Every engine part changed, still has P0171 P0174 codes Pt2

Part 2 of the series looking a car with lean condition that everyone kept guessing parts at, but we want to diagnose instead of just guessing..
Part 1 is here: • Every engine part chan...
want to learn how to do advanced diagnostics instead of just guessing? Join my website for instructional videos on step-by-step diagnostics at www.schrodingersboxqm.com

[@SchrodingersBox]

So I wanted to give a shout out to Dennis Rindlisbach and Joshua Pruden who, in Part 1- BEFORE I released Part 2, correctly made the call WITHOUT GUESSING and they each gave their data and calculations on exactly how they knew the issue. That’s exactly the point of the channel- to not just fire our guesses but to use data and analytics to determine the issue. Congratulations guys- extremely well done!!!

[@TheOnespeedbiker]

So I'm wondering what was the original problem. The owner replaced the MAP intake sensor chasing a lean O2 sensor and the other garage said there was a marked improvement with new fuel pump, so did the owner create a second problem replacing MAP intake sensor with a faulty part? Or with the parts cannon being fired will we ever know?

[@Face2theScr33n]

That's why this is a great channel, not just your content but the comment section is full of info as well. You have a great community following you, Matt! Rock on!

[@SchrodingersBox]

We will never 100% know however I am sure the fuel pump was the issue originally but owner introduced the MAF issue.

[@SchrodingersBox]

We will never 100% know however I am sure the fuel pump was the issue originally but owner introduced the MAF issue.

[@TheOnespeedbiker]

@@SchrodingersBox I think it is very confusing to a lot of DIY mechanics that the brand new aftermarket parts they are putting in their cars may actually not only not work but hide the real problem. I remember in auto shop our instructor advised when trying to diagnose a problem never do more than one repair at a time, that way you'll know what fixed the problem or made it worse. Today you could add, if it doesn't fix the problem, or at least make an improvement, put the old parts back on until you find the real problem.

[@mrk130]

Many years ago, an older mechanic told me, “A new part doesn’t mean it’s a good part.” Great job with this.

[@evontrizmo]

See folks, this is the difference between someone doing something that they love vs. someone who does something because it's another paycheck. When you have professional repair shops coming to your home garage, you're obviously doing something right. Congratulations on all you accomplished so far Matt!!

[@SchrodingersBox]

Good point, and thank you!!

[@kellismith4329]

What about someone who just wants their vehicle to run right?

[@blackCladLad]

I highly appreciate the self correction and awareness around the 29 minute mark when you discuss why you ‘just know’ that vacuum isn’t a problem, and then go back to elaborate on it. Very respectable!

[@SchrodingersBox]

Thank you for noticing that. I totally missed the whole point of the channel is to not do stuff like that!!! I am glad I caught it and even more glad you did.

[@KG-vr3te]

I'm hooked, I love it. 27 years Jaguar tech but so many good reminders. You're doing exactly what we need. I guarantee no one remembers the basics and it's great to hear thought turned into word

[@drg424]

Like this analytical approach, and this guy don't ramble on like some do about things completely not about the topic.this is a automotive chanel not a comedy chanel if you get the drift,it's OK to have some comedy but not half the video, I respect him for this and his approach.

[@FFcossag]

Excellent work, Matt! This was one hell of an issue to diagnose, and it's very refreshing to see you question new parts! "It's been replaced" does not mean the same thing as "it works as it should", and it's very easy to forget that. This was a thriller to watch!

[@SchrodingersBox]

Thanks so much, yes this was a lot like a murder mystery!!! The satisfaction of solving these cases never gets old!!

[@serengetilion]

Single female here. I just joined your pay site because I want to know what I need to know to diagnose my car issues. I'm currently having stall issues with codes po171 and p2096. I'm loving the thought of being able to find the problem through your tutorials help.

[@SchrodingersBox]

I would totally start with fuel trim. See if it gets better or worse as rpm increases.

[@serengetilion]

@@SchrodingersBox I'm elated you responded to my comment. A giant-normous thank you.

[@BlackCubone]

As soon as you showed how vastly different the MAFs were, I was already shaking my head.

[@hmroa3056]

I too was a victim of my own parts cannon. One of the parts I replaced on my '99 Ford Ranger was an aftermarket MAF. My mechanic found it to be of the wrong voltage. He replaced it with a Ford part. Problem fixed.

[@fredflintstone4715]

Did the same with my 98 Ranger. Aftermarket MAF didn't work right...

