P0171 bank 1 lean condition. Car running rich poor Mileage

[Jetblack786]

Hello, please help me with my Rav4 2.0 2004 so the story starts my engine light comes on read with the scanner Engine running lean P0171 bank 1 car is giving extremely poor mileage things I have done so far 

1: vaccum leak check 
2: Maf clean checked working fine 
3: replaced the Bank 1 sensor 1
4: fuel injectors cleaned 
5: Air filter changed 
6: fully serviced 
7: fuel system cleaner added
8: Fuel pressure is 45psi and holding above 40 psi for 30 minutes 
9: on Idle Stft -3% Ltft +17% 
10. Coils and harnesses wiring All correct volt in and out 
11. Battery and Alternator both checked and good working perfect 
When press the Acceleration LTFT maxed to +25% 

On Full Tank giving 140 miles 
I'm just tired 😩 
Please Help 🆘

[GBgraham]

You obviously have a fuel mixture problem so I would suspect a bad Lambda circuit that needs test at the ECU, or maybe it could be a partially blocked cat. 

It's expensive to try and cure such problems by guessing and/or replacing so I would find some reputable diagnostic guy and go from there.  

[Jetblack786]

Thank you for your reply we have done the cat cleaning the lambda circuit at the ECU will update after test and there is no exhaust leak aswell 

[GBgraham]

Go to the ECU and test the Lambda circuit from there. 

You can find the pin diagram on Autodata if you can get access to this.

[Jetblack786]

question Graham is this A/F sensor a high-volt sensor the reading is 3.3 3.4v even the previous sensor was giving the same range reading but I changed the new one original correct part for sure 

[flash22]

2.0 petrol with the 4 O2 sensors ? Or just the 2

 

Edit. Just the 2 - Denso DOX-0505 A/F

 

Are you getting power and ground to the heater on the A/F ? check the main EFI relay and EFI 1 and 3 Fuses

 

If the A/F is constantly above 3.35v the sensor or wiring maybe open and/or the heater is open circuit

[Jetblack786]

Just 2 bank 1 and bank 2 

[flash22]

sorry was editing my post above

 

[Jetblack786]

Okay now I will check the fuse and relay you told me and plus the wiring to and from the sensor what readings should I be looking for 

[Jetblack786]

So if it's a open-circuit do I have to change the wiring 

[flash22]

What is your engine temperature sensor reading on live data, if it's too low it will over fuel like mad and the ecu will try to pull it lean

[Jetblack786]

I will update you with that info soon 

[Jetblack786]

It's 90 c 

[flash22]

After the car has been run or cold ?

Wiring - do an end to end resistance test <1 ohm = short, >10k ohms = open

[Jetblack786]

Warmed up engine 

[flash22]

Check it when it's cold

[Jetblack786]

One more thing I have noticed when I pump the brake couple of times  the short term fuel trims start climbing up to 25 positive any concerns ?

[GBgraham]

"the short term fuel trims start climbing up to 25 positive any concerns ?"

I'm not sure what you mean here

There is plenty on Youtube regarding testing your lambda as this

https://electrouniversity.com/how-to-test-o2-sensor-with-multimeter/

It's not a difficult process if you have a multimeter, even better with a scope.

One other thing to note, never use silicone sprays or grease on or near a lambda sensor

Edited October 25, 2023 by GBgraham
added info

[Jetblack786]

What I meant was is this normal to see stft maxed out when pumping on brakes when idle 

[GBgraham]

I wouldn't be concerned if your engine idle speed remains constant at the point of pumping your brake pedal.

[flash22]

Under certain conditions like deceleration the ecu will go into fuel cut - be aware, the fuel volume  controls the o2 and heater

 

i think you need to go back to the basics, if pressing the brake pedal affects it when stationary - look at the PCV system especially the non-return valve on the cam cover (left-hand rear IIRC) part number is 12204-28020 this goes into the intake basically pulling in unmetered air if not working correctly

[Jetblack786]

The light came on Again 😭 here is the freeze frame data 

[Jetblack786]

On 10/25/2023 at 2:32 PM, flash22 said:

Under certain conditions like deceleration the ecu will go into fuel cut - be aware, the fuel volume  controls the o2 and heater

 

i think you need to go back to the basics, if pressing the brake pedal affects it when stationary - look at the PCV system especially the non-return valve on the cam cover (left-hand rear IIRC) part number is 12204-28020 this goes into the intake basically pulling in unmetered air if not working correctly

Is there any way I can check if it's working correctly before ordering from Japan 

[flash22]

ltft show a major vacuum leak, have you tested the PCV valve it should only work in one direction, why parts from Japan most parts are still available over here

[Jetblack786]

I checked it's not available I can found the non-original ones plus the original part is even cheaper and I can get it by 2nd December