2002 Volkswagen Jetta p0171 code

2002 VOLKSWAGEN JETTA
112,000 MILES • 4 CYL • FWD • AUTOMATIC
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JMECH1000
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have done compression test ,vacuum test, changed all injectors ,fuel pump ,fuel preasure regulator, vacuum valve , combi valve,fuel filter ,all coil packs ,spark plugs ,secondary air pump, fixed all vacuum and exhaust leaks I can find, and the first o2 sensor... have also changed out the maf sensor ...code still wont fix where can I go from here?
Aug 20, 2009 at 5:58 PM
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RASMATAZ
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2002 Volkswagen Jetta p0171 code

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)
Aug 20, 2009 at 6:02 PM