[@Lando1020]

Part 1 and part 2 is greatest "tv" I've watched in long time. Has everything. Comedy, drama, suspense. Pure gold. Thank you, sir. Btw I'm in the early stages of chasing these 2 lean codes on my 10th gen F150 (2003). Also your Scotty impression is spot-on.

[@billsmith2212]

Thanks for taking us along on this . As always , there is a risk of throwing parts at a problem . Especially if one is bad , a joker is now in the deck . Beware of " white box , no name , one size fits all parts " . On general principle , I tell friends with a drivability issue : clean the throttle body , MAF and IAC = just good maintenance . Most times they were never done . And a visual inspection BEFORE anything else .

[@TheCowgirlNiamh]

That was great Matt! It really enforces the need for proper diagnosis before launching the parts cannon 👍 Well done you! 🤗

[@SchrodingersBox]

Hahaha I knew you would like this one!

[@carbonlarge]

Brilliant fix mate, I'd love to see the mans face and response when you hand his car back.....

[@reneneron2971]

For reference, a velocity stack and larger intake on a Toyota 2GR can change measured air flow by 30% (!). The ECU has to be programmed specifically for the intake and MAF sensor used. It is another reason that “performance” aftermarket intakes can negatively impact the performance of a car if used with the stock ECU…ignition timing can also be impacted. Changing just one sensor (or airflow through the MAF) can have multiple negative consequences (fuel trim, ignition timing, etc).

[@reneneron2971]

Matt, opening the air box or even not having it sealed completely bypasses the air filter (which has pressure drop). This will change flow though the MAF sensor completely (introduces air turbulence as well), so air measured through the MAF can change dramatically. Hence the dramatic changes in fuel trims at idle when opening or closing the air box. They are very sensitive to flow and location in the air box. OEM is best for these type sensors (knock sensors are another example where aftermarket replacements can have very significant negative effects).

[@nyeahgarner2420]

I went to Autozone to buy my second set of knock sensors for my silverado since one of the $8 aftermarket sensors went bad after 2000 miles. Opened the boxes and one had the same dots that I saw pictures of oem sensors online. The other had the same exact markings as the $8 aftermarket. I paid $60 each for them. This is most definitely not the only time a parts store passed aftermarket parts as OEM.

[@carnivorebear6582]

I don't think pressure drop itself across the filter would make a difference (the maf by design works across a range of different intake pressures), but the irregular airflow patterns would.

[@davidmendenhall5826]

I love your content. I have learned so much about diagnostics from watching your videos. Thank you for what you do

[@SchrodingersBox]

My pleasure! I am glad to hear it.

[@mikesautomotivediagnostics8080]

In the past, I didn't mind using aftermarket sensors, but here lately most of them have been a bust. Seems like in the last few years aftermarket has gotten worse.

[@SchrodingersBox]

Unquestionable since Covid, for sure. I use almost exclusively aftermarket parts however I have had more out of box failures in the last 2 years than all the previous 8 combined.

[@TheOnespeedbiker]

One of small positive affects of the parts shortage is some aftermarket brands have had to repackage OEM parts. Standard for example has been repacking some Japanese OEM sensors, when the Dealerships show them on backorder. The problem is your just as likely to get a repackaged Dorman part.

[@MowSow]

Yes .. I have a Porsche .. and we’ve seen parts fails out of the box .. injectors .. vario cams solenoids .. etc

[@geraldgordon1976]

Alot of these manufacturers are making it to where you need original dealer parts for normal performance

[@TheOnespeedbiker]

@@geraldgordon1976 I don't know if it's the manufacturers or just cheap aftermarket parts. Interestingly automotive law states manufacturers are only required to manufacturer parts for vehicles while they are still under warranty. I don't see the problem of not manufacturers making proprietary parts, rather the inability to purchase OEM parts, due to shortages resulting from manufacturing defects of cars still under warranty. In some cases dealerships are restricting OEM parts strictly for warranty repairs due to OEM shortages. Then once cars are no longer under warranty, OEM parts from dealerships tend to dry up and one is forced to buy aftermarket parts of unknown and often poor quality.

[@clutch5sp989]

Learned my lesson with aftermarket parts from OR & AZ. Particularly the electronic parts.

[@nicktruitt5589]

This video saved me! Been fighting lean codes for a while ( I assumed it was vacuum leak) turned out it was and aftermarket MAF! I am so glad I stumbled across this video, my old fishing boat hauler seems to be better! Thank you for putting this out there!

