99.9 liters per 100km anyone?

[mrjpaterson]

Hello all,
I thought I saw someone post something similar to this at one time (but the numbers were maybe reversed for 99.9 mpg) but not this one yet.
I've had this show up on the display a number of times just before the engine shuts off. I've had the car for a week now (new 2006 model) and this behaviour has been pretty consistent in the first 10 - 15 minutes of driving.
And perhaps related is that when I am at a standstill with the ICE off I have displays of using the ICE (with a range of liters per KM) showing up as well.
I'm sorry if this has been previously answered, but I could not find either of these despite looking.
Thanks for any help on this,

James

[Dan.]

Not sure quite what your asking, but I'll give it a shot.

Given:
For non Metric models (ie only US I think), the display is in Miles-per-gallon (MPG).
For the rest of the world the display is in L/100km.

The two ratios are inverses of each other. High MPG = Low L/100km and Low MPG = High L/100km. This is because one is distance/fuel and the other is fuel/distance.

So in the Prius, when either distance or fuel go to zero, wierd things happen.

Fuel goes to zero when the gas-engine cuts off and you run off batteres. This gives you 99.9 MPG and (probably) 0L/100km.

Distance goes to zero when the car gas-engine is running but the car is stopped. This would usually yield 0 MPG and (probably) 99.9L/100km.

The final possibility is if both fuel and distance go to zero. This would be when your stopped but the gas-engine has cut out. In the US this displays 0 MPG. The rest of the world could conceivably show either 0L/100km or 99.9L/100km.

0/0 is basically undefined, or arguably zero. I think it technically depends on the whether the top zero or bottom zero converge on zero faster to truly determine if the ratio converges to zero or infinity (undefined). But none of this really matters since the ECU is discrete and will just have to decide what to do with 0/0.

something like:
if (fuel==0 && speed==0)
{
show99_9(locale);
}

But only Toyota really knows what they coded. Either answer is ok.

Basically if the gas-engine isn't running or your stopped, fuel efficentcy isn't really an instantaneous value that can be calculated.

[Tideland Prius]

<div class='quotetop'>QUOTE(Great White North @ Feb 19 2007, 10:20 PM) [snapback]393147[/snapback]</div>

Hello all,
I thought I saw someone post something similar to this at one time (but the numbers were maybe reversed for 99.9 mpg) but not this one yet.
I've had this show up on the display a number of times just before the engine shuts off. I've had the car for a week now (new 2006 model) and this behaviour has been pretty consistent in the first 10 - 15 minutes of driving.
And perhaps related is that when I am at a standstill with the ICE off I have displays of using the ICE (with a range of liters per KM) showing up as well.
I'm sorry if this has been previously answered, but I could not find either of these despite looking.
Thanks for any help on this,

James
[/b]

Hey James,

yeah it's typical to see the first 5 min bar shoot up to the max on the Consumption Screen. If the engine is warm, it'll be between 5 and 7.5L/100km.

It should go down as the minutes pass unless you go uphill or are stuck in traffic for the following 5-10 mins (so total of 15 mins on the screen).


Also, if you're stopped, then of course it'll show 99.9L/100km because it's idling. Then it'll shut off and read 0.0L/100km.

[dmckinstry]

<div class='quotetop'>QUOTE(Tideland Prius @ Feb 20 2007, 12:45 AM) [snapback]393179[/snapback]</div>

Hey James,

yeah it's typical to see the first 5 min bar shoot up to the max on the Consumption Screen. If the engine is warm, it'll be between 5 and 7.5L/100km.

It should go down as the minutes pass unless you go uphill or are stuck in traffic for the following 5-10 mins (so total of 15 mins on the screen).
Also, if you're stopped, then of course it'll show 99.9L/100km because it's idling. Then it'll shut off and read 0.0L/100km.
[/b]

Well, at least readling 0.0L/100km makes more sense that 0 mpg when stopped and shut down. On the other hand, 99.9 mpg doesn't make sense either in that situation, since both numerator and denominator are 0. Well, I guess neither really makes sense, and when programming the output they had to make up something. Saying the output is meaningless in that case probably wouldn't fly with most people. "Insufficent Data"?

Dave M.

[mrjpaterson]

<div class='quotetop'>QUOTE(Tideland Prius @ Feb 20 2007, 03:45 AM) [snapback]393179[/snapback]</div>

Hey James,

yeah it's typical to see the first 5 min bar shoot up to the max on the Consumption Screen. If the engine is warm, it'll be between 5 and 7.5L/100km.

