Fuel_Economy calculated pid?

[kbracing96]

if you have a bunch of instant values, just sum them up and divide by the number of them. numerical integration at it's simplest.

how to do it in hpt? umm... make a histogram with ONE cell, that grabs all values, so make it on like scale of 0-512 g/sec of airflow, and then use the instant milage pid as the data. the average in that histogram is going to be your integral of instant milage values across time.

Like I was telling Justin, the problem with instant MPG PID is then when you not moving instant is 0, but the engine is still running, but average instant is not changing, where your actual MPG would be getting lower as you are still burning fuel, but your not going anywhere. That the problem with this pid and what I want to do.

[joecar]

To get miles from MPH, need to integrate VSS over time (mulitply each instant VSS by the time since the previous frame, sum all these up, divide by the number of samples, mulitply by some constant to account for hr->sec).

Same thing with injector flow -> gallons.

This will be easy to do when Paul puts the integrate function back into the software.

[dc_justin]

Like I was telling Justin, the problem with instant MPG PID is then when you not moving instant is 0, but the engine is still running, but average instant is not changing, where your actual MPG would be getting lower as you are still burning fuel, but your not going anywhere. That the problem with this pid and what I want to do.

I started to work some more on this, but stopped short due to time constraints. Basically, I was coming up with a "fuel used per frame" PID, which, when summed, would give you the total fuel used. Could then create a distance traveled per frame PID and calculate out an MPG PID from a combination of the two.

Justin

[DMaxME]

Typically I dump it in Excel and spit out large regions for MPG estimation. I like the instant on my computer, as it reminds me to take my foot off it while driving.

When i make my estimations i cruise control it at a fixed speed for about 1/2hr or so. I also am sure to take notice of my altitude on my GPS, as it is important to limit absolute elevation changes. I export the data, and run a macro to average all columns. It's the overall average data i'm interested in, so I copy the averages to my active spreadsheet, and delete the logged data for computer space conservation.

[oztracktuning]

Do you notice how much fuel economy drifts with changes in intake temperature. warmer is better - but it would be interesting to know some figures.

I love playing with fue economy tuning. We are putting a small 206 212 112 comp cam in a Statesman and hope to see it improve overall fuel economy. I have seen heads, UDP and TB, extractors all help improve economy.

[kbracing96]

I started to work some more on this, but stopped short due to time constraints. Basically, I was coming up with a "fuel used per frame" PID, which, when summed, would give you the total fuel used. Could then create a distance traveled per frame PID and calculate out an MPG PID from a combination of the two.

Justin

I'm gona bump this. Did you ever come up with anything Justin? I still want to make an actual, MPG gauge, not instant.

[joecar]

For gasoline, use post #17 of this thread: showthread.php?t=1667&page=2

For diesel, use the same equation but replace the pids GM.INJFLOW.lbpm and GM.IBPW1 with their diesel equivalents.

Oh, but this gives the MPG based on vehicle speed ("instant MPG") and not on distance travelled ("actual MPG").

[dc_justin]

I'm gona bump this. Did you ever come up with anything Justin? I still want to make an actual, MPG gauge, not instant.

Nope, I haven't played with it since then. I'll think about it some more and see what I can come up with.

Justin

[Extinct]

Bump

Justin, did you ever do that fuel economy tuning out near fresno ? Just wondering what you came up with as optimum AFR ?

[dc_justin]

Bump

Justin, did you ever do that fuel economy tuning out near fresno ? Just wondering what you came up with as optimum AFR ?

You know, I never got around to it. Spent more time using the straight flat roads for other purposes.

Coincidentally, I'm in the area right now, but don't have any of my vehicles with me to test out. Perhaps the Chevy HHR from Hertz would be a good test subject.