2004 ES330 - Nonlinearity Of Gas Gauge

Aug 20, 2004 4 Replies

When my gas tank is full, my 2004 ES330's computer says that the range is 320 miles. When the range says 80 miles (%% of 320), the gas gauge says exactly 3/8th of a tank. According to the range reading, the gas gauge should say 1/4th tank. Anyone know why the gas gauge overstates the amount of gas by 50% (1/8th of a tank)?



Alternatively, if the gas gauge is correct, then the range should say



120 miles instead of 80 miles (a 33% understatement).

The gauge really just reads a level but the tank itself isn't always regular in shape so the lever change to volume change may no be linear depending on the shape of the fuel tank. Sounds like the ES tank has a tapered shape to it.

Probably to allow for people who run their tanks all the way down. Then you have a 40 mile chance to still get gas before you're stranded for good! LOL

This degree of non-linearity is pretty common. It sound bads at a 50% error, but absolute errors get amplified when you get to the bottom of the tank - when you have a teaspoon of gas left that will take you 50 feet and the computer says 1 mile, that's a 10,000% error.

- Mark

IMHO, it is the calculations in the trip computer that vary more than the fuel gauge.

I frequently do 250 mile commutes in my 2003 ES 300. When the computer shows my average mpg at 27 and I top off the tank, the range should show 450 miles or more... yet it never shows more than 308 or 310. After I have traveled 100 miles on the tank, the range shows 250 miles remaining.

So somewhere the range calculation gets very ambiguous.

Dealer has no answer or insight.

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