Don't underestimate your audiences thirst for knowledge, you are doing us a great service and we appreciate what you have to offer, thanks!

Perfect as usual. Whatever the lenght of your videos, the 2% are all ears

When you added the additional layers it went to what I know as spectrum analysis. As a retired Calibration Specialist your electrical analysis of what is stored in the control module landed right at home. Your training videos are in fact teaching the auto service technician to walk before you run.

Dang, this is like the last element to your “secret of engine diagnosis” video. The fact that then we rev up we are pulling the Pre-established learned fuel trims on the fuel strategy, and not necessarily the “live” data per say. Learned so much more again. THANK YOU.

Hello Matt. I am a sixty year old former marine engine fitter living in the north east of a small island off the west coast of Europe called England where four cylinder engines are rather NORMAL and any more than four is abnormal!! I have repaired and serviced first, my own and subsequently my family’s cars for decades. My first rebuild was a FOUR !!! cylinder 1100cc engine I n 1968. I grew up on and revered Weber twin choke carburetors with their numerous options of chokes and jets. I am of the old school mentality but now, decades later, I am staring into the abyss of engine management systems and diagnostics. Admittedly we now have reliable, efficient comfortable cars with performance that would have been breath-taking in the 1960’s and 70’s and we are spared many of the frequent frustrations that afflicted us. The need to get to grips with engine management and its diagnosis is critical. Just like air moved faster than fuel through the venturi of a carburetor and caused a weak spot until the fuel caught up or an enrichment device opened up, technology became the equivalent of the air and our knowledge, like fuel lagged behind. Now thanks not only to the availability of diagnostic equipment but also to the likes of, Schrodinger’s Box, Scanner Danner and Eric the Car Guy etc. the public and professionals alike are eventually becoming more informed, less intimidated and aware of the real value of engine management and how to deal with its “manifold” issues. I am profoundly impressed by the generosity of spirit of those, like you, who have given so much time to share with the world what they have learned themselves, but am a little embarrassed that almost all of the amazing things I am learning are thanks to Americans and that there doesn’t appear to be any similar quality and quantity from my countrymen who one time prided themselves on their engineering prowess. That said, I think that thousands of people the world over will look back and thank you for what they have learned from you. Who can tell what the full extent of your sharing will have, now and in the future, even in remote, small, four cylinder cultures. Having seen quite a few of yours and Paul Danner’s videos, I am now feel that diagnostics is much less intimidating than I previously did, so much so that I went out and bought some PC based diagnostic software and can’t seem to put it away. It goes on almost every journey and already I find I need a much more capable one. Tonight’s viewing was your Adaptive Learn Fuel Strategy. Pausing the video repeatedly allows me to make notes, six pages tonight. I don’t pretend to have understood all I saw, but it was far from the “serious students” palate that you suggested. It really did help me to understand L & STFT better than I did after watching the videos on fuel trims. It was fascinating and while it might seem weird or sad to some, I find these videos technically exciting. At last I am able to grasp terms and principles that until three weeks ago were merely terms or at best vaguely understood ideas and more importantly I am now learning for the first time how to apply what I am learning. A person needs to be working on cars day in day out to acquire real diagnostic skills, but at least now I stand a good chance of correct diagnosis, even if it takes a comparatively long time to arrive at a conclusion. I have a question about mapping that I will withhold until I have watched the video again in case It proves that it would be better to keep my mouth shut and let people think I am an idiot, rather than open it and prove them right. Thank you very much indeed for the considerable effort and time you devote to the videos. Thanks also for the generosity of spirit to share. Tom

I love your videos because I actually come away with new knowledge every time I watch one. You have a way of boiling down complex processes into simple bite size pieces easy to digest.

I'm a retired heavy duty mechanic with 35 years on the railway.Your lessons videos have really opened up my understanding of today's vehicles allowing me to have fun in my garage.Thanks

You're a good explainer. Most people go too fast. I understood everything and I don't have very high intelligence. I thought this was VERY important to know and went along with the fuel trim videos I just watched.

this guy does a WAY better job explaining everything, including fuel trim, than Scanner Danner does. I know I know its sacrilege. Ive learned SO MUCH watching this channel. It just gloriously clicks.

