Long Commute? WHo has gone the furthest on 1 tank?

[infinite012]

Originally Posted by rice_classic

My hypothesis is that the Avg MPG trip indicator is skewed high do to the "off-throttle-127mpg" computation. I think if the off-throttle computation was reduced to 99mpg (like it is in other vehicles) the Avg MPG trip indicator may be closer to real world calculations.

This is just a hypothesis.

Shouldn't the injectors be turned off completely when you're off-throttle, in gear? That would give us a theoretical fuel efficiency of infinity miles per gallon, since there are 0 gallons being delivered.

And we all know you can't divide by zero...

[Gixxersixxerman]

Originally Posted by infinite012

Shouldn't the injectors be turned off completely when you're off-throttle, in gear? That would give us a theoretical fuel efficiency of infinity miles per gallon, since there are 0 gallons being delivered.

And we all know you can't divide by zero...

Nope.. The engine needs fuel to stay running.. If the injectors shut off then the engine would just die.. Just like a engine idling the injectors are providing fuel..

[rice_classic]

Well we all know what happens when you shut off the injectors.

That picture is funny and ironically those things are called "Glory holes". Go figure.

[ravenblackfrs]

Originally Posted by rice_classic

Well we all know what happens when you shut off the injectors.

That picture is funny and ironically those things are called "Glory holes". Go figure.

GIGGITY!

[infinite012]

Originally Posted by Gixxersixxerman

Nope.. The engine needs fuel to stay running.. If the injectors shut off then the engine would just die.. Just like a engine idling the injectors are providing fuel..

From my short experience with opensource tuning of my 2005 WRX, data logs would suggest that injector duty cycle is at 0% when off throttle, in gear (obviously while driving, not just sitting in a parking lot). Off throttle in neutral showed something like 4% IDC.

But prove me wrong...

[ravenblackfrs]

I'm confused... why would anyone think the fuel injectors... would stop spraying fuel... just because the car is sitting still while running and in gear....

if the car is RUNNING... its running because fuel is being sprayed into the compression chamber VIA the injectors... using fuel from the tank. The car doesn't stay running on air. LOL...

[bugxster]

Most I got was 421 and it filled up 12.9 gallons (60% city/40% hwy).

[Carbon420]

Originally Posted by rice_classic

Well we all know what happens when you shut off the injectors.

That picture is funny and ironically those things are called "Glory holes". Go figure.

Ummmm really? I know glory holes suck but.


Sent from my iPhone using Tapatalk

[jshadeck]

http://www.popularmechanics.com/_mob...l-fuel-economy

Coasting in gear uses 0 fuel. Coasting in neutral uses fuel same as idling.

[rice_classic]

Originally Posted by jshadeck

http://www.popularmechanics.com/_mob...l-fuel-economy

Coasting in gear uses 0 fuel. Coasting in neutral uses fuel same as idling.

DFCO=Deceleration Fuel cut off. Engine and Catalyst must be at operating temperature otherwise no DFCO.

DFCO (as my understanding) was part of the OBD1->OBD2 changeover so if your vehicle is newer than 1996 is should utilize DFCO in some form or another.


Here's an OBDII easy reader:
http://groups.engin.umd.umich.edu/vi...ganesan_w2.pdf

DecelerationEnleanmentand Idle Speed Control: When the driver decelerates the vehicle very hard, the PCM reduces the engine torque by cutting off fuel , withdecelfuel cut off mode in which the fuel injector is turned off or the duty cycle is drastically reduced.

Originally Posted by ravenblackfrs

if the car is RUNNING... its running because fuel is being sprayed into the compression chamber VIA the injectors

In this case, under DFCO, the momentum of the car via the wheels/drivetrain is running the engine.

Let's see, how would the Chief say it?
Uphill, engine run make car go.
Downhill, car go make engine run.

Well, it was funny in my head.

[Gixxersixxerman]

Originally Posted by infinite012

.

But prove me wrong...

Originally Posted by rice_classic

DFCO (as my understanding) was part of the OBD1->OBD2 changeover so if your vehicle is newer than 1996 is should utilize DFCO in some form or another.
.

This here showed me what has changed since I've done my tests.. Back with my old 93 grobe GT, coasting down hill with the car in 5th showed the injectors firing, when the car had the ignition shut off and the injectors stopped firing, the car would decelerate much faster and harder, the engine exhaust would change and everything.. But that car and all cars when I came to my conclusion was OBD I I didn't realize things have changed that much since I did my testing back in 03

[ravenblackfrs]

Originally Posted by rice_classic

DFCO=Deceleration Fuel cut off. Engine and Catalyst must be at operating temperature otherwise no DFCO.

DFCO (as my understanding) was part of the OBD1->OBD2 changeover so if your vehicle is newer than 1996 is should utilize DFCO in some form or another.


Here's an OBDII easy reader:
http://groups.engin.umd.umich.edu/vi...ganesan_w2.pdf






In this case, under DFCO, the momentum of the car via the wheels/drivetrain is running the engine.

Let's see, how would the Chief say it?
Uphill, engine run make car go.
Downhill, car go make engine run.

Well, it was funny in my head.

ifsofacto....

ur telling me, that when i start my car and start coasting down hill, NO FUEL is being consumed to keep the car running? It runs cause the gear is engaged, and the car is rolling, but no fuel is pumping into the combustion chamber...

Thats what your saying? I suppose the electric spark could be turned off and the engine would still run too then...

If thats what you are saying, and ur right then cool, but it sounds like BS. I'm just sayin...

[infinite012]

Good info to know. All I know is that when I coasted in gear with my 2005 WRX my IDC was 0% and my calculated mpgs were always better than if I coasted in neutral. That's a habit I carried over to my STI and now to the BRZ as well. I'm returning ~30-32mpg in the BRZ going mostly 70mph on my commute (90 miles round trip per day).

[GTFrank]

I average 31 mpg suburban driving in Washington D.C. on the winter time mixture. Summertime Mixture 32 mpg. Playing in the snow 27 mpg. D.C. to Philadelphia trip never exceeding 60 mph 37 mpg. Ny to Dc just after purchase during brake in averaging 70 to 75 mph and moving between 6th and 5th gear I averaged 34.2 mpg. I have a manual transmission and I subtracted 3% for computer error.

On a 1000 mile trip with my wife and I and maximum luggage the 10 foot trunk can hold. I averaged 32.5 mpg on mostly 75 mph highway driving in the rain.