[@JoeSevy]

My son and I had identical Ford Rangers, his had a problem with the MAF. I bought two from RockAuto, both were bad. The first worked perfectly... for about ten miles. I actually swapped in the old one from mine to prove the problem and solution. The second one didn't even pretend to work. Bought another from Autozone which worked properly. That MAF was actually the reason we were able to buy his truck so cheap, because the shop that had done enormous amounts of work on the truck couldn't figure it out. When I started watching the first video my ears perked up when he read that the MAF had been replaced. You'd think that would mean it's good. It doesn't. The aftermarket MAF he shows there looks exactly like the MAF for a Ranger 2.3 4 cylinder. Wouldn't have thought it would physically fit the intake for a V8 engine, but maybe it does. The really frustrating thing is that the readings from the sensor on live data can look pretty reasonable, just like this case, and still not be close enough to right. A mechanic I know keeps a "known good" MAF for every model he works on often, because it's quite simply the fastest and most accurate way to test it. If swapping the MAF fixes the problem he takes it back out and buys a new one for the vehicle. I have a known good one for my rig stored in a filing cabinet, just in case. Funny that the customer could have avoided all this trouble with a can of MAF cleaner. Sad they fired the parts shotgun at it without figuring it out.

[@bensexploring1791]

Thank you so much for the detailed info! I was stumped with my Cruze and did exactly what you did and you helped me find the MAF sensors was the culprit. Defective sensor.

[@RobertoSantiagoRodriguez]

First-rate diagnosis, superb detective skills, Maestro! Thanks so much for your help!

[@SchrodingersBox]

Glad you enjoyed it

[@petemoss8625]

Always enjoy your methodical problem solving. happy new year, from the UK.

[@SchrodingersBox]

Happy new year!!

[@roncarne206]

Fascinating. I was totally engrossed and how you went about determining a mass airflow. Clearly not easy to determine. Outstanding job

[@SchrodingersBox]

Yes it’s a very difficult call for sure. I would have been nervous if I had to buy one!!

[@labradormcgraw]

A great video to kick off the new year, Matt. Wishing both Vicki and yourself a safe and happy 2023.

[@SchrodingersBox]

Hey Andy, happy new year!!!

[@legallass9905]

HapPy New Year!!!!

[@jamesparks2242]

This is James Parks again. I know at one time there was a bulletin on lean codes and spark knock on 4.6 Fords. MAFs were replaced without necessarily fixing the problem. Ford created a software download that had to be done to change the failure parameters in the ECM. This may not be applicable in this situation. It may be so old that it is no longer in the dealers database. You may have to find a dealer who has maintained a hard copy library, or an older Ford tech that remembers. It also seems like there was a relearn or "burn" in procedure that required different drive cycles and some WOT operation. I am NOT a Ford tech, worked at GM dealerships off and on from 1976 to 2007. Did more Ford work than I ever wanted at independent shops.

[@coycarlson4979]

To be able to locate the faults / malfunctions and repair vehicles today - you have to be very analytical of EVERYTHING - because all it takes is a part designed ONLY SLIGHTLY different and , as you ALREADY KNOW - look at what can happen - VERY FINE JOB Matt , and ONCE AGAIN , thanks for the EXCELLENT video / troubleshooting demonstration you teach / share 👍✌️✌️✌️

[@gomezpedro10]

Been watching a lot of your videos and learned a lot don’t stop making videos! Felt that happiness when you found the problem lol

[@SchrodingersBox]

Don’t worry I plan to keep making these!!

[@andrewthompsonuk1]

I knew an aerodynamics professor many years ago, he used to talk about contracts he did for car companies around airflow and metering. Its very complex and there is little chance of an aftermarket sensor of a different design ever working properly unless its something very special that has had the engineering and testing put into it. The same goes for the airbox and intake pipework if its close to the sensor.

[@kingdavidjr6641]

Was having trouble backfiring and loosing power at low speeds and even trying to get back up to Hwy speeds today with this same motor and truck. Cleaned my maf sensor and it’s running normal again. I have the K&N aftermarket cold air intake box with their tunnel that looks similar to the aftermarket one you showed in the video. The kit used the OEM MAF sensor though and it’s cut to fit OEM. Thanks for making this an informative video worth watching. 👍👍

[@TommyOhmalley]

Great series sir. Thank you for the knowledge and right on to you for fixing it

[@SchrodingersBox]

Many thanks!!

[@PaulCTownsend]

Good job from start to finish.

[@ignacioromero5014]

Great work! I've learned so much from you, I need to work on better processing the collected data and I am excited to learn more... Thanks!

[@The_Noticer.]

