Diagnosis and Understanding: MAF Sensor Pt2: P0100, P0101, P0102 ...
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- Опубликовано: 31 июл 2024
- In Part 2 we take our understanding from Pt 1 and apply it to two different vehicles and see if we can figure out the circuitry design and output data using non-scantool methods, scantool methods, and a new surprise method ;-)
Part 1 (includes references to other videos) is here:
• Diagnosis and Understa...
Part 3 is HERE: • Diagnosis and Understa... 
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I am very grateful for this channel, I am from Brazil, here it is very difficult to find technical information of quality or even in the Portuguese language. With this channel I learn a lot for work in my workshop that is near Curitiba.
Thank you very much .
Alexandre K.
I like the way you teach, your understanding is very strong and you do it in a simple way
Thank you very much
At 22:13 ish "I hope I'm not loosing you here" no way I was getting way into it! A great video series as usual Matt thank you!
Great video and congratulations on the new toy. I'm looking forward to future videos where you can put it to use. You do a very good job of explaining everything to enthusiastic beginners like myself. Another thumbs up for this series!
Johnny M Thanks Johnny- this definitely opens up a whole new ability to cover even more advanced component diagnostics like crank and cam sensors, ABS sensors, etc
Amazing and very informative!!! Thanks for posting these!!
Congratulations for the new tool .
Good luck with it .
You're doing a great job for a lot of people thank you for all your help
So nice of you to say!
Awesome video. I learned a lot. Thank you for sharing your knowledge.
Great informative videos, I just stumbled on the one you did on fuel trims and eversince then I've become an addict, thursting for more knowledge. All the stuff you've shown was greek to me but now, at least some parts of it, I'm starting to translate into english. Thanks you so very much for taking the time to show us how to do this and keeping the atmosphere light with your funny quips here and there
Thank you! And yes I totally get it. I also don't learn it the first time. Watching many times, sometimes over and over again and watching consistently is necessary before it finally sinks in. Sometimes you might watch a video years later and it suddenly makes sense now when it was greek the first time!
Thanks for the great vids!! I'm learning a lot!!
As always Matt the diagnosis and understanding vids are very informative and congratulations on your Vantage Pro.
White Tiger Thanks Tiger- it's definitely one of the best investments I've ever made (I refer to both the vids and the scope lol).
Matt,
Like many others have already done, I’d like to thank you for taking the time to create these videos. I’ve watched most of them already and I’m trying to rewatch some of them. You really need to watch video A before B to get the most out of B, but you need B before A to get the most out of A. I worked on vehicles many years ago and now after spending 45 year working in IT, I would like to try my hand at it again. When I started looking for information on how vehicles now work, I didn’t know where to start. I came across your site after watching some of Scanner Danner’s videos. I was looking for information about scanners in general and reviews in particular.
You have already saved my family several hundred dollars without me having to turn a wrench, by giving me enough information to know that a shop my son was going to use was trying to rip him off with some head work that didn’t need to be done.
I know you don’t like to do the bolt by bolt type of videos but there are “tricks of the trade” that can be taught by doing a little more in detail than you currently do. I know that I often reflect on how much easier a task would be the second time if I ever had to do it again. Just how to work in such a cramped engine compartment is helpful. The vehicles from the 60s and early 70s had enough room under the hood to hide a body or two. Now you need a feeler gauge to measure the distance between components.
Also you mentioned that you don’t want to do a tool box review, but an idea of what I should have/purchase would be helpful to me and probably more so to a younger DIYer. Based on your experience, you could list items in some kind of priority order, e.g., cheap DVOM - required, better DVOM with these features - nice to have or needed for this type of diagnosis. Based on your videos, it appears that many problems can be diagnosed without a scan tool, but it looks to take a whole lot longer. Based on this, I’ve purchased the Auto Enginuity scan tool. I work on Fords more than anything else, so it wasn’t that expensive. How about what tools you have or wish you would have had when you go to the U Pull It type salvage yard.
What other resources would you suggest for the times where I would run across a problem where you have not done a diagnosis and training video? I know that you have mentioned service manuals several times, but that seems too specific. I want more general information on how something is supposed to work and the process to verify that it is working correctly. Where can I find some text books and are they worth the effort to find?
Thanks again
Ray
Ray Gordon Wow great comment Ray, and almost had me rethinking some of my "policies" about more basic and generic information. The problem with doing things like tool reviews or procedural type stuff is you get a real dilution in the aptitude of viewers and therefore the comments and the whole "Advanced DIY" experience is diluted. For example, if I do a video on how to replace an A/C compressor, I am going to get a whole different population of viewers than a video on how one works and how to diagnose it. My philosophy is that my place on RUclips is for the catering to the latter, and the thousands and thousands of other channels that cater to how to actually change parts and stuff can cater to the former. Similarly, I would a severe dilution of my intent if I were to show a video on how to use a DVOM. Thousands of videos do that- how much better to narrow to an audience that knows how to use one, but I show what to look for in diagnostic application.
