Fuel_Economy calculated pid?

[rennoc442]

Hey guys Ive tried doing this,and it wouldnt work. Said the pid I have selected is n/a, and wouldnt display it since it is n/a. Any ideas? I can see the mpg pid in the data, but it reads n/a?

[ferocity02]

Has anyone used the MPG calc pid with big injectors? The equation should account for the injector size, but some people are saying the pulse width might be too low with big injectors. I cruise at 3.2ms and idle at 2.1ms. They are 72# @ 3bar Bosch injectors from FIC. According to the calc pid, my cruise fuel economy went from 19-20mpg with stock 25# injectors to 12-13mpg with the 72# injectors. The actual fuel economy appears to be much lower as well. Just trying to figure out if an error in the calc pid is partially to blame. Here is mine:

MPG(mi/gal) = {SAE.VSS.mph}/({GM.INJFLOW.lbpm}*(({GM.IBPW1}+{GM.IBPW1})/2)*{SAE.RPM}*4/6073)

[joecar]

Hey guys Ive tried doing this,and it wouldnt work. Said the pid I have selected is n/a, and wouldnt display it since it is n/a. Any ideas? I can see the mpg pid in the data, but it reads n/a?

On the PIDs tab, on the MPG pid do rightclick->More Info and take note of all the pids mentioned... then go and select all those pids.

[EagleMark]

On the PIDs tab, on the MPG pid do rightclick->More Info and take note of all the pids mentioned... then go and select all those pids.

November 18th, 2009

Your slipping joe...

I found this thread couple weeks ago and the MPG PID works great, but have to check and see if you have your liters and gallons mixed up.

[bimbleuk]

4 and 6250 accomplish that.

I don't have my notepad in front of my that accomplished all of this, but the only constant you need (I think) is the weight of gasoline at 6.25lb/gal (thanks google).

I was about to log some data and as I'm using imperial gallons (not US) I think I just need to change 6250 in the equation to 7500 to account for the bigger gallon measurement used here? Imperial gallon being 20% more volume.

[EagleMark]

What is the purpose of this PID and 2 "GM.IBPW1" then divide by 2?
"MPG(mi/gal) = {SAE.VSS.mph}/({GM.INJFLOW.lbpm}*(({GM.IBPW1}+{GM.IBPW1})/2)*{SAE.RPM}*4/6073)"

Also looks like the weight of fuel has changed from 6250 to 6073? Could this be an E fuel adjustment?

[ferocity02]

What is the purpose of this PID and 2 "GM.IBPW1" then divide by 2?
"MPG(mi/gal) = {SAE.VSS.mph}/({GM.INJFLOW.lbpm}*(({GM.IBPW1}+{GM.IBPW1})/2)*{SAE.RPM}*4/6073)"

Also looks like the weight of fuel has changed from 6250 to 6073? Could this be an E fuel adjustment?

It averages the two injector pulse widths because they may not be the same. As for the fuel density, not sure where that value came from. But you'll find a wide range of values depending on where you look.

[EagleMark]

Shouldn't that be "(({GM.IBPW1}+{GM.IBPW2})" notice 1 and 2... the origianl is 1 and 1... ?

[ferocity02]

Shouldn't that be "(({GM.IBPW1}+{GM.IBPW2})" notice 1 and 2... the origianl is 1 and 1... ?

Good catch, typo