Seems Like Easy DIY Car Fix, But Can Send You On Wrong Path!

[@sanctealphonse4510]

My wife probably thinks I'm crazy but seriously, we just got back from dining out... sat down on the couch and was like 'Alright! Schroedinger's got a new one!' I really do look forward to seeing notifications that you've uploaded! Thanks for sharing your knowledge and methods!

[@SchrodingersBox]

She is crazy for not watching too lol.

[@sanctealphonse4510]

​@@SchrodingersBox Actually she has on occassion LOL

[@Isaiah5417GdLk]

One thing to note, with the leak being there, i believe not sure, it was a scanner danner vid that he showed a car having wonky issues witha vacuum leak that didnt make sense. Come to find out the torque of the engine would open the crack up more and let more air in under load. Then close up when idle or off. Love the videos!

[@SchrodingersBox]

Oh wow that makes total sense!!! Yeah I didn’t think of that. Totally explains the variability!!

[@atlantasamedaydelivery1769]

"He didn't change the snorkel, this video sucks" lol priceless!!! Thank you for your education and time!!!

[@thecardoc100]

The long term trim is learned in load cells. One of the data pids would show you what cell the vehicle was currently operating in. The load cells are typically based on specific air flow rates as measured by the MAF (mass air sensor). For example, cell #1 might be 1-4 grams of air per second, cell # 2 would be 4-7 grams of air and so on. (Speed density systems, MAP sensors, are a block grid instead of straight numerical) Each manufacturer determines the conditions under which long term trim will be updated in the different load cells and the rate of change that the system will achieve. There is another data pid that will say if fuel trim learning is enabled or not. Most of the movement "usually" seen in the long term trim data pid is the result of having the engine load change from one learned cell to another. Yes, under some circumstances you can watch the pid change while a relearn is taking place, but there is a lot of GDI strategy that has forced us to change our expectations. There are two other data pids to pay close attention to and they are the Calculated Engine Load and the Absolute Engine Load. The Calculated engine load is written into the software based on how much air the engine pumped on a dyno at wide open throttle at various engine speeds. When the mass airflow sensor is reporting the expected airflow for a given RPM the calculated load will be 100% in the scan data. The tear in the boot would have allowed air to bypass the MAF sensor and that would have caused calculated airflow to fall short of expectations. In rough numbers if the calculated airflow at wide open throttle is 70% when it should be 100%, seeing a correction of 30% in the total fuel trims is either an air leak or a misreporting MAF sensor. That calculated engine load pid comes in real handy when you have an engine low on power with the calculated load at 70% and the fuel trims are not making a correction. now you have a mechanical issue where the engine is simply not pumping enough air. There is more to it than just this but it's a start. The Absolute engine load pid is the amount of air in each cylinder as the intake valve closes. It's the one that the system truly relies on for part of the base injector pulse-width calculation. On a naturally aspirated engine seeing 90-95% with overhead cam engines and 85-90% with a cam in block engine at wide open throttle would be normal. If you have a boosted engine today we sometimes see values as high as 202% absolute engine load. Learning these systems was like starting over again from the beginning. You should see how fun it gets when a car has short term trim, long term trim, rear fuel trim, and alcohol fuel trim and someone is trying to use a scan tool that doesn't include the last two in the data stream.

[@1McMurdoSilver]

Thanks. I've always had a desire to understand what specific factors go into determining fuel trim and how the long term fuel trim is calculated. It's probably proprietary though.

[@SchrodingersBox]

I get what you’re saying John and in fact I have a video on exactly that but what I want to know is now that the LTFT is accessing those fuel cell data BUT the conditions are now different- I don’t see how it would adjust that data to lower the LTFT without seeing negative fuel trims on the STFT. What is changing the fuel cell data to pull LTFT down if the STFT isn’t changing?

[@thecardoc100]

@@SchrodingersBox The long term didn't move real far. Since you replaced the boot and the MAF is more accurate it might simply have been in a different load cell than the earlier capture. I would have to see more data to say for certain but that is the most likely at this point. Right now I couldn't even say if the long term fuel trim learn was even enabled or if there is still another issue lurking.