So all this guy had, was a faulty fuel pump. And by firing the parts cannon at it created a secondary problem he associated with the first problem. This is such a good example of why you need to double/triple verify your diagnosis. And I guess also why you should use OEM sensors, however expensive they are (caveat: especially if you dont have the kit to verify the voltage etc, or the comparitive data of a known good. It's still safer to just get an OEM one to save the headache). 8:05, Dont know if you've heard of this tip, but if you're dealing with multiple clips it sometimes really helps sticking tie-wrap ends into them so they dont clip back.

[@kennykrylov4513]

I think the way to do it is only use Chinese sensors if you are certain this is the problem. After all they are times cheaper. Otherwise you're swapping unknown bad for unknown good. If it doesn't fix it I'd swap it back for the original part

[@SchrodingersBox]

Correct cohen. I think a lot of wasted money and effort for what was one problem.

[@jeffbridges344]

Superb diagnostic service been watching your videos from the UK 🇬🇧 keep up the good work. 👍

[@SchrodingersBox]

thanks so much. I have a bunch of UK viewers. They are always so well spoken and polite. I love it!!

[@grenvillephillips6998]

Another great win for Matt: I was totally led astray by the fuel pump improvement!

[@SchrodingersBox]

I would have been too.

[@DependableAutoTruck]

in my life as a mechanic have only found 2 or 3 maf sensors that were bad most of the time when checking and find bad its aftermarket and the factory one that was in it works after cleaning

[@SchrodingersBox]

Oh I totally agree. Man when I first started doing this stuff I always was thinking bad MAF. Over time I realize it’s never a bad MAF- so it’s really really tough to make this call. I have had more bad PCMs than bad MAF. But I have had tons of dirty MAFs

[@nyccorvette]

Great video. This has really helped me in diagnosing and fixing my c5. Thanks for sharing yourself with us.

[@SchrodingersBox]

Great to hear. I have a viewer “C5 Diag” who also makes diagnostic videos but on his C5.

[@bullgamer7343]

Wow this is good! I remember on one his older videos he said if you start changing parts this isn’t the video for you! Lol this man is awesome on diagnostics.

[@SchrodingersBox]

Thanks. This is definitely one of my favorite videos for sure. Parts cannon would never end on this one if it wasn’t diagnosed.

[@paulpaquette1961]

Happy New Years Matt!!! Great job both videos!!!

[@SchrodingersBox]

Happy new year my friend

[@SS-en8gx]

Matt, had a problem with my Buick would not start and idle so watching your previous vids and your recommendation was to disconnect the MAF sensor to see if the conditions improved and it did so after cleaning the sensor still no improvement. Went to the store bought a aftermarket one and it improved but still would not idle correctly. In the parking lot I asked the guy for a AC Delco changed it and the car performed perfectly. My long term fuel trims pulled down to normal immediately, just goes to show the importance of OEM style sensors for correct operation.

[@0tt0z]

Great fix and great job to you sir for figuring it out. Knowledge of system operations is important. GROUNDS!

[@SchrodingersBox]

You got that right! GROUNDS ahaha!!

[@paullozolla7699]

I love this guy. My dad is a good mechanic but damn I wish I can be this guys helper I would work for free.😂

[@rich13la1]

I am still waiting for your first failure to fix an issue ,,,,,, amazing diagnostic skills , thanks so much for taking the time to make this video and share to all ! Best wishes for 2023 .

[@SchrodingersBox]

Hahaha thanks man. I do have several videos where I made the wrong call.

[@timschreiber1584]

Cool videos enjoyed watching the fix!

[@SchrodingersBox]

Glad to hear it!

[@donho9670]

Thanks Matt...I needed at least one more GROUNDS!!! to end 2022.

[@SchrodingersBox]

Rotflmao!!!!

[@TheOnespeedbiker]

Watching Ivan at Pine Hollow and Eric O from South Main, I was suspect of your dismissing replaced parts as assumed good. I believe it was Eric O that said NEW aftermarket, especially sensors and other electronics stands for "Never Ever Worked". There also Rainman Ray saying of "Chinesean" parts, "Just because it's new doesn't mean it's good" 👍. Ivan often often had to reverse the parts cannon just to have a good starting place and it's fantastic when the owner has kept the OEM parts he (usually a he) replaced. In this case as I posted elsewhere the original problem appears to have been the fuel pump but with so many other parts replaced we may never know.

[@rubenarevalo81]

Hey I just looked at your video and it seems that you just solved my problem thank you so much I am happy that you made this video

[@SchrodingersBox]

Glad to hear it!

