1998 Chevy Truck Really bad gas milage

1998 CHEVROLET TRUCK
174,000 MILES • V8 • 4WD • AUTOMATIC
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CHEVYKODIAK
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I recently bought an old business owned truck that had a few problems that i have been trying to fix but i have noticed my fuel mileage has been dropping since i got it. it used to be near 15mpg, but the last i checked it got 8.6mpg. IAnd what really gets me is that the check engine light hasn't come on. It my be a little off because its winter and i idel more but it shouldn,t be that bad. I have new spark plugs and wires, new air filter, new fuel filter, changed the oil recently. I think it has most of the factor parts on it to. My guess is a sensor/s. and one more thing one of my catlytic converters is no more. its not cloged its completely empty but i heard that O2 sensors only can change mpg by 15%. I have no way to test them either and i realy don't have money to have a dealer look at it.
Jan 31, 2010 at 1:15 AM
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BLACKOP555
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if the vehicle is running just fine there shouldnt be a issue with engine wise sensors that could cause that bad of a fuel economy decline. to me it seems that the o2 sensors are failing. on average they can have a 15% decrease in mileage but it can be alot more.
Jan 31, 2010 at 1:44 PM