resources to indicate normal range of sensor data?

[@MaicSalazarDiagnostics]

Paul that p1372 is related to the crank sensor and actually is a very common failure on Hyundai.

[@ScannerDanner]

Got it, thank you. I never looked at it.

[@weeverob]

My 2000 Ford Ranger which I have not driven for 5 months has lost its ability to drop into the passing gear. I can put the pedal to the metal and there’s no gear change. Otherwise the truck idles beautifully, accelerates smoothly, gets great mileage and there’s no check engine light. The reason I came to this video is that on a forum it was suggested the mass airflow should be cleaned as well as the IAC sensor. By the way I cleaned the MAF sensor using the cleaner specifically make for that part. Any thoughts? Thanks much!

[@ScannerDanner]

IAC definitely has zero to do with the kick down. MAF could be related but only if you're starving for fuel from a contaminated hot-wire in the MAF. You said it runs good right? No low power at wide open throttle (WOT)? If so, its not a MAF issue either. So if you drop it down a gear manually, it runs as it should? If so, focus on your TPS, this is the input used my the engine computer for transmission shift points. It should be near or over 4 voltage at WOT

[@weeverob]

@@ScannerDanner Mr. Scanner, thanks for replying. I appreciate your help!

[@wyattoneable]

Nice graphics to support the diagnostics.

[@SurvivalInFlames]

Awesome video as usual. Quick question, When the MAF voltage dropped out and throttle angle was 40-45%, why was the RPM PID acting wonky? I can only assume because the engine is bucking and the crankshaft sensor is reading erraticly?

[@RobertHancock1]

That's what the engine was doing. When the engine would start to rev up, the ECM would see the abnormally low MAF reading and cut down the fuel delivery, causing the engine to bog down. Once the engine slows down it's not so lean so it starts to rev up again, and repeats.

[@dittybur]

Ty for you video awesome teaching me better than when i went to school.

[@ricardorgm30]

How clogged was the throttle valve?

[@jimeylee2036]

Awesome video! Would a MAF cause hesitation/hiccups at only one rpm range? Say 13-1500? Otherwise it runs fine.

[@ScannerDanner]

it is possible my friend

[@allgood2791]

Hi have a funny story,started watching these videos after having hesitation issues in low gears low revs on a 2004 TJ Wrangler with no codes in Australia. Suspected TPS or some other sensor. Was asking about scan tools in a parts store and a customer overheard me and asked did i want him to scan my jeep.So yes and he just happened to have a snap on scanner like scannerdanner him. I him a some cash and did a scan and every thing looked ok but he seem to think it was fuel related or plugs but i already changed them. Was running 91 which i heard can be pretty dirty here after asking around. So i ran a bottle of fuel system cleaner and started using 98 octane. Seem to have fixed the problem for the most part. Was thinking fuel pump or regulator,will wait and see.

[@HUBBABUBBADOOPYDOOP]

*LOL...Desolate country road, pouring rain, engine dies. Only Scanner Danner says "AWESOME"*

[@ScannerDanner]

haha for sure!

[@yewwtooob]

You hear banjos....run!!!

[@johneric3886]

That's such a funny comment Hubba Bubba. Really made me laugh out loud.

[@thomaswilliams2780]

Got a 2000 Holden Astra (Vauxhall/Opel) 1.8 No lights on, but hiccups under acceleration, much worse in warm weather. Watching this as I suspect it may be a bad maf HT leads + spark plugs are only about 18 months old Any other possibles?

[@emilysoloman7698]

@scannerdanner I’ve got a 1988 Turbo Supra. Car hesitates badly under mild throttle or jerks under hard acceleration when in 4th or 5th gear. It’s good in 2nd or 3rd unless you go pass 4K rpm. Then it jerks really hard. It doesn’t have anything to put an obd scanner in to look at those readings. How would you diagnose it?

[@AnthonyPetitt]

Hey Danner, I ordered a new mass airflow sensor because cleaning it didn't fix the problem also the sensor wiring harness kind of broke the clip so I'm not sure if it's good connection so I ordered another one of those.. my question is splicing the wires... do they have to go in a certain order? I also read somewhere ....Scotty kilmer... that if you spray mass air flow cleaner while it's still on the vehicle you could short circuit things.. I hope that's not the case, what does he mean by that?

[@ScannerDanner]

yes, absolutely you need to wire a new connector properly, and Scotty is not wrong, you do not want to spray MAF cleaner into the MAF sensor with the engine running as the MAF circuitry can be damaged by the cleaner when it is active

[@roadstar499]

So how did you fix??? new connector? I think i have same issue with a 2001 blazer runs horrible no power ..just put a brand new MAF and i get PO102 code... so i think its a bad connection or ground but am not sure how to fix...any suggestions ??? No fancy scan tools available...