[@jum5238]

I've had two parts newly replaced cause me more problems. Both were distributors. One for an old corolla with mechanical points. I didn't know you were supposed to lube them. It blew up a few days after I replaced it, and I never bothered to go back and look at it because I had just replaced it. The other was an aftermarket distributor cap. Caused random misfires. I put it in storage for awhile because I couldn't figure out what was going on. A year or two later, I'm reminded... and was about to replace the distributor cap again, thinking by now it was rusted, etc. and just before I did, I found someone who described the EXACT same misfire cylinder problem. I went OEM, and voila! FIXED!

[@sollykhan2385]

Another AWESOME video, again i had sped up the video to 1.7X above normal, not actually sounded like the 'Chipmunks' but hey brilliant work, Thank you for posting, and the time and effort involved to create great content, keep up the leading edge,,,as ever,, Bless 😇

[@davyarthurs]

Always go genuine for electronic parts I say. The computer is looking for certain range of values and dodgy aftermarket parts might not operate within those parameters. When you unplug the MAF the ECU will use substituted values. Great work as always Matt

[@SchrodingersBox]

Agreed it’s best policy for any computer inputs.

[@mikebaz7843]

Even new OE sensors for the same engine can throw you. I bought a new non-counterfeit Bosch maf for my om646 diesel engine and it didn't run right, I ended up forking out for the genuine MB maf (which is Bosch with an MB number added on) and it was fine. I have however had two dud brand new Bosch M112 engine mafs through the dealer, so that's always fun.

[@johnpopzgrace1900]

Wow, you are amazing! I learned so much and I love your way of doing things! You are very easy to follow and understand and that makes a huge difference! Keep up the excellent job you do! "U Rock" Thank you and have a wonderful day! 😀

[@SchrodingersBox]

Wow, thank you! Made my day!!!

[@tickyul]

Great job, interesting video!

[@marksullivan5885]

Cause and effect. proof! Nice job!

[@dangerdavefreestyle]

i also have a ford and drove it a bit with a bad maf sensor. it has a preset mode aka limp mode and will actually run ok. this is interesting because whatever you had going on with it was ofcourse resolved by going with a set of ok parameters. these trucks are very picky about the air they get. if i run mine with the outer portion of the air flue removed but the maf is still intact it will run rough just idleing. everything snug as a bug it runs great. i once was doing a bunch of testing not just replacing parts. luckily mine was not outputing any gpm and its iat function was way out of wack. i got a brand new hitachi brand and have been very pleased with its performance. the way you graph and analyze waveforms and such is well within my understanding and impressive and surely something more involved than i ever have done for diagnosing. it is a method where nothing gets past you. HOLY SHIT can you imagine how easy it would have been to OVERLOOK the maf sensor as being a problem because "it was replaced". yeah a dirty one was replaced with the wrong type!!!

[@williamhanna5224]

Awesome video Great work!

[@georgebonney90]

Great job Matt👍that was awesome

[@SchrodingersBox]

Wasn’t that fun!!!! I am sure you will agree one of the better ones since you have been here.

[@joeblow6786]

Sweet! This is an illustration as to why we can't assume that aftermarket parts will correct a known issue. Which is sad because a person is already miffed about having to fix it. They just injected a new set of variables into an already potentially complex problem.

[@mohabahmed202]

Excellent my favourite teacher. I really enjoyed every second in both videos. And i'll put this to my list of lean condition possible causes (dirty OR inaccurate MAF reading) ❤️🌹

[@SchrodingersBox]

I added it to my list too hahaha.

[@modeeper1]

You are correct about the MAF sensor that what it was from the beginning

[@brianw8963]

I think I was in the ball park on the “installed variables “,though I would have needed more data. , especially on that lbs. / grams thing. It was working but I had no idea if it was accurate and You concluded it was not. 👍👍

[@grabbag6314]

Great video, very impressive

[@TheDisgruntledMechanic]

Well I hate to say this, but if you would have checked the GROUND 1st.........., HAHA! Great work Matt. I have gotten so much bad aftermarket shit I go with OEM as often as I can. Just had this problem with an aftermarket park sensor. Bought 1 off of Rockauto for $14 because the stock 1 was $170 and the $14 1 was no good. And I love being THAT Asshat! Have a Happy New Year!!

[@Tony-rl2fr]

😂 I love to see the GROUND gag living on! But what about POWER⚡!?

[@SchrodingersBox]

Happy new year Mike!!!

