Long trim fuel trim unstable

I have an Lexus ls 460 2007 gcc spec with two narrow band upstream o2 and two narrow band downstream o2 car only have aport injection car has i bad mpg in the city while in the highway i get better mpg I have look to the fuel trim long trim it is at 0 while idling when i rase the rpm fuel trim start to go up in both bank i have to replace the o 2 before due check engine light and its gone i checked the map sensor and its ok air filter replaced spark plugs no vacuum leak injector have been checked still lean when rpm go up it like the trim change immediately while keep your foot at the padel any car seem to run good suggestions for next daignosis Part ??

How far out are the fuel trims going high and low?

Also I don't know if you're using voice typing or need to spell check as if I use voice text I screw up my sentences.

Why was the O2 sensors replaced before? You shouldn't be having to replace sensors regularly.

My suggestion would be try the scannerdanner.com premium subscription trial if you haven't used the free trial.

If you do use the trial or even a subscription (Great Resources & Videos) watch the videos that cover fuel trim.

Ordering the book is a great investment if you do your own stuff or just want to learn more.

Don't just replace parts because of a Code or parts store telling you to because of a code.

You need to properly diagnose the problem.

I haven't had a whole lot of experience with fuel trim except that you don't want them to far out of range.

The closer to 0 the better.

You didn't mention the fuel trim numbers? At what RPM ?

Check the fuel trim numbers at idle and at 2500 rpm once the vehicle is warmed up.


Paul does really good videos on the diagnostics he does and explains the theory and operation well also.

Here's a couple videos I found.

The first one is long but you need to watch to understand.







Let us know those numbers and how things turn out for you if you resolve it.

I found those videos by searching YouTube and searching "scannerdanner fuel trim videos"

If you have a code maybe try searching but remember because someone else solves the problem with one part that may not be the same part that solves your problem. This is why it's important to do a proper diagnosis so you're not throwing the parts cannon at it meaning just put in Parts on until the problem goes away as you were just wasting money then.


Better off to take a little time and learn something and save the money that you would spend on parts can do a monthly subscription the scannerdanner premium then you can take all of his class that he's did where he taught at the Vo-Tech.

There's hours upon hours upon hours of videos where you can just sit and watch his videos and not have to worry about having cable TV because you wouldn't run out of videos for a while. He's also got a ton of videos just on repairs that he does as well so what those videos and his class videos you will be busy for a long long time.

I have been check the fuel pressure it was 56 psi i clean the maf sensor and the fuel injector its showing lean in both bank bank 1 about 3.4 long trim and bank 2 about 4.7 long term and it increases till 10% in both bank and it show 4.7 % at throttle wide open in both bank

I have been check the fuel pressure it was 56 psi i clean the maf sensor and the fuel injector its show lean in both bank bank 1 about 3.4 long trim and bank 2 about 4.7 long term at idle and it increases till 10% in both bank and it show 4.7 % at throttle wide open in both bank

musab.alnajem wrote: I have been check the fuel pressure it was 56 psi i clean the maf sensor and the fuel injector its show lean in both bank bank 1 about 3.4 long trim and bank 2 about 4.7 long term at idle and it increases till 10% in both bank and it show 4.7 % at throttle wide open in both bank

What was the short term fuel trim numbers on this?

Have you watched any of scannerdanner's (Paul's) videos on fuel trim and analyzing the fuel trim data that I posted about?

You have to learn this stuff as there's no quick magical cure because it takes time to learn over time.