Excellent video! I picture the fuel map in my head like a big Rubik's cube. This video fits right in with programming my motorcycle's Power Commander. It sits between the ECU and the injectors to allow custom mapping. Pretty cool.

Very informative. Thanks so much. Great to now know how the LTFT, STFT and lookup tables all interact and to learn they’re stacked. Wow. Just got through diagnosing a P0171 lean code that showed up immediately after swapping the turbo on my ‘13 Chevy Cruze 1.4L 4 banger. Used propane while watching both LTFT and STFT and found the air leaking in around the PCV-to-intake fitting. Replaced O-ring and viola’, everything back to normal in just minutes. Now, when the fuel pump gets lazy, I’ll know how to tell difference between low fuel pressure and a vacuum leak. Smart whiteboard!

This is a old video with great information, this guy really know his shit 💯

I am understanding and repeatedly watching your videos. It's very interesting and well presented. Thank you Matt.

Great video. Although a simple and commonly used computer control concept, it is difficult to explain and visualize, you did an awesome job. My comment is that the PCM algorithms utilizes either an equation or ROM table(normally this) to determine base value and then adds LTFT and STFT. In this discussion you are talking about fuel, so the PCM has an internal values set up by the engineers for each cell representing fuel injector duty cycle, usually derived from characteristic equations of the system being controlled but implemented as a table. The LTFT table and STFT are used to have the PCM adapt to changing car conditions, sensors and actuators aging or injectors getting dirty for example, by either adding or subtracting from the duty cycle for example. You stated this. What I'm adding is that the PCM has internal non-changing values of which are tweaked at run-time by these dynamic learned values. And this technique is used for other PCM controlled activities, like timing curve, fuel, idle adjustment, shifting, .... From the programming angle, the reason multiple dimensional arrays are used versus always calculating the base values is that the desired value can be determined in constant time. For embedded engineers writing a PCM that controls a motor in real time, this is a very important factor. In addition, using this technique, a lower powered processor can be used or CPU cycles can be devoted to other activities. And, lastly, changes to the engine specification can be done easier using tables versus having to re-develop and test new internal characteristic equations. So, the whole motivation for this comment was to point out that these base values are what are manipulated by performance chips and PCM tweakers,.... I hope I was able to explain what I had in mind. Like I said, this algorithm is not easy to state in a short paragraph or video.

This video is the perfect complement to the 'Understanding Fuel Trims' tutorial. I must admit that I had to watch it a few times in order to get it pegged, but it really does have its benefits once you understand it. I think the main take-away here is understanding the relationship between dynamic data (stft) and stored data (ltft). Whilst learning about the grid system has no real advantage in the field, it can facilitate those tricky analyses that demand deeper investigation. For the die-hard DIYer, this video is essential viewing.

27:27 Matt, its more than 9 years and we are still hanging with this video 😂 Don't worry keep going with the great stuff

Such valuable information, i enjoyed every minute. THANK YOU. You are a natural teacher that speaks a learner's language.

Best video i ever seen about feul map adaptation

I have been a Mechanic for around 25 years and i must say your videos are great i have learned so much especially about air fuel sensors ! i understood o2 sensors and knew how to use the data to help diagnose the issue with the car but A/F sensors threw me way off ! your video was invaluable for understanding them better .! you not only have a great amount of knowledge and others do as well the difference is you have a gift of being a great teacher ! yes teaching is a gift ! i have met many people who are very very smart and knowledgeable but could not teach anyone how to make a sandwich ! You do a wonderful job at explaining the subject from the very basics at the beginning and work your way through the subject with great detail and thought into the best way for it to make sense as any good teacher will do ! Thank you for passing on your knowledge to others that's why i am willing to pay for your full version it's more then worth it ! Tech students in automotive this is a must ! you will most likely learn more on here then in the classroom at least get the best of both if i could go back and this was around in the early 90s i would have had a much easier time of learning ..Great Channel !!

Matt, I finally saw this video and now I can say I understand what the guys are doing when they play around with those numbers during a car remap. I didn't understand even a bit what was a remap all about, but with this information, I now understand exactly what they are doing but I am still skeptical about sending my cars for that remap due to not trusting. Thank you so much for these videos, I always watch them until the end, it's interesting to work on these new cars.