It is all part of commitment to quality over quantity.
Schrodingers Box Matt, I think you misunderstand what I’m trying to communicate, I
don’t want you to do a video on a DVOM.
What I would like is a prioritized list, based on your experience of
what tools I should have to be able to do 2%er diagnosis. Say I have the basics and I have some cash to
spend on something. Should I but a Leak
down tester, or a fuel pressure tester or better DVOM with extra features. I don’t like to be working on a project and
need a tool right NOW. I like to take
some time and look for a good deal and then have time to learn how to use
something before I need it. This is what
I did with the scan tool, took me several months to decide on Auto Enginuity
and it should be here with a day or two.
Once I have it, I will hook it up to every vehicle I can to learn the
tools features and functions. As far as the bolt by bolt vs what you do today, I believe
you can add some more detail without losing your focus or lowering your
standards. You have done this in some of
your videos, I just watched the door hinge and instrument panel bulb ones. I know how to take things apart, usually
without breaking parts, but there are many tricks that would help me. Although I have taken a door panel off
several times to work on the lock or window, I almost always have trouble
getting the panel reinstalled with all of the clips. If I break or bend on beyond use, it is
probably going to be on the install. You
must have had similar issues in the past and learn a trick or two that you can
pass on. My guess is that you think
everyone already knows that, kind of like ATF and acetone. Believe me, I don’t want you to lower your standards, your
site is the best one I’ve found for teaching me what I want to know. Once I learn a little more and can put it to
practice, I’ll try Scanner Danner again, but I didn’t know enough to get the benefit
from him. Ray
Wow what a surprise! new scope, congrats!
Matt, Congratulations on the Vantage! You will find that it is worth it's weight in gold! It will help you see things that you could not before and see the language that the PCM is seeing. It's good that you are staying with the basics and you don't need to use the Vantage in your diagnostic's on the channel but now you can use the Vantage as teaching tool to help people see what you are trying teach them. Great set of vids! Enjoy your fishing trip!
Billy R Exactly Billy, the purpose of the Vantage as far as this channel is concerned is as a teaching aid- though I have found myself using it regularly to save tons of time for personal use.
Really informative I have achieved a lot since watching
Literally have made pages of notes based on these videos. Matt you have awesome hair by the way I’m jealous.
Hahaha yeah I also have pages of notes myself!!!
Thank you for the knowledge! This is a fantastic channel.
Glad you think so!!
You might have just saved me a trip to milton ruben thanks
this series is good. Helps understanding of interaction of various sensors. Thks.
These lectures are brilliant, just right for my way of learning anyway. Though to get the RMS voltage I always thought you had to multiply the peak number by the square root of two, or to simplify just multiply by the peak by 0.707. ~Thanks anyway.
Schrodingers Box great video! Someday you're gonna and up at AIAG (studying GD&T) at the rate your going!
For the 99,9937%'ers, that's about calculating tollerances between parts, for example in car production. i.e. the tolerance of width for 2 parts that have to fit inside each other. Like your engine and gearbox connecting parts.
"What do you do if you're a mobile mechanic?..." Six cheap DVOMs, two cheap amp-clamp style meters, an AVOM, and two vacuum gauges. I am King of the Spaghetti!
Seriously though, I get asked a lot which scantool I prefer, and people are surprised that I just use my cellphone with a Bluetooth OBD II adapter. There are so many different ways to come to the same conclusion, and the nature of the diagnostics I do just hasn't put me in the position yet of needing to outright scope something.
All that being said, I won't lie: I bounced up and down for a moment when I saw the Vantage Pro come on screen there. ;D
Gawd bro, just change the MAF already! I can't undo two clamps and a connector without a detailed video tutorial!
rhkips Yes, I was all smiles as well. When I'm ready to get such a device I'll be jealous of myself. I'm too mature to be jealous of others (mostly) ;).
ON THIS VIDEO YOU TOOK ME BACK TO SQUARE ONE. YOU REMIND ME OF THINGS I DID LONG AT SCHOOL. AT LEAST BECAUSE I DID ELECTRICAL WHICH HAS A SMALL PORTION OF ELECTRONICS IT DOES NOT TAKE ME LONG TO UNDESTAND YOU. I AM NO MECHANIC BUT LIKE IT AND WANT TO BECOME ONE
REMEMBER , I AM WITH YOU FROM TOMORROW ON YOUR PAY CHANNEL. WELCOME ME. LOL
I hereby welcome you, lol!!
