Fuel Trims-- Mass Air Flow (MAF) Case Study Diagnosis (P0171, P0172)
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- Опубликовано: 3 май 2017
- **SURVEY** www.surveymonkey.com/r/WellsTech
In this video we go over a mass air flow sensor diagnosis step by step. Also, some bonus BMW diag!
If you love what you see please thumbs up, subscribe and share! Thanks!! 
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A +++ on this one. Excellent case study very impressive. Thank you so much for sharing.
Thanks KY HomeGarage! Glad you enjoyed the class!
Mike Becker, Technical Services Instructor
@@GoTechTraining has always made
@@GoTechTraining has always
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I am extremely happy that I stumbled accross your videos. I am learning SO much! Excellent job! Makes me want to quit my current job and start repairing cars using your knowledge! Keep doing an amazing job!
Hey Daniel, thanks so much! Repairing cars isn't nearly as fun as it looks on camera! haha ;)
Mike Becker, Senior Instructor
Damn Mike, what a lot of information in this training video! First, let me say that when you first started doing these video training series that you seemed a little nervous. You've really come a long way in your presentation of where you're relaxed and the passion in your teaching automotive diagnostics really shows. Great job! Now some comments about the video... You're right about European vehicles are harder to work on as I own a VW Getta VR6 and it's a bear to work on. What would seem as an obvious solution to an engineering problem, the German engineers have their own way of thinking which is, let's see how complicated we can make this :) As for MAF sensors, it would be nice if the engineers could give specs on the air flow such as at idle and other RPMs such as 2000, 3000, 4000, etc. and wide open throttle.
I've run across that same spec of where you mentioned of taking 80% of the horsepower and that should give you the g/s of the MAF at wide open throttle. So, I did a little calculations with a VE calculator program written by one of the members of AutoNerdz of where I'm a member also. You didn't have a PID for the IAT, so I took an educated case of 100F. Here's how the numbers stacked up, before and after on the Colorado and then we'll see how accurate that 80% rule of thumb is.
Before Repair:
IAT = 100F
RPM = 6123
MAF = 148.6 g/s
Engine = 3.5L
Calculated Values:
Air Density = .071 lbs/ft
Theoretical Air Flow = 378.41 cfm
Calculated Air Flow = 267.85 cfm
Estimated Power = 141.75 HP
Volumetric Efficiency = 73.16% (mmm, Not Good)
After Repair:
IAT = 100F
RPM = 6173
MAF = 185.64 g/s
Engine = 3.5L
Calculated Values:
Air Density = .071 lbs/ft
Theoretical Air Flow = 381.5 cfm
Calculated Air Flow = 345.86 cfm
Estimated Power = 178.14 HP
Volumetric Efficiency = 90.66% (Wow! Big Improvement)
Now, let's take a look at the 80% versus HP in checking the max flow rate for the MAF at wide open throttle. The HP from the data that you looked up is 220. 220 * .80 =176 g/s. It's a little off from the 185.64 which is not to bad considering that it's a 5.2% difference. For this car, a figure of 85% would be good. That would put the numbers at 220 * .85 = 187 g/s. Maybe 85% is the magic number for other cars :) This would probably need more research on different vehicles to see how close it is.
A tip that I use on my PicoScope is to have the sample rate of where the sample interval is at 1uS. At this interval, you can look at pretty much any signal on the vehicle and don't have to worry about the scope alias. Right mouse click on the screen and select 'View Properties'. You can also select it from the menu by going to Views>View Properties. Turn your sample rate up until you get the sample interval of whatever you want. As mentioned, I like to use 1 uS.
And congratulation on your new son born 4-17-17!!!
I'll send you an email about the question on the purge valve. Have a great evening Mike, and again, very nice training video and I'm sure it will help lots of folks out there who wants to understand how systems work on their vehicles.
Terry
Hey Terry! Thanks! You are right, I was very nervous in the beginning. I was and still am just a wrench in the shop. Presenting my ideas in an organized manner to people was foreign to me. I'm glad you've noticed I've settled in...because I truly feel like I have. It took a little bit of time but now i'm comfortable and excited for what the future holds!
