Instant MPG calculation

[cmaje72]

I found an old post at TGO with instructions and a formula for calculating instant MPG:

For the MPG conversaion equation, use:

X/(C*0.0000212*Y*Z)

Where:

X = Vehicle Speed
Y = Engine Speed
Z = Base Pulse Width
C = Injector constant (lbs/hr)


Now on my setup I am not sure about the base pulse width part. I am using the $DA3 mask (1993 LT1). From the stream I have left bank BPW and right bank BPW. Do I add the two together for use in the equation above? If someone could better explain to me the equation that would probably help too. I googled around for equations to calculate this but none of them are similar to the one above.

[robertisaar]

to answer your question quickly: average the BPWs. add the left BPW to the right BPW, then divide by 2, all in ().





i use a different equation, one that works a bit more accurately for me...

A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

where 16.7 is your injector flowrate in lb/hr, the 3 represents half of the cylinders in the engine, and the 2 represents how many injector pulses per 4 stroke cycle(double fire, SFI or single fire mode would need a 1). A is BPW in mSec, and E is RPM.

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.



A/B

A is MPH, B is gal/hr of fuel flow, then you'll have a MPG value.

[cmaje72]

Thanks! Your formula seems to work better.

[AnimeFunTV]

to answer your question quickly: average the BPWs. add the left BPW to the right BPW, then divide by 2, all in ().





i use a different equation, one that works a bit more accurately for me...

A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

where 16.7 is your injector flowrate in lb/hr, the 3 represents half of the cylinders in the engine, and the 2 represents how many injector pulses per 4 stroke cycle(double fire, SFI or single fire mode would need a 1). A is BPW in mSec, and E is RPM.

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.



A/B

A is MPH, B is gal/hr of fuel flow, then you'll have a MPG value.

Lemme get this straight since I'm an n00b.
What I have = 1994 Buick Roadmaster Wagon 5.7L LT1 ALL STOCK.

I created a new Item in the Values tree in ADX Editor.

I named it 'Average BPW', I click on the 'Conversion' tab on the bottom and added to the Equation set and typed in

Code: Select all

(X+A/2)

"X" being the Left BPW & "A" being the Right BPW, adding

Code: Select all

+

between the "X" & "A" will add them up together for a total sum and then adding

Code: Select all

/2

at the end would divide them in 2 giving you the Average BPW.

I'm not sure if I did do this right, example I data logged in TunerPro, at engine idle, scrolling through the timeline I see Left-BPW is 8.29 while the Right-BPW is 7.43, if I add them together it comes out to 15.72 and dividing that by 2 comes out to 7.86, but the Conversion calculation is 10.57. If anyone can help explain this to me it would be a great help

Anyway, moving on.

Now that I have my "Average BPW" I created another Item in the Values tree and called it "Economy Calculator" I did the same as usual and added

Code: Select all

A*(1/3600000)*(24.87)*(4)*E*(60)*(1)

into Conversions, I linked "A" to my "Average BPW",

Code: Select all

(24.87)

is my Injector Flow Rate @Lbs/Hr according to what is flashed into my PCM.

Code: Select all

(4)

is half the cylinders, and

Code: Select all

(1)

is there because I'm not sure if this is a Sequential Fuel Injection system or not. "E" I linked to my "Engine Speed" aka RPM

The rest like the

Code: Select all

(1/3600000)

and

Code: Select all

(60)

I really don't know what they mean, so I just left them alone, maybe someone can explain to me what they mean?

So, Now Out of that Value I'm getting a reading of 4.90 at engine idle.

Created another Item, named this one "Injector Flow Rate" and added

Code: Select all

A/6.073

"A" is linked to "Economy Calculator". I'm not sure what "6.073" means or what it represents.

Out of that value I'm getting "0.81"

Lastly, the big one.

Added another Item, named it "MPG" and added

Code: Select all

(A/B)

into Conversions, "A" is linked to "Vehicle Speed", and "B" is linked to "Injector Flow Rate"

and it works! Drove around and I was getting about 20-21 Instant MPG on the highway.

I'm just not sure of the rest of the variables, plus it dose not seem like the two BPW's are averaging correctly or not. Can anyone just go through and see if everything seems okay?

[EagleMark]

I think A was created by the eqaution in his exaple:

A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

where 16.7 is your injector flowrate in lb/hr, the 3 represents half of the cylinders in the engine, and the 2 represents how many injector pulses per 4 stroke cycle(double fire, SFI or single fire mode would need a 1). A is BPW in mSec, and E is RPM.

