» » »

Buick Q&A

Ask Your Question

2004 Buick Rainier Question: 14.2 mpg highway & no error codes or lights



41willyguy, 4.2L 6 Cylinder, San Diego, CA, July 11, 2010, 13:52

fuel mieage on local & highway, using high or low grade fuel, increasingly getting worse. Bought from dealer 1 year ago doing 16.0mpg, now down to 14.2mpg. no signs anywhere. mechanics won't look at it without a code to trace.

2 Answers
Flag This
  • Answer #1

    patrick mannion from Greg Solow's Engine Room, July 11, 2010, 14:00

    Check this government website for 2WD Rainier. http://www.fueleconomy.gov/feg/findacar.htm

    They are not brilliant for MPG but some tires even can help fuel economy, (less rolling resistance). I wonder on a scan tool what the fuel trim figures are Long Term Fuel Trim figures show if your car's computer is adding or taking away fuel which may not yet have set a code.

    Flag This
  • Answer #2

    Visitor, July 31, 2010, 16:16

    you may want to seek professional help because my 2006 AWD Rainer needed the stabiltrac serviced and after that the fuel mileage went from 15.7 to 19 mpg highway

    Flag This