Test Your Lean P0171 / P0174 Diagnostic Skills-Pt3

[@صلاحالحراصي-غ1ض]

Hi Matt. I'm a new subscriber. I got P2179 code on my GMC terrain 2009 which indicates a fuel trim system lean at cruise/acceleration bank 2. One guy tested the car with his scan tool and he asked me immediately to replace all the 6 fuel injectors🙄😅 after watching your logical, scientific, reasoning diagnostic approach, I'm not going to spend 375 dollars on buying new injectors 😊

[@SchrodingersBox]

GREAT CALL!!!!There is absolutely zero chance new injectors will fix it.

[@rsawyer05]

Hi Matt, great video. I really enjoy your content and learning about the advanced diagnosis. I've been able to apply it to help correctly diagnose my own car issues.

[@mkuehn5450]

24:45 step 1, verify customer concern. i spend a lot of time in an unobtrusive approach just gathering information, freeze frame, koeo, then koer, underhood visuals, fluid checks, then possibly a test drive. baseline numbers. i have questions, but am watching these videos in order to see your process.

[@pfsantos007]

Late to the party. When testing the injectors, aren't you spraying fuel into the cylinder? Did you take out the spark plug or check that one of the valves are open? Just worrying about hydro locking the engine or washing down the cylinders of oil. Maybe the testing isn't spraying enough to be an issue? Edit: missing link to Part 2 in description.

[@SchrodingersBox]

There is really little fuel injected. You would have to do it many many times for a hydrolock to be possible.

[@pfsantos007]

@@SchrodingersBox Thanks.

[@clutch5sp989]

LOL at Matt...many have their lil sayings like "there's your dinner" -Tyrell fixes all etc. Matt always has something to do with punched, stabbed, kick'd in the throat.

[@christopherkelly8522]

Fantastic! Your videos are brilliant! Thank you very much for your informative teaching & posting for these videos on youtube for all to learn...

[@DAZ_SR]

How did you plug the weep holes in the exhaust system when you smoked it Schrödinger?

[@georgebonney90]

what a great series,thx man

[@jefftuesley4997]

Matt Love your videos and im learning so much. Having trouble with my 05 Grand Marquis with a p0171 and p0174 both banks running lean. I hooked up my scan tool and watched the ltft which are both at +25%. Took the car for a test drive and found that around 1500-1800 my fuel will go down to about +18% but go right back up around 25. Checked for vacuum leaks, cleaned maf and thottle body. Any help would be greatly appreciated. Thank you for the videos you rock man

[@SchrodingersBox]

Looks like vacuum leak to me.

[@jefftuesley4997]

Thank you so much. Keep making those great videos

[@spelunkerd]

Wait, doesn't the propane have to be burned to reliably change O2 sensor readings? When you add propane to the intake, it is burned in the cylinders and more O2 is consumed, causing the downstream O2 sensors to detect less oxygen. However if you add propane to the exhaust manifold, there is no ignition there for the propane to burn and consume O2. Of course it would burn downstream in the cat. Same O2 at the upstream sensor should read same upstream voltage, no?

[@SchrodingersBox]

My assumption is the propane is diluting O2 in the exhaust, creating the lean condition by having the unburned propane molecules competing in place of Oxygen.

[@spelunkerd]

Oh, I see, thanks.

[@Karreth]

Would that propane test really work for detecting an exhaust leak? I would expect the exhaust system to have positive pressure, preventing any propane passing by a leak from entering the exhaust and causing the sensor to read rich.

[@SchrodingersBox]

Yes but remember there is also venturi effect from the flow of the exhaust.

[@DENicholsAutoBravado]

At 11:15, I stopped laughing from your choice to stab your exhaust in the throat. :)

[@DENicholsAutoBravado]

I would have laughed longer, but I paused the video when my wife came to see what happened to me.

[@DENicholsAutoBravado]

I really wasn't suspecting an O2 sensor, but that is something that would only effect one bank.

[@DENicholsAutoBravado]

Wow, those propane tests were really surprising. The car didn't react correctly to the brake booster being pulled either.

[@SchrodingersBox]

DE Nichols Yes I am convinced that the bank 2 LTFT is a substituted value that is being used- I don't know why- but that's what it is I am sure.

[@crazycadillacman]

You seem like a freakin genius! Would you happen to have a video on diagnosing a lean condition that only affects one bank? Mainly for code P0174? My friends a half ass mechanic that doesn't believe in following proper diagnostic flow charts..he has a 99 f150 with a 174 code that he keeps throwing parts at. Id like to show him up and fix it cause he says theres no one in the world that can figure out whats wrong with it

[@SchrodingersBox]

One bank is easier- you have less variables. Look at the fuel trim against load and you’ll easily identify the problem.