[@Isaiah5417GdLk]

I believe the fuel pump was the original problem, but in the mix he created another which "masked" the fuel pump fix. The delay in the pcm correcting helped in this masking between the part changing. Ive always tried to be a tester. I hate throwing parts. And when i do change a part , always, always keep the old one, at least for a while. Also im pretty skeptical of aftermarket parts. I love the way you approach these issues and your diagnostic process. Keep up the good work. One more thing. I definately share your excitement and enthusiasm when you fix it. Im gonna have the same in a few weeks if i find my evap leak on my Forester. Oh that brings me to another, I was watching one of your older videos and noticed you werent so fond of Subarus, yea they are a little quirky and different, i just took a likeing to them for their amazing awd system and reliability. Love your channel. Keep up the awesome videos.

[@SchrodingersBox]

Thank you, I agree with your assessment of the issue- “masking” the fuel pump is a good description.

[@jasonputtock4428]

All I can say is, yes disconnecting MAF allows the car to use it main map configuration in emergency and bypasses true valves that its taught to read. IDK how they do it but its something BMW and i think merces use in those similar years. well done. grats.

[@falafelandthings.4332]

I really appreciate your dedication and knowledge. I am a professional chef and not a mechanic I am fascinated to know things. I just bought ford econoline e250 4 2l v6 with lean codes p0171 & p0174. the mechanic without any diagnosis it's 100% head gasket needs to be replaced. he did replace the head gasket & one exhaust manifold . with total charge of $1500. I drone the van for about 30 miles & the engine light back on with same lean codes p0171 & p0174. took it back to him & left after three days called me & told me me it was ready . I drove it for about 5 miles & and again, light engine back with the same codes . the van hardly drives even if press on Gas all way. took back again and left it another two days. and told that he changed the mass air flow sensor . and told if the problem won't resolve the next step is to change the fuel pump. and yes, the problem didn't resolve d and then changed the fuel pump. the van got more power, but the problem is still the same same engine light and same codes. I really got frustrated . I checked the fuel trims, and both banks showed very high 24-23 %. I did not know what to do next. the rpm show is a bit higher than normal, so I thought maybe I clean the throttle body & the idle control valve myself. after I did and checked. I find that the fuel trim on both banks went down to about 15/16% on idle, and the engine light is off now. but if I raise rpm, the fuel trim will balance, and that means a vacuum leak as I learned from you. I did a smoke test. I saw smoke coming out from the EGR valve. I did show the mechanic a video of that & he told me that he already knew about that & already checked & and EGR Valve is fine. now he is telling that he is very sure that the problem is that the intake Manifold isolator bolts need to be changed . I really appreciate your time reviewing my message & if you find the free time. to give me your input on all this. many thanks

[@SchrodingersBox]

Where is your fuel trim data? That’s the very first step.

[@falafelandthings.4332]

@@SchrodingersBox thank you for taking from your free time to respond to my message. I sent a reply with information you requested but I am not sure if my message went through so sending again. When I did purchased this van I was kind a illiterate regarding reading scanners or what to look for. I only could read a code. So I don’t have any information prior prior giving the mechanic to work on the van. While the mechanic was trying to fixing the & back fourth, I did find your channel & started to learn as much I could & bought the D7 scanner tool you recommended. so after all the he done I checked & the long fuel trim bank 1 & bank 2 was about 24 & I think the same regarding the short trims( but I am not 100% sure about the short trims).engine light is on. after I did took out the throttle body & the idle control valve & cleaned them I checked & bank 1 & bank 2 short trims between -3 & 3. & long trims between 17-18 ( now engine light is off)today I did watched video ( 02 Ford) & I did took the time & pulled out the EGR valve & cleaned it & I replaced the gasket. then I did scanned again . short trims both banks between-3 & 3 & long trims both bank about 14-15.but also I did another smoke test but find that still same smoke coming out from the EGR. So basically the new gasket didn’t helped. But this time I did looked very carefully to the exact location the smoke is coming from & I find out that smoke is not coming from EGR gasket but it’s come from the lower body of the EGR it self. Where is small rounded holes around the lower body of the EGR. I don’t know if this a normal because the engine is off & EGR valve is not activated or not I don’t understand how it should operate. But the good news is that after the first clean of idle control the trims went down & engine light is off & after the second clean of EGR the trims went a bit further down. I hope this answers your question. again I appreciate you taking from your free time & many thanks. Amir

[@billsmith2212]

Thanks for taking us along on this . As alw

[@DuaneDonaldson]

This is one reason why AM Air Filters and K&N should not be used. thanks for the case study, awesome.

[@markstafford399]

hi matt,, i figured out my problem!! it was the firing order on my truck!! thank you for all your help!! you the man!!!

[@SchrodingersBox]

Hahaha… did you cross the spark wires up???

