What's up my friend nice to meet you hope your day is going well! I was watching the fuel trim videos and im trying to understand and comprehend it but im struggling to because i have a learning disability. I like your videos your doing a good job helping people and i want you to continue bringing more fuel trim videos. I struggle alot to understand and comprehend but if the person teaches me in a way where my brain can understand and comprehend i can become very good at it.
Thank you! I'm glad to be back. Maybe I misspoke or maybe I worded that part funny but yes and no. And idle it will fluctuate a bit but should stay pretty steady in the .4-.5 range. With increased followed by decreased engine speed it should continuously read rich and then lean if working correctly. If you hold the rpms steady at say 2500 for 15-20 seconds it should show a rich and taper down on the graph and it goes back down to idle speeds. With age and wear they tend to move a lot more at a steady idle, but I've also seen them stick and not move at all with any engine speed. Hope this helps clear things up a bit. Anymore questions just let me know!
Hey good video. I am currently trying diagnose a P2191 on my hyundai . My long term fuel trim is very high 30-40% 😮 . Any thoughts on what could be wrong?
Hello and thank you for your time. My STFTB1S1% rises to 14% for half a second after stepping on the gas. Then it goes to normal numbers while idling. Do you sir think this may be normal? Thank you, stupendous videos!
Hello, I could really use some help diagnosing my OBD2 live data, I have an uploaded video on my channel, it's a screen recording and basically in closed loop the LTFT is +14%, and the STFT fluctuates somewhere between -10% to -21%. If we add these values together (+14% - 21% I still get around -7% which is not that bad I guess) but does it work that way? Or am I having some much bigger problems? Btw, MAF sensor and throttle body were cleaned. Thanks for help.
Hi My engine light went on board and I used my scan tool to detect DTCs and it came up I have a code for oxygen sensor and a Code for MAF sensor. If MAF sensor is not functioning it will affect oxygen sensor readings right. Best method to rectify if issue is in the oxygen sensor or MAF sensor? Thanks 🙏
I would like to thank you for your videos on understanding what the machine is telling you about the oxygen sensor is telling you..I am 72 and disabled. I cannot afford to pay an overpriced mechanic to do the things I used to do to keep an engine running but now can’t because everything is electronic.I am hoping you can explain everything on these readers especially the extra functions like bi direction. Never in my life did I think I would need to learn all this crap.. I have a 2013 Silverado ltz. The amount of plastic is mind blowing but to replace what breaks is purely theft. Thank you again. Leroy Latham. Springfield louisiana
Just a little Heads Up from an Electrical Engineer over from Germany... I will have to unfortunately tell you, that the automotive industry is right in the middle of transitioning towards implementing the so called "Security Gateways" which are supposedly there (and advertised) to secure every single Diagnostic-Port Access from Hackers, looking into hacking your Car just over the OBD2-Port. That means, that you buy your own Car, just to then plug in your own Scanning Tool (most costing hundreds & licenses fees) to check the MIL (Check Engine Light) or smth else, but will then be prompted to access the Internet first in Order to buy a single Security Gateway unlock Token for more than 10$. But if you then unplug that tool to eat your Lunch and return back to work afterwards, you will find out that one token expires after 24h, or the second you unplug your tool once! Next car, next Token for a bunch of money! Somebody has to stop this!
Regarding next video: would be great if you could tell as what we should look at when buying used car - which data items to look at and what it means. Trims I suppose would be the first thing to look at to know if the engine is OK.
Absolutely! I actually have a video coming soon on what to check when buying a used car, I'll definitely add the data stuff into the video! Thanks for watching man!
Long Term is the window of time the adaptive memory dictates the fuel trim, Short Term is live data calculating to learn the parameters for the adaptive memory to update the Long Term. The O2 sensor signals lean below .45 volts & rich above .45. The Engine Controller only cares about that threshold & uses that to determine fuel trim. .. in other words the computer calculates the % of time that the O2 sensor is past the threshold of .45 volts & does that each time the threshold is crossed.
