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1998 Ford Expedition System too lean bank 1 and 2

Tiny
CASEY129
  • MEMBER
  • 1998 FORD EXPEDITION
1998 Ford Expedition V8 Two Wheel Drive Automatic 135k miles

My expedition has a 5.4 Triton V8 I just changed all 8 plugs and replaced 4 new coil packs. I now keep getting the system too lean in bank 1 and 2 codes. I have since changed the fuel filter, 2 oxygen sensors, took out the MAF sensor and cleaned with brake cleaner, and sprayed vaccum lines with carburator cleaner. Please Help! Im about to loose my mind with this thing.
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Friday, July 24th, 2009 AT 11:05 PM

1 Reply

Tiny
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)

* DPFE Sensor

* 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)
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Saturday, July 25th, 2009 AT 3:11 AM

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