A Toyota master diagnostic technician explains Toyota fuel trims both short term and long term. Also does a demonstration of real world engine live data reading techniques.
In this video I continue my series on how Toyota engine controls work. In this part of the series I will cover Short term fuel trims and Long term fuel trims.
First I’ll cover the basics of fuel trims, Then I will cover the common diagnosis uses and the common misconceptions about fuel trim. Slightly elevated or decreased fuel trim is not a problem!
Many people assume that a perfect zero fuel trim is what’s needed and that is not the case, I’ve seen many people spend a lot of money in the pursuit of dropping their fuel trim down to zero without success and with big disappointment I hope this video helps clarify that!
Also for majority of this video I will explain a very simple and basic data list to show how things work in a diagnosis situation. I want my viewers to slowly start seeing that car diagnosis is not just experience and mechanical know how. It’s actually involves a lot of simple science and actually a specific form of Art!
Understanding how things work is the stepping stone on understanding how to approach diagnosis and repair. I see a generation of parts replacement technician without attempting or wanting to understand how everything works. I hope this series helps someone out there truly start to understand how diagnosis is carried out from a live data list.
I simulate some common issues like a vacuum leak and a bad coil so you can see how the computer reacts to these situations. Also I share some basic tricks that you won’t read in a book or a repair manual on injector diagnosis! More to come from this series!
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0:00 Intro
0:52 Fuel Trims
4:41 Fuel Trim Diagnosis
11:28 Live Data Demo and Tips
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could u do more on reading live data/ or just data in general, i have a Foxwell nt650 elite scan tool that i purchased on ebay of about $170, it has many functions and data but i dont kno wut it all means, thank you
nice video, would u say that I should wait til the car idle settles from a cold start to start driving or can i drive the car right away after starting the engine?
Wonderful Job, I have found that "TechStream" is not really available as a scan tool to the public. Is it possible to get it from somewhere? If not what similar function scan tool would you recommend that is also bi-directional?
Thank you AMD, I always wonder what is a fuel trim numbers means.
Thanks again for such a great video. A quick question. A Toyota Highlander 2013 AWD almost 105k miles , Couple of months ago while i was cleaning MAF sensor and i forgot to connect the connector back to MAF sensor. It tripped a code p0102 mass or volume air flow sensor "A" circuit low. I reconnected the electric connector and reset erase the code with a scan tool. After that i have driven almost 2000 miles The code and check engine light never came back but when i scan with scan tool it shows there is a permanent code p0102. I even tried by changing the new maf sensor but still it is not going away from permanent code section. Any suggestions. I will really appreciate it. Thanks.
Great stuff. I love your channel! I have a question about my 2009 Toyota Sienna that has a bit of engine knock or perhaps piston slap when cold. The noise subsides once the engine is at normal operating temperature. I’ve read this may be a characteristic of the 3.5L due to it having ground cam pistons. Is this noise something to be concerned about?
Hi, I just bought 2021 Toyota Camry Hybrid Le. I use consumer reports and they gave Toyota Camry's Hybrids excellent reviews. I'm reading now that there are serious problems with the A25A-FXS engine . Can you shed some light on this. I have watched a lot of your reviews and find you very knowledgeable.
It should read that changing canister did not change the condition. Thank you
I have a 2014 Avalon Ltd. I couldn’t fuel the tank. The gas nozzle would immediately kick off both in automatic or hand held. I took it to Toyota Service. The changed the charcoal canister but it did correct the problem. They changed the gas tank. The only change was that I could fuel it if I held the nozzle out about 3” but not if I put the nozzle in or in automatic mode. I took it back and still waiting for them to repair it. Any ideas?
Ahmed. Wow! I had to watch this one twice. Amazing all the things happening when we run our vehicles. Also amazing how you are able to look at the data to diagnose issues and what the numbers mean. Its great that you explain how all of this work. Thank You.
Do you know if Tacomo 2013 4.0L transmission A750F has a overflow tube or is build into the pan? Do you have the part number if there's one?
Thank you!!!
Thanks for info sir. Could you talk about NiMH battery on new 2020 corolla hybrid. Why they don’t use li ion battery like prius, any cons, pros? Thank you so much!
Awesome! thank you granted my request.
Absolutely love this episode.
I am poking into the fuel trim on my 98 and 99 Camry. My Camry is in fuel trim rich condition under idle (about -7%), but they would go back to normal under driving condition. I suspect it may be due to a partially clogged IAC. I wonder if there is standard / reference values under idle for use to compare to.
I got a little lost with lean and rich. Is rich mean too much fuel and lean mean less fuel?
Hi! Thanks a lot for your videos. I have a Toyota Highlander 2013 3.5 AWD SE with 104k Miles. While just before coming to a complete stop it revs up around 500 to 400 and and then comes back to normal. Transmission shifts fine on all gears while driving. I will really appreciate it if you have any suggestions. Take care.
Hi thank you for amazing video! I have a question about the Engine Air Filter. I have 2014 toyota venza. I just bought and used the STP Premium Engine Air Filter (from Autozone). I just realized that this air filter has the oil in the filter. Therefore, I took it off and replace with the other air filter (air filter without oil). I’m very worry about the oil in the air filter. Will the oil from the air filter damage my vehicle (engine, mass air flow sensor, intake, etc)? I just drove with the STP premium air filter about 25 miles. Thank you so much!
Love it, thank you for the information
Thanks for the great explanation of engine tests. I am no longer clueless, just old.
Really liked the explanation on both short and long term fuel trim. Always wonder how to read that type of data. Thank you so much for that information.
I have always wanted to see someone explain these values in "real time" etc. Great explanation, and I don't even own a Toyota
The app he's using is called "techstream"
This is the video I was waiting for!!!
Thanks AMD.
What version of Techstream are you using? I'm having trouble with V 12.10.019 displaying the Data List for Engine and ECT Live on a 2010 ES350 and a 2010 RX450h but it works perfectly with a 1998 ES300. It simply won't connect with the Engine module live data but works with all the other modules.
Also, thank you for the detailed information. I've been studying Fuel Trim for the last few months and this has been the most helpful video I found, including your A/F and O2 sensor video.