E90 320 swallowing petrol

[Schwepps]

IC. The OBC way of resettiing is different from the iDrive way then.

What does your average speed show? My av FC of 11.9l/100 is achieved because my av speed is 46kmh, from day one. Which means I spend very little time in stop-go traffic and idling, which is indeed true. Eg, the last time I went into the city centre was in August when I went to Starhill to pick up a watch strap! If your av speed is below my 46kmh, your driving pattern would be more stop-go, resulting in higher FC than mine.

 

[astroboy]

I no iDrive. So my reset has to be done either on the OBC stalk or thru the radio. Whichever way, both gives tallying reading. My av speed is 33.2kph, FC is 13.3L/100km.

Why do I say the OBC not accurate? Because everytime after refill, it will give me false hope of able to cover 600km which was never true. It count down a lot faster and when I'm almost reaching 450km, low fuel warning of 72km to go lighted liao!

Of course when it comes to tank to tank divided by mileage covered, I would agree that the OBC FC meter is fairly accurate. Only the countdown part, just like our oil change or brake wear counter. The count down sucks, start slow and faster towards the end!

 

[Schwepps]

IMO, that only means it's a pretty accurate real-time system, AB. When you fill to full tank, the tank sensor detects that and displays the default value - max km with a full tank at the designated l/100km FC for your model. As you drive, your actual FC will probably be higher than that, and the default value will drop. This indicator cannot be based on the total average FC and should be based on the current FC since resetting, ie whenever the sensor moves up (gas pumped into the tank) This sort of programming is what I do for a living and this is how I would design the algorithm too. :wink:

Earlier, I thought my front brake wear counter is stuck, but now it's started to drop and that matches with my recent discovery that only 25% of my front pads have been used after 42K km. There's probably a set-point before which the counter won't move. So now I feel that the brake wear counter is accurate too.

 

[astroboy]

.. I would prefer an algorithm that's more "real", unless there's no reference point, then default value shall be used but since there's already readings in the FC counters, then might as well simulate using that info? Like our Garmin.

I hate the false hope of seeing the 600km to go after every refill.

 

[Schwepps]

The Total Av FC reference point might be an average over a few years, eg 2.5 years and 42K in my case. Similarly the Journey Av FC, eg in my case over a few months because that's the last time I reset it. THESE readings would be the ones that are out-of-date for a realtime system. I would design the system to use only data from the last reset, which I can trigger whenever the tank sensor value goes up. Easy if-then-else logic programming. :wink:

 

[hsiengloong1985]

IC. The OBC way of resettiing is different from the iDrive way then.

What does your average speed show? My av FC of 11.9l/100 is achieved because my av speed is 46kmh, from day one. Which means I spend very little time in stop-go traffic and idling, which is indeed true. Eg, the last time I went into the city centre was in August when I went to Starhill to pick up a watch strap! If your av speed is below my 46kmh, your driving pattern would be more stop-go, resulting in higher FC than mine.

Hi Schwepps,

My average speed onli shows 27kmh and you''re right, probably my car is still new and also plenty of stop-n-go. I shall do a manual calculation based on my current fuel tank to see how much it can bring me. Have pumped 38L of fuel yesterday and as of now, i have travelled 120km and it still shows half tank with OBC showing that i still have another 250km to go...

Finger's crossed...

 

[Schwepps]

Sorry bud, but that's not the way to measure FC manually. The right way is to fill to full tank, then start recording your distance. Then the next time you pump, fill to full tank again and stop recording your distance. The 2nd refill represents the volume of gas used to travel the distance recorded. No guesswork involving where the needle was/is, etc.

Your way, you don't know exactly how much gas there was in the tank before you pumped the 38L, and you won't know exactly how much gas you have left when you pick a distance to calculate your FC. Only estimation. :wink:

 

[Cobra Kai]

IMO, that only means it's a pretty accurate real-time system, AB. When you fill to full tank, the tank sensor detects that and displays the default value - max km with a full tank at the designated l/100km FC for your model. As you drive, your actual FC will probably be higher than that, and the default value will drop. This indicator cannot be based on the total average FC and should be based on the current FC since resetting, ie whenever the sensor moves up (gas pumped into the tank) This sort of programming is what I do for a living and this is how I would design the algorithm too.

Not sure if this is correct. I think it uses your average fuel consumption over the last 20 - 50km when doing the prediction. If I have been pushing the car hard before filling up, after a full tank the estimated mileage shows 500+. If I have been more conservative, it shows 600+...

 

[Schwepps]

You could be right CK. I don't think mine is a constant kick-off figure either. That algorithm is also possible, using the most recent samples as the start value. Could also be that the OBCs have different program modules from the iDrives.

 

[SapphireBlack]

erm... my e90 320i fc as follows:

Ron97: about RM110 for full tank drive until the fuel indicator appears. I clock in about 400-450km... sometimes i do get naughty by flooring the pedel... hehe

Mine is about the same range as yours. 325i full tank... approx RM120++ (i think petrol price increase liao for Ron 97.. ouch!) will give me about 450-500km. If I'm heavy footed, usually around 450km will be by average. I have yet to hit the 600km per full tank unless i practice butterfly throttling and use only highway most of the time! :-D

 

[cslau]

Mine is about the same range as yours. 325i full tank... approx RM120++ (i think petrol price increase liao for Ron 97.. ouch!) will give me about 450-500km. If I'm heavy footed, usually around 450km will be by average. I have yet to hit the 600km per full tank unless i practice butterfly throttling and use only highway most of the time! :-D

How to do butterfly throttling?