Specs and known goods from the engineers from the factory would be amazing. They have to have that information, the program the PCM to look for it. Why not share, right?
You are right, I should have IAT up on the screen. That 100F seems to be reasonable. Interesting numbers on the VE. Makes sense though.
I will have to keep an eye on my sample interval. 1uS sounds good. I'll keep that in mind. Thanks!
My wife and I are thrilled. Our first child. He is a wonderful little man. I hope to introduce him to cars at a young age. Hopefully he will be as intrigued and interested as I am.
Thanks you so much for the long comment! I really appreciate the time you take to watch and converse. Means a lot to me!
Mike Becker, Technical Services Instructor
The difference with MAF resistor cleaning between starter and carb cleaner is amazing!!! I thought my first employer was off by the cleaning off such a delicate sensor. What great videos
Hey Zackary! Thanks for watching man! Amazing the difference, huh?!
Mike Becker, Technical Services Instructor
Owned my shop for over 30 years now. When even I get a chance to take a class or rear an article, I do. Your videos are a great source of information. I always come away with more knowledge. 👍👍
That's great to hear! Thanks a ton!
Mike Becker, Senior Instructor
@@GoTechTraining I have a 2008 Chevy Express with a 6.0 vortec...I have p0300 p0171 p0174 I have checked fuel pressure and it was 58 psi I've checked vacuum with vacuum tester and it was at 17 my scan tool says 2 & 4 have misfire so I swapped coils around still there short term fuel trims on bank 1 is hanging around 3-4 % and bank 2 short term is about the same long term trims are at 16% bank 1 and 24% bank 2??? When I accelerate the long term goes toa aboit 15 % bank 1 and same for bank 2 and short term trims go to 16 bank 1 and 24% bank 2 ??? When vehicle gets hot trims all ho to zero and O2 sensor run lean and don't go over the .450 threshold? Trying to figure out where I should go with my diagnosis
Watched this a week ago. Had a 13 Silverado come in with a p0101 maf code today. On test drive I watched the load pid on WOT max reading was in the 80s. O2s we’re slow to go rich and we’re not steady rich on wot. Checked maf it was dirty. Cleaned the oem sensor and now on test drive we get 99% load at wot as well as fast and steady rich front 02s on wot. Great info here I was able to use to quickly diagnose this truck!
Hi Lloyd,
That's awesome! We love to hear stories like that!
Thanks for watching!
~Ryan Wilsing
Dude. You’re an excellent instructor!
Thanks man! I appreciate that!!!!
Mike Becker, Technical Services Instructor
I am currently watching this video for some review as I am taking my L1 ASE soon this channel has helped me (along with other teachers) get my A8 and A6 ASEs. knowing data pids and circuit design has helped so much in my diagnosing.
I love the 80% figure! I didn't know if my issue was a bad maf or injector till I applied it... Replaced my injectors and my problem was solved
Great video Mike you have demonstrated having the fundamentals and the right approach with a generic $100 scantool can fix certain issues, also having a $10,000+/-... scantool with no diagnostic fundamentals is useless.
Hey Vin Brown, exactly. You don't need tons of expensive equipment to diagnose every issue!! Understand the system...understand the failure...fix the car!
Mike Becker, Technical Services Instructor
I like to see a young people and very profecional in this industry, like YOU.
Thank you very much Jesus Hernandez Brito!
Mike Becker, Senior Instructor
Both A and B. The carbon canister could be saturated in hydrocarbons causing rich code. A clean canister with no hydrocarbon in it would supply fresh air to the engine causing lean code.
My fellow teacher, excellent explanation .
Great job.
Great video Mike. I like the way you think and explain things. And you do not have a parts change mentality 😊 Awesome channel. Thx
Thanks Dylan! Definitely not a parts changer...there is no money in fixing a car the 2nd time for free! Thanks for watching!
Mike Becker, Technical Services Instructor
This video was great!!! Please continue with this type of production where you actually demonstrate on a vehicle. We get the most out of it this way.
Thanks Toodm1, not sure if you've seen much of our recent stuff, but this is how we do it now. Some classes have a section of systems learning, then on car demonstration and learning. I'm glad you enjoyed the training!
