1997 Ford Thunderbird Fuel too lean in Bank One & Two?

Engine Mechanical problem
1997 Ford Thunderbird V8 Automatic 69,000 miles


My name is Crystal and I was hoping you could please help me. My car's "Service Engine Soon" light turned on and I did an OBD2 scan and it said my fuel was too lean in bank one and two. The codes were cleared and soon after driving the light returned. My manual recommends 87 grade gas and I have been filling up with 89 so I'm not sure why it is saying it is to lean. I was told it might be a bad spark plug or an old O2 sensor I want to get a second opinion. In the mean time I fille dup with super and will clear the codes tomorrow in hopes it wont return. It is kind of urgent because my smog is due for my insurance by the 17th and well it's the 11th. :( I hope to hear from you soon and thanks for the help. Thank you and have a great day.

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Friday, July 11th, 2008 AT 10:08 PM

1 Reply

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, July 12th, 2008 AT 8:43 AM

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