Hesitation

[d0nkey]

Hi all,

I'm working on 2008 NCP91 1.5 1NZ FE Yaris stock, trying to fix hesitation issue which happens when battery disconnected, then first drive is poor acceleration, lack of power and once it re-learns trims it becomes mildly ok but when I accelerate under load e.g. 4th gear long term fuel trims goes to 39% that eventually triggers engine check with lean condition code P0171.

What was checked:

1. Maf cleaned and tested by collecting reading of it and rpm into excel dividing rpm to maf reading producing constant value means maf values increase as engine accelerates

2. Injectors taken out cleaned with carb cleaner and 12v adapter to open close them manually, no volume tested as I don't know how to measure if they deliver up to specs, mist was coming fine I guess.

3. First O2 sensor replaced
4. Fuel pump replaced (btw what are 2 vacuum hoses that goes into it I though it is return less system?)

No result yet, the only logical place can be injectors (blue ones stock Toyota) somehow not delivering required amount but that would be evident on idle as well where idle is fine and fuel trims under 2000 RPM are -7% total.

Air leaks not applicable as idle is fine, only when butterfly opened wide e.g. under load hesitation occurs.

Maybe if someone has OBD can measure your readings in case its normal for that car, mine Long Term sit -7% under 2000 RPM then goes to +16-39% when under load and accelerating e.g. going uphill. I measured other car I have and Long Term trims always under 10% no matter how you drive.

Another place I'm not sure if ECU is programmable in these cars and someone uploaded different firmware say from 1.3 engine as what is suspicious I can't read VIN number via OBD in that car.