Aurion Fuel Tank Average

[teebee]

Am wondering if Toyota have lost the plot on their method of fuel consumption calculation. Every other major (and some minor) car manufacturers allow you to reset (or zero) the fuel consumption readout at any given time to be able to calculate the actual figure between any two points. Toyota for some reason have opted for a pretty useless 'Tank Average' which can only be reset by refuelling the car - cannot see any value in that. Does anybody know of a way of zeroing the readout without having to refuel? I have had some really good numbers out of my Prodigy which I am sure would be better if I were able to get some actual A to B figures.

[riftime]

Yes, that would be useful. I wonder if the resetting is triggered by the opening and closing of the fuel cover/flap moreso than refilling itself. Have you tried just opening and closing the fuel door? I know that it's not ideal, but it might be a workaround allowing you to perform those A to B calculations. Let me know if that works, if I remember, I'll try that myself.

[BanHien]

Am wondering if Toyota have lost the plot on their method of fuel consumption calculation. Every other major (and some minor) car manufacturers allow you to reset (or zero) the fuel consumption readout at any given time to be able to calculate the actual figure between any two points. ......

I always play 80-20 rule and I think Toyota is playing with this rule too.

BH

[saintly]

Yes, that would be useful. I wonder if the resetting is triggered by the opening and closing of the fuel cover/flap moreso than refilling itself. Have you tried just opening and closing the fuel door? I know that it's not ideal, but it might be a workaround allowing you to perform those A to B calculations. Let me know if that works, if I remember, I'll try that myself.

opening/closing the fuel cover won't reset the average... I think you would have to put in a substantial amount of fuel before it does a reset because I only filled-in 8 litres on sunday evening and the average still reads around the same the following day.

[vnbm]

Yes, that would be useful. I wonder if the resetting is triggered by the opening and closing of the fuel cover/flap moreso than refilling itself. Have you tried just opening and closing the fuel door? I know that it's not ideal, but it might be a workaround allowing you to perform those A to B calculations. Let me know if that works, if I remember, I'll try that myself.

opening/closing the fuel cover won't reset the average... I think you would have to put in a substantial amount of fuel before it does a reset because I only filled-in 8 litres on sunday evening and the average still reads around the same the following day.

Call me stupid, but i thought it calculated it by fuel weight.

Edited January 29, 2008 by vnbm

[AcoustiK]

mmm im more thinking of the fuel level triggers the calculations, which is not accurate as a fuel tank is not square in shape and has less surface volume area towards the bottom and possibly top. because when I fill my tank to around the halfway mark i get better city fuel economy than if I were driving close to empty...

As posted just before fuel weight would be more precise unless they make a perfect square fuel tank...

[riftime]

Just looking through the technical manual, found the following:

The meter CPU uses the fuel sender gauge assembly to determine the level of the fuel in the fuel tank. The resistance of the fuel sender gauge will vary between approximately 15 Ω with the float at the full position, and 410 Ω with the float at the empty position. The meter outputs battery voltage through two 820 Ω resistors that are mounted in parallel inside the meter ECU. The meter CPU measures the voltage between the variable resistor in the fuel sender gauge and the two resistors mounted in parallel in the meter. Voltage measured at this point will vary as the float of the fuel sender gauge is moved.

HINT:

The fuel level warning light will come on when the fuel level is below 10.5 liters.

Average fuel consumption (after refueling) - Displays the value that has been calculated by the meter CPU, which is based on the driven distance and the fuel consumption volume after the ignition switch is on (IG).

Driving Range Display

Displays the range, calculated by the combination meter which continuously monitors and stores fuel consumption data and the residual fuel volume when IG-ON has been selected.

Updated every 1 km

Average Fuel Consumption Since Refueling

Displays the value, calculated by the combination meter, based on the distance driven since refueling and the fuel consumption volume (fuel injection signals from the No.1 injector).

The combination meter determines the vehicle has been refueled through the signal from the fuel sender gauge.

Updated every 10 seconds.

Based on the red outline above and the variable resistor/voltage combo for measuring fuel in the tank, you need to increase the amount of fuel in the tank for the combination meter to determine that it has been refilled and reset the fuel consumption calculation. Since the flotation device in the tank moves slightly around with bumps in the road and the car going up/down hills, a minor difference in fuel level is most likely ignored and treated as "movement related variance" (which would explain why 8 litres of fuel did not reset the calculation). I expect that the movement related variances are averaged out, and at some point the car realises that it has more fuel than it did some time ago, and hence your range (distance to empty) increases. However, because the increase in fuel was lower than the allowable "movement variance" (below the trigger threshold), there was no trigger to reset average consumption calculation.

[Stealth]

Just looking through the technical manual, found the following:

The meter CPU uses the fuel sender gauge assembly to determine the level of the fuel in the fuel tank. The resistance of the fuel sender gauge will vary between approximately 15 Ω with the float at the full position, and 410 Ω with the float at the empty position. The meter outputs battery voltage through two 820 Ω resistors that are mounted in parallel inside the meter ECU. The meter CPU measures the voltage between the variable resistor in the fuel sender gauge and the two resistors mounted in parallel in the meter. Voltage measured at this point will vary as the float of the fuel sender gauge is moved.

HINT:

The fuel level warning light will come on when the fuel level is below 10.5 liters.

Average fuel consumption (after refueling) - Displays the value that has been calculated by the meter CPU, which is based on the driven distance and the fuel consumption volume after the ignition switch is on (IG).

Driving Range Display

Displays the range, calculated by the combination meter which continuously monitors and stores fuel consumption data and the residual fuel volume when IG-ON has been selected.

Updated every 1 km

Average Fuel Consumption Since Refueling

Displays the value, calculated by the combination meter, based on the distance driven since refueling and the fuel consumption volume (fuel injection signals from the No.1 injector).

The combination meter determines the vehicle has been refueled through the signal from the fuel sender gauge.

Updated every 10 seconds.

Based on the red outline above and the variable resistor/voltage combo for measuring fuel in the tank, you need to increase the amount of fuel in the tank for the combination meter to determine that it has been refilled and reset the fuel consumption calculation. Since the flotation device in the tank moves slightly around with bumps in the road and the car going up/down hills, a minor difference in fuel level is most likely ignored and treated as "movement related variance" (which would explain why 8 litres of fuel did not reset the calculation). I expect that the movement related variances are averaged out, and at some point the car realises that it has more fuel than it did some time ago, and hence your range (distance to empty) increases. However, because the increase in fuel was lower than the allowable "movement variance" (below the trigger threshold), there was no trigger to reset average consumption calculation.

Yes well the whole thing is kinda stupid. I traded a Volvo 850R on the Aurion. The Volvo system has a toggle switch/dial that allows you to change back and forth between displays. It also showed the current fuel consumption and had a reset button for the average fuel consumption, average speed and distance traveled. Having said that, the car was around $80,000 new. Still the Aurion is good value for money so we can't expect that Toyota will go all out on every detail of the car.

[riftime]

Yes well the whole thing is kinda stupid. ...Still the Aurion is good value for money so we can't expect that Toyota will go all out on every detail of the car.

Toyota folks were overly ambitious in automating this item. It would not have been a matter of saving $. They could have easily implemented a feature whereby pushing a manual button resets the readings... but they opted for the "bells and whistles automatic / computerised method" which leaves the user with no control over it. I don't mind computers doing the thinking for me as long as there's a way I can override it (disable it) when I need it.