Join Date: Dec 2005
Location: Mechanicsburg, PA
Re: Gas mileage huge drop ideas?
Best bet would be to track your mileage and look for a trend. Get a GPS and verify that your odometer is measuring correctly.
The only 'real' way to track fuel mileage is to get an accurate distance, and number of gallons. Every pump will shut off at different fill levels. The way to do it would be to 'top it off', until you can see the gas in the filler neck. This is not recommended by many, since it may back up into the vent system, leading to more issues.
This is why I recommend looking at a trend, some times you may fill it a little closer to full, other times you may be a little less, but over a few tanks, you should be pretty close. I have a spreadsheet that I use, and I graph the mpg. This just makes it easier to see what I am getting, and it also makes it very easy to see if I am going up or down in mpg.
I typically only fill up when the tank gets below 1/4, as opposed to filling with only a few gallons, this way, if you did get a bad tank of gas, you won't keep diluting it, and extending the poor performance.
Then if you want to be scientific, do a maintenance procedure, or a modification, and run a few tanks through. Do only one thing at a time, and you will see the results - good or bad. If you don't care, or don't have the time or patience, do what you think you need to do all at once.
How many miles are on the truck? Do you know what the maintenance records look like? As mentioned above, a throttle body cleaning, and MAF cleaning may be a good place to start. Plugs may be next, if you don't know the history (I recommend factory plugs, or equivalent). Air pressure in the tires should be checked.
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