Correct, this was a revision of my video from years ago on learning to read 02 and fuel trims. Just the basics for the beginners. Next few videos will go into detail including all of that stuff and more. Easier to teach people the very basics first and then add in the more complicated details. I want people to be able to learn, even if they have never used a scanner before in their life! Thanks for watching 👍
@good2boost529 If anything I would hope a Mechanic learns is 1> your books R your best tools U do not need to remember everything U just need to know where to find information & quickly. 2> There is nothing that can not be diagnosed to a conclusion, never let the parts dept. fix the car 4U.
I have LTFT %25 and STFT zero with P0068 related to Map sensor, I replaced Map sensor but LTFT still really high and not go less 18% whatever RPM I attempted smoke test and no vacuum leak at all, Replaced lowe pressure fuel pump with filter but still LTFT %25 with 900 RPM and Change to be %18 once touch accelerate paddle and stop at 18% even if 5000 RPM, may I know if you have an idea to solve this issue especially I replaced Bank1 sensor 1 O2 sensor ?
Hello there! Amazing video. I have a Dodge Ram 1500 4.7 that I restarted after sitting in the driveway for 11 years. 89k on it. Had to replace pretty much everything to get it rolling again. Driving nice, good vacuum, one thing that's bothering is the fuel consumption. I scanned the engine, STFT oscillates -3.13 to +2.34 at idle,1500rpm, 2500rpm and when I drive 45 mile per hour, sometimes it gets to -7. LTFT negative from 0.78 to 12.50. The O2 sensors oscillates 0.14 to 0.85. Been reading a lot of fuel trim material online, so far I cannot figure it out what it could cause the negative fuel trim. I created an exhaust leak before the catalytic converter and the fuel trim jumped at +28, 29, 30. As of now I keep researching and running tests on this truck. Do you cover Dodge Ram fuel trims at all? Thanks!
Hey, thanks for watching man! Did you replace the fuel pump, injectors, fuel filter? Those numbers aren't to bad especially given the age. Could be something as simple as a leaky injector but unless it's running really rough I wouldn't worry to much. Hard to say without more information of course. Report back!
Fuel pump brand new, fuel pressure within spec, fuel filter is inside the pump, fuel regulator came attached with the pump. OEM injectors brand new. Before getting these injectors, I had a set of remanufactured ones, thought if I get new it will sort out the rich condition, but it did not. It is running great, but the fuel consumption is bothering me a lot, reason why I started to look into the fuel trims. To my understanding the running rich =not enough air to the stoichiometric air/fuel mixture. Something is restricting the air after the throttle body, TB cleaned up several times. TPS replaced. Throttle position reads 12.16% at idle, MAP sensor replaced reads about 5 psi at idle. O2 sensor brand new, both fluctuates up and down 0.08 to 0.90. Oxygen sensor 2 is fluctuating same as the Oxygen 1, like it is following. Thanks for getting back!@@good2boost529
Hi. I have a high negative fuel trim but I can’t find any leaks. I used the smoke test machine(but I am not sure if it’s 100% going to confirm no leaks) I have a ODB2 gauge showing -25 STFT(slowly dropping to -7) when I let go of my accelerator with no brakes. But this doesn’t happen all the time. Sometimes it’s goes to 0 in a second or sometimes it 0 right after I release the pedal. I have replaced MAF sensor, MAP sensors and O2 sensors. PCV valve, IAC valve and EVAP valve and most recently spark plugs Do you think I should change my fuel Injectors next? My tuner told me it’s very likely a vacuum leak(mentioned fuel pressure is fine and didn’t once mention an exhaust leak)
I really enjoyed your video. It gave me some ideas where to look. I went and bought a scan tool and 1 code came up. The code was P065E intake manifold tuning valve Bank 1. Do I need to change the bank I oxygen sensor or the tuning valve or both. Your reply back will surely be appreciated. Needing Help. I'm New at this. Thank you!
You are reading wrong oxygen sensor. It is supposed to be bank1s1 which should be fluctuating ( if it is narrow band ) On the other hand, bank1s2 shouldn't be fluctuating normally, but i noticed when you rev the engine, bank1s2 didn't respond when tells me either the sensor is bad or wiring issue.