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.

So that would not be right for your engine.

LT1 is SFI so 1 would be correct in eqaution...

[AnimeFunTV]

I think A was created by the eqaution in his exaple:

A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

where 16.7 is your injector flowrate in lb/hr, the 3 represents half of the cylinders in the engine, and the 2 represents how many injector pulses per 4 stroke cycle(double fire, SFI or single fire mode would need a 1). A is BPW in mSec, and E is RPM.

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.

So that would not be right for your engine.

LT1 is SFI so 1 would be correct in equation...

Thank you for your help.

The "A" I have linked to A*(1/3600000)*(24.87)*(4)*E*(60)*(1) is what I'm getting off my average BPW value that I have created before-hand, since my data stream only has Left and right BPW and no single BPW for just one single Injector.

The "A" in A/6.073 is linked to the A*(1/3600000)*(24.87)*(4)*E*(60)*(1) formula

I'm not very good with formula's but I was able to get everything working and reading on the Dashboard, I just want to make sure I had the formulas right so I can know that I'm getting the best accurate reading of instant MPG.

Also, I did some searching around, dose anyone have a formula that would do Average MPGs?

[EagleMark]

Also, I did some searching around, dose anyone have a formula that would do Average MPGs?

Fill tank, drive, fill tank again, divide miles by gallons.

I'm sure someone with math skills could but I still can't keep up to you!

I have the same car as you and was going to try this as I had seen it done on TBI engines with TunerPro ADX. But the SFI and 2 BPW stopped me dead till I saw this thread.

Seems you have this part right:

I named it 'Average BPW', I click on the 'Conversion' tab on the bottom and added to the Equation set and typed in Code:
(X+A/2)
"X" being the Left BPW & "A" being the Right BPW, adding Code:
+
between the "X" & "A" will add them up together for a total sum and then adding Code:
/2
at the end would divide them in 2 giving you the Average BPW.

Individual fuel trims at idle are differant for each cylinder, let alone right and left, same for off idle. That and BPW is constantly changing so I wouldn't worry about the difference not being exactly half when you checked by math/calculater.

Curious as to the ADX you are using? I could never get one to work and built one, is it the one I did? $EE-Auto-V3.adx I did some more work on it and it got a rename $EE-16188051.V3.adx and xdf that have data tracing working together on some items.
http://www.gearhead-efi.com/Fuel-Inject ... ion-EE-EEB

[AnimeFunTV]

Also, I did some searching around, dose anyone have a formula that would do Average MPGs?

Fill tank, drive, fill tank again, divide miles by gallons.

I'm sure someone with math skills could but I still can't keep up to you!

I have the same car as you and was going to try this as I had seen it done on TBI engines with TunerPro ADX. But the SFI and 2 BPW stopped me dead till I saw this thread.

Seems you have this part right:

I named it 'Average BPW', I click on the 'Conversion' tab on the bottom and added to the Equation set and typed in Code:
(X+A/2)
"X" being the Left BPW & "A" being the Right BPW, adding Code:
+
between the "X" & "A" will add them up together for a total sum and then adding Code:
/2
at the end would divide them in 2 giving you the Average BPW.

Individual fuel trims at idle are differant for each cylinder, let alone right and left, same for off idle. That and BPW is constantly changing so I wouldn't worry about the difference not being exactly half when you checked by math/calculater.

Curious as to the ADX you are using? I could never get one to work and built one, is it the one I did? $EE-Auto-V3.adx I did some more work on it and it got a rename $EE-16188051.V3.adx and xdf that have data tracing working together on some items.
http://www.gearhead-efi.com/Fuel-Inject ... ion-EE-EEB

I normally use AccuFuel app on my iPhone to help me out with my Average MPG during the tank fill up, But i've been looking around for a instant MPG gauge that will help discipline my heavy foot. XD MPGuino was an option but it has been on hold since December and the kit is no longer available. My only next option was to use my ALDL cable and software to get it going. Its definitely working but I would have to come up with a netbook or something that would allow me to view the MPG without having to take my eyes of the road and look down on the passenger seat or floor to get my MPG. Currently I'm using my 13" MacBookPro using Bootcamp.

Looking back, Yes, I am using your ADX from the Gearhead-efi forum. Works very well! There are times were I have to turn on and off the data stream in order the readings to read correctly.

