I have a 2001 Toyota Corolla.
Lately it has been throwing the P0171 code (system too lean). My short term fuel trim is normal at idle. +/- 5 % at idle and long term fuel trim is high at idle +18 %.
When I rev the engine to 1500 rpm the short term stays the same and long term fuel trim goes down to about 14%. Weird thing is when I drive the car, the short term fuel trim is normal and the long term goes down to 7 percent or so, BUT intermittently at around 2200 to 2500 rpm the short term shoots up to around 25 percent and long term fuel trim goes to 35 %. This is the point where I throw the P0171 code.
Any help would be appreciated.