I have a quick ? My vehicle is tuned and has been for 3 years passing inspection I get headers put on and now after everything disconnected/ re connected it says my 02 sensors aren't ready. 2019 ram2500 6.4
Sorry for the late response. They reading ready now? That's normal when you disconnect power. You just have to drive a few miles for the monitors to make sure everything is reading within spec. Then it'll pass and say ready!
Give me a carb any day over sensors and all that crap. Like he said there a million things that can cause a lean or rich condition O2 sensors to fuel filter CV would cause that.
When I’m driving about 70 miles an hour mile long fuel trim is about 40 then it fluctuates almost as fast as my short trim does, and from at idle, it’s at -7.9.
WHAT CAN CAUSE LOW VOLTAGE IN SENSOR 2? There are a handful of issues that can cause voltage to drop in O2 sensor 2. Some of the most common issues are the following: An exhaust leak A short in the O2 voltage circuit Loose connections Excessively high or low fuel pressure An engine that’s running either very lean or very rich A faulty O2 sensor
You're wrong. Bank one sensor 2 is after the cat. That's telling you how good the cat is working. You need to be reading bank one sensor one
Yep, it's called downstream
What's up my friend nice to meet you hope your day is going well! I was watching the fuel trim videos and im trying to understand and comprehend it but im struggling to because i have a learning disability. I like your videos your doing a good job helping people and i want you to continue bringing more fuel trim videos. I struggle alot to understand and comprehend but if the person teaches me in a way where my brain can understand and comprehend i can become very good at it.
Excellent now I know what I'm looking at on my live data
Hi, really good to see something new from you. One question, I was under the impression that the#2 o2 sensor was not supposed to fluctuate in voltage.
Thank you! I'm glad to be back. Maybe I misspoke or maybe I worded that part funny but yes and no. And idle it will fluctuate a bit but should stay pretty steady in the .4-.5 range. With increased followed by decreased engine speed it should continuously read rich and then lean if working correctly. If you hold the rpms steady at say 2500 for 15-20 seconds it should show a rich and taper down on the graph and it goes back down to idle speeds. With age and wear they tend to move a lot more at a steady idle, but I've also seen them stick and not move at all with any engine speed. Hope this helps clear things up a bit. Anymore questions just let me know!
Hey good video. I am currently trying diagnose a P2191 on my hyundai . My long term fuel trim is very high 30-40% 😮 . Any thoughts on what could be wrong?
Do you need both upstream and downstream o2 sensors for the fuel trim learn function ?
My 1FZ-FE without any O2 sensors from factory is reading -100% both short and long fuel trims. What could be the issue?
Hello and thank you for your time.
My STFTB1S1% rises to 14% for half a second after stepping on the gas. Then it goes to normal numbers while idling. Do you sir think this may be normal?
Thank you, stupendous videos!
Hello, I could really use some help diagnosing my OBD2 live data, I have an uploaded video on my channel, it's a screen recording and basically in closed loop the LTFT is +14%, and the STFT fluctuates somewhere between -10% to -21%. If we add these values together (+14% - 21% I still get around -7% which is not that bad I guess) but does it work that way? Or am I having some much bigger problems? Btw, MAF sensor and throttle body were cleaned. Thanks for help.
Hi
My engine light went on board and I used my scan tool to detect DTCs and it came up I have a code for oxygen sensor and a
Code for MAF sensor. If MAF sensor is not functioning it will affect oxygen sensor readings right. Best method to rectify if issue is in the oxygen sensor or MAF sensor? Thanks 🙏
Thanks for the video, my obd2 scanner is reading that my o2 sensor is -2356ma any idea why is that?
I would like to thank you for your videos on understanding what the machine is telling you about the oxygen sensor is telling you..I am 72 and disabled. I cannot afford to pay an overpriced mechanic to do the things I used to do to keep an engine running but now can’t because everything is electronic.I am hoping you can explain everything on these readers especially the extra functions like bi direction. Never in my life did I think I would need to learn all this crap.. I have a 2013 Silverado ltz. The amount of plastic is mind blowing but to replace what breaks is purely theft. Thank you again. Leroy Latham. Springfield louisiana
Just a little Heads Up from an Electrical Engineer over from Germany...