[EagleMark]

They used to sell gauges for fuel milage, red was bad and green was good. All it was, was a vacuum gauge, higher vacuum = less throttle (foot) more MPG. Don't know of any digatal types...
I got 24.3 on a highway trip, but normal is lots of cold starts around town and WOT whenever I get next to a Ricer or hotrod is 15MPG . They can't understand how a white woodgrain wagon goes so fast!

I've still never had a problem with getting data with mine? First shot every time. Tried everything I could to get it to screw up... Windows 7 PC and TunerPro V5 RT.

Are you using a MAC?

Is it not connecting properly first time and you have to try again? You may have an earier version, it has been tweaked a little more here and there, not been out all that long.

[AnimeFunTV]

MPGuino is a sweet little device http://ecomodder.com/wiki/index.php/MPGuino I haven't seen the vacuum gauge like the one you mentioned.

I still have room to program the PCM for more MPG, but yeah, them wagons are wicked fast when they are running right. XD

Yeah, I'm using a MacBookPro loaded with Windows XP using Bootcamp. I downloaded these http://www.gearhead-efi.com/Fuel-Inject ... 1#post3131 the ones from the TunerPro site didn't want to work at all. Yours works, just sometimes when I try the Data Monitoring the gauges go crazy until I stop and try again, then it would work. Sometimes I have to do it more than once. I'm using an ALDL usb cable from aldlcable.com

My main goal now is to find either a windows xp tablet with usb input for dirt cheap and load TunerPro on it and use it as a LCD gauge or locate a mobile LCD screen like the ones you see on the back of head rests or window visors and use a netbook with video out going to that LCD screen.

[dex]

I named it 'Average BPW', I click on the 'Conversion' tab on the bottom and added to the Equation set and typed in

Code: Select all

(X+A/2)

This is wrong because it does not allow for the mathematical hierarchy of arithmetic operations. You need to use (X+A)/2 otherwise the value 'A' gets divided by two before being adding to X.

As to why the TunerPro calculated value differs from the manually calculated value I am guessing that this is because the data values used for X and A differ from the displayed values.

[EagleMark]

Thanks Dex!

This is wrong because it does not allow for the mathematical hierarchy of arithmetic operations. You need to use (X+A)/2 otherwise the value 'A' gets divided by two before being adding to X.

That would explain why his displayed value is off! Almost exactly on paper.

The files at that link have changed, see if you have the latest. If you email me your's I could make a small change in each and send back several to try. So far no one has had issues, first shot... but it may be a MAC w/windows thing? So a couple clicks to get connected is not bad.

Some of those small notebook/tablets run Windows CE which will not run TunerPro I have read here. There is also an issue with those small notebook/tablets that no Com 3-4 is available which is also a problem with TP. So careful what you get. I see loads of them at the pawn shop for cheap. But have yet to find a Com 3-4 available...

or just put a block of wood behind the skinny pedal!

[JP86SS]

Once you get that all working, just use the Histogram (or make one) that gives you the MPG at RPM and load.
The AVG function works good for showing where your "sweet spot" is for cruising.
Also run the output of the calculation into a lookup table.
Set up a lookup that has 0=0, 50 = 50 as the points.
Then your calculation will not go negative or exceed 50.
Keeps the data within a normal range when you get off the throttle or have blips of bad data.
HTH

[AnimeFunTV]

Once you get that all working, just use the Histogram (or make one) that gives you the MPG at RPM and load.
The AVG function works good for showing where your "sweet spot" is for cruising.
Also run the output of the calculation into a lookup table.
Set up a lookup that has 0=0, 50 = 50 as the points.
Then your calculation will not go negative or exceed 50.
Keeps the data within a normal range when you get off the throttle or have blips of bad data.
HTH

Not sure what you mean by a Histogram, a little bit of more info on how to achieve that would be great.

I made the adjustments to the Average BPW formula and yes, now its averaging correctly, thank you!

EagleMark, here is the ADX file I used and modded for MPG
$ee-mpg.adx - https://files.me.com/animefuntv/xfbz8u

here is a log file I also created

55.xdl - https://files.me.com/animefuntv/7wedor

[EagleMark]

Here's a write up on how to make a histroy table, it's geared for BLM but same thing needs to be done fore MPG. Just enter differant X axis and Y axis. There are BLM and Knock history table built into the $EE adx I made to give you an idea.
http://www.gearhead-efi.com/Fuel-Inject ... n-TunerPro

[EagleMark]

I don't think you got it right yet...

to answer your question quickly: average the BPWs. add the left BPW to the right BPW, then divide by 2, all in ().





i use a different equation, one that works a bit more accurately for me...