By the way what country are you from?
@@SchrodingersBox SOUTH AFRICA , GROBLERSDAL
Ok send me a PM with your email and I will check it and give you access to the pay channel
You are a great man.
Excellent pair of videos, top information, thank you.
Regards Roger
Glad you like them!
Hi Matt, congratulation for you new tool toy ejejjeje.
I am sure you will enjoy it. Now you can make new experiments and let us enjoy these.
Pablo A Thanks Pablo- that is the plan. I absolutely love it- I will discuss it in an upcoming video
Whenever your wondering about the motivation of a manufacturer. If it's cheaper, it's the way they'll get things done. So some MAF staying analog isn't surprising. It keeps them from having to change PCM design. Heck, since VANE's ran on potentiometers, I think the analog MAF's were designed that way to purposefully not need a PCM redesign.
This is just me making things up, but it makes sense.
exelente clase cada dia se un poco mas
You’re an artist
Nice sign on top of your clock. Have the same one at my shop.
Thanks for the awesome explanation.
Small correction: 7:20 duty cycle is the ratio of time on to the period (time on + time off)
thanks for the uploads, i really learnt something about the maf and diagnostics :)
bkktony Learnt? lol
Schrodingers Box im dyslexic
bkktony Lol just pulling your leg bro. It's "learned" but then again perhaps you are from Great Britain in which case "learnt" is normally used.
yer same same ;)
Saweeet! Congrats on your latest acquisition.
I'll be going to school soon for auto tech. During (Oh no. I forgot the word. The word when you are familiarized with something. Begins with an I. Not interview and not interrogation.) the instructor told me that most students go straight for the Verus with a touch screen even though it supposedly isn't as capable as the Modis with keypad integration. I have a feeling that I will probably be up there near the top of the class. Particularly thanks to you! Thanks Matt!
***** I believe the word you are thinking of is Orientation?
Do I get extra points since it didn't start with an "I".
Otherwise it would be Introduction.
Schrodingers Box Ahhhhhh, indeed the word I'm looking for was orientation. Thank you!
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 RUclips is also the most under-rated. Forget the others, just filter your search results to include only those from Schrödinger's Box.
Well done, I followed every step and understood everything. Congrats on the new tool, your upping your game quite a bit. I think it is great your mastering another trade. Hey if they cure cancer your out of a job. With advanced vehicle diagnostics under your belt and mastered the trained monkey bolt removal technics you can open your own shop :)
Steve Rob It has crossed my mind....
Leaving comment for the youtube algorithm! Watching these videos so I can become a 2 percenter!
You rock!
9:40 4volts not 0.4 volts. Excellent lectures very good technical advice.
2:30 - 2:50 ah yes, do not set your multimeter to amps! Do not spaz out and cross the streams while backprobing!
The hz part gives me a headache, i went through advanced electronics school and my brain can crunch all of it, i'd just rather watch only the stuff i want to see, but skipping around will get me nowhere, and if i watch your whole 1 hr video i know i'll have everything i need because your videos are the very best.
thanks man!!
yeah when I need to do hz I always use a scope. I don’t even use a multimeter capable of reading hz but even if I did it will only show an average and its entire possible to have variable frequencies in a sample in automotive application.
I always wanted to be an engineer, your a great teacher.
Matt congrats on the Snapon scope... swweet price.. Have a good 4th.
Congrats on the purchase of the scope Matt.
Thanks Tom!! Its a game changer for sure
Great vid! @9:40 I think because the multimeter has a capacitor in in, to level out the reading. Also, the pulse width is 80% off, not on. Remember, the sensor is not the source of the signal, but the 5V wire is, which is on all the time. The sensor, just sends the pulses to the ECU (ground) that's why the signal cuts from 5V to 0.
The pulses are in reverse, since you used the 5V as your baseline. If you would have tapped the signal wire off to the ground, you'd have an upwards pulse, instead of a downwards pulse. :)
5:30 -Indeed you are learning,young electro-jedi! I was waiting to see if that would throw you a curve ball..and then you nailed it. :)
Hahaha yeah I was pretty proud of myself for that! I am sure you can see how much I have learned since just a year ago eh? A year ago I would have thought I was measuring an analog signal for sure lol
Does your scope has a way to synchronise the sweep signal, so that the wave pattern does not drift.
I’m not a mechanic but I’m learning a lot with all your videos. Thank you…
I appreciate that. I have a lot of viewers who don’t even work on cars at all but they just like following along solving the mysteries!!
you should start a mechanic school!!❤
Air intake pressure sensor was the MAF on oscilloscope
Hello, Sir. The second car in your video is a Subaru. I got a workshop service manual. Counting from left to right, The first one is MAF signal. The second one is Ground. The middle third one is 12V positive. The fourth one is IAT Ground, The last one is IAT signal with 3.1 V when the sensor is unplugged.