Mike Becker, Technical Services Instructor
Excellent explanation and diagnosis video
Well done Wells
Thank you for doing this
Thank you for watching!
Mike Becker, Technical Services Instructor
Nice Class on this Problem. You know your craft buddy. Took me years to get to this point. Keep it up. One thing I can add, and this has happened to me on numerous different Mass Air Flow Sensors with a car coming into the shop with Lean Condition at Idle, different from this issue but relative to this problem. I found Bugs in the Mass Air Flow Hot Wire skewing the Mass Air Flow reading and not easy to see since the Hot Wire is buried in there on some of the newer style Mass Air Flow Sensors, example 2015 Cruze. Not really sure how they get in there but since the first one I diagnosed I try to take a look at the Mass Air Flow first, just in case when I have an obvious lean condition. One for the Books...
Hello,
Yeah, I have also found a few bugs through out the years stuck on the MAF hotwires. No idea how they make it past the air filters. One car was a Infiniti and it created a no start and it was towed in!
Thanks for reaching out!
~Ryan Wilsing
bro your a good trainor, im happy watching you.
I want Pajama pants with Wells logo all over them for lounging whilst watching NGK videos!
Sounds comfy!!
Mike Becker, Senior Technical Instructor
Great explanation and thanks to you we learned something
Thanks for the Colorado videos. 👍
About 25 years ago I was a Bosch fuel injection tech trainee and we had a problematic Opel/Vauxhall. Now, they're front wheel drive and this is important: in any of the forward gears, the vehicle would stumble, and generally run terribly. In reverse it was 100%.
5 mins with some brake cleaner found a cracked inlet hose after the afm.
The engine torque, when in forward gears, would pull the crack open, but reverse forced it closed, hence the symptoms.
These were the days of open loop, mapped ECUs.....
Sounds like a fun diagnosis! Thanks for sharing!
~Mike
Congratulations on the new family edition
Thanks Grumpy's Garage!
Mike Becker, Technical Services Instructor
Amazing!! I’m hook on your channel. Thanks for your teaching!
Awesome! Thank you!
Mike Becker, Senior Instructor
Both technicians correct. When the charcoal canister has little to no vapor stored, a sticking purge solenoid will drive the mixture lean. Potentially causing a p0300 random multiple misfire or lean exhaust code. After refilling with gas a sticking purge valve will cause rich exhaust as the vapors in the tank are displaced by liquid fuel and since the purge is open they will go right to the intake manifold.
Spot on Michael! Well done!
Mike Becker, Senior Technical Instructor
Ah Mike, it looks like I missed the class. I'll catch it later tonight and I did fill out the survey :) Have a good one!!!
Hey Stuzman! Good thing it's posted as a recording so you can catch it later :) Thanks for filling our the survey! Please do watch and let me know what you think.
Mike Becker-Technical Services Instructor
Best explanation video on RUclips!!!!!!!
Hey Shawn, thanks a ton!!!
Mike Becker, Senior Technical Instructor
You welcome, Scanner Danner Jr!!
You are an Awesome instructor!!
Thanks man! That means a lot to me.
Mike Becker, Senior Technical Instructor
You should get an Autel so you can reset adaptations. Your "total trim" is within spec. Just adding, maybe you've described it using that verbiage before, the short and long trims together would be your "total trim". In which case if they essentially cancel each other out they're within specification.
Thanks for watching Edwin! Very true, that was part of the lesson if I remember right.
Mike Becker, Senior Instructor
Did you use chlorinated brake kleen or the non chlorinated brake kleen to clean the new sensor?
Science! TOP!!! Ypi are godd, you are good. Thanks. ALSO CONGRATULATIONS FOR YOURS NEW BORN, LET BE LIVE AND HEALTHY.
Thank you all great info good job!
Thanks Mike
Have two questions
1. With regards to getting wide open throttle maf/gm sec reading, do you actually have to drive the car outside to get the reading or can put the car in park and rev it to wide open throttle? Slaming the accelerator to full throttle in a sec is good once its gives good reading or you must stay on the accelerator for a while in wide throttle to get a good reading either at park or driving?