A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

where 16.7 is your injector flowrate in lb/hr, the 3 represents half of the cylinders in the engine, and the 2 represents how many injector pulses per 4 stroke cycle(double fire, SFI or single fire mode would need a 1). A is BPW in mSec, and E is RPM.

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.



A/B

A is MPH, B is gal/hr of fuel flow, then you'll have a MPG value.

But we still don't know what 60 is in this equation?
A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

And where did 6.073 come from? He said

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.

so is 6.073 value of equation? Or A is value of equation A/6.073 so what is 6.073?

[AnimeFunTV]

I don't think you got it right yet...

to answer your question quickly: average the BPWs. add the left BPW to the right BPW, then divide by 2, all in ().





i use a different equation, one that works a bit more accurately for me...

A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

where 16.7 is your injector flowrate in lb/hr, the 3 represents half of the cylinders in the engine, and the 2 represents how many injector pulses per 4 stroke cycle(double fire, SFI or single fire mode would need a 1). A is BPW in mSec, and E is RPM.

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.



A/B

A is MPH, B is gal/hr of fuel flow, then you'll have a MPG value.

But we still don't know what 60 is in this equation?
A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

And where did 6.073 come from? He said

and that will create a value showing injector flowrate in lb/hr.



A/6.073

A is the value that was just created, and will now create a injector flowrate in gallons/hour value.

so is 6.073 value of equation? Or A is value of equation A/6.073 so what is 6.073?

I'm not sure how he got that formula either.

the original MPG formula is

X/(C*0.0000212*Y*Z)

X = Vehicle Speed
Y = Engine Speed
Z = Base Pulse Width
C = Injector constant (lbs/hr)

its easy to get the vehicle speed, & engine speed. Now that I found out how to get the Base Pulse Width, all is left is to get the Injector Constant, but I'm not sure if thats the that my PCM is programmed with and if I just add that in there

ie X/(24.87*0.0000212*Y*Z)

[EagleMark]

OK the formula you have came up with from Roberts is correct. I had a friend whos good with math explain what the other numbers were. But he questioned A* may need to be A= but that may not be correct because he was only thinking RPM, we are using vehicle speed as well. Hence 0 MPG at 0 MPH

I think it should be "A=(1/3600000)*(24.87)*(4)*E*(60)*(1)". when you input the RPM, then this should output your LB/HR

It looks like 1/3600000 is the number of msec in one hour, and 60 is there to convert the RPM(minute) into hours. because everything has to be in the same term to put it all together.

then once you have LB/HR, you divide by 6.073 which is the density of gasoline, and that gives you GAL/HR.

Looks like you are on the right track.

So now we know what all the numbers meen and do!

On you adx it looks like the latest. It has a couple spots where things are done twice and has always worked for me. When I have time later I will make a subtle change and send you back 3 to try. They will all be the same as you sent me but a little change in the way in connects to data. I will number them 1, 2, 3, so try them in order. Can you PM me your email and I will send you them? Or I could host them somwhere on gearhead-efi.com for you to grab?

[AnimeFunTV]

OK the formula you have came up with from Roberts is correct. I had a friend whos good with math explain what the other numbers were. But he questioned A* may need to be A= but that may not be correct because he was only thinking RPM, we are using vehicle speed as well. Hence 0 MPG at 0 MPH

I think it should be "A=(1/3600000)*(24.87)*(4)*E*(60)*(1)". when you input the RPM, then this should output your LB/HR

It looks like 1/3600000 is the number of msec in one hour, and 60 is there to convert the RPM(minute) into hours. because everything has to be in the same term to put it all together.

then once you have LB/HR, you divide by 6.073 which is the density of gasoline, and that gives you GAL/HR.

Looks like you are on the right track.

So now we know what all the numbers meen and do!

On you adx it looks like the latest. It has a couple spots where things are done twice and has always worked for me. When I have time later I will make a subtle change and send you back 3 to try. They will all be the same as you sent me but a little change in the way in connects to data. I will number them 1, 2, 3, so try them in order. Can you PM me your email and I will send you them? Or I could host them somwhere on gearhead-efi.com for you to grab?

Thats good to know that formula is okay, Just in time too since I picked up a laptop for free Needed a hard drive and I had a spare available, now its up to find a Garmin GPS with video in so I can have the Garmin as my MPG gauge! I'll send you my email via PM

[EagleMark]

You ever watch where your driving? Or just the gauges?

[AnimeFunTV]

Of course

[robertisaar]

even i'm getting confused...