This MAF has no 5V reference voltage. and IAT signal wire should have 5V with an unplugged sensor. but I only got 3.1V .
My Subaru runs well.
LMAO at the scope's fanfare music and fireworks! I'm hoping it'll be just as exciting when I finally get my own scope.
It will probably be better for you because with all these videos you’ve been watching you will be better educated on it than I was at the time!
the duty cycle of 50% would give you the 2.5v
as the flow increased, the change is expected. you assumed it would go up, but not all signals go up.
sometimes the signals are inverted.
Schrodingers Box So can you fry the PCM when back probing the MAF, or any other sensor that grounds to the PCM, by just probing the wrong two wires? Or is that just if you touch the leads together accidentally while probed?
Sincerely Great Work.
Thank You!!!
Rock Is What You Do !!!
Congratulatons on the Vantage Pro!!!
Randall Dalton Thanks Randy! Total game changer!!
For sure. I love the component part that shows the pin outs and component locations.
With the frequencies put out by the digital MAF sensors, all being within audible sound range, it seems like you could directly wire a small speaker in place of the oscilloscope, and listen to the change in frequency as it corresponds to air flow. Not sure how well that'd work with the duty cycle being ~80% but it would be interesting to try.. less of an investment too. There are a lot of apps you can put on a smartphone that can tell you the sound frequencies picked up by the mic and plotted over time, so you could get precise and accurate readings in that way.
Its a good idea but you also may as well use the DVOM for that because its a qualitative test. You need to really check for proper square wave characteristics, not just amplitude or pulsewidth changes.
"Daamm!! Dude when are you gonna change the MAF" lol!!!
So the reason that when he is taking the DC reading of the signal before the engine starts reads 5V is because thats the starting point. because its a pulse width signal the meter reads the average voltage. When he revs the engine the pulse width frequency is decreasing, thereby increasing the amount of time that the low 0V is being read by the DMM. So it appears as tho the voltage is dropping due to the inaccuracy of the DMM. This is one of the reasons why you need a scope to test the signal. You can make some guesses using the DMM but need the scope to get a proper diagnosis.
i’m watching you now with your new red box tool!!! i’m kind of lost!! lol but i’m sure you will figure it out 😊
I remember when I got my first scope - feels good huh? About the digital sensors, 2-6khz falls within the audio spectrum so I don't see why you couldn't probe the sensor with a simple audio amplifier with a speaker connected. If fact I'd bet you'd be able to hear the data if you connect a wire to the aerial of a pocket transistor radio and probe the output with the other end of the wire. These methods might only give an indication that the sensor is operating. Disclaimer - I haven't tried this so I don't accept any responsibility for anyone else doing so.
Hopefully you will not become lazy because of new toys... :)
That happens to me every time. And more often than not I regret it later.
I dont really care about scope. I do care about content here. And its still on very high level! Thanks for amazing MAF vid
Also lately videos appear more often. How cool is that :)
messer7bc True. He was on a video making binge since he won't be able to produce for a time. I loved it too.
I think Max finally got what I said in the previous video. Duty cycle is the explanation.
Enjoying this series. I've been thinking about purchasing an oscilloscope to use in building amps (the guitar/stereo variety). So, it's Interesting to see its applicability for automotive work as well. Well done on this so far. Very clear and simple to understand.
Gerald Hinson Yes someone else mentioned similar- there are many, many uses for an oscilloscope and it doesn't even have to be a top end model- any basic old fashioned will work for most automotive applications. Only a very few things need extremely fast data sampling.
Schrodingers Box Agree. I actually lean a bit more toward the old-school analog variant because of their real-time nature - they are perfect for signal analysis and amp building. But, all of those automotive features I see on yours are pretty compelling too. Obvious solution - one of both... Ha! Keep up the great work on this channel. Really dig the material and your approach.
Excellent vid.
Matt, are you saying that you could damage an ecu if to find out which wires were 12, 5, grd, you SHOULDN'T put test lead negative to batt earth or chassis and then start probing the disconnected wires with test lead positive??
i am saying never do the identifications by checking for AMPERAGE
Schrodingers Box
Ahh, ok. Thank you so much for replying. Really appreciate EVERY vid you put up here! N/W Scotland.
Hello I have question what do you think about the Blue driver bluetooth diagnostic ? I´m looking at it and think for the 100 dolars probably the best scan tool for DIY can you make your opinion on it sometime ? thanks
hey Matt. I didn't know what video to post this question on. Do you have any videos explaining how all the types of crankshaft position sensors work? I've tried many many videos on RUclips but none of them are detailed enough, and they all assume that you understand basic concepts that most people would not. Given the awesome teaching that you've done on all these other sensors, I'm sure you'd do a great job with it. Please let me know. Thanks and if there's a better place to post questions like this, let me know that too.
