Getting too lean on one bank and too rich on another & p0303

the p0300--p0301-p0302=p0303 are misfire codes and can mean needs tune up or wiring problem and p0171 is system to lean bank 1 with this code if you correct it will probably correct the misfire codes your receiving
http://www.obd-codes.com/p0171 Fixing Hesitating Car P0171 Code YouTube P0171 System Too Lean Bank 1

PO 171 Bank 1 too lean
PO 174 Bank 2 too lean
Why ?
The front O2 Sensors need to be replaced at
100,000 miles or sooner, if they have actually failed
They are reading too lean because the system is too
rich & the computer is driving the fuel trim or injector
pulse lean, thus the codes or failed sensors, yes both
Have to check fuel trim with a scan tool
Have to check fuel pressure
Have to check there are no leaking injectors
Have to check for Vacuum Leaks from the intake
all the way to the exhaust converter
Your working a rich condition keeping in mind the system
is driven lean
You look at fuel trim short & long,sort of a past history
of events
May want to look at converter temps also
The converters won't last long if you have or has
a rich condition from fuel or cylinder misfires
Now the spark plugs can't be over 3 years old
& no mifires,get that out of the way before working
the O2 issues

Hi Paul, Have you had a fault code relating to the knock sensor? That sensor controls ignition timing which can have a relationship to the fault codes you report? Regards John

The cylinder misfires cause lean or rich
fuel trim

A constant lean on fuel trim, is a rich condition
driven lean by pcm to correct

If two cylinder are affected & are together or maybe
not ,then smoke the intake for vacuum leaks

A leaking injector is obviously a rich senerio

Converter only works with the O2 Sesnors to report
back the rich or lean to pcm

You need to get rid of the misfires before any fuel control
returns to normal

Sounds like it is still lean & driven rich by PCM

I assume a repair shop can't resolve the issue !

That seems to be why thousands of people come
to this site & ask questions

I know the MAF is common to both banks, but you diagnose
short & long term fuel trim & perform several tests, before you
replace a MAF Sensor

MAF Sensor is common to both banks of the motor

If your not the one doing the work- take it back

Rich may be a lean condition & driven rich by the pcm
from a vacuum leak or other reasons

Have to start with the codes you have & understand
how to use trouble charts or pay a shop to do so

p 0300 code is for random misfires
random misfires are more from dirty /faulty injectors or low fuel pressure than anything else
have a pressure test done to check pressure regulator , filter and pump operation
use a can of quality injector cleaner or remove and clean the injectors

I've come across these codes before. In almost every case there was an air leak in the intake air hose (hose between the engine air filter & the throttle body). Inspect this hose & tubes attached to it. This is especially true when the lean code includes the comment 'at idle'
P2187 - System too lean at idle Bank 1
P0174 - System too lean Bank 2
P2189 - System too lean at idle Bank 2
P2195 = HO2S Signal Biased/Stuck Lean (Bank 1 Sensor 1)
P2270 = HO2S Signal Stuck Lean (Bank 1 Sensor 2)
P2272 = HO2S Signal Stuck Lean (Bank 2 Sensor 2)

P2187 & P2189 = In order to provide the best possible combination of drivability, fuel economy and emission control, the PCM uses a closed loop air/fuel metering system. The PCM monitors the HO2S signal voltage and adjusts fuel delivery based in closed loop fuel control. Changes in fuel delivery will be indicated by the long-term and the short-term fuel trim values. The ideal fuel trim value is around 0%. The PCM will add fuel when the HO2S signal is indicating a lean condition. Additional fuel is indicated by fuel trim values that are above 0%. The PCM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the amount reaches excessive levels because of a lean or rich condition

I could be wrong but it sounds like you need to put some attention towards the cat and the O2 sensors.

Usually it's an air leak in the intake and /or exhaust that throws fuel trim off.Bad/dirty injectors are the 2nd common cause.