P0171 System too Lean (Bank 1)

[Power_Pusher]

I get both codes
P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)

I started with changing the Mass Air Flow Sensor but it did not fix the problem. I do not get an error for any of the o2 sensors (I would think I would). It is kind of strange that both banks are Lean at the same time. What could be the problem?

 

[Sepiroth]

It's not really that strange that both the codes came on at the same time.

Now let me explain this code for you. Typically these codes are letting you know that the PCM is commanding all the fuel within its parameters to achieve a desired air/fuel ratio.

Whats going on is that there is too much air and not enough fuel. Some of the causes could be aif filter, vacuum leaks, MAF sensor, defective O2 sensors, incorrect fuel pressure, or incorrect fuel volume.

I'm willing to go out on a limb here and say that your codes are fuel related. Have your fuel pressure and fuek volume checked. Also be sure that there is not obstruction in the fuel system.

 

[u2nv]

+1 also whens the last time u put a fuel filter in it and or vaccum leak take carb spray and spray around intake and vac lines see if it changes the way it runs, also exhaust leaks if you have any exhaust leaks could also cause this code.