[AnimeFunTV]

Is is best to leave the MPG Value item as a "Percentage of Defined Range" in the conversion output format or as a "Floating Point"?

[AnimeFunTV]

even i'm getting confused...

lol what we were doing is trying to break down your equation of "A*(1/3600000)*(16.7)*(3)*E*(60)*(2)"

[robertisaar]

i noticed, and i'm going through my notes to come up with it now.

A*(1/3600000)*(16.7)*(3)*E*(60)*(2)

creates fuel flow in lb/hr

A is BPW and E is RPM

the 1/3600000 is for creating the "hr" portion, since there are 3.6 million mSec in one hour.

the 16.7 is injector flowrate

the 3 is half of the number of cylinders

the 60.... i'm not sure off-hand why it was needed, but it's there for a reason.

and finally, the 2 is how many pulses of the injectors there are in 1 4-stroke cycle.(2 in the case of double-fire MPFI)



now i create fuel flow in gallons/hr

A/6.073

6.073 being how much a single gallon of fuel weighs. it can and will change a lot based on fuel composition, but that's a reference number.



now i create MPG thus:

A/B

A being MPH, B being fuel flow in gallons/hr

so miles per hour / gallons per hour = miles / gallon.



make sense?

[EagleMark]

Dude you need permanant internet!

http://www.gearhead-efi.com/Fuel-Inject ... tory-table

[robertisaar]

Dude you need permanant internet!

it's now a reality, Mark.

[EagleMark]

Sweet!

[aggiemarine07]

Am i missing something? (sorry im a complete noob to auto-tuning) but I dont see a BPW in my .ADX file that Im using

Im using an ADX from gearhead-efi for a 1990 chevy c1500 4.3L (A104); is anyone can offer some help or advice I'd greatly appreciate it.

http://www.gearhead-efi.com/Fuel-Inject ... rmation-AO

[robertisaar]

it's entirely possible that your datastream doesn't output a BPW value, few if any 160 baud ECMs do.

[aggiemarine07]

That sucks :-/ I was really hoping to do something like they described above. thanks for the reply.

[aggiemarine07]

it's entirely possible that your datastream doesn't output a BPW value, few if any 160 baud ECMs do.

Just thought of this, is there a way to calculate BPW based on another value such as TPS or MAP? Cant the percentage that one of these is open tell me how much fuel was injected?. Am i wrong? Thanks.

[robertisaar]

you could roughly approximate the amount of fuel injected with either a TPS vs RPM or MAP vs RPM lookup table..... but at that point, you might be further ahead to modify the datastream to output the BPW value.

[aggiemarine07]

you could roughly approximate the amount of fuel injected with either a TPS vs RPM or MAP vs RPM lookup table..... but at that point, you might be further ahead to modify the datastream to output the BPW value.

so when you say modify the datastream, are you saying to create a new value? or something else? Do you know a good site/write-up on how to do this? Thanks.

[robertisaar]

described shortly: adding BPW into the datastream, 2 other bytes would need to be removed to place the BPW value into the stream(PROM ID, if present, is what I would suggest). it's a bit more complicated than that, but you would essentially end up with a unique ADX for a BIN with a modified datastream.

[aggiemarine07]

described shortly: adding BPW into the datastream, 2 other bytes would need to be removed to place the BPW value into the stream(PROM ID, if present, is what I would suggest). it's a bit more complicated than that, but you would essentially end up with a unique ADX for a BIN with a modified datastream.

Alright so i got a hold of the datastream from gearhead-efi but there are some things within the DS file that I dont understand:
-Word 10 is Base pulse (fuel) closed loop correction?
-Word 19 is BASE PULSE COURSE CORRECTION(BLM)
I got basic descriptions of these Words from: http://www.seanster.com/scantool/copies ... htm#MW2160
Link to A104 datastream file:
https://drive.google.com/open?id=0B4L0K ... authuser=0

Will these give BPW or something similar?

Also, as a side note: Word 17 has some Bits that talk about A/C, does this mean I can control the Air Conditioning through TunerPro?

[robertisaar]

closed loop correction is a short term fuel trim and BLM is a long term fuel trim. a BPW can't be derived from them, only an indication of how much the BPW is being effected by O2 sensor readings.

160 baud datastreams are unidirectional: data can only go from the ECM to a scanner/laptop. 8192 baud streams are bidirectional, a lot of which have mode 4 commands, which can control outputs like A/C, EGR, CCP and a lot of other functions.