Fuel per Hour gauge showing right value?

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bertjeconti
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Fuel per Hour gauge showing right value?

Post by bertjeconti »

I've made my own gauge in TS which shows me the fuel consumption per hour in liters.

On the stimulator all seems to work well, but when TS hooked up in the car the gauge shows realy low value's which would be very nice if the figures are correct. That should mean i have a fuel economic car.

While driving around at a constant 80kph the gauge shows 4 liters/hour , which means "20km/l" or "5L/100k". My car could never be that economic, it has never done better as "10km/l" average in the old days when it was running on a 4 barrel carburettor. Its running Megasquirt MS 2 for a few weeks now.
After a 50km logged run, the log tells me the engine has consumed 2.83 liters of fuel, which means 5.66liter/100km or 17.6km/l. i know for shure it consumed more. (a lot more)

This is what i've added in my custom.ini in my project:

Code: Select all

[GaugeConfigurations]

   gaugeCategory = "Custom"
   FuelFlow  = fuelFlow, "Fuel Consumption", "Ltr/Hour", 0, 50, -1, -1, 20, 30, 2, 2
   
[OutputChannels]
   
   maxFuel	    	= { (staged_pri_size/1000)*nCylinders*60} ,"L/H"	; FuelFlow @ 100% dutycycle (injector size(L/min) * Nr cylinders * 60 minutes)
   fuelFlow	    	= { (pulseWidth1 > 0) ? ((100.0*nSquirts1/altDiv1*(pulseWidth1-deadtime1)/cycleTime1)*(maxFuel/100)) : 0 }, "L/H"    ; if pulsewith > o then calc netto duty cycle, actual time injectors are open,*  maxFuel/100%   	
  
  
[Datalog]
  
   entry = fuelFlow			"Fuel Flow",   float, "%.2f"
Under [Outputchannels] i've first defined 'maxFuel' which is the maximum fuelflow @ 100% dutycycle for all injectors together.
Then i've defined the 'fuelFlow' value, which is derived from the dutycycle, only taking the deadtime in account to. When changing the deadtime in TS, the Fuel consumtion stays unchanged, tested this on stim.
The 'fuelFlow' output value is also logged.

i've 6 HighZ Bosch 0-280-150-716 injectors on my car which have a fuelflow of 134cc/min@3bar, on the fuelrail is a 2.5Bar pressure regulator (checked the pressure), so real fuelflow should be 122cc/min.
In TS the injector size = 130cc/min (should be 122, but then i should get even lower fuel consumtion figures)
This means that maximum fuelflow (100% dutycycle) should be (130cc*6inj*60min)/1000=46.8L/H
I'm running semisequential injection with 3 injector drivers, this means each injector fires each engine revolution. (twice each engine cycle)

When running on the stim revving 6000RPM and MAP=100KPA i've a dutycycle 80% and the Fuel Consumtion gauge shows 33.7L/H, which seems OK !(pulsewidth = 8ms, deadtime = 0.832ms, 1 engine rev=10ms)

When running on the stim revving 3000RPM and MAP=50KPA i've a dutycycle 16.8% and the Fuel Consumtion gauge shows 5.9L/H, which seems OK too!(pulsewidth = 3.35ms, deadtime = 0.832ms, 1 engine rev=20ms)

Recalculations give the same figures. recalculating the last example:
- real injection time = 3.35 pulsewidth - 0.832 deadtime = 2.518mS
- all injectors are 6*2.518mS=15.108mS /revolution opened
- engine does 50 revs/second (3000RPM/60S)
- so all injectors together are 50RPS*15.108mS=755.4mS open per second
- so all injectors together are 60S*755.4mS/1000=45.324seconds/minute opened
- this means all injectors are squirting (45.324/60)*130cc=98.202cc/min
- this gives 98.202cc/min*60min/1000=5.89liter/hour fuel consumption. same as TS is showing.

I do not understand why tunerstudio gives low fuel consumption figures while driving aroud, as the car uses more fuel for shure

By the way, the car (BMW E12 with M20B20 engine) runs great on the MS2
ptl
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Joined: Mon Dec 07, 2020 10:43 am

Re: Fuel per Hour gauge showing right value?

Post by ptl »

Can I "borrow" this old topic, the subject is the same, liters per hour fuel consumption.

TunerStudio has gph (gallons per hour) gauge/channel, and I made my custom channel
using formula gph * 4.5461. I believe this is imperial gallons, singe US gallons per hour
is a separate gauge/channel in TunerStudio.

The LitersPerHour gauge shows a bit over 4 lrt/hour when the engine (Rover 3.9 V8)
is idling warm. Looks like a bit high, but OTOH the engine could be that uneconomic.

Q1: does the LitersPerHour = gph * 4.5461 formula look OK?

Q2: what should be the typical LitersPerHour (warm idle) for ~4.0 V8?

Q3: If the formula is right, but LitersPerHour is too high (=gph is also too high),
should I adjust MS1 settings (and what/how)? I could adjust the multiplier in the
formula to get LitersPerHour right, but does this leave some internal config
in non-correct state (and if yes, does this matter if VE fuel table works well)?


-Paavo
jsmcortina
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Re: Fuel per Hour gauge showing right value?

