Hello, if you raise the idle up to 2,500 RPMs and the LTFT and STFT Bank 1 comes down below around 5% then it's going to be a vacuum leak. Those are the Long Term and Short-Term fuel trims. and they are both extremely high. With a positive number like that the ECM is adding fuel to air fuel mixture. The oxygen sensor voltage being low is also indicating a lean mixture.
Looks for any broken or leaking vacuum lines, stuck open purge valve (which I'll post a diagram of), leaking Intake manifold gasket, etc. The Bank 1 Sensor 1 Oxygen sensor voltage should become more active at higher rpm also. Your Mass Air Flow reading is a little low as well, that also shows there is "false air" entering the engine at some other place besides the air intake boot. Here's a diagram of the Intake manifold and the components to check. Try temporarily blocking off the purge valve hose going to the intake manifold and see if the Fuel trim numbers come down towards 5%. Do the same with the Brake Booster hose.
For Intake manifold gaskets I just used a spray bottle with water, while the engine is idling, you'll be able to hear the water being sucked into the section of gasket that is leaking. With the size vacuum leak, you have it should be pretty easy to find. There are some guides below to help. Let us know what you find.
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers
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Tuesday, May 9th, 2023 AT 7:28 PM
