Mechanics

WHY IS MY 'S GAS MILEAGE GRADUALLY DECREASING?

2004 Chevrolet Tahoe • 105,000 miles

Several years ago, when I bought my 2004 Tahoe K1500 LT w/the 5.3L V8 FFV, it averaged 13.5 mpg in town. Since then, fuel economy has been gradually decreasing, and now it averages 10.9 mpg in town. I have performed all the scheduled maintenance, and keep the tires at the proper level of inflation. Why might this be? Thanks
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Chargerfanatic
December 7, 2011.



Bad gas mileage is usually tied to an oxygen sensor or a leak near it. The sensor sees a lean condition and adds gas that is not needed. Other possibilities are blockages in the air intake path or exhaust path.