[@TroyStevensStelzerPaintingInc]

I always appreciate your explanation of methodology, but I'm a bit confused. Earlier in this series, I remember you praising your viewers for not suggesting swapping plugs or wires as a means to troubleshoot the problem at hand, yet you swapped O2 sensors at the end of this video? I'm sure there's a reason that I just don't fully grasp. Not trying to be argumentative or combative in any way. I've watched all your videos and have learned a great deal from them. Thank you for your contributions.

[@SchrodingersBox]

I did not change the O2 sensors. I moved the left side one to the right side and vice versa so I could determine if there was a valid bank-specific condition.

[@TroyStevensStelzerPaintingInc]

@@SchrodingersBox Thank you for the reply. I think I may have misunderstood your initial comment regarding praising viewers for not changing plugs. I took that to include swapping one plug with another existing plug as a means to troubleshoot, whereas, (if I'm now understanding correctly), you were referring to not being a parts changer by going out and buying new plugs and changing them.

[@jasond7046]

hello Matt sir great video , i bean dealing with a lean conduction with my 96 f 150 v8 5.0 i did some modify my indushion system .question is would relocation like intake temp sensor and mass flow should be in any order or closer or farther form throttle body thank you for your time .

[@SchrodingersBox]

it would make no difference whatsoever with the IAT because the fuel trim would simply correct anyway. the “relocated IAT to a cooler area to get more power” is a complete myth. the MAF should be close to the throttle body ideally so as to get most accurate airflow closest to where is enters engine.

[@kalabwesteron9252]

That’s what I originally did is put in the y induction pipe Relatively closer to the throttle body . it doesn’t give it more power but it run little better I know it’s a little better fuel mileage I had no idea that people did that to modify it I just gave it a try

[@jasond7046]

I just to say thank you sir for the feedback and your videos .

[@jasond7046]

And is crank case vacuum pressure could possibly have any relevance in any lean condition issues? Thank you sir for your time

[@billpawelczyk5855]

O2 sensors are switched I did it on my Xterra a few years ago

[@billpawelczyk5855]

Just on Bank One I

[@wtbm123]

very interesting the long term not reacting much .

[@mtrltoolman]

interesting false O2 sensor ? i always trying to understand a lazy O2 sensor now i have seen it if i am right :) .

[@SchrodingersBox]

No it is a false LTFT. The O2 sensor is working normally

[@apollomedia7210]

26:26 so true 😂

[@jamalmarafi4076]

i'm sorry to interfere ,so i had to tell you ; it`s necessary to be alerted to not runing the engine in closed place thanks for that .

[@SchrodingersBox]

everyone knows that, no one is running an engine in closed space. what is your interpretation of the LTFT relative to the STFT on this application though? That is what this video is about v

[@GlycerinZ]

It's like they say.. give a man a fish, feed him for a day. Teach a man to fish, and.. he probably won't show up to learn.

[@mexskal]

love this dude XD

[@jocrp6]

Shut the front door! lol, smoke machine not making it past cat converter,,, maybe with engine running at operating temp probly kill the baby oil smoke, too funny!

[@jcsaves9725]

Anti seize 👍

[@DJDevon3]

You didn't specify the comment about anti-seize on the oxygen sensor was a joke. Probably goes without saying that anyone who would do that isn't the right skill level for this channel. You should avoid making jokes like that without specifying your sarcasm. Why? Because there are dumb asses who put NOS energy drinks in their gas tank. Never underestimate the power of the ignorant or stupid.

[@SchrodingersBox]

It just aggravates me because there are always those people who are trying to find the one single thing I did wrong out of a 2 hour video with 12 hours of filming, editing, and not to mention focusing on the repair itself. If that mistake I made is a logic flaw, then I welcome it- but when it's something from chapter 1 of the Haynes manual just so the person can try to act like they are "one up" on my efforts I want to throat punch them! It's like the grammar police pointing out a minor typo on a 200 page medical dissertation about a new AIDS vaccine but not saying anything relevant on the procedure or conclusion.

[@DJDevon3]

Throat punching seems to be a recurring theme. I always get a kick out of it though. Don't like my cat? Throat punch! Stupid comment? Throat punch! Misspell vacume? Throat punch! Your daydreams of fuel trims are almost as elaborate as throat punching haynes jockeys.

[@danielhigginson2438]

***** just a comment, its the first time I've viewed this but I have a pretty good grasp of this stuff. I was taught it slightly different but is the same old sh*t, nice to see it from both sides of the canvas.liked the punch in the throat I even rewound and showed the wife. I maybe a nerd but I even laughed at the potential joke before he gave the answer. FACT: if you can do better than this guy prove it... nuff said keep up the good work Schrodingers Box yours your 2%

[@SchrodingersBox]

daniel higginson Thanks Daniel- well stated! Glad you get the humor and point of the content but more importantly, I agree- there is always more than one way to approach this kind of material and different people may have best responses with different approaches. I fully recognize my approach may not suit everyone but I always have respect for people who attempt to learn this higher level stuff and never have respect for people who don't know it yet criticize it because it isn't "turning bolts". There are more than enough idiots out there who can replace an O2 sensor but how many aren't doing it on a guess?