2002 Nissan Pathfinder Fuel Consumption

2002 NISSAN PATHFINDER
109,000 MILES • 6 CYL • 4WD • AUTOMATIC
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HARPOON1976
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I'm having an issue with my '02 Pathfinder since having a tune-up about 6 months ago: I went from getting 16-17MPG to getting about 10-12MPG. Other then fuel consumption, the car runs absolutely great- no unusual sounds, no engine problems, etc.

I consulted with my cousin who's a mechanic for a dealership and he pulled the plugs guessing they were gapped wrong. They were slightly off so he changed them out for better plugs, but the issue is still there: crappy fuel mileage.

Not sure what the issue is now: maybe a lazy O2 sensor, clogged fuel filter? Anyone have an idea?
Jul 28, 2009 at 8:11 PM
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JACOBANDNICKOLAS
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Has the check engine light ever come on? You sound like you have the same luck I do. Try to improve something and it gets worse.

As far as the O2 sensor, that could be a problem, but I would think the check engine light would have come on or performance wouldn't be that great. You could remove the sensor and check to see if it is carboned up. Also, I will assume that power hasn't changed indicating a potentially plugged catylatic converter.

Let me know about the O2 sensor and the check engine light.
Jul 29, 2009 at 12:17 AM
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HARPOON1976
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Check engine light has never come on and the engine power is fine. The only thing I noticed is that it's struggling a little bit going up steep inclines, but nothing major.
Jul 29, 2009 at 7:37 AM
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JACOBANDNICKOLAS
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I wonder if the catylatic converter is starting to plug. Have you ever notced any ratteling from that area that may indicate the insides are loose?
Jul 29, 2009 at 11:50 AM
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HARPOON1976
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Not that I've noticed at all, but I haven't been paying attention. I'll start it up and see when I get home tonight and let you know.
Jul 29, 2009 at 1:10 PM
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HARPOON1976
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Checked it this morning- doesn't sound like anything's wrong with it. Engine sounds fine.
Jul 30, 2009 at 8:59 AM
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JACOBANDNICKOLAS
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THen chances are you are right with the O2 sensor.
Jul 30, 2009 at 4:39 PM