Fuel_Economy calculated pid?

[Zeus]

Anyone know of something like this, or a way to do it? It seems like it would be super easy to divide vehicle speed by the amount of fuel being delivered (through injector pulse widths?). Alas I know nothing of programing Live so I'm wondering if anyone can help out.

I for one think it would be cool to have a gauge or graph that shows how your fuel economy varies based on tuning/hardware changes or driving habits.

[Blacky]

Tricky to do, because there is no PID (as far as I know) to retrieve actual fuel flow. There is a PID that returns injector pulse width in milliseconds but how to convert from pulse width to actual fuel flow (i.e. liters per hour, or gallons per hour) is not trivial. The conversion would need to be based on fuel pressure (not available on LS1) and injector characteristics.

Regards
Paul

[Zeus]

I guess if your VE table was dialed in so your BEN was right around 1 you could calculate it based on the VE, cylinder volume, and AFR couldn't you?

[joecar]

You can calculate approximate fuel consumption using airflow, AFR, VSS, density of fuel, and some imperial/metric conversions:

fuelflow (g/s) = airflow (g/s) / AFR

then use density of gasoline (petrol) (737.22 g/L found on web) to convert fuelflow to from g/s to L/s,
then convert to L/hour,
then convert to gallon/hour,
and then divide this into VSS (miles/hour), giving miles/gallon.

[Tordne]

You can calculate approximate fuel consumption using airflow, AFR, VSS, density of fuel, and some imperial/metric conversions:

fuelflow (g/s) = airflow (g/s) / AFR

then use density of gasoline (petrol) (737.22 g/L found on web) to convert fuelflow to from g/s to L/s,
then convert to L/hour,
then convert to gallon/hour,
and then divide this into VSS (miles/hour), giving miles/gallon.

There you go Paul, simple as that. So there will be a new calc PID in the next patch right

[ace68]

or you could just divide the miles driven by the gal used

[dc_justin]

Couldn't you also use GM.INJFLOW to get the injector flow rate, rather than using airflow (g/s) / AFR? Assuming you're not using a wideband, the AFR would only be commanded and not dead on, no?

[Blacky]

Couldn't you also use GM.INJFLOW to get the injector flow rate, rather than using airflow (g/s) / AFR? Assuming you're not using a wideband, the AFR would only be commanded and not dead on, no?

Riiiiiiiiiiiiiiight (in my best Dr Evil voice). Don't I feel stupid now. I had forgotten about that fuel flow PID

I'm sure the maths gurus among us can come up with a formula to convert {GM.INJFLOW} and {SAE.VSS} into a fuel economy value...

Regards
Paul

[emarkay]

Jeez, this was an old request I made way back in the V6 days... Easier way would be VSS and inverted MAP. Vacuum in In/Hg is an easy and close "instant" MPG figure, and when VSS gets to zero MPG also goes to "0"...

What about it, programmers?

[dc_justin]

Welp, Calculated Injector Flow Rate doesn't work properly. My whole 30 minute drive home it stayed in the narrow range of 0.48lb/min to 0.52lb/min. Time for another idea.