Fuel_Economy calculated pid?

[dc_justin]

One thing to remember when creating calculated PID expressions that use PIDs with both metric and imperial units, is to append the units to the PID name, like this:

If the speed is in mph and the flow is in pound per minute then use:
{SAE.VSS.mph}/({GM.INJFLOW.lbpm}/737.22*3.785412)

If the speed is in km/h and the flow is in grams per second then use:
{SAE.VSS.kph}/({GM.INJFLOW.gps}/737.22*3.785412)

Otherwise EFILive won't know which units to use when computing the expression.

The units are listed in
\Program Files\EFILive\V7\Configuration\sae_generic.txt
in the *UNITS section.
The first entry in the "Code" column is the one you need to append to the PID name.

Regards
Paul

Yeah, I screwed that one up.

[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.

[Blacky]

That value is the value looked up by the PCM from {B4001}*{B4002}.
You would need to multiply that by injector base pulse width and then by RPM and some constants thrown in as well.

Maybe something like this:
{GM.INJFLOW.gps}*({GM.INJBPW}/1000)*({SAE.RPM}*4/60)

Notes:

• divide INJBPW by 1000 to convert from ms to seconds.
• divide RPM by 60 to convert RPM to RPS (revs per second).
• multiply by 4 to convert RPS to injector openings per second (8 injectors, each one opens every 2 revolutions)

That's just off the top of my head, I have not checked it for accuracy.

Regards
Paul

[Blacky]

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?

I thought of your original request... I was about to send you an email.
Paul

[dc_justin]

That value is the value looked up by the PCM from {B4001}*{B4002}.
You would need to multiply that by injector base pulse width and then by RPM and some constants thrown in as well.

Maybe something like this:
{GM.INJFLOW.gps}*({GM.INJBPW}/1000)*({SAE.RPM}*4/60)

Notes:

• divide INJBPW by 1000 to convert from ms to seconds.
• divide RPM by 60 to convert RPM to RPS (revs per second).
• multiply by 4 to convert RPS to injector openings per second (8 injectors, each one opens every 2 revolutions)

That's just off the top of my head, I have not checked it for accuracy.

Regards
Paul

Thanks, I'll play with that some more. I couldn't find any documentation or anything that was able to help me with determining just how to use that calculated injector flow rate.

[dc_justin]

OKAY, I worked this one all out on paper first to make sure all units cancel out properly and whatnot, and it looks like you nailed it there Paul.
I've got this expression set up:
{SAE.VSS.mph}/({GM.INJFLOW.lbpm} *{GM.IBPW1}* {SAE.RPM} * 4 / 6250 )

and it looks to be pretty close.

[joecar]

If the speed is in mph and the flow is in pound per minute then use:
{SAE.VSS.mph}/({GM.INJFLOW.lbpm}/737.22*3.785412)

If the speed is in km/h and the flow is in grams per second then use:
{SAE.VSS.kph}/({GM.INJFLOW.gps}/737.22*3.785412)

Both equations have mismatched units...!

Edit: Oh, I didn't see page 2.

[joecar]

I've got this expression set up:
{SAE.VSS.mph}/({GM.INJFLOW.lbpm} *{GM.IBPW1}* {SAE.RPM} * 4 / 6250 )

The units don't match up (fails to convert lb->gal and min->hr or sec->hr)...!

What are the units of 4 and 6250...?

[dc_justin]

The units don't match up (fails to convert lb->gal and min->hr or sec->hr)...!

What are the units of 4 and 6250...?

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).