+jawojnicki Yes I have hall effect, optical and inductive sensor Diagnosis and Understanding videos on my pay channel.
Interesting, the voltage change is just a product of the not so perfect square wave that you MAF produces. Its simply because of the slow increas and rounded out edge in the signal. Thats what i would think, since this round edge stay the same, even if the frequenzy goes up
hahah those idiots thats funny you remind me today my first stupidity i did when i was like 18yrs old so my car has a dead battery and yeah i know what you thinking and you are absolutely right i plug 🔌 some 120v on my damn car well i fried my pcm instantly and well thats how i started knowing about cars now im 39 and can disassemble and assemble back and entire engine lesson accomplished thanks bro i keep watching your videos and keep learning you know have a beautiful day man. god bless you…
This is really fascinating. So the decrease in voltage noted at higher throttle levels is based on the lessening [shortening?] of the duty cycle which may be a limitation of the speed at which the MAF can operate? Not that it really matters because the PCM doesn't really care what the voltage is...only the frequency of the signal.
+Christopher Eaton Not exactly- it depends on the system. On a digital MAF then yes you are correct- although remember on some cars the duty cycle interpretation may be inverse (e.g. the "ON" time is actually "off time" in which case the relationship between airflow and voltage is reverse of what was shown. But in either case- yes Hz is the value used.
But on an analog system the PCM interpretation it is indeed purely potentiometric through voltage.
The duty cycle explained here seems a bit different then a duty cycle on a welder which I always thought was a percentage of time on, relative to the amount of frequency, or power that you are using and in a cars situation it would be relative to the throttle. The way I understood you on duty cycle was that it is a percentage of the time on regardless of the frequency or the throttle or in a welders case of relative electric power being used. If I am thinking of something totally different I apologize please don't scold me to hard.
+Micscience i see your question and I don't know anything about welding so I can't say your definition is correct but my understanding is that duty cycle is independent of frequency because it is a percentage, as opposed to pulse width which is measured in time on and frequency which is duty cycles per second.
You can not calculate the others if you have just one- so for example if you have a 50% duty cycle you only know you have equal time on vs off but is it one millisecond or one minute? If you have a frequency of 1Hz is it a 10% duty cycle or 90%? But given, say, a 1Hz signal with a 70% duty cycle you know each cycle must be pulse width of .7s on (and .3s off).
Thanks brother
Hey dude when are you working or even sleeping hahahaha. You haven’t been binge watching for 7 straight days without sleep I hope!!!!
Very good video, learning a lot. Telling my co-workers about you. If you don't mind, what is your regular job?
+B crinshaw I am a molecular biologist for my real job
is this also known as a dwell, just as in the old points system the time between on and off are calibrated at a certain speed and increase or decrease as speed changes. would it be possible to use a dwell meter on some systems to measure changes
Great point. I have never used a dwell meter but it seems like a reasonable idea. some of these frequencies however are super fast- much faster than distributor dwell - not sure if a dwell meter would keep up.
1996 Olds.Lss P0102 code..With the Ign.on I do not have 5V on the signal wire. Shows 2.68V. Slight variation with Eng.running.
Hz varies 2.5-5.0 Hz.idle to 3900 RPM rev. limiter kicks in. I do have a problem that just started also. Letting foot of the gas pedal the vehicle will not slow down. RPM goes down only while braking. Like having a run away speed control.
Intermittent T/C light and will not turn off with switch.
I have no diagrams. Nice videos,Thank YOU.
See if there is response bridging the 5V ref to signal. If there is not, you either have open or short in signal wire or bad PCM. Test for continuity to PCM to rule out.
Frequency Frequency Frequency are the values the tECM reads, Hz MHz its a determination of pulses per second, the duty cycle is only relative to the power output and frequency at the source
How can you determine whether the sensors are digital or analogue, and how to know wheter the maf is proprietary in the fuel mix criteria or decided my map ?
The MAF is always priority over MAP so that part is easy. Determining a digital vs analog MAF is done by looking at if voltage or frequency changes.
At 10:45, would you purchase a used Snap-on Vantage Pro again for about $700 or go with a two channel Pico for the oscilloscope functions?
Gosh man, hard decision. Really, I think the main thing I would look for is 4 channels- so in other words, given the same price, I'd go for a 4 channel Vantage over a 2 channel Pico. But also given same price AND same # of channels, Pico either way.
