[Delta Flyer]

I have noticed that right after my lifetime milage increments up, it will sometimes go back down to what it was. If I had couple of low MPG trips, I could understand that, but it happens even when my trips for the day have better MPG that the life of the car. Anyone else notice this?

 

[Armin]

might be long update intervals?

I have seen this, too.

First, I thought of a bug, but then I realized it might just be that the lifetime mpg isn't updated as frequently as the trip indicators. So when we see lmpg drop after a trip that was actually better than lmpg, mabye the update was somewhere in the middle of that trip. In that case, it was just the first (lower mileage) part of the trip that got factored into the lifetime. Or it included part of a previous trip that might have been lower mpg.

I have seen it happen in both directions, but never payed close enough attention to really prove the theory.

Any thoughts?

 

[Resist]

I have noticed that right after my lifetime milage increments up, it will sometimes go back down to what it was. If I had couple of low MPG trips, I could understand that, but it happens even when my trips for the day have better MPG that the life of the car. Anyone else notice this?

Remember your lifetime is an average that has to factor in the total miles for the car, not a trip. Your instant mileage is still an average that may show great gaines in mpg. But if you have some low mpg factored in, that will effect your lifetime average. Yet you may not see it in your instant trip average, because of the lower mileage numbers.

 

[Tonpilot]

I have seen this too. After I bought the car, the lifetime avg crept up steadily until it reached 70.2. I've seemed to have peaked there. Sometimes it drops to 70.0 even after a good mpg segment, like it was lagging. It always seems to go back up to 70.2 after a low mpg segment. I realize that as miles accumulate, the lifetime average will change less frequently. However, as the average display has a tenth digit, I feel that the figure does not change or compute finely enough. For instance, I never see 70.1 on my liftime average...it's always 70.0 or 70.2 and occasionally 70.5 and no other numbers in between.

 

[Rick Reece]

FCD Reading

The FCD probably has odd readings (70.0 jumping to 70.2) because of the way it is calculated. First off they are probably calculated in the metric system (litters/100km) since the car is Japanese made. Second the orginal numbers are probably rounded 2.82 liters as opposed to 2.823 liters. Thus when the numbers are converted to our mpg ratio some intervals will be missed. If you havn't used the liters/100km setting do so. It is the only place you can see the fuel cut mode on the 5sp. (The mpg has a upper limit of 150 mpg but in litters per 100km you will see 0 l/100km meaning no fuel is being consumed. Have fun, Rick

 

[Tonpilot]

FCD Reading

Good tip from Rick...I'll try driving with the metric readout and look for the 0 L/100km reading!

 

[ncnightowl]

I have seen this too. After I bought the car, the lifetime avg crept up steadily until it reached 70.2. I've seemed to have peaked there. Sometimes it drops to 70.0 even after a good mpg segment, like it was lagging. It always seems to go back up to 70.2 after a low mpg segment. I realize that as miles accumulate, the lifetime average will change less frequently. However, as the average display has a tenth digit, I feel that the figure does not change or compute finely enough. For instance, I never see 70.1 on my liftime average...it's always 70.0 or 70.2 and occasionally 70.5 and no other numbers in between.

I have had an identical experience with mine, right down to the lmpg..
The FCD will report mileage numbers in a predictable fashion..here are all the possible mpg readings from 50 to 60 mpg:

50.0 50.2 50.5 50.7 50.9 51.2 51.4 51.6 51.9 52.1 52.3 52.6 52.8 53.0 53.3 53.5 53.7 54.0 54.2 54.5 54.7 54.9 55.2 55.4 55.6 55.9 56.1 56.3 56.6 56.8 57.0 57.3 57.5 57.7 58.0 58.2 58.5 58.7 58.9 59.2 59.4 59.6 59.9

If you start at 50, 70, 90, etc. the pattern will be exactly the same. The FCD goes in .2 .2 .2 .3 .2 .2 .2 .3, etc. increments. Hope this was not TMI!

 

[Delta Flyer]

I Noticed That Pattern Too

...The FCD goes in .2 .2 .2 .3 .2 .2 .2 .3, etc. increments...

I noticed that too!

 

[Rick Reece]

Mark,
Your close but slightly off on the numerical series. I figured it out once but I don't have it with me but a few of my fuel log numbers don't match 57.1, 57.8 103.8, 99.6, 91.8, 92.5, 101.9 etc... Have fun, Rick[/img]