It should go down as the minutes pass unless you go uphill or are stuck in traffic for the following 5-10 mins (so total of 15 mins on the screen).
Also, if you're stopped, then of course it'll show 99.9L/100km because it's idling. Then it'll shut off and read 0.0L/100km.
[/b]

Thanks for the reply for the first part of the problem. As to the second, should there be a discrepancy between when the ICE is NOT running, yet having the display show that it is consuming gas? And/or having the display showing arrows from the ICE to the wheels, yet having the engine off? It seems there are many little quirky things that don't reflect reality, or am I missing something? I was to understand that if the ICE is contributing to the movement of the vehicle then arrows from the ICE would flow towards the wheels, and something similar will happen when the ICE is charging the battery, or if the wheels are charging the battery, or if everything is at a standstill. What I am seeing, however is ICE function when it is clear that the ICE is not running, or even sometimes that the wheels in the display are moving when the car is at a complete standstill. And just to clarify, even if I consider a time lag of 2-3 seconds things still don't add up to what may have happened in those past seconds.

Saying all that, though, I'd just be happy to know that I'm not the only one experiencing these things, but don't really trust the dealer to tell me (after reading many posts about less than satisfactory encounters with dealers on this site).

James

[Balt]

that's a typical result of a question that started out with improperly thought through units. if "consumption" is meant, the number in question will always be an amount over a distance. Or does anyone consume miles? :-)

so quite naturally, 0 mpg makes no sense, whereas 0 l/100km does.

[dmckinstry]

<div class='quotetop'>QUOTE(Balt @ Feb 21 2007, 04:31 AM) [snapback]393846[/snapback]</div>

that's a typical result of a question that started out with improperly thought through units. if "consumption" is meant, the number in question will always be an amount over a distance. Or does anyone consume miles? :-)

so quite naturally, 0 mpg makes no sense, whereas 0 l/100km does.
[/b]

And ultimately neither makes any sense, since it's a 0/0 question in either case.

Dave M.

[Tideland Prius]

<div class='quotetop'>QUOTE(Great White North @ Feb 20 2007, 10:34 PM) [snapback]393788[/snapback]</div>

Thanks for the reply for the first part of the problem. As to the second, should there be a discrepancy between when the ICE is NOT running, yet having the display show that it is consuming gas? And/or having the display showing arrows from the ICE to the wheels, yet having the engine off? It seems there are many little quirky things that don't reflect reality, or am I missing something? I was to understand that if the ICE is contributing to the movement of the vehicle then arrows from the ICE would flow towards the wheels, and something similar will happen when the ICE is charging the battery, or if the wheels are charging the battery, or if everything is at a standstill. What I am seeing, however is ICE function when it is clear that the ICE is not running, or even sometimes that the wheels in the display are moving when the car is at a complete standstill. And just to clarify, even if I consider a time lag of 2-3 seconds things still don't add up to what may have happened in those past seconds.

Saying all that, though, I'd just be happy to know that I'm not the only one experiencing these things, but don't really trust the dealer to tell me (after reading many posts about less than satisfactory encounters with dealers on this site).

James
[/b]

There is a slight lag between the display and actual because the computer updates every 2 seconds I believe.

If the engine is running and there's no arrows, that's fine. Sometimes it'll run but won't charge the battery

HOWEVER, if it's NOT running and there are arrows from the engine to the wheels, then I'd be worried. Again, give it 2 seconds for it to update.

If there are arrows from the battery to the wheels even though you're stopped, that just means you're not pressing the brake pedal hard enough.

I hope that helps.

[mrjpaterson]

<div class='quotetop'>QUOTE(Tideland Prius @ Feb 21 2007, 06:09 PM) [snapback]394219[/snapback]</div>

There is a slight lag between the display and actual because the computer updates every 2 seconds I believe.

If the engine is running and there's no arrows, that's fine. Sometimes it'll run but won't charge the battery

HOWEVER, if it's NOT running and there are arrows from the engine to the wheels, then I'd be worried. Again, give it 2 seconds for it to update.

If there are arrows from the battery to the wheels even though you're stopped, that just means you're not pressing the brake pedal hard enough.

I hope that helps.
[/b]

Yes, thank you, I think it does help. I'll check about applying the brakes more next time, and also ensure that I wasn't imagining the ICE arrows (or the 8.9l per 100km) showing when the ICE has been off for more than two seconds.


You've been a great help Tideland, thanks for everything so far. And thanks to all others for their input as well, it's all been very useful so far.

Cheers,

James

[Tideland Prius]

<div class='quotetop'>QUOTE(Great White North @ Feb 21 2007, 05:58 PM) [snapback]394305[/snapback]</div>

Yes, thank you, I think it does help. I'll check about applying the brakes more next time, and also ensure that I wasn't imagining the ICE arrows (or the 8.9l per 100km) showing when the ICE has been off for more than two seconds.
You've been a great help Tideland, thanks for everything so far. And thanks to all others for their input as well, it's all been very useful so far.

Cheers,

James
[/b]

np. If you see me wave, wave back! haha.