[@thecardoc100]

@@1McMurdoSilver No it's not proprietary. It does take a good bit of time to learn all of the variables in play especially if you work on more than one vehicle manufacturer. One of the big surprises is how many of the things we learned in the past are wrong. For one thing the engine controller does not try to keep the A/F ratio at 14.7 to 1. In fact, it doesn't even keep it at stochiometric ratio for the fuel that is in the tank all of the time. Then you get to learn about Lambda and Equivalency Ratio and Commanded Equivalency Ratio. That of course leads us to all of the different fuel trims and the realization that an oxygen sensor does NOT sense oxygen. At one point in time that definition while incorrect was close enough for techs to use it. With the higher functions on today's cars and especially with trying to understand just how the catalyst works you need a more accurate understanding of how everything really works. VW/Audi has always called an O2 sensor a Lambda sensor and that starts you on the path towards deeper understanding of fuel control.

[@abdul-kabiralegbe5660]

The plot thickens....🤓

[@8953147]

Enjoyed the lesson on short/long term fuel trims and of course the reindeer hat!

[@SchrodingersBox]

Isn’t that hat the best!!! Cracks me up every time!!!

[@jgeorges3061]

Matt, great catch on the fuel trim data I, think my LAUNCH SCANER showed that too so I always go to generic OBD to check fuel trims and other data first thanks for the information and stay healthy brother. cheeers

[@SchrodingersBox]

I really like the Launch scanners! I have a CRP touch pro that I really like and it seems to have good communication with European cars.

[@georgebonney90]

Thank you sir, I hope you and the missus have a great Christmas

[@SchrodingersBox]

We will!! Thank you!!

[@kennykrylov4513]

Why, you said you were Jewish and a darwinist? Where's logic now

[@SchrodingersBox]

Hahaha quite observant my friend. I must admit. So my criteria for a good christmas is based solely on how many presents I get and I can already tell by the plethora or packages Vicki had received from Amazon that the criteria will easily be met. So regardless of whether there is a creator that “blesses” us or not- it will still be a good Christmas. And a good Hanukkah. And Vicki celebrates Christmas so if she is happy then so am I and that’s a good Christmas.

[@kennykrylov4513]

@@SchrodingersBox I'm not big on Christmas, at least hanukkah is based on real events. Nobody 7 and older believes Santa is real

[@MattyEngland]

@@SchrodingersBox I thought the Talmud says jesus is burning in excrement for eternity?

[@DANNYN224]

Wow easy fix sometimes that code can be maf too just reference great work

[@therealspixycat]

Is probably not a communication problem but you are looking at the fuel trim algorithm adjusting long term setting when there is a sudden massive change in settings: the algorithm doesn't instantly changes these settings but it will take a while. Here also it would make sense to reboot power cycle the ecm so that it will relearn the long term fuel settings ( all history is gone after power cycle)

[@alexdehann1621]

Hi, I'm not huge on KZbin and just came across your channel from a link on the Cadillac Forums about a two part video on fuel trims. Just wanted to say how much I've enjoyed watching your videos. I can't decide if I enjoy the content or your intellect more. Or the fact that you apparently don't suffer fools. Anyways, thanks!

[@SchrodingersBox]

Thanks for stopping by!!

[@alexdehann1621]

@@SchrodingersBox Don't suppose you'll be in Assachusetts any time soon? My Cadillac could use some serious diagnostics my local guy can't seem to figure out. Lots of money replacing parts did nothing to solve the problem. I'm just joking about being in Massachusetts soon, I wouldn't wish that on my ex wife!

[@fordtruckguy5545]

I have seen ethanol blended fuels do some weird things with fuel trim numbers.

[@wonderwalls3565]

Should we observer the MAP/MAF values as well and clean them and the throttle body as well?