This is probably the best video i have found explaining fuel trims! Keep it up! So many videos explain fuel trims and how they respond to each other, but they don't explain how they would be interpreted in a real world situation. This is by far the best video on the web! Explained the discrepancy you would encounter and why you don't see fuel trims move in the hypothetical way extremely well! This definitely helped me understand why you can see both LTFT and STFT trending positive but settling at a specific point, because the computer is using its adaptive learn under a preset. So under idle if you see a higher fuel trim that might be completely normal according to the engine management vs when you are driving down the road. LTFT is the learned average assuming it has had a chance to fill in that cell, where STFT is an adaptation based on engine management and current conditions. So perfect zero is not always realistic or should be seen as a problem. Which can get really confusing when you compare fuel trims with a faster reacting wideband vs a slower reacting narrowband o2 sensor. Thanks a bunch! Keep on makin them dank videos.

Having made a good number of multilevel spreadsheets it is easy for me to understand the concept. Now, applying the concept to real world problems that is a different matter. I think anybody who has watched the other "fuel trim videos" should absolutely watch this one. It might even be good to watch it first. Fantastic.

For the ultimate understanding of fuel trims, this video has to be studied in conjunction with the original series (parts 1&2) and also with the advanced fuel trims video on the pay channel. As a set, these videos comprise the most informative tutorial on the internet.

Makes sense to me. Great job. Just started using a scan tool for a BMW and have had high LTFT numbers. I was thinking that they were real time, but the "adaptive cell" and learning concept was like a light bulb going off. Thanks.

Very well explained what you wouldn’t think when dealing with real time problem. You opened up another level of understanding and I appreciate the knowledge you have passed on.Thanks once again.

I should have watched this videos sooner. I never knew which Fuel Trim to look at and was always hoping for a Net Fuel Trim PID. Thank you!

Wow. Before this i thought, well i kind of understand fuel trims. After this.. hmm, not really. Excellent demonstration, sir.

For what it is worth i thought you did a very good job explaining a very complex and mind boggling subject and knocked it out of the park. And yes i did watch to the end understood some of it before but completely understand it all now and i quit wrenching 25 years ago. I did go to school for diag but wow, keep it up , u inspired me to rethink it.

Beautiful, made perfect sense. Just witnessed all of this a few days ago with a 01 Nissan Quest I was working on. Explains everything I was seing. Turns out it was a leaking fuel pressure regulator and a leaking fuel injector.

Well done Sir. I finally understand the need for and use of LTFT; without knowing the concept of the map the idea of having both STFT and LTFT seemed redundant and caused me to doubt my understanding of them - but now it's clear. Thanks.

Dude, thank you so much!! I am an auto tech student currently entering the 4th and final semester. Your videos are amazingly helpful in understanding fuel trim and it's importance. All the best:)

Great example @ 18:40 really helps in clarifying the need to look at both long term and short term and what to conclude from them

way-to-go-buddy....You did your home work!!! Thank you sooooo much!! You were not talking to yourself...

My big takeaway from this was the fact that there is an array of LTFT values and not just one for the system. It makes a lot of sense. Thanks so much for all this!

I contradict, it was a very exiting and very educational vid. It helped to understand things much better! Thank you, and keep on to your excellent teacher Performances. Greetings from Germany.

Thanks for the heads-up on 3D fuel tables. I didn't think they were that complex. Are there really discrete vertical cells or is the base table offset by programmed amounts based on MAP, IAC, etc at the time of sampling? I can see either being used. I was surprised to learn that the PCM uses the LTFT table before live data but I guess it makes sense as performance lag is reduced since the PCM is not constantly sampling and correcting each cell until a threshold is reached just like a threshold has to be met before setting a cell value in the first place. This sure explains why a car can run like poop for awhile after a PCM swap or reset - especially if the problem that filled the old PCM's cells with correction data is not fixed and all the old corrections need to be re-learned. I admit I don't always think to hit the LIKE button. When you watch enough good videos like yours ya tend to set the bar high and take it for granted and then wear out the DISLIKE button when others don't meet that high standard. I pressed it this time, though! :)

I'm going to have to have a staff meeting in the morning and show them this. Thanks again for another great video. While it all made perfect since to me I don't think my guys will get it. I'm about the only one who does fuel trims for this reason. Excellent video Matt.....

