2000 GT Fuel Economy Problem

darren94darren94 Member Posts: 3
edited June 2014 in Pontiac
I have a 2000 GT with 98000 miles on it; I am the original owner. Had the oil changed and fuel system cleaned about a month ago. At that time, I was getting 21 MPG, and the fuel system cleaning was supposed to (possibly) add 2 MPG. Since then, I have dropped 1 MPG from each successive tank of gas I have put in...down to 17 MPG now. I removed the air induction assembly to check for any rags they might have left in it when they "checked" the air filter (which is only 3 months old and not dirty)...but there were no air flow restrictions. The engine runs smoothly still, and has as much or more power than it did before the fuel system was "cleaned". Tires are still inflated to the same PSI. I plugged my OBD II computer into the care, and there are no codes, either active or stored. What could be causing this problem???


  • sonyarsonyar Member Posts: 5
    well . i have the same problem with me 2000 pontiac grandprix.....i get very low gas mileage...i would like to find it out also.
  • darren94darren94 Member Posts: 3
    Have you done any troubleshooting to your car?
  • jeves715jeves715 Member Posts: 6
    I have the same problem! It's probably your MASS AIR FLOW SENSOR. They are expensive, but worth it. I'm still looking for the cheapest one and can't decide on a remainufactured $75 or new $160. Both come with a 1 yr warrenty.
  • darren94darren94 Member Posts: 3
    Nah...mine went bad and lit the "Check Engine" light last year. Forced me to go buy my scan tool...you'll know if the MAF is bad, as it can't go bad without turning on the light. The Bank 1 Oxygen Sensor can be on its way out without causing the light to come on, but I'm having a hard time parting with the $75 for it because I can see it working when I plug my scan tool into the car, I just can't tell if it's switching quickly enough (because it's supposed to make adjustments in increments of at least one hundredth of a second). Either way...I turned over 100,000 miles on Saturday, and I'm almost back up to 20 mpg after changing plugs and wires, so I guess I can't complain all that much. I have a car that's getting pretty good mileage, that's not costing me a monthly payment, and it runs great.
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