[@markstafford399]

@@SchrodingersBox yes #2and3

[@donlightbody8270]

I've been chasing this issue on my 08 explorer 4.6 for a year. "no, can't be the mass air flow sensor, it's new." ugh. i got so desperate i even changed the throttle body yesterday!!! Back to the airflow. Thank you so much for this video!!!

[@SchrodingersBox]

I recommend starting with the MAF voltage. If your MAF voltage goes over 4 at WOT you should eliminate it as the problem.

[@MsRa3d]

this video deserve more than 790 👍

[@thecardoc100]

@31:48 The MAF waveform. When you snap the throttle, you do get the initial inrush of air that part is correct. The drop off and then the ramp is caused by the intake manifold filling up with air that the engine isn't running fast enough yet to use. Then as the crankshaft accelerates and the engine starts pumping more air you get second peak. I would expect that second peek to go over 4v on that system with a snap throttle like that. The changes in what the MAF was reporting as you opened and closed the air cleaner assembly is a direct result of turbulence changing the density of the airflow at the MAF sensor.

[@thecardoc100]

You have to drive it to recalculate the BARO as I described in the response to the previous video. I'd like to see data from what this does on the road at this point before it gets the full approval.

[@mtrltoolman]

Good video Matt!

[@SchrodingersBox]

Great to see you again!!

[@spirit_wolf123]

excellent diagnostic skills it made your video a pleasure to watch. I am a new viewer and look forward to future videos.. each sensor is calibrated to thetype of tunnel it is in so I would suggest it was the sensor not the tunnel

[@SchrodingersBox]

Thanks for watching!!

[@tiitsaul9036]

I've had funky experience with aftermarket MAF as well. Is that MAF correct part? Could be for different ford model or year. Happy holidays Matt.

[@walkertonheights]

great video, thanks.

[@ljaeracer4152]

Great work 👏. The only data missing is that of the original maf sensor before cleaning it.

[@SchrodingersBox]

Yes I though about that after I cleaned it lol :-/

[@billyfox384]

Nice catch.. I was really leaning towards restricted injectors, especially on older truck that had a bad fuel pump, although most of the time they will cause a misifire or at least a bank to bank difference. Injector P/W is a good PID to look at. I had an old ford truck that had restricted injectors basically even on all 8. Tough to diag even with a flow test or injector drop test. Sad part is that the bulk of the parts thrown at it would not cause a lean issue. Gotta have OE sensors. I won't use aftermarket unless I have to

[@luisponce1472]

WHAT IS THE OE SENSOR?

[@billyfox384]

OE= Original equipment. Ford Motorcraft, AC Delco, Mopar, ECT@@luisponce1472

[@rogereastman3187]

I'm very Leary of the shape of the wind tunnel theory.....dagnabit I guess I'll have to fall back on the aftermarket part usage. (Unless of course I want to take the time to customize a way to mount the sensor system......) I'd have to be way down the list of things that need to be done to do so. Great exciting video Matt

[@flycatchful]

Scotty, and you have one thing in common. That is you both say "don't worry about it". One thing Scotty always says don't buy after market parts just OEM.

[@SchrodingersBox]

We have that in common because we say but, but not why we say it. He says don’t worry about it because he doesn’t understand it. I say don’t worry about it because I scientifically eliminated it.

[@crasher88]

my guess is the customer inadvertently purchased a MAF for the other engine option for that particular year make and model of vehicle. If my memory is correct the intake ducting for the 5.4 and 4.6 is the same its just the internals(ie the MAF and its housing) are different and physically interchangeable but won't work due to its construction. Ford used that style of air filter housing on a lot of its vehicle lines during the production of that truck so its very easy and reasonable to assume the wrong MAF was installed and caused the problem as you said.

[@nancykeefe317]

I think ur very thorough in ur troubleshooting. As for ur thinking on the sensor, I think u have overlooked the most obvious reason why it didn’t work: it was the wrong part! The person who sold it to the owner gave him a ford MAF, just not the correct Ford MAF! The Triton engine has lots of parts unique to it. I know this as an 8 year veteran parts counter person at a major after market retailer. It was close enough to fit it to the truck, but as we saw the guts were completely different inside, and none of the screw holes lined up! Major clue there…..

[@rogereastman3187]

I love how you hate fiddling with air filter box connections.... Lol.....I get it😂

[@andymasiddo8180]

You’re the BEST!!!!

[@SchrodingersBox]

Hahaha there are others better for sure but I do think I hold my own lol.

[@HouseCallAutoRepair]

I WAS going to get some sleep.... Later, I guess.... I frequently struggle with misreporting MAFs.... Nice job Matt!