2. I have a Nissan that doesnt have a barometer sensor, only MAF sensor.
But i have barometer data pid in my scanner; where does this reading comes from? Btw when the MAF sensor is unplugged the barometer reading is still present!
Help
Great class today, Thank you.
Thanks for watching Jeff! Glad you enjoyed it. I had fun as well presenting!
Mike Becker, Technical Services Instructor
Outstanding! Thank you.
Thank you very much!
Mike Becker, Senior Instructor
Also I believe that the current increase is because the sensor is being cooled off so it will need more current to reach spec temps so the film element will draw more current to heat up.
Thanks for watching Car Cheer! More air, cools the sensor, more current needed to maintain the temp.
Mike Becker, Senior Technical Instructor
Hi fella , technically brill video much appreciated .
looking at your short term fuel trim I noticed it was running at - 2 % showing it was taken fuel away slightly, so
sorry added comment too early and not fully explained.
continuing from previous post my thinking is that on the sensor inside the mass airflow as
extra dirt on the sensor itself making the surface area digger and the ecu determine s that more air as enter and this not being the case and actually adds slightly more fuel making it richer on the fuel trim readings - 2%.
Toyota yaris with a anolog type sensor as shown that type off reading before when idling .
not sure if you fully agree with this .
quick note, carry on with the great videos.
Hey James! Don't you hate it when you accidently post before you finish your thought! Happens to me all the time, especially out on Facebook.
So, the dirt makes the surface area bigger, but I think it does the opposite of what your thinking. Remember that when air rushed past the sensor it cools it. If we put a bunch of stuff on there, the sensor does not cool as much, therefore the computer thinks less air, therefore less fuel. Then we get a lean condition. As for the negative 2% I would say that's probably normally. Anything around 0 i'm happy with...and the computer doesn't get mad until +/- 10%.
Mike Becker, Technical Services Instructor
Excellent!
N/W Scotland.
Thanks Fox Brendon!
Mike Becker, Senior Technical Instructor
powerful work from you ,bravo
Thank you very much!
~Mike
Hi! Question Please: Have a 2011 F150 3.7 with 256,000 miles engine was replaced by Ford on the warranty at 90,000 miles. The truck ran great and flawless for me until lately I got stuck on the road into limp mode at one point and it would just start install start install on up spray need to run to the engine and it started up and I was able to get it home from a major highway very dangerous and overnight went to talk to engine up again and it ran like nothing happened the news and it ever since then couple months I would say now I have negative pend fuel trims I have replaced spark, plugs, mass, airflow sensor, air filter, and left the bank2 downstream O2 sensor. I have checked for air leaks, vacuum leaks my short time fuel trims are flexing any wheels between 02, +13 and my long-terms are packed at -25 on both banks, and they seem not to move at all except for on the cell bill move down to -23 to -21 open tinkering with this quite or a lot I’m watching a lot of videos and repetitively on yours laughing out loud. I’m trying to learn what you’re trying to teach us which is very appreciate it. If you can help me out, I would appreciate that very much. Thank you, Mike.
Hey Mike, sorry to hear of the troubles your facing with your F150. Rich conditions can be very tricky. Is the truck stock? Have you inspected the purge solenoid? It could be siphoning fuel from the tank if it's stuck wide open. If you start the truck up and unplug the connector there shouldn't be any vacuum on the port that goes to the hose going to the back of the vehicle. Other than that, I'd have to see the data being read by the scan tool to give you more advice. Any trouble codes?
Mike Becker, Senior Instructor
I am glad that you recognize you need more than just snap on scanners , there European car coverage will not get you that far anyway . Keep the videos coming .
Hey 8power0, There is definitely more to the diagnostic world than Snap-On Scanners. The reason we use them is because for one, that's all we currently have. And for two, I would say the majority of the viewers who work in a shop have some form of Snap-On scanner. They seem to own a lot of the market. I am working towards showing other scan tool options in the future though. Stay tuned my friend! :)
Mike Becker, Technical Services Instructor
Autel is a very capable and quite powerful scantool . They are gaining a lot of ground in a short time and bringing down the competitions unreal prices…, also competition is good but good competition will make you strive even harder and that is always a good thing . Three to four years ago all that was herd off was snap on for a good general based scanner now that Launch , Gscan and a few others have brought there a game things are looking up . I like your channel the coverage on the drive by wire it was top notch your very informative would love to see more coverage of systems like this… can communication , no communication ,anti theft , electric steering , programming and so on . Thank you for the videos and your time .
