The past month my gas mileage has been down by about 4mpg or so. It was not a gradual drop, but an over-night change. I change my oil regularly, clean my intake and keep all my fluids in check. I have about 47k on it. There has not been any change in the way the truck runs or sounds that I can tell. The filter is fairly new. Depending on the county I buy gas, either it is or is not formulated, so I usually have a mixture of both at any time. So I am thinking maybe some sensor is out like the O2 or something. Any help is appreciated.

Runnert

 

For a quick fix, try disconnecting your neg battery terminal, and turning on your headlights to drain the residual charge in the system. After about 5-10 minutes, turn your lights off and reconnect your battery, then take your truck for a rip.
This will help the computer re-learn your driving habits, and might do the trick. I have to do this from time to time when i move to different climates and different altitudes.

HTH
Bambino

 

Could the spark plugs have something to do with it? Will they really last 100k? I was just thinking that if the gap was out, it would not get the full fire of the spark.

runnert

 

Runnert,
irt the spark plugs, i just took out the stock autolite platinums @ 70k and they were frigging gorgeous! I replaced them but they were still good...
Assuming your air cleaner is good, i would tend to say that you may have got a bad tank of gas. Not all gas was created equally...
if at all possible, STAY AWAY FROM ETHANOL GAS. I would run the tank dry, replace the fuel filter ($8), clear the computer (i just unplug for 3 hrs), and fill up w/ Amoco regular and ensure they don't have additives (don't they have to post it if they use etanol?). Just use 87 octane unless u have a superchip.
Good Luck

 

4mpg.

hrm, check the tire pressures, wheel bearings, brakes.

You did not leave the ebrake on did you? Did you leave it in OD?

Other than that, the MAF and the O2 sensors is where I would start. If you have a code scanner or have a manual, run the codes see if anything pulls up.

 

LOL
Nice sig, Matt

 

Mine dropped from an average of 21 mpg to 16.5 mpg this past week.

From checking the board regularly, I've seen quite a few complaints about this as well as pinging engines across the country all of the sudden.

I'm thinking it is a simple as oil companies switching to their winter fuel mixture. I asked the Texaco that I have always had 1st class fuel at and they said they switched to the wintrer grade in mid October.

An O2 sensor failure is a possibility but you would have more general drivability problems and the gas milage would probably drop in half.

 

I had a tank that was down about 2 mpg recently ( I keep very accurate track). I believe that it was from a certain station because only that one tank was bad. Boy I hate the MPG loss that comes with winter gas. How am I ever going to get my total avg MPG over 20 with the winter blend?