1997 Mercury Marquis failed emmision

Tiny
DIVIS
  • MEMBER
  • 1997 MERCURY MARQUIS
  • V8
  • 2WD
  • AUTOMATIC
  • 96,000 MILES
I bouoght the car from my elderly nieghbor. It has been sitting for 6 months. I took it to get the emmisions checke to register it and transfer title. It failed codes P0171 & P0174 system too lean bank 1 and bank 2
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Saturday, August 8th, 2009 AT 3:16 PM

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Tiny
RASMATAZ
  • MEMBER
It failed codes P0171 & P0174 system too lean bank 1 and bank 2

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)

* TIP: On many Fords, a P0171 and/or P0174 Lean Code may sometimes appear because of a bad Differential Pressure Sensor (DPFE). This sensor monitors EGR flow, and is located on the engine near the EGR valve. There are two hoses that connect the sensor to the tube that runs from the exhaust manifold to the EGR valve. The sensor misreads EGR flow and the computer increases EGR which has a leaning effect on the fuel mixture. The fix is to replace the DPFE sensor.
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Saturday, August 8th, 2009 AT 5:11 PM
Tiny
DIVIS
  • MEMBER
Should I try the EGR fix first?
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Saturday, August 8th, 2009 AT 5:31 PM
Tiny
RASMATAZ
  • MEMBER
Do the EGR and MAF sensor
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Saturday, August 8th, 2009 AT 5:42 PM

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