[@SuperScopeLLC]

I agree with the stft/ltft being reversed, never seen it before but makes sense

[@embreesmith7613]

Bernie !! You, Ms Vikki, and the Cat 🐈 What more do I need than this ?? 🙂

[@sanctealphonse4510]

Homeboy's still checking those powers and ground right now... probably for the next couple of days tearing apart the dash. It's super quick though.

[@rich13la1]

Matt, interesting (almost glad ) to hear these fuel trims are not responding as they should, thought just my car was odd in the fact stft going 0 to slightly - while ltft always hangs around +10 , still searching for the problem, just have not reached an conclusive evidence of a problem. Engine has turbo with gdi so issues with that might be more than I understand.

[@SchrodingersBox]

I don’t understand - what’s the problem? What are you expecting it should be?

[@nectorin4635]

Appreciate for the next perfect video with TOP value comments from another tech gurus! Special thanks for remembering of "other country" subscribers... :)

[@erikkirby1]

love your explanation... will make shure my guys look at you video... Been trying to teach them lambda values but just wont sink in... forget the one and look after! and then they tell me it .96!!!

[@johnmilner6484]

Years ago a friend of mine worked as a mechanic ( pre obd). Customer left his car with a note that said " check engine".So being the smartass that he was ,he made a check mark on the air cleaner...... Lol

[@mikesautomotivediagnostics8080]

The reason that your trims didn't go down at higher RPM's is because the air leak is ahead of the throttle body and isn't a vacuum leak, it's unmeasured are after the MAF sensor.

[@mikesautomotivediagnostics8080]

Unmeasured air.

[@simonparkinson1053]

Yes and the gap won't open up in the workshop like it will on the road when the engine moves on its mounts due to drivetrain torque.

[@SchrodingersBox]

If it’s unmeasured air then that is the cause of fuel trim adjustment. Now that the unmeasured air is removed why are the fuel trims not reflecting that?

[@SchrodingersBox]

Good thinking Simon but if that’s the case, why are the fuel trims high at idle to begin with them? If the unmetered air is not entering during idle there is no need for fuel trim adjustment. It’s all measured by the MAF.

[@rplayer9969]

HEY........ MATT MATT MATT, THERE IS NO SOUND. I switched to another video and came back, now I have sound. Great video as always

[@volvo09]

Click another video and come back... Very common KZbin issue. I have sound.

[@rplayer9969]

@@volvo09 Thank you it worked

[@markchidester6239]

Excellent video

[@deerhunter8533]

LTFT is a learned value so it might take a while to adjust depending on the car. Generic OBD is better to diagnose fuel trim problems. As cars get more complex enhanced data gets harder to read due to the growing number of data pids

[@embreesmith7613]

LTFT. ?? is that like LGBT. ?? 🙄

[@bensolomon1997]

Hi Matt,..about the dtc can I clear/delete the dtc before checking my new values?God bless

[@SchrodingersBox]

you can but in general it isn’t a good idea because you are in essence erasing your baseline. ideally you want to see the correction happen in real time confirming the Fix. this is different than resetting the values and seeing that they don’t change much from zero.

[@bensolomon1997]

@@SchrodingersBox thankyou so much Matt ...I got the reason why u didn't do that.

[@mtrltoolman]

I think the ecu needs to discharge the capacitors. disconnect the battery maybe it's came back to normal condition. Another good video Matt!

[@everardocamacho5063]

Great matt,just a question, in the first part of the video where fuel trims showed 1.11 and 1.14, what numbers you go buy, before or after the point.thank you again, have a wonderful time

[@SchrodingersBox]

on some models the fuel trim is done in an equivalence ratio format instead of a percentage so in those cases you will use the numbers after the decimal. 12% would be 1.12 as an example, and -12% would be .88

[@brownwrench]

The fact that boot was so easily gotten should tell you something.

[@dimisrambodimisrambo7285]

GOOD EVENING MY FRIEND WE WISH YOU A MERRY CHRISTMAS AND HEALTH IN YOUR FAMILY

[@SchrodingersBox]

Thank you my friend!!!