Fuel maps are learned and can change depending on A/F for the purpose of fuel efficiency. Everything it does is for goal of keeping the best MPG it can depending on the situation. Fuel maps use an adaptive algorithm. Fuel maps vary by manufacturer too. You'll never fully understand every manufacturers maps there are simply too many but the basic principle is the same. Also depends on what components and sensors they use like electronic IAC vs mechanical and so on because different components will react at different speeds. PCM chip and network bus speeds also play a role and why some cars seem to react slower than others. Older vehicles generally have slower chips but the change shouldn't be a difference of minutes but in seconds. Like 2 seconds vs 4 seconds it's not as dramatic as minutes that you make it out to be. Each fuel map is designed specifically for the ECU. One of the best things you can do to avoid triggering an adaption is to inflict quick changes. Blips are ignored and not adapted to. However if you sit there and hold propane in it for a minute or two it will indeed start to relearn and remap the cell except in the case of it being too far lean to come back to stoich as in your Jeep example. ECU/PCM's are pretty darn smart. Another major part of the fuel map is the startup idle enrichment map. It slowly subtracts fuel and adds air as the engine and IAC warms up. You can't really use it for diagnostics since it's in open loop but there are plenty of other sub-sections of the fuel map. Bless me I watched the whole video. :) Good video. :)

Matt I had a Volvo years ago and it had an unsteady slightly reving and falling idle. No vacuum leaks but the valve was faulty. Now I realise the SHTFT must have been responding to the varying bypass air if I have got that right, car was fine apart from that. Replaced the valve and it was fixed.

This was one of the best videos I have ever watched. This video, as well as your other videos on understanding have made me a better mechanic. The devil is in the details, and this detailed breakdown on how the system operates helps me immensely. I enjoy Scanner Danner, as well as a few others, but YOU are the best.

Great explanation. I've actually found that sometimes when I fix a major vacuum leak that I have to completely reset the pcm because after doing the fix, trying to run a key on engine running test on some vehicles the study will be so negative that the computer can't get the o2 sensors to switch during the test. This happened on a ford excursion that only had the maf wire plug that sealed the air box housing was out causing a massive vacuum leak after the maf sensor. Again, I found that you explained this really well.

Good explanation on the "behind the scenes" of fuel trim percentages. Good info for any car geek like myself

Great video I run heavy equipment for 12 hrs a day so I have tons of time to listen to your videos and learn while I work I had to chuckle when I heard you tell me I had no life lol

april 20 2016......just thank you.. for giving us all this info...GOD bless you.

That was awesome . One word that drives me crazy our friend ScannerDanner says after a deep subject like you just did is - "variables" Ha - just when you think you got it down (WHAM) - oh yeah there are variables you have to take into account. I have no idea now what the fuel mapping strategy would look like on a wide band . Now we have to consider the downstream O2 into the mix, another "variable ". Mapping strategy is only as good as the sensor inputs and if their defective guess what another "variable " I do know clearing codes does not reset everything on all models oh yeah more "variables " There's such an advantage with just working on one brand . There are no variables in your vid quality Matt , your very consistent. 👍👍

honestly... the best ever channel i came across with, thank you very much for all videos

Great video. Really helped to re-enforce those fuel trim concepts. Itching for a chance to put some of these concepts into practice. Thanks!

Great stuff! I've never heard these concepts articulated so succinctly and clearly. It really broadened my knowledge. As always, you put the cookies on a higher shelf. It's good for us to have to reach a little. Keep up the excellent work.

well done............ this certainly rounded out various concerns

Nice work Matt!! Always wondered what the pcms fuel maps were. New they were important, but didn't know how. I can visualize them now and see the role they play. You may feel like your loosing us, but I think it is just your repitition of the main points, it helps a lot with retention. Anyway, thank you again for your knowledge

Priceless even after 7 years

Hi Matt So glad you did a recap at the begining as it helped to confirm some points. Thanks a lot and all the very best.

Excellent. I think another way to think about it is to look at the first oxygen sensor as a quality control system for the fuel map. If sensor is switching rich to lean for a given set of RPM, Load, and MAP values, then the LTFT value in the table is correct. Otherwise, the PCM must adjust LTFT value in table to get the 02 sensor "working", a.k.a switching again, and this will be accomplished by changing STFT.

