2001 Ford Escort CEL 0171

EDETWE

MEMBER
2001 FORD ESCORT
4 CYL
FWD
AUTOMATIC
17,000 MILES

2001 ZX2 2.0L CEL Code 0171

Struggling with this diagnosis - lean condition on one engine bank. The engine {180,000 miles} runs fine at idle and fast and or heavy throttle exceleration, only stumbles when excelerating from dead stop or during 1/2 throttle situations{clearing a hill or cruising straight aways}.I've so far replaced upstream O2 sensor, installed new plugs and PVC, removed and cleaned IAC valve {too expensive to replace without certain knowledge its the problem}, Spark good to all cylinders - one of 4 injectors replaced recently, newer fuel filter. Did not check TPSensor, Valve cover gasket is leaking somewhat, and cleaned breather element from valve cover{surprised to see that element was completely overflowing with oil sludge}. Anybody have any suggestions, all would be appreciated

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)