We are going to keep getting deeper deeper down the rabbit hole of diagnostics. Stay tuned...network issues, EPS, and programming are all on the list for the future!
Mike Becker, Technical Services Instructor
I will be watching with anticipation keep up the good work .
Such an excellent Video - a true eye opener -, still I kinda like the idea of the wells yoga pants, I think it will be really professional thing to have......haha
Thanks W. Khairi, that yoga pants joke is still going strong among some of the viewers haha!
Mike Becker, Senior Technical Services Instructor
Both techs are right. Initially it will be rich from sucking the fumes stored in the canister but it will start to suck air after awhile.
Hey Kirk, well done! that's the answer I was looking for :)
Mike Becker, Senior Instructor
I'm having trouble with my number one fuel injector the fuel cleaner seems to help fix it is it weird to diagnosed a temporary I got a 2002 Nissan Quest 3.3 V6
Maybe it just needs a new injector?
Mike Becker, Senior Technical Instructor
i have a vw in the shop it has p2181 and p0171 and p2271 it also had p0300 with 301 302 305 codes so i did the t-stat and then found the pcv bad and the oil cooler adapter so i changed that as i was there and it was cheap. it came back with the p0171 and i found the purge valve was also bad. so i have the purge on order and i expect that to fix the p0171. the trims are real close and the p2171 did not return them maf is .01 .02 .03 lb/s at idle 1500 and 2000 rpms i think the maf is ok but when it comes back for the purge valve fix i will test that a bit more. it seems i have to run it out to full throttle in 2nd gear to get the maf to full numbers. thanks
Hey Bob, hope the leaking purge fixes it all up for ya! Thanks for watching
My Pajero i0 2002 started to hesitate when I would put my foot down, the the engine light came on, I had already cleaned mag ect. However It was still happening , what I had to do it take the top of the mafd spray the electronics with electrical spray cleaner and toothbrush, after waiting for it to dry. I started car, runs great engine light, it’s a 2 ltr and I get about 9 klm a ltr, what else should I do ,?
13:17...I have seen that your short term trim for both banks of sensor 2 shows a Not Used. My E46 M52 shows n/a% on same, but there is a voltage. Is it normal?
Do you recommend cleaning dirty MAP sensor with MAF cleaner on modern cars. Does it give good results.
I've seen videos on that but I trust your opinion / experience
Great class!
Thanks Cobra Ninety Six!
Mike Becker, Senior Technical Services Instructor
Excellent explanation informations very well presented ❤❤❤
I have 2001 Chevy Silverado 1500 4.8L This is going on I got no Check engine light , Truck is Pinging under normal load , Hesitation .
I had knock Sensors replaced I am positive they are not OEM , EGR was replaced also not OEM , Smoke tested for vacuum leaks is perfect no leaks could it be I have a fuel pressure issue or Bad Coil , Mass Airflow problem
I think both mechanics are correct, but to a certain extent. A stuck-open purge valve will INITIALLY cause the engine to go rich. This only lasts until the EVAP canister is emptied. Then the engine will run lean because it will now suck only air through the open purge valve.
Hey, great answer...it's all dependent on how much vapor is stored in the canister. Well done!
Mike Becker, Senior Instructor
Hi mike ,I would like to participate in the question, I know that the video is old, here I am, technician b is correct because the solenoid is sucking air, causing a lean condition and a po171 , thank you mike take care yourself
What do the LT trim levels look like now and did they improve
Tech A only because the charcoal canister store fumes that is used during wide open throttle. If it's always open then it will give the engine extra fuel when it doesn't need it.
Hey Kirk, what happens if the charcoal canister doesn't have any fumes stored in it? Would it still run rich?
