Rapidly decreasing MPG

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Dec 3, 2000 | 06:44 PM

Avanti

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Rapidly decreasing MPG

Feb 4, 2001 | 01:03 PM

ajstephan

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Rapidly decreasing MPG

My 1995 4.9L Ford F150 4x4 has never got good gas milage, but going from 14/14 to 11 over the past 2 months has me worried. It's been tuned with new plugs, wires, dist. cap, etc. but it just keeps erroding. Any ideas???

Feb 4, 2001 | 01:09 PM

PAUL_2

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Rapidly decreasing MPG

How many miles on the truck ? How does it start & run ? If it has higher mileage the O2 Sensor may be getting lazy ? Check for any stored fault codes . Even under inflated tires or alignment problems can steal some mpg .

Feb 4, 2001 | 10:45 PM

ajstephan

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Rapidly decreasing MPG

It's got 96,000 miles, and I haven't noticed any change in the performance or startup. The tire pressure is good.

I checked the trouble codes repeatedly, and I get 522522 then a series of 1's. According to the manual, the 522 means that my tranny isn't in neutral (it was) and the 11's means that everything checks out OK.

Should the error codes show if the O2 sensor is bad? Is there any other maintence that I should do with this many miles on it? (e.g. clean the throttle body, etc.) I'm wondering if the clutch is slowly going - although it seems fine. Any help would be appreciated.

Feb 9, 2001 | 07:33 AM

Josh00

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Rapidly decreasing MPG

On the 4.9l engine when you are checking the codes, the clutch has to be pushed in for the codes to be sent, not just the transmission in neutral, so you'll either have to get somebody to help you or you can do it if you have really long arms.

Josh
Blue '91 F-150 Custom
300 I-6 Manual 5sp Transmission
31x10.50R15 Tires
Cat back duals with 12" Glasspack

Feb 9, 2001 | 10:47 AM

daywalker

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Rapidly decreasing MPG

Mine loses 3 mpg every year when it gets cold. Have you noticed this before?

Daywalker
92' F-250 351 4x4 xlt 4.10 5spd sprcab lngbed
Sound System: Stock Stereo, Rockford 800 watt amp, Vega 18 inch sub 400 watt rms, one Cerwin-Vega LS-12 3 way floor speaker with a 300 watt power capacity, and one Boise floor speaker with a 75 watt power capacity.

Performance Mods: K&N Air Filter.

Cosmetic Mods: Black Grill Guard, 5% window tint, bug guard, bed liner.

http://albums.photopoint.com/j/View?u=1426655&a=10683799&p=36629681&Sequence=0&re s=high

Feb 11, 2001 | 11:01 PM

tye

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Joined: Feb 2001

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From: Oregon

Rapidly decreasing MPG

Make sure you don't have any loose bolts on your exhaust manifolds, a friend of mine has a 94 300 I6 and it lost a bolt out of one of the exhaust manifolds and his mileage went way down. Replacing it fixed the problem, all I can think of was that it was sucking in some extra air and fooling the O2 sensor into thinking the engine was running lean thus dumping in extra fuel.
1991 F250 4x2
300 I6 5speed