[@advancedleveldiagnostics]

Nice video thanks! I can tell you really enjoy saying nomenclature😂

[@SchrodingersBox]

That and “areola”.

[@FreeKanal]

Hi Matt, Do you know yet what can cause LTFT to remain stable after a leak is repaired? Does the ECU need vehicle speed reporting, or is the A/F sensor data interpreted differently by the ECU? This can really lead people down the wrong path :) It is interesting.

[@SchrodingersBox]

If the STFT is correcting the LTFT will eventually adjust. sometimes the vehicle has to actually be driven for it to happen.

[@FreeKanal]

@@SchrodingersBox I remember you talking about an adaptive fuel system or something like that. Where the ECU has to relearn all the fuel memory cells to change the LTFT values. Is this because different car manufacturers use different ways to update these cells? For example, what does the ECU take into account to change this. Is this the reason that in one brand the LTFT changes when parked and in another you have to drive a car? Correct me if my understanding is wrong. And thanks a lot again :)

[@SchrodingersBox]

Yes as described in that video, often only specific cells are affected by a condition. As an example- a vacuum leak. A vacuum leak will ONLY affect cells at idle. Any cells where the throttle is open will not be affected by a vacuum leak. So if you are driving the car after fixing the vacuum leak it may take forever for the LTFT to adjust because if the car is being driven, it’s only occasionally at idle and therefore there is no correction because those cells are not used. You may also have a condition such as, say, a weak fuel pump that is only unable to meet fuel demand at WOT. In that case you will only ever see corrections take place during WOT. If WOT is never reached, that LTFT will stay in memory indefinitely until that condition is met and even then it has to be long enough a time for the STFT to take effect on it.

[@FreeKanal]

@@SchrodingersBox Thanks for explaining that to me. Sometimes i need to confirm data and update my own brain cells. Sometimes it takes more than one cycle to do that :D Thanks again

[@pigeonsil240sx]

at 9:15 how do you figure out what protocols to use?

[@SchrodingersBox]

It depends on vehicle year and make. There is a reference available. On a CAN vehicle it will almost always automatically identify protocol.

[@dimisrambodimisrambo7285]

HI FRIEND WHILE THE TRANSLATION IS ON YOUR VIDEO DOESN'T SHOW SUBTITLES IF YOU CAN WATCH IT MAYBE SOMETHING IS STUCK.THANKS

[@DuaneDonaldson]

Torn Intake Bellows, when doing a brake torque to check for an air leak, similar to what you have done by simply raising the RPMs to get a correction in STFT. When you brake torque in drive, you will stretch the bellows and still have a vacuum leak as you show, but maybe less of a correction as in park as the Bellows may open further & when you brake torque in Reverse, you will move the engine in the opposite direction and close the leak in the Bellows and make it a bit smaller and you will get a better correction of STFT, now you do your visual inspection of the Bellows based on 3 higher RPM tests, park, drive, reverse, which according to ASE, the visual inspection should have already been done which most of us do not do, so mistake right there brother. Now you update your lean fuel trim diagnosis checklist to include the 3 higher RPM tests and expected STFT changes which might point to a torn Bellows if you did not find it on a visual inspection up front. You may be correct about the higher throttle body percentage, this is where cleaning the TB will come into play, clean it and recheck the percentage at idle and charge for a marked improvement, and put on the work order that this was ONE of the problems with the lean code. In some vehicles, the LTFT will only change over time as the STFT cells clear out and normalize, then the LTFT cells will clear out one by one and normalize. Visual first according to ASE, BUT do not fix that until you get your baseline readings, then clean the TB take another reading, fix your Bellows, and recheck your readings. After the repair, I agree that the fuel trims were not corrected in the normal manner but were corrected, that is the important part, and chalk this action of the scan tool to experience on a Honda of this model and vintage. With your customized live scan data list and the experience here today, I would add the MAF or MAP to the list and we must know that normal is also. Now in the 21st century, we ought to be videoing the data lists with our cell phones and keeping some screenshots of the known good data and known bad with notes on the problems related to the bad readings in our Library, cheers, thanks so much for the case study.