Mike Becker, Technical Services Instructor
31:28 So a plugged or bad Cat can cause LTFT to be low/rich? I have a 2006 Scion XB with no problem at idle or cruising. Only a hesitation/studders once or twice a week from a cold engine. I get one code, P0420. O2 levels seem ok, pre-cat between 0.5 to 0.6, post-cat 0.2 to 0.8. Pre-cat and post-cat temperatures are similar. LTFT are -20 when I get from 0mph to 40mph. At cruising speeds its around -14. So would a plugged cat cause LTFT to be rich? Or should I look at something else? Thank you for the videos
Hey Manuel, it is possible a plugged cat could be causing your issue. But it is also possible that something caused the cat to get plugged in the first place. It may be a result, and not the root cause. I would be inspecting things like the MAF sensor, verify O2 operation, maybe do an injector balance test...see if you can fix the rich issue before installing a new cat, and potentially wrecking that one.
MIke Becker, Technical Services Instructor
Any other ways of condemning the mass air if you can’t do the unplugging it technique??
Andrew, you could compare scan data vs a known good. That may help.
Mike Becker, Technical Services Instructor
How do we know which cars or engines , we can disconnect the mass sensor like you've shown us. ? Weres that info located.
Great and informative video.
Thanks Mike!
Mike Becker, Senior Technical Instructor
P0171 can be hell to fix. Any idea why the MAF on sentra 2005 would read normal 4.5 g/s at idle and shoot over 18 g/s at higher RPM 3500. been replaced twice both MAF sensors do the same. there is no air leak. done several smoke tests . if MAF monitors air coming in from air filter side, it shouldn't react like that. even wideband is new . long fuel trim over 28% short term -2.5 at high RPM or idle,
Both... The General Motors EVAP reads the opposite from other vehicle models on the voltage multimeter numbers. It rises when it burns too lean & goes lower in numbers when the fuel is burning rich.
Do you still have the video class of the scanner readings you mention what they mean?
Wish you would do these live at a time we could actually watch it. At least can watch it once it's recorded though just can't do the question thing.
Hey, i'll tell ya what...since you watched it still today, send me out an email with your answer. I would be happy to take a look at it...and if you are correct, send you out a shirt or hat. Also, the time of the broadcast may change in the future. Please do the survey and let me know your input. You guys, the viewers, are driving this show. I do this for you guys! If you want to see a different time, please let me know on that survey. Thanks Techman 48917!
Mike Becker, Technical Services Instructor
Your max is 185.64 220 x 85 = 187. Excellent job.
Thanks for watching and commenting Richard!
Mike Becker, Senior Technical Instructor
Hey Mike, any training available on how to interperate the live data pids such as MAF, TPS, MAP, and so on.
Hey Stoney, are you looking for how to read the pids and understand what is good and bad? How to know what exactly you are looking at? We did a video on scan tool data pids a while back. Here's the link. ruclips.net/video/ScyorXztqN4/видео.html
If you have any specific questions, please, ask away!
Mike Becker, Technical Services Instructor
good job, better than scannerdanner, he said on GM the top g/s is around 150..
Does the throttle plate open all the way is there any slack in the throttle cable
This vehicle is drive-by-wire. There is not throttle cable on here.
Mike Becker, Senior Technical Instructor
I think it could be either one. By having an open purge valve, the motor will have unmetered entering causing it to be lean. 02 sensors will tell the cem to throw more fuel out. This can mak it rich. It depends on how well you CEM compensate for th unmetered air
So what could be if the ltft it -25 and the short fuel trim is at 0
i used the same test on a 2003 eclipse with a bad maf sensor. it wouldnt go 15 mph down the road both o2's dead lean. to lazy to hook up a fuel gauge unplugged maf rechecked ruled out pump first/injectors... 2 cardone sensors later its all fixed
Hey Phil, nice! Glad you got it fixed...funny how it took 2 to do it haha!
Mike Becker, Technical Services Instructor
Tech A only.A canister purge stuck open causes rich mixture because is always sucking fuel vapors at all engine speeds.
Hey Isaias, you're half right...but what happens once the canister doesn't have any fuel vapors in it any more?
