1. the american gallon is 3.785 liters vs 4.546 liters for imperial. I see ecutalk uses the imperial gallon.

2. why divide number of cylinders by 2?

fuel used in millilitres = (numcylinders / 2) * (injectorccpermin / 60.0) * (pulsewidthms / 1000)

3. Does any other software calculate fuel economy?

4.I assume Econ liter/100 km is fuel econmy at an instant in time. Does minimum gauge refresh
have to be set at a particular rate for this this economy number to make sense when you are watching the gauge display?

5. I see you have to set you cc's per minute in options














================================================== ====

as for MPG, think no more:

from log files, per log entry, you can calculate:
1) speed (miles per seconds) = speedmph / 3600
2) fuel used in millilitres = (numcylinders / 2) * (injectorccpermin / 60.0) * (pulsewidthms / 1000)
3) engine rev period in seconds = 60 / rpm
4) distance in miles = speed * engineperiod

so for each log entry, you can calculate distance travelled, and fuel used in millilitres. then just add up the values for all entries, and you get total MPG:
MPG = totaldistance / (totalinjml * 0.000264172051)

the big 0.000234324 number is converting from millilitres to gallons.

and you should probably check out feature requests page, peak hold is there at number 20.

after using my pda a bit more in car, the one u mentioned about auto-connecting is probably pretty important (ie for it to "fall out" of gauges and do the retry/autoconnect stuff so when u start car, it connects)

1) no both the software and the ecutalk lcd, use 3.7854118 (see that 0.000264172051 number in my post you've copy pasted at the end of yours, if you were to invert it (1/0.000264172051) you would get 3785.4118etc, divide that by 1000 (given the injectorml is mL or 1/1000th of a L) and u have the Gal-> conversion figure of 3.785

2) in any given revolution, in a 4 stroke engine, only half the cylinders will have had their injectors open (the other have are on compression/exhaust half of cycle). actually in my first attempt of economy readings on the ecutalk LCD display, i forgot to divide by 2, and the few beta testers of it were wondering why it read so high for economy.

3) havent seen any, though no software is really being actively developed. someone asked datascan to add it after seeing it in ecutalk, but i dont know if/when that will happen.

4) yes both the L/100KM and the MPG (depending on options) gauges are instant fuel economy. gauge refresh has no impact, aside from how often this value updates. the instant value is calculated based on all data in that given packet (that you're seeing on all the other gauges or in the same log entry) at the given time, theres no averaging to make a 'smoother' instant reading, its as instant as she gets.

5) yep, these economy/trip meter gauges arent natively given from the ecu, but are all derived from the other sensors and need to know injector size/number of cylinders since the ecu doesnt tell you this.

thanks for the detailed answer. I end up using ecutalk because the gauges are so much easier to read. The fuel economy capability is really useful. so is the logging. definitely exceeds my expectations.