[@SchrodingersBox]

amazing summary!

[@geryloftis7985]

Matt which scanner tool would be best for the D.I.Y.

[@SchrodingersBox]

I use autoenginuity myself.

[@dimisrambodimisrambo7285]

WE NEED YOUR HELP I HAVE A 2003 MODEL GOLF THAT HAS A POOR MIXTURE AND WHEN I SPRAY THE BRAKE CLEANER INTO THE INLET MANIFOLD IT GOES TO NORMAL.THE ISSUE IS I CHANGED THE GASKET AND IT DOES THE SAME. I SPRAY ON THE PLASTIC INLET MANIFOLD IN THE SOLID PLASTIC AND IT DOESN'T SEEM TO HAVE A CRACK!!!!!!!!!!HOW CAN THE SPRAY PASS THROUGH THE SOLID PLASTIC AND BE SEEN BY THE O2 SENSOR?

[@SchrodingersBox]

I am sure if you did a smoke test you would see there is a leak somewhere. it won’t go through the plastic. it is being drawn in somewhere.

[@dimisrambodimisrambo7285]

@@SchrodingersBox Ι DID SMOKE TEST REPLACE GASKET INTAKE MANIFOLD STFT GO DOWN TO 10% FROM 21% I DID AGAIN SMOKE TEST I DONT FIND LEAK BUT IF SPRAY UP TO PLASTIC STFT GO TO -2% - 0% I'VE NEVER SEEN ANYTHING LIKE IT IN MY LIFE IT'S CRAZY

[@joeblow6786]

Doesn't the computer have to relearn the new data after the air leak has been corrected?

[@SchrodingersBox]

Yes it does. And that’s what is confusing to me on how the LTFT on this car is returning to normal. So what we would expect is now that the unmetered air is no longer entering the engine, we would see the engine runs rich because it was adding extra fuel to that unmetered air. But now that the unmetered air is gone, that extra fuel added should be causing the STFT to go negative and that will eventually pull the long trim down to normal. However I don’t see the STFT going negative. So first of all - how is the LTFT reducing? And second, why isn’t the extra fuel added not causing a rich condition that drives the STFT negative? I have never seen a response like this before. It doesn’t make sense.

[@joeblow6786]

Got it... You probably mentioned such in the video but I missed it or was in the twilight zone.

[@LeverPhile]

@@SchrodingersBox Re the long term trims dropping immediately after the fix (instead of seeing negative short term trims for a while) ... I observed the same thing in my 2004 325i that had an intake manifold gasket leak that was killing power and fuel economy. On the first startup after the fix, the long term trims (after warm up) were at a new much lower level closer to 0%. There was no adjustment period with negative short term trims, which surprised me.

[@northpoint1039]

I noticed there was two 'engine RPM' s selections on the scanner. Why would that be?

[@SchrodingersBox]

It’s a communication thing. Sometimes I see the same PID repeated even 3 or 4 times. But also it can be that one RPM is calculated from the crank sensor and the other from the Cam sensor.

[@northpoint1039]

@@SchrodingersBox Thank you very much. I always wondered about this. I get two sets of LTFT and STFT pids on my 2008 Lucerne 3800 car. :)

[@SchrodingersBox]

Yeah I can’t think of a time I didn’t see at least a few duplicate PIDs. I just yesterday looked at a 2015 Malibu and almost every single PID appeared 4 times… if not more. And not even in sequence- they would seemingly be random throughout maybe 20 screens of data.

[@SuperROMAN83]

Hi Matt do you own or tried autel oscilloscope is it any good? Also is there a pressure transducer that goes with it or not. Thanks

[@SchrodingersBox]

I have never used one sorry. I am not familiar with the Autel scopes nor accessories. I imagine it works as well as the Snap On versus scope and I have used that and it was excellent. Way better than their Vantage Pro. I totally tried to talk Autel into providing me a version of their scanners with the scope for my project with them but they couldn’t do it.