I will have to unfortunately tell you, that the automotive industry is right in the middle of transitioning towards implementing the so called "Security Gateways" which are supposedly there (and advertised) to secure every single Diagnostic-Port Access from Hackers, looking into hacking your Car just over the OBD2-Port. That means, that you buy your own Car, just to then plug in your own Scanning Tool (most costing hundreds & licenses fees) to check the MIL (Check Engine Light) or smth else, but will then be prompted to access the Internet first in Order to buy a single Security Gateway unlock Token for more than 10$. But if you then unplug that tool to eat your Lunch and return back to work afterwards, you will find out that one token expires after 24h, or the second you unplug your tool once! Next car, next Token for a bunch of money!
Somebody has to stop this!
I have -3.93 stft -6 ltft idealing at running temperature 92 is this oxygen issue or ok jumps in to limp mode when starting clears 2nd start up
Regarding next video: would be great if you could tell as what we should look at when buying used car - which data items to look at and what it means. Trims I suppose would be the first thing to look at to know if the engine is OK.
Absolutely! I actually have a video coming soon on what to check when buying a used car, I'll definitely add the data stuff into the video! Thanks for watching man!
Very nice video what should be right reading.idel& hi speed.
Long Term is the window of time the adaptive memory dictates the fuel trim, Short Term is live data calculating to learn the parameters for the adaptive memory to update the Long Term. The O2 sensor signals lean below .45 volts & rich above .45. The Engine Controller only cares about that threshold & uses that to determine fuel trim. .. in other words the computer calculates the % of time that the O2 sensor is past the threshold of .45 volts & does that each time the threshold is crossed.
Correct, this was a revision of my video from years ago on learning to read 02 and fuel trims. Just the basics for the beginners. Next few videos will go into detail including all of that stuff and more. Easier to teach people the very basics first and then add in the more complicated details. I want people to be able to learn, even if they have never used a scanner before in their life! Thanks for watching 👍
@good2boost529 If anything I would hope a Mechanic learns is 1> your books R your best tools U do not need to remember everything U just need to know where to find information & quickly.
2> There is nothing that can not be diagnosed to a conclusion, never let the parts dept. fix the car 4U.
my 2010 suburban has a fast switching LTFT, is this ok?
I have LTFT %25 and STFT zero with P0068 related to Map sensor,
I replaced Map sensor but LTFT still really high and not go less 18% whatever RPM
I attempted smoke test and no vacuum leak at all,
Replaced lowe pressure fuel pump with filter but still LTFT %25 with 900 RPM and Change to be %18 once touch accelerate paddle and stop at 18% even if 5000 RPM, may I know if you have an idea to solve this issue especially I replaced Bank1 sensor 1 O2 sensor ?
Hello there! Amazing video. I have a Dodge Ram 1500 4.7 that I restarted after sitting in the driveway for 11 years. 89k on it. Had to replace pretty much everything to get it rolling again. Driving nice, good vacuum, one thing that's bothering is the fuel consumption. I scanned the engine, STFT oscillates -3.13 to +2.34 at idle,1500rpm, 2500rpm and when I drive 45 mile per hour, sometimes it gets to -7. LTFT negative from 0.78 to 12.50. The O2 sensors oscillates 0.14 to 0.85. Been reading a lot of fuel trim material online, so far I cannot figure it out what it could cause the negative fuel trim. I created an exhaust leak before the catalytic converter and the fuel trim jumped at +28, 29, 30. As of now I keep researching and running tests on this truck. Do you cover Dodge Ram fuel trims at all? Thanks!
Hey, thanks for watching man! Did you replace the fuel pump, injectors, fuel filter? Those numbers aren't to bad especially given the age. Could be something as simple as a leaky injector but unless it's running really rough I wouldn't worry to much. Hard to say without more information of course. Report back!
