Breaking down fuel mileage

[ripping r]

Ok i cant figure this out. I get 8ish miles per gallon pulling my rv. How do i get to how much fuel is sprayed in the cylinder for each stroke? Just curious has to be a good amount.

 

[jws123]

Mileage sounds about right for hailing a heavy rv are you going up alot of hils stop and go ect? It would not hurt to hook it up to a good scan tool and check the live data to make sure all is good. Also dont use the evic estimate for mpg do it manually.

 

[Rado]

Found this test on Google , Pretty cool

Injector Balance Testing

If you suspect that an injector is restricted or malfunctioning, an injector balance test may help isolate the bad injector. This video is sponsored by Standard Motor Products

www.underhoodservice.com

can a scan tool show injector flow - Yahoo Search Results

search.yahoo.com

 

[mtnrider]

That would be difficult to calculate (a lot of variables) but it's less then you think, it's a really fine mist but it adds up of course.

Some quick math (I think I'm close). If you were running 60mph it would come out to 16oz a minute or 2oz a minute per cylinder. Of course you would need to know your RPM and divide that down even further but 2oz per cylinder per minute I think is pretty close?

Disclaimer: I'm no math genius so I could be wrong Lol
.

 

[kurek]

I don't know if it can be monitored with AlfaOBD or JSCAN but I seem to remember the Mitsubishi equivalent (MUT3) tool has a live monitor that shows fuel delivery per injector so no guessing or math required (on modern Mitsubishis) - I'm guessing a similar thing exists for every modern gasoline powered car, just not sure if the Android/IOS apps can access that PID

 

[ripping r]

Mileage sounds about right for hailing a heavy rv are you going up alot of hils stop and go ect? It would not hurt to hook it up to a good scan tool and check the live data to make sure all is good. Also dont use the evic estimate for mpg do it manually.

Found this test on Google , Pretty cool

Injector Balance Testing

If you suspect that an injector is restricted or malfunctioning, an injector balance test may help isolate the bad injector. This video is sponsored by Standard Motor Products

www.underhoodservice.com

can a scan tool show injector flow - Yahoo Search Results

search.yahoo.com

there is nothing wrong. i was just thinking about how much fuel it uses in each revolution. the balance is very interesting.

I don't know if it can be monitored with AlfaOBD or JSCAN but I seem to remember the Mitsubishi equivalent (MUT3) tool has a live monitor that shows fuel delivery per injector so no guessing or math required (on modern Mitsubishis) - I'm guessing a similar thing exists for every modern gasoline powered car, just not sure if the Android/IOS apps can access that PID

that would be great. if it was available.

 

[ripping r]

That would be difficult to calculate (a lot of variables) but it's less then you think, it's a really fine mist but it adds up of course.

Some quick math (I think I'm close). If you were running 60mph it would come out to 16oz a minute or 2oz a minute per cylinder. Of course you would need to know your RPM and divide that down even further but 2oz per cylinder per minute I think is pretty close?

Disclaimer: I'm no math genius so I could be wrong Lol
.

sounds good to me. i am very bad with math.

 

[Randy Grant]

Hate to say it, but I think you are really over thinking, over analyzing, over doing and over board on this whole mileage thing. It is what it is because it is the way it has to be in order to get from point "A" to point "B", or wherever it is you are trying to get to .

 

[ripping r]

Hate to say it, but I think you are really over thinking, over analyzing, over doing and over board on this whole mileage thing. It is what it is because it is the way it has to be in order to get from point "A" to point "B", or wherever it is you are trying to get to .

really? your not the least bit curious? because thats all i am. its not like im looking to fix something thats not broken. maybe mileage is the wrong term.

 

[Sluff Track]

Hemi395 did this and mentions it in the synthetic oil thread post #18,475. I tried to post a link to it this morning, but I haven't figured that out, yet...

Jim

 

[ripping r]

Hemi395 did this and mentions it in the synthetic oil thread post #18,475. I tried to post a link to it this morning, but I haven't figured that out, yet...

Jim

yep i found it.

 

[Jessica Smith]

Not sure how that number could help you. I'd be more interested in research like how much speed affects fuel economy.