The map is a learned data base for differing engine loads adding more fuel as the throttle plate is opened. The figures in the map adjust fuel injector pulse width I think to maintain stiochiometery .

awesome video, not only did I make it through the whole thing I fully understood it and took notes in my textbook, because I am a automotive tech student going to UTI in sacramento, CA. This video along with your other fuel trim video made an awesome educational supplement for the material we covered today. My current course in introduction to driveabilty and todays lecture was electronic engine management (sensors, actuators, ECM-PCM, and STFT/LTFT) I can tell you from having studied thoes things the past feew days and wastchi9ngt your video you are teaching industry standard procedures. You, scanner danner, and eric the car guy along with scotty kilmer make up my group of professors at KZfaq University. Keep on rocking

Just to reiterate a point to my fellow viewers about liking or giving a thumbs up to videos. The information contained within the videos on this channel is always highly informative and delivered with enthusiasm and wit. Please don't forget to like them - if you do. In the past, and irrespective of channel, I admit that I am guilty of finding some videos so engaging that I feel motivated enough to comment only to forget to like it! I do accept that this process may be unique to my grey matter but I thought I'd mention it anyway.

I doubt I ever need this info but it was informative and interesting. I never thought about the "map" being three dimensional. Good to know If I ever have a weak but still functional fuel pump. Yes I do need a life. Thanks for pointing that out.

Great videos. Learning alot watching your videos DIY Tutorials. I have a Innova 3140d OBD1&2 DTC. And trying to diagnose codes from internet searches has been leaving me with alot more optional multiple choice repair decisions and costing more money. Currently have the O2 sensor STFR & LTFR decisions.

Engine management light has not returned Matt, you helped me fix my car.

Thank YOU .... Well done... I appreciate your efforts.

Yo man. I really respect this guy to the fullest… he’s teching all of us in ways most people are too dumb to explain in a understandable manner… I watch his videos on a learning basis to understand the science behind engine operation and computerized fuel control and he hits it on he head every time. Makes a living Being a scientist to develop medicines to cure sicknesses for people while helping people with their cars and donating the money he makes from the channels despite all the time he has into em.. MATT! My hats off thank you for helping me with understanding all of this your the man.. BEST CHANNEL ON KZfaq!

Interesting Video there Matt mate. The biggest thing I took away from it was a better knowledge of when it is prudent to wipe the map, or leave it as-is. Also your observation that under certain conditions, there will be cells on the map with zero trim, that are so because that cell(s) have not been used yet since the last wipe, was a minor eureka moment, which tied up a loose end question (I love those) I have often graphed long/short term fuel trim under normal driving conditions, and observed the changing long term values, but never through the lens of a more thorough understanding of the fuel map. Now I see there is diagnostic value to test driving the vehicle with the map as-is, and after clearing, and comparing the two graphs. And, if you wipe the map, it is like the fault (eg vacuum leak) has just occurred, and you can see the short term trims working hard to correct the problem, generating a very definite graph, which is always easier for diagnosis. 50% of my work is on BMW`s, and they use the term "adaptions" to describe fuel trim. There is, on most scan tools, a facility to "clear adaptions" which saves having to disconnect the battery, with the attendant nause of having to reset clocks and radio stations etc. Top Notch , carry on....

Thank you for your time

The best explanation ever I found..thank you sir

Wow watching this video has helped me understand what all the graphs are that tuners are looking at when tuning a car thank you! Also I have learned that as a DIYer I need to get a life. Lol thanks Matt once again for an excellent video.

Good job explaining a complex subject. GM relies on Freeze Frame/Failure Records to help the mechanic/tech identify the lean or rich conditions that set the Fuel Trim DTC (likewise with other DTCs).

One of the best videos in the Channel

Once again one of your best video you were Wright those two engines secret videos help me to understand this one thank you sir for all your unique videos.

Thanks for the information . That was something new and interesting

LTFT is a learned response, SHTF is a reactive response. The latter kicks in when oxygen sensor detects a rich or lean condition and it sets the LTFT as the new base line.

The computer locks onto the recorded LTFTS as long as the oxygen sensor does not affect the SHTFT. In other words only when the 14.7 to 1 is changed will SHTFT move to compensate and then eventually create new LTFTS in the grid, when it does the SHTFT will go back to 0.