Knew you would say four channel Pico! Found Justin Miller and his video. You may like this video and his channel content ruclips.net/video/ty0mAOSKE6Y/видео.html
Hello, I have an Opel Astra 2010 that revs up to 4000rpm when I remove the mass airfllow sensor. Is this normal? Also the engine stalls when I start the car (when is realy hot outside) and the car was not started for a few hours....in the winter it works like a charm )) Can you help me with this problem?
What data do you have? What are you trying to solve. You cannot say if it is normal without knowing any etiology
Great video. I just measured my Subaru MAF reference voltage wire. it is 3.6 V instead of 5V, cannot figure out what's wrong?
What is the signal voltage?
@@SchrodingersBox , Thank your for your reply. I double-checked workshop manual
.and measured again.1 maf signal 0V.2ground, 3.feed 12v. 4 IAT ground.5 IAT signal 3.1V. so weird. MAF signal 0, IAT signal 3.1V. sensor was unplugged. I measured from connector from harness.
@@SchrodingersBox I connected with my OBD tool, 3 g/s at idle, live data is perfect when I stepped on gas pedal. car runs well.
@@SchrodingersBox ,Great news, after I did a lot of research online. Now I understand that ECM doesn't feed 5V to MAF at all, on the contrary, ECM just acts as a voltmeter to measure to voltage from MAF sensor. with unplugged maf, we will never get any voltage from ECM. MAF sensor creates voltage due to current change in hot wire.
I was lazy and just bought a new MAF but the problem was spark plug wires after replacing plugs. Guess my old MAF is still good . $115.
I have a 4 pin plug MAF 12volt, ground and the other 2 wire show 5 volts ignition on is this correct
The other two should vary depending on airflow
i ve got an over-reporting maf sensor and i cant figure out why. it shoud read around 4g/s on my vortec 4.3 engine but it reads 8g/s at idle. i find strange that with KOEO i have a reading of 2g/s but my signal, ground and power is normal. i already tried a new maf and i didnt change anything ( because of KAM? ). i figured out that coincidently when i create a vacuum leak, either with pcv breather off or oil fill cap off i then have a correct 4g/s and fuel trims also become normal. truck is running rich. lean commands. its a 1997 4.3 s10. please help out. its not dirty. cheers
i would start with a volumetric efficiency calculation.
@@SchrodingersBox Update. I still haven't done the VE calculation but after some studying I think I came up with a good hypothesis and it is related to the distributor. Spark timing is negative 19 at idle so that should make my RPM lower than normal. To compensate for that, my IAC valve is open more than it should causing the MAF to read this extra air. Unfortunately my scan tool doesnt show me IAC counts to confirm. Rich condition around -30STFT and -18LTFT might have other contributing factor like old injectors that have worn spheres by someone trying to clean it. Do you think this is possible? I think so lol but I never did engine diagnosis before and you and Paul Danner taught everything I know so I just want your thought on this. Thanks a lot. My truck is thanking you as well.
thanks
You're welcome!
hi Matt, can you tell me where can find autoTap software , or from where i can order the entire kit with cables to. ty, greatings from Romania
Unfortunately auto tap is no longer made.
Another great video, where can I get a tee shirt?
Wouldn't the original test you performed on the voltage readings be incorrect due to the sensor being unplugged? We could have voltage drop that can not be noticed by the sensor being unplugged causing a unloaded circuit?
Yes that’s a good point. i did not show voltage drop checks in this video.
My MAF power source with it connected, on 2014 6.7L diesel is 10.5 not 12.5. Signal wire Key On NOT running is 2.03. Idle is 4.03. If MAF is bad could it cause the low voltage of 10.5? When i rev it up I get 4.56 at 2500 rpm. I know you get thousands of questions a day, but no one talks about diesels. Keep up the videos.
Sorry I don’t know anything about diesels. however - what is the voltage at the connector with the MAF unplugged?
It has 11.43 even when running. test leads on battery when running is 14.03. ok thanks for the reply anyway.
thanks again. For you trying to help me and replying here is website for ram & others computer pin out. connectors.dcctools.com/home.htm
Is that a pull down ckt? If it is can we check it using a scan tool by grounding the 5v and watching the scan tool or will that mess up your pcm?
That is a perfectly valid way to test it and in fact I do this in another video.
@@SchrodingersBox is there a good way to insure what is a pull down ckt and what isn't?
Yes it’s super easy. Look at the voltage on the ground side and induce the signal. If the ground side switches it’s pull down. If it stays constant it’s power side switched. Or you can look at the power side with terminal plugged in vs unplugged. If the power side voltage stays on then it is power side switches.
Relative to the scope menus part of the video : "Intake pressure sensor" is pretty much the same as Manifold Absolute Pressure sensor. I suppose you figured this out already.
