System Bank 2 Too Lean

[maximus2]

Good evening all,

Thank you for taking the time at looking at this thread. I have a 2002 Lexus ES 300 that keeps throwing "System Bank 2 Too Lean" code, sometimes Bank 1 too lean is also in pending codes but disappears. I know that vacuum leaks are a slim possibility since i replaced most of the hoses and replaced faulty VSV's, along with the MAF sensor reading around 3.6-3.9 g/s at idle. The alternator and battery are brand new. It used to throw a EVAP System code as well as a Bank 2 Catalyst below threshold code, but now i never see them come up since i replaced the alternator and battery. Its very slight, but i can tell the engine is not running at its best overall. I recorded both banks at operating temp and idling, and here's what has consistently come up:

-B1 S1: 3.337v

-B1 S2: 3.454v

-B2 S1: 0.760v

-B2 S2: 0.445v

I didn't see any further but for bank 2 for both sensors, the short term fuel trim is 99.2%.  This is the short and long term fuel trim for both banks overall:

-Short trim B1: 0.1%

-Long trim B1: 31.2%

-Short trim B2: 0.9%

-Long trim B2: 35.3%

Any help would be greatly appreciated before i fire the parts cannon at my car, budget is not a problem to me and i love this car dearly. Thank you all!

[McBrian]

I'm in the process of replacing ALL of my crusty vacuum lines up top (and anything I can reach) and it has made a HUGE difference.

To start run a can of Red Line Fuel System Cleaner or BG 44k (the only ones worth it) through with non-ethanol fuel if you can get it.

All of the codes are being thrown downstream from the heads so you have a fuel/air issue most probably. Don't overrthink with data just yet.