Mike Becker, Senior Technical Instructor
I am working on 1992 gmc Ventura changed fuel injectors and everything else I can think of still wants to hesitate in idle
Hi mate
Use a maf calculator instead of 80% of hp it's more accurate and I use it at work! Petrol or diesels
I know I am a bit late with this comment but if you still dont have the noise problem figured out you need to turn on hardware filtering within your scope options, lowpass is the software option, keep in mind once you turn hardware filtering on the noise signal will be gone forever - it will be filtered before capture
Hello Eng
Please I have a problem Nissan Pathfinder 2003 am replace Airflow meter sensor every six months.
What can cause it
Hello Rabiu, A few things that come to my mind for repeat failure would be a aftermarket air filter or intake system causing MAF contamination or an inferior part that is of poor quality. Are you replacing the sensor based of a diagnostic trouble code or a symptom. You may need to dig into how the sensor has failed to determine the root cause of the failure.
Ryan W. Technical Instructor
Question
Will doing a smoke test find that vacuum leak.
I have use wd40 and nailpolish remover as well and its working like new
Working like new...but for how long? The non-stick coating is gone now. It is likely to fail again!
Mike Becker, Senior Technical Services Instructor
When you replace a MAF like you did on the truck in the video do you go back with an OEM part or do you get a local parts house version? My personal preference would be OEM but I wanted to know what others do.
Brandon, that is a great question. I avoid reman sensors. Some people like them...others hate them. Many times the parts store sensors are remans. If you can't find a brand new one, then go back to the OE. That's my .02$
Mike Becker, Technical Services Instructor
excellent
Can you spray carb cleaner to find a vaccum leak
LT trim level
Have they come down
Improved yes/ No
Thanks 😊
Max. MAF reading with a brand new MAF sensor should be somewhere between 80-85% of total engine's horsepower
That's what i noticed too working on many makes and models
Hello G.skillz, maybe you meant to say is a brand new MAF sensor should read 80-85% of pistons calculate displacement in relative to rpm & corrected air density
At 750rpm/2/60 x 1.8litre engine = 11.25litre/second total piston calculated displacement action.
Corrected air density at manifold of 0.53g/litre at IAT of 105F at 0.5bar. 11.25 x corrected density = 4.7g/second.
4.7/5.7 = 83%. 🤔🤔🤔. This should be what you had mentioned. Also most engine suction valves close off only when pistons are at 50 to 60 degree after BDC. Regards.
Mike Backer ,thks for the show hahha I have a question about trimas, pid fuel trim lean enable or disable do you know whats the strategic for the pid to change from enable to disable of courses when the vehicle is not under mixture control. thaks.
Hey David, thanks! I am not exactly sure what you are asking here? You wondering about the fuel trim enable pid?
Mike Becker, Technical Services Instructor
Yes I saw some GM when the vehicle is under mixture control that PID would show as fueltrim lean enable, but when the vehicle is not under mixture control the PID would show as fuel trim disable. I just wander is you know what s driving tha PID. I hopefully I make myself clear . thanks
Hey David, yeh I have seen that PID before. I believe that PID is showing you if the criteria is met for the computer to learn the long term fuel trims. This is based upon coolant temp, throttle position and engine speed. Also, loop status open/closed would affect this as well.
Mike Becker, Technical Services Instructor
Why do you say "can't reset the fuel trims" . I understand the concept of clearing the CEL code(s) but wouldnt the DME automatically adjust to the changes applied?
Hey, it would begin to adjust, sure. But will it get into parameters fast enough to not set another check engine light?
Mike Becker, Senior Technical Instructor
I will like to watch the beginning of the class about fuel trims
This is what we called ( in the 70’s ) as KISS or keep it simple
Well explained.
Thanks D.D!!!
Mike Becker, Senior Instructor
I have a 1991 chrysler imperial that runs but while you are driving it will cut off or stall on you. And you will be stuck for 5 minutes to hours where ever the car stall or cut at. can you help tired of buying parts that related to the problem. And it is also throwing codes 1225 and 0146
Hey Myz Bird, could be a lot of things. You may want to take this thing in and have it diagnosed. It sounds to me like a sensor is getting hot and failing and then once it cools down it starts working again.