Xavier Thomas Yes I saw that but figured it wouldn't give me mass airflow connector data. In retrospect, I probably should have clicked on IAT and seen if that gave the connector pinout for the MAF.
just curious is the LT1 MAF a digital OR analog type?
andrew donohue No idea- try probing it and find out. It would literally take 3 seconds. If the signal to ground is 5V you know it's digital. If it's under 1V it's analog.
I think the scan tool is programmable to work with newer cars I think. Anyway I have to ask. Gotta learn as much as i can before I can say im a 2%er. To not burn a PCM, do you have to have the load between the DVOM and ground or can you just hook it up in series. I may have completely missed it but thats why im asking, Obviously not going to do it until i have more knowledge under my belt.
argonian bilbo If you are in Amperage detection, it is essential you have a load on the circuit (it doesn't matter where). Same if you put 12V to a system- there damn well better be a load between your 12V feed and wherever it grounds.
If you are measuring voltage it is not an issue- just make sure not to cross the leads or accidentally have the one from the power side touching ground.
The 5 volts you read on the signal line is not a 5 volt reference. This signal is used by the PCM to verify the integrity of the signal circuit. This is also common to other inputs. The HZ signal rides over the voltage signal. The reason you see a slight change in voltage is simply caused by a change in HZ. The 5 volts is just for diagnostics used by the PCM.
Stephen Cook Good to know, none of my sources clarified that and it seemed to me that it isn't truly a refertence.
Schrodingers Box You will see the same thing on some TPS signal circuits. I have seen technicians condemn a PCM due to the PCM sending out this voltage. I do like your videos.
anybody has been use the hantech scopes ?
are they accurate or they are junk ?
sorry for my English .
Wish you would go into detail on how & when to use volt meter fro troubleshooting on a user friendly lvl ... I still have issues with the proper steps and If I can test for resistance while car Is on etc :)
+Dave Jr Ok good to know. I'll make videos on DVOM basics on my pay channel ;-)
Shazam , sorta feel sheepish for as many vids U have utilizing the device lol but heh thxs
Dave Jr The fact is, most people are in the same situation, they just don't admit it. At least by admitting or at the very least acknowledging it you aren't going to be one of the 30 people or so who asked me for help when they fried their PCM doing testing wrong!!
No... I've tried... but it's no good - I'm going to have to get a scope. I've been watching the 'Cam and Crank Sensor' series on the pay channel, and it seems that some of the most interesting diagnostics require an oscilloscope. The Snap On unit shown here is probably out of my price range, but are there any viable alternatives?
Hahahaha yeah I am not surprised you are already considering a scope. Once you get to a certain level of ability, you actually need one. It wasn’t even 4 years ago i thought I would never need one- i think I may have even stated as such in a video even lol.
The thing is- even when I got the scope- i didn’t think I would need more than 2 channels. Now I constantly run into issues where 4 channels would be preferred and sometimes necessary.
My advice is get the best one you can afford. DO NOT get a single channel though- it’s almost useless. Get at least 2 channels. my Vantage model was $600 used with all the accessories that I got from a retired mechanic. It’s probably the lowest end model I would recommend.
@@SchrodingersBox Thanks for the valuable advice, Matt. The units I've been looking at all have at least two channels. I've seen your Snap On model on eBay, but I'm a little worried that it may come with more accessories than I'd know what to do with - haha. I'll keep you posted.
Hahaha mine came with stuff I had no idea what any of it was at the time but since then I have used all of it AND bought several new accessories that i wouldn’t have known what they are 2 years ago. Honestly- the more accessories the better but for sure you want a DC Amp Clamp - that’s a necessity. I use it more than anything else other than the normal needle leads. 2 channels and a DC Amp Clamp and I would say it will cover 80% of any situation you will ever encounter. If you also get a capacitive ignition wire pickup clamp your kit will cover 90% of what you run into and if you get all the above and an inductive ignition wand you will pretty much be prepared for 99.5% of anything you will ever encounter. I got both the ignition pickups from AES wave.
@@SchrodingersBox Thanks again, Matt. I've just had a look at AES Wave and it certainly looks like the place for specialist diagnostic equipment. I'll keep you posted for sure.
I think, the MAF and IAT are thermistors, whose resistance changes with temperature. You scan test your IAT by measuring changes in its resistance by blowing hot air on it. r
Correct. The MAF is a bit more complited (the hotwire style) but can be thought of in that regard. The IAT is definitely one though, as is a CTS.
how do the pcm control the maf with duty cycle ?
I was thinking the maf is feeding the pcm with signals for the amount of air .
I need an explanation for this point .
toolman talal That's an awesome question- I don't know the intricacies of the frequency MAF sensor and how the PCM "knows" how to control it. Maybe something I will look into at some point.