I sometimes see Rams like mine but with giant mud tires sticking out two feet on each side of the vehicle towing these massive trailers passing me at almost 80mph and I'm wondering how much fuel those guys are sucking down.

I believe that most vehicles max out on fuel economy at around 40mph, but don't start to see an exponential increase in fuel consumption until after 60mph when it dips a lot.

If not in a huge rush, I'd be curious how much your economy would improve if you slowed it down to 50-55mph.

 

[Randy Grant]

really? your not the least bit curious? because thats all i am. its not like im looking to fix something thats not broken. maybe mileage is the wrong term.

I keep an eye on it from time to time to see if there is a drastic change, and I try to get reasonable mileage for my truck, but I don't try to figure out why it isn't better, or why someone else has better than me. It is what it is, and that's the way it is.
Life is short, so I fix what I can, don't try to fix what I can't, and try to remember the difference.

 

[62Blazer]

As mentioned above knowing that information when there is nothing really wrong with the truck is just something that might be interesting. I would think with a good scan tool that live streams data and collects it you could see it. You could look at the injector duty cycle and pulse width and compare it to the injector output.....basically it would say something along the lines that the injector was spraying fuel at 65% capacity for X seconds each time the cylinder fired. Just keep in mind the % it is spraying and the pulse width will be constantly changing based on the speed of the truck, rpm of the engine, and load on the engine (includes throttle position). Not like the injector puts the exact same amount of fuel in the cylinder every time regardless of what is going on. That information is also what is commonly used to calculate the MPG on the display. Some vehicles may be different but when I was heavily involved in new automotive testing most vehicles did not have any type of actual flowmeters on the fuel lines, but rather the MPG displayed was a calculation based on the above mentioned variables.
For speed versus MPG the faster you go the more power, and thus fuel, is required. Aerodynamic drag is a squared value, or raised exponentially. These are not the exact numbers but just for a rough reference if you drive 60 mph and take the square it is 3600. If you drive 70 mph the square is 4900. The difference between 60 mph and 70 mph is 17% higher speed, but the difference in 3600 vs. 4900, or the aerodynamic resistance, is 36% increase. Basically to go 17% faster requires at least 36% more work or energy just from aerodynamics.

 

[gfh77665]

There is a wide spectrum of concern with MPG's. Some obsess over it, some are mildly curious, some don't give a flip. I care some, but that's about it. To optimize, we tailor our vehicles to our driving. For my 7 miles to and from work, I drive my 2004 5.3L Chevy Avalanche. Who cares if it only gets 15-16 mpg, since it does not accumulate many miles. My wife drives our 2017 Ford Fiesta for her 35 mile highway run to a neighboring city twice a week. The 70+ mile round trip X2 only costs us 4 gallons of gas total. Thats where we economize. Our 3.6L RAM is our traveling vehicle because its the roomiest and nicest of the bunch by far, and we get 22+ mpg highway.

 

[Randy Grant]

For the wife saving gas matters, so she drives her Prius plug-in to town and back, (10 miles round trip) and plugs it in every night. She is happy with her 199.9 mpg and it costs her less than a buck per day. And , I'm happy that she is happy.

 

[turkeybird56]

For the wife saving gas matters, so she drives her Prius plug-in to town and back, (10 miles round trip) and plugs it in every night. She is happy with her 199.9 mpg and it costs her less than a buck per day. And , I'm happy that she is happy.

Happy Wife Happy Life.

 

[turkeybird56]

I am a BOIRD of a different feather. I went from a 2nd Gen ED to a MY 19 Hemi. When it needs gas, a trip to the ole gas station is in order, LOL.

On trips, I tried to stay above 1/4 tank and put in fuel from heavily traveled places, not off the road Mom and Pop and use 89 Octane.

But then, I's a BOIRD. I neva worry about all that above complicated stuff, lol. Besides, shucks, it is a Hemi, lol.

Heck, I averaged 18-22 MPG hand calc on a 4050 mile roadtrip, not too shabby. That was with the SRA's on, now I got more tire, Falken AT3W's "C" rated, so my MPG dropped 1 to 1 1/2 MPG. But a lot more safer tire on the road, worth the small loss. Beats blown up Balloons, LOL.