Mike Becker, Senior Technical Services Instructor
could it be the map sensor or the throttle position sensor? because i just bought both to replace them.
Possibly, could be a cam sensor, or a crank sensor maybe? Could be a computer? Hard to say at this point.
Mike Becker, Senior Technical Services Instrcutor
Molex so many things I want to say! All good
can you do anything with a volt ohm meter the prove it to measure it with voltage or with ohms
Hey, not sure what you're asking here?
Mike Becker, Senior Technical Instructor
Yes u can: easyautodiagnostics.com/misc-index/maf-sensor-test-basics-1
Unless it's dead, cleaning it is almost always worthwhile. Every failed maf I've seen puts out a constant voltage signal.
Do the air filter makes a difference on the map sensor
Hey Harry, hmmm usually not as long as the air filter is a quality filter. Some makes/models are a little more particular, BMWs can be finicky.
Mike Becker, Senior Instructor
What if the long FT just sitting at 24.2 the Whole time I'm Driving Fast or Slow ??? #ChevyTahoe07 5.3
Hello I have an 07 gmc canyon 3.7 in line 5 I have the P0171 code I've have the smoke test done changed the upstream O2 sensor and the maf, code still comes back
Hi Jared, I would inspect your fuel pressure. It sounds like fuel is one of the few things you haven't checked yet.
Mike Becker, Technical Services Instructor
Hello I did what you did in the video and unplugged the maf sensor tho I didn't get a rich condition the truck ran better, I inspected around the exhaust manifold and felt hot gases hitting my hand, in short air is entering through the exhaust before the o2 sensors
Sounds like the problem then, excess oxygen going past the O2 sensor will definitely cause a lean condition!
Mike Becker, Technical Services Instructor
Is everything plugged in?
What if you have no codes and you fail emissions for high Nox?
Good video. nice concise ♍♏
Thank you!
Mike Becker, Senior Technical Instructor
It would be running rich, right? Because the purge Valve is stuck open which would keep pulling the fumes from the canister??? Yes? Maybe? 🙏🏽
Hey Luis, It could run rich, yes...but that is not the complete answer. You should check out the TechConnect Episode. I actually go into this in-depth and explain the complete full answer. Here is the link ruclips.net/video/JKovg8lELNU/видео.html
Mike Becker, Technical Services Instructor
thank you! ill check it out:)
What about the MAP sensor causing a p0172 code
Hi Mike,
another generic data for MAF grams per second is 40 grams per liter engine displacement at 5000 rpms. This comes out of a MODIS manual from DEWITZ DIAGNOSTIC SOLUTIONS.
BTW, question for you: WHY actually does the pcm go into open at WOT? :-} (tip: happens on circonia sensors, not so on wideband ones.)
Congrats to the birth of your son, best wishes for all of your family.
Hey Jurgen! That's good info to know. I'll have to try that out!
So why open loop at WOT? A standard zirconia sensor has no way to know how far rich or lean... an engine at WOT wants power, that would be rich of the stoic mark, maybe 12.5 to 1 or so. But the standard zirc sensor can't read 12.5 to 1...just that it's rich. So, the PCM says, if you can't read it accurately, I can't trust you. Open loop, goes into default fuel map strategy. A wideband sensor can read rich and lean, that's why we are able to stay in closed loop fuel control during WOT. So, how did I do my friend?
Thank you! We appreciate the wishes. I hope I can get him into cars :)
Mike Becker, Technical Services Instructor
Hey Mike,
well done on the open loop! The information I have states the window of a narrow band sensors do work reliably within the range of 14.3 to 14.9 ratio.
Greetings Jürgen.
Hah! Great! I studied up :)
Mike Becker, Technical Services Instructor
Great videos Mike!! Juergen , I hope my comment isn't too late but I recently came across two wideband sensors one Mazda 2016 the other Toyota 2009 and in both cases the pcm went into open loop at WOT even at 75% throttle.
@@professorlanguagepartners3112 Thanks for the feedback, always good to know.
Why did the MAF cause a code on Bank 1, but not Bank 2?