*****
thanks for this info,
what i understand from your comment is :
1-the hot wire is not always hot .
2-the pcm control the hot wire by heating it in periods of time by pulses .
did i understand it good ?
*****
thanks again
if meters internal DAC decides to check value when maf sensor output is at zero then, meter will measure rise of pulse until it's DAC resets....meaning that, if it resets by the time the maf's sensor output reaches 4 volts only then the meter will show 4 volts ...at that point the meter's DAC will reset and take another measurement, if the maf's sensor output value is at 2.5 volts and the meter begins its next scan at 2.5 volts up to 5 volts...then the meter will show 2.5 volts....hence the varied values shown on your meter......digital meters have the capability to measure rise times even from square waves but since maf sensor output is independant from meters reference scan input time, the meter will not accurately determine output,......the meter will only average out between ground reference to peak measured value at irregular intervals.....depending on switching speed of meters internal DAC......
Hi. How many channels your scope has? I can buy cheap pico with 2 channels but I don't know if I should rather look for 4 channels later... What is your expert opinion? Thanks
Gregory May Lol I wouldn't say I have an expert opinion but I at least know mine is 2 channel.
I totally was set on a 4-channel "Picoscope" (model 4424 to be exact). But we're talking almost a $4K investment with all the accessories I wanted like low amp probe, coil detection, inductive detection, and all the connectors. I was prepared to do this but then suddenly I came across this guy selling the Vantage pro with ALL those accessories PLUS hi and lo pressure transducers and a whole set of Cornwell electrical probes and accessories.... all for $600!!! Sorry but as much as I wanted 4 channels I just simply could not pass up an offer like that. Trading 2 channels for $3400 is a deal I will take all day long!!
Schrodingers Box
DIY expert;) When would I REALLY need 4 channels? Thanks
Gregory May Yes indeed- exactly what I was thinking too, especially when trading the 2 channels for the deal on this Vantage.
I guess the answer is it's hard to come up with legitimate cases where you "need" 4 channels. But I can think of a few. One example, you are determining a IAC problem vs a MAP problem. The IAC is a stepper motor which alone takes up 2 channels. How will you simultaneously compare MAP response to IAC position with a 2 position scope?
Also there may be time savings with 4 channels vs 2- say you suspect fuel injector problem on one bank of a V6 or V8 (or even a 4 cylinder). You can check the entire bank at once with a 4-channel but only 2 injectors at a time with 2 channel, thus doubling your analysis time.
But again, given that a 4 channel is easily going to cost 2X and maybe even 3X as much as a 2-channel, you do have to ask how often will you really need that 4 channel to justify the expense? For me- not enough to spend $3400.
Schrodingers Box One more question. Are you planning to update your snap on. I just bought the same as yours for £320:)
I think that they call it the air fuel ratio sensor -- not a very good fit, but they have an O2 sensor and apparently NOT one of the newer exhaust sensors. I just don't think that they would leave it off of the list. Or maybe they cover it all under IAT.
And AFR and an O2 are very different. Usually on a modern car you will find AFR’s as the front sensors and are primary responsible for determine fuel trim while the post cat sensors will be oxygen sensors and primary validate catalyst efficiency.
congrats on the vantage pro.lol
I bought a used sonata 2011 y20 from Korea. It give me 6.5km/L on patrol and 5km/L on lpg. Is that consumption normal?
The total Km of car is near 200,000 .
I have changed the spark pluges . .There is no check engine sign.
What makes me so confused, I meet a person who has a twin of my car and it has the same consumption.
I opened the maf sensor I found it coverd with oil. I don't know where the oil came from.
What data do you have for fuel trim? can't help without relevant data.
+Schrodingers Box I can't get this data. I used a cheap obde scanner it gives me P2192 error code is that a useful info.
can't help without data bro otherwise I'd just be guessing.
Hey, Matt. I am just trying to understand how a dirty throttle body can cause a p0101 code? Would you care to explain if you can, please? I am trying to fix a p0101 on a 2001 Nissan Altima, with idle instability problems.
What is the evidence a dirty TB would cause that? I wouldnt expect it to UNLESS somehow the dirty TB caused a miscalibration of the TPS- that would obviously do it but I don't see how that could happen.
Thanks, Matt. By the way, the car is a drive by wire. Maybe, a dirty throttle plate could?
Yes maybe TPS is showing increased angle that is not proportional to airflow due to induction interference. That would be the dirtiest TB in history though.
That's the only thing I could think of. TPS is showing a higher voltage and engine speed is showing an increase. PCM sees that the vehicle is under more load than the poor MAF sensor is showing and blames the MAF