2010 Scion XB P0171

Hi Ya'll As title says its throwing a P0171 code. Truck runs fine, no starting or driving issues. Just throwing code and reflecting it on plugs and poor mileage. No indication of vacum leak and squirted propane everywhere just to double check
I am using a Topdon Artidiag Pro scanner and ordered SD's book. I am no longer in car biz, and no wish to return, its just my hoopties. And I live across from a Toyota Service director so i have little faith in dealer diagnosing
LT trim is 22+ to almost 40 at snap throttle
ST trim goes from -18 to +7 " " " " "
MAF goes from about 4gms to over 45 on snap throttle
AFS is going from -1.6 to +1.6

I'm kind of leaning to AFS being wonky as it should be 3-4 area correct? Cause it still acts like a battery right?

I would add the truck has 250K + and I have gotten my monies worth Would add pictures but do not have Tapatalk fired up anymore.

Now pic uploads

Sent from my SM-G991U1 using Tapatalk

What field did you go to? Hold the rpm steady at 2500-3000 rpm see what fuel trims do. Post pic of that

2500 rpm ish
Still unable to combine graphs on my scanner.

First afs is after unplugging purge to initiate vacum leak. Other pics from holding pedal and toggling scanner while taking picture with phone.

Sent from my SM-G991U1 using Tapatalk

Where can I find Fuel Trim Limits ? anywhere on line? Still trying to fix a 171 code.

TIA,
Michael

They may be posted somewhere in service info, but I'm thinking that we still want to just look at the general +/- 10% and determine if it is inside that total trim range or not.

What is the vehicle you are working on, and if you want to share some of what you are dealing with, you may get some more help here?

Thanks for replying, Most of what I am dealing with is under my P0171 2010 Scion thread. I got to the point I AAA it to a friends shop and so he could smoke it in case I missed something. He also redid my tests and got the same results.
Vehicle runs too good to have a fuel delivery issue, but he might as well check pressure anyway.
And injector ms and FT limits are shots in the dark at this time. ANY info just might be handy at this point

will add pics from phone below

Added pics

Sent from my SM-G991U1 using Tapatalk

The picture shows that the ecm (at this moment) is able to maintain fuel control. It has to make a BIG effort to achieve it which is reflected by the high LTFT number.

In general I have seen a good number of Toyota engines with dirty injectors exhibiting similar symptoms: lean code(s) without driveability issues.

With no unmetered air and fuel pressure in spec you want to look close at the injectors.

I added your fuel trim question thread to the original help request to keep everything in one spot.
Please try to keep questions about the same car within the original thread. It makes it MUCH easier for anyone trying to help you, and for people who may have a similar issue in the future.
No harm done

Thank You Herr Scholl,
thats the only issue i have not tested, just because it does not exhibit usual low pressure drivability issues.
Whats that 'when all other avenues ' quote?

Have you ever had a chance to do what Cheryl suggested? Increase the RPM to 3000 and see if the fuel trim gets better or worse. You can also do the fuel delivery test by watching the o2 at WOT. If you have a fuel-related issue, the o2 will be lean.

Check your MAF and see if its dirty, its probably under reporting. If you dont know how to clean one properly I would suggest googling it because you do need to know where to clean. I am going to bet money its your MAF sensor being dirty and its under reporting the amount of air going into the engine which is why the LTFT are high because the O2's are sensing this command and therefore sending a command to the ECU to signal the injectors to add more fuel.

Did those test while driving actually, but my pictures were very poor. And as i mentioned above, i sent vehicle to another shop last Monday. And he redid everything and found same specs/issues i did.
And being fixing drivability issues has not been my day job for 40 yrs. I actually replaced. MAF and AFS with new Densos and saw same readings.
Its an injector issue i am 90% sure, cause it runs to good at 60-70 mph but still reads over 35 % LTFT.
If he does not find time to run fuel pressure test and install the rebuilt Denso injectors by end of today, i will have it towed back and do them myself.
And now my junk Topdon ArtidiagPro will only charge thru vehicle on top of being unable to graph 4 items at once!
I spent day yesterday calling in favors from dealers i work for and the Toyota tech looked at my screenshots and and actually was impressed i kind of knew what i was talking about, but he was also in his 60's.

sure you can go 60 to 70 mph, and still have an under reporting MAF. You can also still have bad new parts, dirty fuel filter or bad fuel pump.

Going 60 to 70mph is not really constructive, load is more pertinent in this case and the associated LTFT, STFT Upstream and downstream %'s and V's

So under full load you have a max LTFT value....plus 40%LTFT's and a STFT around 0% and a low downstream V you have having a fueling problem.

Although I wonder what the case would be if the voltage was high on the down stream

finally ! Just wanted to Shout out to Ben and Juergen ! 717 and 117 issues are fixed ! Turns out Fuel Pump and the Input sensor. And finding wire colors sure helps. The only toyota input sensor video is NOT input but output guess I need to comment on that guys post, but who would think the input is farthest from engine ?
Thanks Ya'll
Michael

Thanks for the follow up, Stryper! Ben and Juergen are definitely rockstars. I moved your shoutout post into this thread so they'd get notified of the reply.

Stryper wrote:

finally ! Just wanted to Shout out to Ben and Juergen ! 717 and 117 issues are fixed ! Turns out Fuel Pump and the Input sensor. And finding wire colors sure helps. The only toyota input sensor video is NOT input but output guess I need to comment on that guys post, but who would think the input is farthest from engine ?
Thanks Ya'll
Michael

Thank you for the update! Good to know you fixed it.