1997 Ford Ranger lean bank one and two??

1997 FORD RANGER
90,000 MILES • 6 CYL • 2WD • AUTOMATIC
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HALFABOX
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hello, i recently drove from the east coast to kansas. afterwords my truck started having a very rough idle, revving up then nearly stalling. also when i would come to a quick stop the truck would stall. i had the O2 sensors replaced before the drive, the fuel filter replaced after. Also when it first started this the fuel system/air intake was cleaned and flushed and was told if it continues it is the mass airflow sensor. well the mass airflow sensor test out perfectly as well as i can not find a faulty sensor nor is the computer showing one. The only fault codes that are coming up are "lean, bank 1 & 2", it is using up more than twice the usual gas, and the idle is getting worse.

At this point I really have no clue what it is. Fuel pump, clogged cat, clogged fuel line? Any suggestions, I would like to hit this one on the head instead if paying a lot hitting around.

thank you
Dec 5, 2008 at 5:27 PM
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RASMATAZ
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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)

*Could be 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.
Dec 5, 2008 at 5:33 PM
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HALFABOX
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So I tested the fuel pressure and the only thing that was not in spec was that on average it was running at 5 pounds under what chilton stated. ??problem??

I know I should have tested the voltage from the pump but I could not find a connector or the wires to the pump. Would coming out of the main fuse box be the best place to get to them?


Also after I tested the fuel pressure it seemed to run better at least for the most part, and I know the only thing I actually did was popping off the return line off the regulator to check for flow. There definitely was, like a geyser actually. Could have let loose a piece of dirt or something?? clogged regulator? or bad?

And the system held it's pressure, for well over 10 minutes. when I turned off the engine of course.

I couldn't find any vacuum leaks.

And the day after I replaced the mass air flow sensor, in the sheer hope that therein lies my problem, the simplest thing; and there was no affect to be had apart from when I cleared the error codes they did not come back on, but i havn't driven it all too far since that to give it a chance.

Also, I was told that the lean bank 1&2 were a sign that the engine was actually running too rich, and wants to lean itself out. It sounds good, but is it??

Thank you
Dec 14, 2008 at 11:31 AM
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