2002 Pontiac Firebird P0171 and P0174 codes

VOICES204

MEMBER
2002 PONTIAC FIREBIRD
V8
2WD
AUTOMATIC
77,000 MILES

I have a Formula showing these codes with no codes for the cause. I cleaned the FAF sensor and the problem went away I also changed the four O2 sensors. I am now getting the codes again and sometimes the engine runs a little rough at idle. I checked the fuel pressure and it was a little low when I started the car the pressure went up I thought it was supposed to go down a little. Any thoughts? I have a new FAF sensor on the way.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)