Fuel pump brand new, fuel pressure within spec, fuel filter is inside the pump, fuel regulator came attached with the pump. OEM injectors brand new. Before getting these injectors, I had a set of remanufactured ones, thought if I get new it will sort out the rich condition, but it did not. It is running great, but the fuel consumption is bothering me a lot, reason why I started to look into the fuel trims. To my understanding the running rich =not enough air to the stoichiometric air/fuel mixture. Something is restricting the air after the throttle body, TB cleaned up several times. TPS replaced. Throttle position reads 12.16% at idle, MAP sensor replaced reads about 5 psi at idle. O2 sensor brand new, both fluctuates up and down 0.08 to 0.90. Oxygen sensor 2 is fluctuating same as the Oxygen 1, like it is following. Thanks for getting back!@@good2boost529
Hi. I have a high negative fuel trim but I can’t find any leaks. I used the smoke test machine(but I am not sure if it’s 100% going to confirm no leaks)
I have a ODB2 gauge showing -25 STFT(slowly dropping to -7) when I let go of my accelerator with no brakes. But this doesn’t happen all the time. Sometimes it’s goes to 0 in a second or sometimes it 0 right after I release the pedal.
I have replaced MAF sensor, MAP sensors and O2 sensors. PCV valve, IAC valve and EVAP valve and most recently spark plugs
Do you think I should change my fuel Injectors next? My tuner told me it’s very likely a vacuum leak(mentioned fuel pressure is fine and didn’t once mention an exhaust leak)
My car is a civic hatchback 2017 with almost 100,000 miles
I really enjoyed your video. It gave me some ideas where to look. I went and bought a scan tool and 1 code came up. The code was P065E intake manifold tuning valve Bank 1. Do I need to change the bank I oxygen sensor or the tuning valve or both. Your reply back will surely be appreciated. Needing Help. I'm New at this. Thank you!
having an issue where long terms only go up in drive no vac/boost leaks possible between exhaust leak or something else
So will a faulty downstream 02 sensor that’s reading lower than 0.450v cause fuel trims to read out of wack?
The downstream sensor talks to the upstream sensor by saying if it's rich or lean
You are reading wrong oxygen sensor. It is supposed to be bank1s1 which should be fluctuating ( if it is narrow band )
On the other hand, bank1s2 shouldn't be fluctuating normally, but i noticed when you rev the engine, bank1s2 didn't respond when tells me either the sensor is bad or wiring issue.
I have a quick ? My vehicle is tuned and has been for 3 years passing inspection I get headers put on and now after everything disconnected/ re connected it says my 02 sensors aren't ready. 2019 ram2500 6.4
Sorry for the late response. They reading ready now? That's normal when you disconnect power. You just have to drive a few miles for the monitors to make sure everything is reading within spec. Then it'll pass and say ready!
i have a car where the bank 1 sensor 2 voltage only fluctuates between 0.700V and 0.850V at idle.
So I think my catalyst is in very good condition!
Does Fuel Trims works on Diesel Engine?
On mines. I get a CL-Fault with the 0036 code. What is the CL Fault for?
CLOSED LOOP
My long term fuel bank one reads 38%
My short term fuel bank reads at -7 at idle. Any ideas? I have code p0171 bank 1 lean.
Give me a carb any day over sensors and all that crap. Like he said there a million things that can cause a lean or rich condition O2 sensors to fuel filter CV would cause that.
Sir What would be the perfect range of long term fuel? On a v8
As close to zero would be ideal. -+5% should be ok. It shouldn't exceed -+10%
If -12 percent long trim at idle and becomes -2 percent at high rpm. What is this mean?
Might be a small air leak from the throttle and on. Spray all lines with soapy water, or smoke test
Troubleshooting a po302 on my Subaru sti. My guess is a vacuum leak.
When I’m driving about 70 miles an hour mile long fuel trim is about 40 then it fluctuates almost as fast as my short trim does, and from at idle, it’s at -7.9.
It's bad if your LTFT moves as fast as STFT. It shouldn't do that
What would cause a p0137 code ?
WHAT CAN CAUSE LOW VOLTAGE IN SENSOR 2?
There are a handful of issues that can cause voltage to drop in O2 sensor 2. Some of the most common issues are the following:
An exhaust leak
A short in the O2 voltage circuit
Loose connections
Excessively high or low fuel pressure
An engine that’s running either very lean or very rich
A faulty O2 sensor
Fuel trim isn't related to sensor 2
*Promo sm*