[@andyclemente4205]

Good video brother. Learning some stuff from you

[@robinsonsmotorcycleandauto3929]

Great job scanner danner thanks for putting up the great videos

[@ScannerDanner]

Thanks so much!

[@brazilianguys568]

Thanks a lot man, I am learning a lot from You, I can"t wait the time that I buy an oscilloscope

[@JustasJ]

How to troubleshoot maf sensor: smacks it. :D awesome video!

[@vt2704]

I have been using a amp probe meter and a separate ohm meter while I been learning as much as possible on the premium channel. I want to get something cheaper right now. What do you suggest? I seen you using the blue tooth scanner and the generic scanner that if I remember correctly you sais it was a $1000. Thanks.

[@ScannerDanner]

I have a bluetooth scan tool that I own and have used listed in the description above. Hope that helps. Thanks!

[@monica93304]

We have a brand new Verus at the shop. I'm hard headed, but you break it down to simple terms that a girl can understand.

[@ScannerDanner]

Thank you! I have a 16 part Verus training series on my Premium channel if your interested.

[@Z14kt12timandjes1]

Question on the wide open throttle test. Do I need to put put the pedal to the floor from from a dead stop or can I gradually put the pedal to the floor to help ensure the car wheels don't lose traction? I've done that test in some low power economy cars with no problem. But I did it once in a more powerful car and the wheels lost traction and the car fishtailed a bit.

[@ScannerDanner]

No, you can ease into it before you go wide open. Thanks!

[@stationaryenginesworldwide]

That o2 was a narrow band sensor lean high volts /rich low volts... so wide band sensor reads high volts rich /low volts lean.correct? Good video by the way Paul.....

[@ScannerDanner]

Widebands operate completely different. There is a 2-4 milliamp change that cannot be measured easily. Everything on the scan tool is processed data. The voltage changes are not really happening like you see it on scan data. But yes, you will see opposite readings on the scan tool on some. I'm not sure I would say all.

[@lastking3216]

Will a bad mass air flow sensor cause your truck to not crank

[@ScannerDanner]

No!

[@cwj9202]

Years ago I hot wired some resistors between the Ref V and the signal (to bypass a sensor which I can't just now recall), and that allowed the 120M grader operator to drive the rig back to the shop. In your excellent video, would it have been possible to achieve the same for the defective MAF sensor?

[@BigD1395]

That's similar to what I'm experiencing on my dads 1998 Chevy Silverado so it seems I should be checking voltage on it, right Paul?

[@ScannerDanner]

Those have good backup strategies for the MAF, unplug it and drive it. See how she runs

[@joniray6686]

New to shade tree mechanics, and no real understanding of the use of scanners. but my guess 1:40 min in is a bad or shorted constant volt reference on or near the maf, maybe the map sensor, probably maf. going to keep watching and see if I'm right.

[@dominicdo]

I'm wondering would the vehicle have run better with MAF disconnected? at least this way you could have go it back to the shop.

[@todayintheshopbanksy5904]

Love the 'That was cool' comment when she was playing up. We would all be thinking, this is anything but cool if it was our car lol

[@ScannerDanner]

Lol guess I'm weird

[@brandonspencer309]

I just felt with this same problem on my ‘01 Audi A4q luckily I figured out that if I unplugged my MAF it would drive me back to my place as long as I stayed under 80km/h!!!!...

[@lerg12]

1996 F150 with the 302 in it, I got the P0102 code, P0113 code, and P0414 code. It bucks and jerks when I feather the throttle to get it to go at creeping speeds under 5 mph, it bucks and jerks as if I’m putting the throttle down 75% of the way from stop. Might I add, from stop to gradual takeoff is the only time it surges/bucks/jerks Not only that, I can cold start it and it’ll usually start up in one go, but when I drive to that first destination, shut it off for like 5 mins then turn it back on again, it’ll take me 2-3 attempts to get the thing started again, the failed attempts are it starting then stalling out immediately. I replaced the MAF sensor, Throttle Position Sensor, Idle Air Control Valve, cleaned the throttle body and valves, changed my spark plugs and wires, still no luck. Any ideas? I’m thinking now it’s either a vacuum leak or a MAF connector issue now.

[@ScannerDanner]

The p0102 code is MAF, what are the other two and do they all come back at the same time after you clear codes

[@lerg12]

@@ScannerDanner the other two are P0113 and P0414, both of which come back after I shut it off then on again after it’s warm, same fine as the stall start

[@ScannerDanner]

@@lerg12 definitions of the codes, I realize I can do the google search myself, but I'm answering a hundred other questions right now

[@lerg12]

@@ScannerDanner I hear that, P0102 was MAF low signal, P0113 was Intake Air Temp sensor high circuit input, and P0414 was secondary air injection switching valve shorted. Although I don’t think I have to worry about P0414 if it has to do with the smog pump because I deleted it

[@ScannerDanner]

@@lerg12 On some of these the MAF contains the IAT circuit within the sensor itself. Focus on your MAF for sure. Try driving it with the MAF unplugged and see how it runs. If it runs good, DO NOT be in a rush to change that MAF because you also have an IAT code, so this is suggesting a poor ground to that sensor.

