Codes PO303, PO171 and PO174

SHEAZY34

MEMBER
2002 FORD RANGER
3.0L
V6
2WD
AUTOMATIC
211,000 MILES

Top portion of the engine has been rebuilt. Check engine light has come back on, there is a definite misfire it is pulling codes po303, po171 and PO174. Replace spark plugs and wires MAF sensor and fuel filter, throttle position sensor, crankshaft sensor. Oil gauge quit working, but oil is registering fine. Rough on start, and pulling a hill and keeping speed is nearly impossible. Check engine light blinks nonstop and turning on AC will cause engine to cut out even in park. Fuel pump hums normal when you turn over engine, but there is a strong gas smell even though it is running lean.

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon.

The first thing I would do is a compression test on the number three cylinder. That is the 303 code.

The 171,174 is for lean condition. Possibilities below.

Roy

P0171
Descriptor
System To Lean (Bank 1)
Probable Causes
Air Leaks
Air Leaks After Mass Air Flow (MAF) Sensor
Engine Oil Dipstick
Evaporative Canister Purge Valve
Evaporative Emissions System (EVAP) Canister Purge Valve Leaking (When Canister Is Clean)
Exhaust Gas Recirculation (EGR) Valve
Exhaust Gas Recirculation (EGR) Valve Pipe and or Gasket Leak
Exhaust Gas Recirculation Vacuum Regulator (EVR) Solenoid Leak
Exhaust Gas Recirculation Valve Solenoid (EVR)
Exhaust Leak
Exhaust Leaks Before or Near Heated Oxygen Sensors (HO2S) Exhaust Manifold Gasket or Mating Gaskets
Fuel Filter
Fuel Filter Plugged or Dirty
Fuel Injector
Fuel Injectors Leaking or Contaminated
Fuel Pressure Regulator
Fuel Pressure Regulator Leaking or Malfunctioning
Fuel Pump
Fuel Pump Weak or Check Valve Leaking
Fuel Rail Pressure Sensor
Fuel Rail Pressure Sensor (Incorrect Reading)
Fuel Supply Line
Fuel Supply Line Restricted
Improperly Seated Engine Oil Dipstick
Low Fuel Pressure or Running Out of Fuel
Mass Air Flow (MAF) Sensor Contaminated, Damaged or Malfunctioning
Positive Crankcase Ventilation (PCV)
Positive Crankcase Ventilation (PCV) System Leak or Valve Stuck Open
Running Out of Fuel
Secondary Air Injection
Secondary Air Injection (AIR) System Valve Mechanically Stuck
Vacuum Leak
Vacuum Leaks