Hello, and thank you for a great video about adaptive fuel mapping. :) I would love to see more advanced video about fuel map layers in the ECU. Also more about how the closed loop system responding on faulty conditions in the engine. I have worked a lot with the old Motronic systems from my old BMW straight six engines, and with my old degree in electronic I have managed doing well. I have never changed a part in any of my BMW just for the try. I have always trusted my volt/multi meter and good reasoning. However on my newer BMW engine it's harder to see the big picture, or at any newer engine in fact. So this input from you really helps a lot. To the summer I will finish my engineering degree in Automation and system control and I really love the beauty of engine management and regulation. Looking forward to more juicy stuff from your channel. Greetings from Norway:)

Thank you for sharing your knowledge with others; even though, this is a difficult topic to learn, I like to challenge myself to improve my knowledge in cars 👍👍👍👍👍👍👍

No, I'm not a fuel trim expert, however, I believe I have learned a lot by watching your theory episodes. What I have pieced together, based solely on your educating principles, is that the fuel trim data is based upon ideal or optimum combustion of the mixed vapors of fuel and air within the cylinder. The computer analyses the amount of unburned air and fuel based upon O2 sensor readout and other variables. Correct me where I lack here.

Great video keep it up, this is starting to make sense. I was confident in the simple explanation of fuel trim in the earlier videos. And I now see that there is basic model for this behavior or a general organizing principal for observing the data in context. So great you see how it helps me and many others with gathering focus on important concepts like this. About this model. I will be assuming that their are published info and there is an industry specific standard software library available. Your explanation in this video should help me to avoid the wrong assumption when I take a crack at automotive live data analysis which is what I'm working to understand. And I think I'll probably still remember how to change a part -even- when i can determine its malfunction beforehand. If that sounds like I worry... You can just remind me It's like riding a hippo sometimes you underwater and sometimes your not, but mostly you wind up a stuck in the mud.

Hi Matt, I've been watching your videos and DAMN you're good. I'm no mechanic, not even changing part person. I just wanted to DIY my own troubleshooting on my cars. Luckily, I had computer science knowledge and construction background as well, therefore you made it so understandable. DAMN, you're good, logical, easy to understand, deep learning which I'm looking for. The videos help me alot, I didn't know anything til I watched your videos. Again Thanks. Keep up the good work, and I do agree alot of mechanic just want to replace parts... Thanks again.

Thanks sir appreciate your efforts.I am from Kuwait and i always watch your videos .

Damn, i followed every word and had some fun listening to you 😁 👍 not hard for me , easy as , i even thought looks like low fuel pressure just b4 you said

1992 Voyager 3.3 Liter V6. Starts OK, Will Idle for about a minute until stalls as the IAC opens and the motor can not respond appropriately. No distinct miss at idle , just struggles to keep idling, notable heavy modulation of IAC trying to maintain idle, application of throttle brings about severe misses /missing, pops and sputters, intake back fire indicative of over lean condition at just barely above idle, very hard to gain any engine speed/ rpm, IF the engine does manage to get above 2000 to 2500 RPM ( estimated because there is no tach) THEN engine instantly smooths out and runs normally /revs aggressively in high contrast to horrible stumble in region of just above idle to 2000 RPM. (I admit that I already did the part swapping gambler approach that you do not like, with no remedy on my part) Already changed TPS (new) no remedy took it back (Thanks AutoZone) , Map Sensor (used from Wrecking yard) and ECM ( used from wrecking yard). No change noted as mentioned parts were replaced. Checked for vacuum leaks in area of Throttle body with unlit propane torch, no effect noted. Contemplated EGR problem. Checked engine for EGR. Apparently this engine has NO EGR system. At this point wondering about any possible IAC issues / suspect of Junk Yard MAP. I tried some stuff, with no success. Seeking outside input at this point before proceeding any further. Can a faulty fuel pressure regulator cause that kind/ degree of problem? I am doubting it. Can a faulty O2 sensor cause that degree of problem? I am doubting it. Crank Evac check valve ? I am doubting it. Anything else ? Thanks in advance. Up date: Watched the video on fuel pressure regulators on this youtube channel. I am doubting that is the problem. FPR are to drop fuel pressure, so if they fail there is no pressure drop resulting in a rich condition. It appears that I am dealing with a lean out condition. The My next planned move is to test the MAP sensor with a multi meter.

