So my TJ threw bank 1 and 2 lean code recently, so plugged the OBD reader in and checked the LTFT and O2 sensor data. LTFT at idle is about 20% at Running Temp in Closed Loop, on throttle open (in Neutral), the LTFT drops for a split second then goes back up to 20% and remains there till WOT, while driving though LTFT is down at 17% at cruise speed but behaves the same when I hit the throttle to accelerate.
The fact that my STFT and LTFT barely respond to throttle and RPM is making this really difficult to diagnose, tried spraying brake cleaner around potential vacuum leak locations and noticed the STFT dropping drastically but sorta slowly when I sprayed around the throttle body while blocking off the Brake and CCV vacuum hoses, so i rebuilt the throttle body, new O-rings on the idle control valve, new throttle body gasket, made it all look really shiny, did Rusty's double O-ring thing too, put everything back together, nothing has changed......
I've got a brand new fuel pump in from Bosch, injectors rebuilt in October 2023 and showing good numbers at the time, new air filter, new spark plugs (double checked the gap), Viper Coil mod done in Jan2024.
It's a late model so havent been able to do a fuel pressure test thanks to the super cool and totally upgraded late model fuel rail and the vacuum leak test showed inconclusive results after i pressurized the system to 10psi with an air compressor and sprayed soapy water around, it did leak but couldnt confirm if it was the vacuum leak at the throttle body, or the rubber gloves i used to block off the intake tube and front vent valve, the bubbles were either too small, or in a blind spot i couldnt get to.
Worth noting that she idles at a very steady 630RPM (same as it's always been) and really doesnt feel like she's running badly, if the code hadnt popped up i would never have noticed anything.
Both banks were running in closed loop
Idle data:
LTFT B1 : 20%
LTFT B2 : 20%
STFT B1 : 0% (+- 2)
STFT B2 : 0% (+- 2)
O2 B1S1 : Oscillating between 0.8V and 0.08v
O2 B2S1 : Oscillating between 0.8V and 0.08v
O2 B1S2 : Oscillating between 0.3V and 0.08v
O2 B2S2 : Sorta stuck at 0.75v (A little sus i know but i feel like this isnt relevant to the Lean condition since it's affecting both banks and post cat O2s are meant to measure Cat efficiency not fuel trim.....right?)
Throttle Position : 12%
Engine Load : 28%
Open throttle in Neutral (around 2000rpm):
LTFT B1 : drops to 13% then back up to 20% after about 8 seconds from when i start increasing throttle position
LTFT B2 : drops to 13% then back up to 20% after about 8 seconds from when i start increasing throttle position
STFT B1 : increases to 7% then drops back and slowly oscillates between -5% and 5%)
STFT B2 : increases to 7% then drops back and slowly oscillates between -5% and 5%)
O2 B1S1 : Oscillating between 0.8V and 0.08v
O2 B2S1 : Oscillating between 0.8V and 0.08v
O2 B1S2 : Oscillating between 0.3V and 0.08v
O2 B2S2 : Sorta stuck at 0.75v
Throttle Position : 15.5%
Engine Load : NA
Tried to get the graph data off my phone but doesnt seem to want to send it to my email address.
I'm stumped, can the B2S2 sensor really be the cause of all this?
The fact that my STFT and LTFT barely respond to throttle and RPM is making this really difficult to diagnose, tried spraying brake cleaner around potential vacuum leak locations and noticed the STFT dropping drastically but sorta slowly when I sprayed around the throttle body while blocking off the Brake and CCV vacuum hoses, so i rebuilt the throttle body, new O-rings on the idle control valve, new throttle body gasket, made it all look really shiny, did Rusty's double O-ring thing too, put everything back together, nothing has changed......
I've got a brand new fuel pump in from Bosch, injectors rebuilt in October 2023 and showing good numbers at the time, new air filter, new spark plugs (double checked the gap), Viper Coil mod done in Jan2024.
It's a late model so havent been able to do a fuel pressure test thanks to the super cool and totally upgraded late model fuel rail and the vacuum leak test showed inconclusive results after i pressurized the system to 10psi with an air compressor and sprayed soapy water around, it did leak but couldnt confirm if it was the vacuum leak at the throttle body, or the rubber gloves i used to block off the intake tube and front vent valve, the bubbles were either too small, or in a blind spot i couldnt get to.
Worth noting that she idles at a very steady 630RPM (same as it's always been) and really doesnt feel like she's running badly, if the code hadnt popped up i would never have noticed anything.
Both banks were running in closed loop
Idle data:
LTFT B1 : 20%
LTFT B2 : 20%
STFT B1 : 0% (+- 2)
STFT B2 : 0% (+- 2)
O2 B1S1 : Oscillating between 0.8V and 0.08v
O2 B2S1 : Oscillating between 0.8V and 0.08v
O2 B1S2 : Oscillating between 0.3V and 0.08v
O2 B2S2 : Sorta stuck at 0.75v (A little sus i know but i feel like this isnt relevant to the Lean condition since it's affecting both banks and post cat O2s are meant to measure Cat efficiency not fuel trim.....right?)
Throttle Position : 12%
Engine Load : 28%
Open throttle in Neutral (around 2000rpm):
LTFT B1 : drops to 13% then back up to 20% after about 8 seconds from when i start increasing throttle position
LTFT B2 : drops to 13% then back up to 20% after about 8 seconds from when i start increasing throttle position
STFT B1 : increases to 7% then drops back and slowly oscillates between -5% and 5%)
STFT B2 : increases to 7% then drops back and slowly oscillates between -5% and 5%)
O2 B1S1 : Oscillating between 0.8V and 0.08v
O2 B2S1 : Oscillating between 0.8V and 0.08v
O2 B1S2 : Oscillating between 0.3V and 0.08v
O2 B2S2 : Sorta stuck at 0.75v
Throttle Position : 15.5%
Engine Load : NA
Tried to get the graph data off my phone but doesnt seem to want to send it to my email address.
I'm stumped, can the B2S2 sensor really be the cause of all this?
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