Lean code! Need advice!

Hey guys and girls this might be kinda lengthy but I’m desperate ,

Side note, please don’t hate me for making yet again another post… about the dreaded p0171 code. But i am completely stumped, so here it is.

I have a p0171 code everything iv done so far.
Replaced-
Maf sensor, both 02 sensors, pcv valve
Now with everything Iv replaced I then got a code scanner, I was looking at the
Stft an Ltft, stft stays around 1.5 to 3.0, Ltft is at 34.9 an these both are at idle.
When I increase my rpm’s to 2000,2500,3000 my numbers don’t get any better, but only by a few digits example, my stft gets to -1.0 Ltft goes to 28.8.
Now I know if it was a vacuum leak those numbers would get way better especially driving it. My maf is reading 2.58-3.0 g/s at idle and 15 just with increasing rpm’s.
So with all that information it lead me to do a smoke test.
When I preformed the smoke test the only smoke I had was coming from the egr valve modulator, which I don’t think it’s suppose to be sealed cause you can remove the cap and check/clean that filter inside of it.
But like I stated that’s the only visible smoke I seen, so all this data is correct, would this be leaning towards fuel delivery issue? Bad injector? Fuel pressure regulator? Or fuel filter?
Sorry again for the length of the thread and another posted but I’m completely lost

 

Change thread title. "HELP", "NEED HELP" are titles reserved for people who need actual help such as broke down/stuck on a trail with no way to extricate themselves or get assistance due to remote location.

 

Rename the title to Help with Lean code. "Help" is reserved for actual distress.

Try blocking off vacuum lines, like from the purge valve. If its leaking it won't sound like a leak but will let unmetered air in. You can watch to see if the STFT % goes down rapidly.

You may need to find a way to hook up a fuel pressure gauge.

 

Best I can do at the moment... go through the docs again and see where you're at in the tree. Good luck and welcome to Tacoma World

 

Okay, my apologies for the thread title, still new to the page, but I’m definitely lost here with this code

 

Maybe a huge vacuum leak.....check pcv valve hose and maybe break booster.....

when booster goes out it creates a huge leak.....

 

Are51 runner thanks for the pdf! When through the list an only things I really haven’t done is with the fuel side.

O silver taco, brand new pcv valve and hose is good, never check the brake booster, don’t know why I didn’t but will definitely check tomorrow!

 

O silver taco, as far as I can tell the brake booster is fine and so is the check valve that only lets air go it one way, I took carb cleaner and spray around everything didn’t change motor at all, so I’m guessing it has to be clogged fuel injector dirty fuel filter or failing fuel pump. Thoughts?

 

Maf numbers are fine. If your ltft is high at idle and remains high under load, I’d suspect fuel delivery like you said. You mentioned a few usual suspects, or your fuel pump could be on the way out too. Good luck.

 

Tacotu3 I’m going to go get a fuel pressure test today and try it out and see what it reads. Does anyone know the specs for what the fuel pressure should be? An how would I hook that up? Iv tried finding a thread but no luck. I suspect you have to hook it up through that banjo bolt closest to the firewall or could I go through the fuel line going into the fuel pressure regulator? Cause unfortunately mine doesn’t have no Schrader valve.

 

Correct, there is no test port, you have to run it in line or with an adaptor, which some people do at that banjo bolt. Someone with a FSM can check me but I believe pressure should be 38-44 psi. Here are a few threads with some ideas on how to do it.

https://www.tacomaworld.com/threads/3-4l-fuel-issue.452218/page-2
https://www.tacomaworld.com/threads/question-about-testing-fuel-pressure.472067/
https://www.tacomaworld.com/threads/how-to-test-fuel-pressure.331808/

 

Okay! Thank you so much for the threads! I will do this, this evening. An see what’s it’s reading an will get back on here and give an update thanks so much for everyone that commented on this thread giving advice! It’s very very much appreciated.

 

When you smoke checked it did smoke come out of the gas filler neck? I had issues with my actual gas filler neck with a lean code it was what smoked when I checked

 

I didn’t have any smoke come out of the filler neck, not that I seen. Might do another test, just to double check.

 

I wouldn’t suspect a vacuum leak at this point, with a vacuum lead you’d likely see your high fuel trims drop under load.

 

Right and my fuel trims are not dropping but only slightly, an when I say slightly I mean from 34.8 to 28 on long term and short term goes to 1.8-3.0+ just like I stated in the earlier post

 

These are tough to test fuel pressure without a hassle...

https://www.lceperformance.com/Fuel-Pressure-Gauge-Kit-2RZ-3RZ-p/2019121.htm

 

O silver taco I managed to get it, I just took off the banjo bolt closest to firewall and put an adapter in there. My truck was reading 46psi which is alittle high, and after doing some test I come to the conclusion that I have a bad fpr, so I have one on the way plus injectors

 

After some checking it seems correct pressure is around 40, 41psi...
so replacing the fpr is not a bad deal.....
dont think that's your problem......

And after watching that video on that hydro-locked 5vz......replacing the injectors in a timely manner may be a good idea too......
those you dont want to try to get your last bid of tread out of.....
one of those stuck open could cao an engine in a blink of an eye.....

Damn sure dont trust any but the denso oem's.....


Toyota Tacoma 2.4 2RZ, 2.7 3RZ, 4-Runner (CA Only) OE Replacement Fuel Injectors (fiveomotorsport.com)

 

Definitely! Already got the injectors on the way along with a fuel filter fpr and in the mist of diagnosing all this my iac went out so I have one of them on the way too lol