Good info and your presentation skills are always spot on!

Oh man, it helped me a lot understanding fuel trims!

This understanding of the adaptive learning & multiple arrays is essential to really understanding fuel trim.

Woaah!! Watched it like three times. You're awesome. Keep such topics coming Sir.

Excellent explanation. Thanks for sharing your knowledge.

Been watching the videos, I keep learning from you. One thing I didnt really catch though was in a rich condition. I have both banks on a v6 running very rich according to the ltft about 24-25%. The stft on both banks is close to 0%. I know it is not o2 sensors from your other videos since it's both banks and they are oscillating normally. I cleaned the maf already. Not sure what else to look for.

Thanks it's so much useful

Great Job Matt. Just a fyi there is a diagnostic tool company called Automotive Test Solutions that makes a generic pc based scan tool that will show these fuel maps at different loads and rpms in relationship to volumetric efficiency. The tool is not that pricey either compared to Autoengineuity. I watched a training DVD on it and the tool looks very impressive. I am planning on getting one. I will share when I get it.

Great video, came to try to understand the adaptive part.😀

Exellent video & Thank you for sharing your knowledge with others; even though, this is a difficult topic to learn, I like to challenge myself to improve my knowledge in cars!

Without this video I was lost on the other 2

Matt in my case the check engine light is on intermittantly can I assume the problem is not in the cars electronic control unit so it must be a vacuum leak or a dirty or faulty sensor. I think I can rule out low fuel pressure too as the car responds well. As you said the car runs normally because the fuel trims will always be adjusted to keep the 14.7 to 1 ratio. Still a fault somewhere though.

Excellent brother

great video starting to understand ST and LT readings and on some of your early O2 videos help me understand how they work. Keep them coming, for one catman to another 'l'

Matt is says FUELSYS1 OL _ FAULT might be the fuel level sensor or the pump I have read. Going to check the fuel pressure anyway but car is running very well. Strange mabe the pressure is slightly lower but no low enough to cause driving problems.

Thank u for teaching us about this cool diagnostic technique, yes, it’s 11pm and I’m watching u on KZfaq, I need a life😆😂

Watched a technical presentation on fuel trim, Where it was noted for Performance cars it was better for them to be run on the Rich side of Lambda 1. The Torque curve is at its highest a few points below lambda 1, ie on the rich side. Thats if you don't mind using a bit of extra fuel.

Thanks for lessons. Who's teaches who, is also a question. Without questions from the other side, you can't play the game. I understand this by almost like a raining in the desert. To find an oasis at midday. I would like to test the correctness of understanding Your subject matter delivery. If we have a car and has factory settings and is equipped as it was when it came out of the factory. The car works normally and has no problems. After a certain time it is no longer new, so we approach maintenance work. In doing so, we find that in the maintenance, higher quality parts, oils, liquids, etc. can be incorporated. We are only trying to improve the work of mechanical, electrical or transmission components, that can influence the improvement of the combustion process itself, as well as the transfer of torque and power with less friction and thermal losses. We are trying to improve the thermodynamic efficiency of the engine and transfer this motion to the ground. We do not interfere with anything in the software scheme. Of course, a cheetah can not come from the hare. However, a small, a few percent can be gained, if we get something here and a little small there. It's possible. Now, because the dyno test is not in our interest or we will not perform it every fourteen days, we decide on another indicator to show us whether we have improved or not, the factory parameters of the vehicle. Would this procedure be reflected in close to 0% STFT and a constant negative range between -3 to -5% LTFT in the long run? Thank You for understanding and greetings from Slovenia. Lojzi

This help explain tuning for racing

Man you are great ! Correct if I'm wrong...That's why after fixing cars replacing some parts like o2 sensor,maf sensor and so on ,we have to do the relearn drive procedure,,,of curse cleaned cods before and erased the read data as well ?

I’m here after watching basic fuel trim part 1 and 2 like ten times. Dealing with no check engine light aT idle LTFT at 11.7 STFT at 24%, Under load both values come down, smoke tested, a slight hint of smoke coming from a below Egr. Car has run rough for a few years and has had parts thrown at it by other garage. I want to commit to EGR but feel something else is going on.