[@Warmwinterz]

Had a maf sensor fixed in my 91 firebird after having the same symptoms as this car with a service engine soon light coming on. After getting it fixed i can still feel a slight hesitation when accelerating around 40-50 mph. Sometimes at lower speeds. The Idle seems to be a little jumpy as well. When coming to stops it feels like it might stall (500rpms)Any idea what i should have checked out? No Service engine light is on at the moment. Thank you

[@ScannerDanner]

Check you injector resistance. They should all be 12.6 ohms each. Search my channel for "shorted injectors" and you will see what I am referring to on your system

[@f1fiftyboost13]

I've replaced the accelerator Pedal? I have a 2002 2.8l GLI I replaced the pedal because it was throwing codes p2138, G79/G185, p1639 but after driving epc light ABS and Trac light come on again.. I'm lost any input would be helpful 18047 - Accelerator Position Sensor 1/2 (G79/G185): Implausible Signal yeah I'm at a loss.. the only codes it threw were the ones listed above. If it had something to do with the TB itself I would think different codes would come up? The scan was done on a Solus Ultra (snap-on) also cleaned the TB (alot of carbon build up) and clean Mass Air flow sensor. But adapted TB Also Replaced the brake tailight switch just to be sure. Still same thing. Also when I release the brake pedal I hear a hissing sound but my pedal doesn't seem hard nor does it make noise while driving just when i let off the pedal? Does this mean brake booster or master cylinder bad?? Guess it sounds like i need a ECU. I have 1/2 throttle though it only comes on in a middle of me drive and limits my power to half

[@robpaul7900]

So on a GM 2001 Silverado positive number would be lean right? I have a problem trim numbers keep going up I've done 2 smoke tests no leaks changed the maf sensor changed all 4 O2 sensors. I'm about at wits end with this trucks trim numbers they are getting up to around 18 and sometimes go down to around 10 bank 2 is always lower than bank one. Any advice? Fuel pressure test was good too no evap leaks.

[@ScannerDanner]

Yes, positive is a lean condition. What are your trims on both banks at idle and at 3000 rpm in park?

[@jorgemecanico10]

good video I have a similar problem with a santa fe year 2002 the voltage is fixed at 0.01, I am waiting for your book in Spanish, greetings from Miami my friend

[@beefeekeefee]

Seems like to O2 sensor readings are consistent with wideband AFR sensors.

[@Destructive_Asylum_13]

I need some help bud. A couple months ago on my vw vr6 the intake manifold blew & I replaced it now keep getting p1136 lean code. I have replaced one sensor bank 1 same code took second hand manifold off & put right stuff seal to make sure no air leak still code. Changed fuel pressure regulator & may sensor still same code. Can't figure it out ?

[@amadafaka]

I lost power on my 04 Subaru Forester XT with a dirty MAF. Cleaned it up with carb cleaner and its now back to normal.

[@ScannerDanner]

I prefer brake clean, some carb cleaners leave a residue.

[@jacobsebastien3910]

I prefer CRC mass air flow sensor cleaner.

[@Shirkatron]

Love your diag. I've a Subaru SM Tech and I would kill to work with someone of your skill level. I've also been on a test drive with a dying MAF sensor, similar situation... wouldn't let me accelerate back on the hwy...wouldn't drive above 10mph. So I unplugged the MAF and forced the ECM into limp mode, do other manufactures have this built into programming?

[@ScannerDanner]

not all of them do, so it is not a 100% reliable test

[@brandonspencer309]

My ‘01 Audi does! So I would assume all/any VW/Audi would fit this category 👍

[@petar443]

Great weather..for being home with whiskey and almond

[@shaunsautorepairs5410]

Hi paul,Refering to a previous maf video where you had substituted values enabling the vehicle to run with a bad maf sensor. On this vehicle scan data was showing the voltage dropping off to near 0v where the vehicle was not driveable..My question is why does it not put substituted values in as soon as it detects this enabling you to continue driving or is it just the case that certain vehicles this kia included do not use substituted values. Is this a difference between digital and analogue sensors.Thanks

[@ScannerDanner]

Not all car have good back-up strategies for MAF sensor failures. Even if it does you'll still have symptoms until the PCM decides it will no longer use the MAF sensor signal and again, every car is different with this threshold. Analog or digital output has nothing to do with this strategy. Hope that makes sense.

[@derschafer1012]

If you had a plugged exhaust on a car with a MAF and MAP sensor, would it still be possible to throw a code for the MAF? Or would the computer see a congruency between the MAP and MAF and throw a code for the TPS since it would be the odd man out?