Post by jsmcortina »

America uses small gallons of only 3.8 litres. I'm assuming that TunerStudio is using US gal in the gph calc. So your * 4.5461 is wrong.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
LT401Vette
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Re: Fuel per Hour gauge showing right value?

Post by LT401Vette »

Yes, TS uses US Gallons. I really should add an option for that.
Phil Tobin
EFI Analytics, helping to simplify EFI
Next Generation tuning software.
Supporting all MegaSquirt versions and firmwares.
http://www.TunerStudio.com
http://www.efiAnalytics.com/MegaLogViewer/
Support the firmware running your engine:
http://www.msextra.com/doc/donations.html
ptl
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Re: Fuel per Hour gauge showing right value?

Post by ptl »

So
LitersPerHour = gph * 3.78541178
is more accurate formula?
LT401Vette
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Re: Fuel per Hour gauge showing right value?

Post by LT401Vette »

Yep.
Phil Tobin
EFI Analytics, helping to simplify EFI
Next Generation tuning software.
Supporting all MegaSquirt versions and firmwares.
http://www.TunerStudio.com
http://www.efiAnalytics.com/MegaLogViewer/
Support the firmware running your engine:
http://www.msextra.com/doc/donations.html
ptl
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Posts: 15
Joined: Mon Dec 07, 2020 10:43 am

Re: Fuel per Hour gauge showing right value?

Post by ptl »

ptl wrote:So
LitersPerHour = gph * 3.78541178
is more accurate formula?
Take that back.
/cygdrive/c/Program Files (x86)/EFIAnalytics/TunerStudioMS
$ grep -i -E -r 'gph[[:space:]]*[=]'
config/ecuDef/MSExtra format hr_10.ini: USgph = { CCpHr / 3785 } ; US Gallons / Hr
config/ecuDef/MSExtra format hr_10.ini: gph = { CCpHr / 4546 } ; Real Gallons / Hr
config/ecuDef/MSExtra format hr_11d.ini: USgph = { CCpHr / 3785 } ; US Gallons / Hr
config/ecuDef/MSExtra format hr_11d.ini: gph = { CCpHr / 4546 } ; Real Gallons / Hr
config/ecuDef/msns-extra.029q-29w.ini: USgph = { CCpHr / 3785 } ; US Gallons / Hr
config/ecuDef/msns-extra.029q-29w.ini: gph = { CCpHr / 4546 } ; Real Gallons / Hr
config/ecuDef/msns-extra.29y.ini: USgph = { CCpHr / 3785 } ; US Gallons / Hr
config/ecuDef/msns-extra.29y.ini: gph = { CCpHr / 4546 } ; Real Gallons / Hr
So the correct formula for should be this:
LitersPerHour = CCpHr / 1000
Can test that next weekend, maybe someone can confirm this faster.

-Paavo
ptl
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Re: Fuel per Hour gauge showing right value?

Post by ptl »

LitersPerHour = CCpHr / 1000

Custom channel works, but this did not make my car less un-economical,
gauge still shows more than 4 liters per hour in warm idle. Which is
not a surprise, if the original "real" gallons per hour based formula was
correrct, the end result should be the same, CCpHr based formula just
calculates the LitersPerHour with one less step (CCpHr -> gph -> LitersPerHour
vs. CCpHr -> LitersPerHour).
ptl
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Re: Fuel per Hour gauge showing right value?

Post by ptl »

How much gasoline is needed for 1 horsepower for 1 hour?

4.0 V8 from -97 land rover discovery for example.

The CCpHr/1000 gauge shows 110 peak, wide open throttle, 5000rpm, 12.5 AFR.

IF (please provide better estimates) it is 0.4ltr per hp-hour, the engine would output 275hp,
which cannot be true. 185hp from factory, but MS1 EFI, custom air intake and exhaust pipe, so
my guess is that the real output is max. 200hp.

Can I somehow measure how close MS1/TunerStudio fuel consumption calculation is?

E.g. something like this: fill tank, zero TunerStudio fuel consumption calculation, drive a few hours
TunerStudio running all the time, see TunerStudio total fuel consumption, fill tank again, compare?

Subject to error in filling up the tank exactly the same, but anyway some data.

-Paavo
jsmcortina
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Re: Fuel per Hour gauge showing right value?

Post by jsmcortina »

ptl wrote:How much gasoline is needed for 1 horsepower for 1 hour?
That's BSFC. (Brake Specific Fuel Consumption.) Typically 0.55 lb/hr/hp from memory.
I think that works out to about 0.35l/hr/hp using a typical density of 0.72.

For reference, my 4.6 Rover is using 38 cc/min at rich idle with 3.8ms PW on 250cc/min injectors.

I'll try to dig out a datalog from the dyno earlier this year. It make 250hp (crank est) but I was on a different manifold and injectors then.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
ptl
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Posts: 15
Joined: Mon Dec 07, 2020 10:43 am

Re: Fuel per Hour gauge showing right value?

Post by ptl »

I have 19lbs (~200 cc) injectors (x8), 2.5bar (-MAP) fuel pressure (std Range Rover classic / Disco 1st series regulator),
and injectors are 2.6ms open in warm idle, 100% PWM since injectors are "hi-impedance".
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