[@SchrodingersBox]

Thanks- this is worth staying up for lol!!

[@kennykrylov4513]

Amen. Why do you always post them at midnight, some of us have to get up in the morning

[@SchrodingersBox]

Hahahaha. I try to post whenever I have time. Unfortunately that’s usually late but I understand!! I was up til 2 uploading part 2

[@coycarlson4979]

Arm chair - WELL, I'm an arm chair 🤨😏 - damn good one too - you are Matt 😏👍✌️✌️

[@4WheelKid]

had P0171 P0174 on my 96 Ford E-350 big block 460 with obd2. fuel trims led me to a possible fuel pressure issue. the pressure was good enough where it would run fine but under load you would see the pressure drop off more than it should. The van had sat for over a year, and someone had stole the fuel cap off of it, I pulled the tank, found a lot of junk in the tank and the fuel pump assembly didn't look great, parts of it were falling off, socks were cloged up, did a full clean with a delphi cleaning kit, no rust on the inside, installed a new delphi pump and sender assembly, new fuel filter, I also realized that the old pump assebly and the new one, on the connector had the grounds for the pump and sender unit mixed up when plugging into the factory harness. this could have been causeing an excessive voltage drop on the ground side for the fuel pump since the sender ground wire is a smaller gauge than the pump ground wire. I fixed the wiring so the pump and sender have their correct grounds. My fuel trims are now good, around +6 under heavy load, not perfect but better than +25 like before. not sure if it was the wrong ground, old fuel pump/filter or both was causing the issue. But I sure am glad it's running great and I won't have to worry about fuel pump issues for a long time to come. I love the Schrodingers Box channel, I have learned and continue to learn so much from him.

[@SchrodingersBox]

Great diagnosis and fix!!!

[@arthurlull8681]

Thank you matt...because of you I am able to solve my mystery problems...thank-U- & SCANNER-DANNER & S-M-A...& RAIN-MAN...YOU MEN -R- THE BEST-& ADAPT/APE...🤠👍🏻

[@arthurlull8681]

AND ADAPT-APE🤠👍🏻

[@Eastahtata]

I've learned Ford (and probably other OEMs) are picky on MAFs and even air filters. I have a guy that puts those stupid cone filters on his cars and gets lean codes. I also noticed fuel trim changes with different brands of air filters, similar to the way you saw the change when unclamping the filter.

[@dicktomasko1553]

Great job....😁

[@SchrodingersBox]

Thank you! Cheers!

[@themechanic6117]

From the first video , "every part changed" . I said to myself "I hope he kept all the original parts because I bet you all the new parts are cheap Chinese parts".

[@MasAUS]

Great video

[@SchrodingersBox]

This is a good one isn’t it!!

[@MasAUS]

@@SchrodingersBox oh yes 100% , All your videos are great I am a mechanic I do that for leaving and I do enjoy your videos

[@CodycoWeb]

BARO will correct during driving, it calculates BARO by RPM, throttle position and airflow during a near wide open pull. Years ago on IATN I did a post using calculated BARO to diagnose partially clogged cats.

[@jayjwin1178]

when DIY-er performs better than a pro 😊

[@Tony-rl2fr]

Lol, the CURSED fuel pressure test shot

[@SchrodingersBox]

Haha it is a curse!!!!!

[@fredflintstone4715]

Unless a vehicle is like my 98 Ranger (aluminum hood), you can get the fuel pressure gauge to stay in place with a magnet. Well, as long as the gauge is also metal.

[@dennissalisbury496]

Plastic carpentry clamps work really well to keep testing instruments in position temporarily.

[@Face2theScr33n]

My 97 Mountaineer has the same air cleaner clamp setup. I hated watching you fight it, but I'm glad it's not just me... This is the greatest diagnostics channel on the internet, at least of which I'm aware. Especially in this era of unreliable aftermarket parts, proper diagnosis is of utmost importance. It's like post-repair diagnostics are now part of the job just to confirm new parts are even good. Happy New Year, Matt!

[@SchrodingersBox]

Thanks so much!!! Yeah F those clamps man hahahaha!!!!

[@joshuapruden6497]

Matt.. I have a question; specifically about the aftermarket MAF. Is there supposed to be a rubber o-Ring or gasket between the silver tunnel bolts up to the black plastic cone? Thanks for the shout out. Love your channel. Excellent content!!!! I wish this was on cable. I would have my butt glued to the sofa.

[@SchrodingersBox]

Hahaha thanks Josh and again nice job on that call and rationale earlier. I have never taken one of these apart before so I don’t know about any gaskets or anything.