[@fernandoq9334]

Any one know what kind of scan tool he's using?

[@jnarez1]

Launch

[@jnarez1]

Get the xtool g8bt it’s great for the price

[@carnivorebear6582]

How do you know the strange data wasn't caused by a bad GROUND? That's why you always check them...

[@SchrodingersBox]

Hahahaha I totally forgot to reference that!!

[@mph5896]

I really would not consider that a vacuum leak. More of a unmetered air issue before the throttle body. I guess it's just verbiage.😆

[@SchrodingersBox]

I agree

[@radleybradford1356]

Bro! You ROCK! Leave it to Honda to jack up protocol. Anyone wanna buy some power steering fluid? Asshats

[@-l_T-]

Don’t get to caught up in the comments. (Not saying you do). But if you don’t know then you might be surprised with how many of the commenters you see, are not real people. You’re a smart man. I haven’t seen anything on your channel about GPT-3, or openai. How it’s also being implemented in all aspects in technology and had made scientific discoveries. I think it’s a very important topic, and could also be used in automotive applications for either design or researching. Openai codex had some interesting results. I think the most interesting part about it, is it’s wide range of capabilities and applications. But it will also write the code for whatever you use it for. Which is also somewhat a bit horrifying too. Like how it was used to write thousands of articles in seconds, making it very difficult to distinguish between reality and fake. Ability to edit video and sound to manipulate it, deepfake Obama was a great example. Just because you or even myself could see it wasn’t real. Think about those who don’t know

[@justliberty4072]

You are so well GROUNDED

[@Tinkerwizzah]

What's your daytime job?

[@SchrodingersBox]

I am a molecular biologist.

[@Tinkerwizzah]

@@SchrodingersBox no really? Wow

[@meatballmagoo6134]

Do you have french vanilla...ILE TAKE FRENCH VANILLA

[@SchrodingersBox]

Hahahaha we only have dulce de leche and chocolate orange!! arbuckles coffee. the best coffee ever.

[@nickayivor8432]

Happy Christmas 🎄 everyone PRODIGY Schrodingers Box My teacher Thanks for sharing what you know with us. Take care and have a great weekend with all your family around you PROFICIENT Schrodingers Box From Nick Ayivor from London England UK 🇬🇧

[@SchrodingersBox]

Merry Christmas my friend!!!

[@HaroRider03088]

Great video, but you forgot to check powers and GROUNDS 😆

[@SchrodingersBox]

Hahahah I am dying that when Vicki offered to get me some coffee I didn’t work a GROUNDS joke in!! Gosh man. Missed opportunity!

[@farerse]

I hear sound fine!

[@mikeconley8111]

With out a code clear, the vehicle need 2 or 3 drive cycles to start a update on fueling and air changes.

[@SchrodingersBox]

That is true!

[@meatballmagoo6134]

BATTLE OF THE SCAN TOOLS !!! BATTLE OF THE SCAN TOOLS !! 💣 AUTEL #1

[@SchrodingersBox]

it is definitely near the top for sure!!

[@calholli]

GROUNDS!!!

[@TheDisgruntledMechanic]

But you did not check the GROUNDS!!!! HA!

[@SchrodingersBox]

Hahaha I was going to work that in but I forgot!!

[@kmg501]

This channel sucks! He didn't show how to replace the snorkel! lol

[@rapa2464]

GROUNDS! ... sorry, I've developed a twitch.

[@brownwrench]

Unmetered air. Get the duct tape.

[@SchrodingersBox]

yea I should have said unmetered air.

[@brownwrench]

No lack of sound here

[@SchrodingersBox]

Hahaha. I waiting a minute before going live this time. Sheeesh man it’s like feeding piranha here!!

[@brownwrench]

@@SchrodingersBox 😁

[@zaytoony]

I got sound

[@onthemolly]

i got sound

[@aymenmohamed1134]

👍🏻👍🏻👍🏻🌷

[@albertoascencio5935]

No sound

[@geneduclos4003]

No sound