What would cause poor gas mileage on a 2001 Toyota Tundra with 40000 miles Went from 18 mpg to 12mpg No other noticeable problems?

Answer 1

Answer

could be one of a few things. clogged air filter,clogged fuel filter,dragging brakes ,slipping clutchand maybe just a good service will fix the problem

Fuel injectors can get gummed up cause a poor spray pattern resulting in reduced mileage. Try using a can of chemtool in a half tank of gas every 5000 miles. This works as good as the fuel injector service that most shops charge upwards of $60 for.

If you drive with a lead foot your ecu will adjust the parameters for performance at the expense of mileage. You can reset the computer by disconnecting and reconnecting the battery (while the ignition is off!) or removing and replacing the ecu fuse. This will reset the engine to use the default fuel/air/timing maps. It will then adjust them based on your driving habits. Note: the engine may seem to run rough when you first do this as it is "learning" the optimum program based on your driving style. To maximize the program avoid jack rabbit starts and stomping on the accelerator.

Other things to check are if you are using the proper oil type and viscosity. Modern engines are machined to tighter tolerances to use low viscosity oils for better gas mileage. Using synthetic oils and gear lubes can increase mileage by 1 mph or more.
If you are using an oil saturated filter i.e. K&N or others make sure that the the iat sensor is not gummed up from excessive oil.Use only cleaner listed as safe for MAP Iat sensors and follow intructions on the can They are delicate!!! Last but not least make sure that your tire pressure is correct. Hope this helps. BTw these tips are applicable to most late model gas vehicles

Must improve on the B-12 CHEMTOOL statement above. The can states that one can will treat a "full tank" of gas up to 20 gallons (If I recall correctly). BUT, if your tank is less than 12 gallons, you should only add 1 fl. oz. of CHEMTOOL per gallon of gas. This can get tricky, especially if you have a smaller vehicle, such as a Kia Rio, which only has an 11 gallon tank. So you'd only add 11 oz. of the 16 oz. that comes in the can. Save the rest of the can for your next fill up so you aren't holding onto a near empty can for 3-5k miles :)


Note: It's been a while since I used CHEMTOOL or read the can, so the numbers (ounces, gallons, etc.) mentioned may be wrong, but just read the can. This stuff DOES work though! :)