2004 yaris hatch, 2nz-fe, DFCO in all gears?

[toyo]

Before I tried DFCO, I used to go downhill in neutral.

then I started DFCO in 5th gear and didn't feel any difference in mpg, I also triend 4th gear and no noticeable difference.

I found in another forum a post saying Toyota implemented DFCO in 2007 models only using 3rd gear or lower, and in 08+ models DFCO activates in all gears.

Is it true? any input for a 2004 HB 2nz-fe?

I found a similar 2007 thread here but no one really answered the dudes question lol

[Yaris Hilton]

The switch in 2007 was for the automatic transmission to use DFCO in Drive. Up to mid 2007 it only activated in the lower gears. I don't understand why they did it that way.

[Tamago]

if you drive a 5 speed the ECU does not know what gear it's in.

[toyo]

if you drive a 5 speed the ECU does not know what gear it's in.

I do, so it does activate dfco then? damn no difference in mpg if it does :(

[Yaris Hilton]

DFCO's not going to make a big difference in MPG for most folks. It's mainly a pollution control measure. An idling engine being spun faster than idle speed is especially dirty.

[2009Toyotoad]

Very, very well said Yaris Hilton. Perhaps this will clear up some of the DFCO confusion. Hypermilers, please take DFCO out of the discussions as its not really any benefit in the pursuit of better MPG, unless your end goal is green rather than saving money.

[toyo]

DFCO's not going to make a big difference in MPG for most folks. It's mainly a pollution control measure. An idling engine being spun faster than idle speed is especially dirty.

awesome explanation, thanks,

so i'm better off using dfco anyway then? is it better for my engine?

[BailOut]

Hypermilers, please take DFCO out of the discussions as its not really any benefit in the pursuit of better MPG, unless your end goal is green rather than saving money.
DFCO does indeed benefit MPG, and more so the less flat your region is. Using no fuel is absolutely more efficient in more ways than one than using fuel to idle.

If you live in a flat area there will be less opportunity to use it, and less time in DFCO per use, but it is always a viable fuel efficiency technique. If you live in a hilly or mountainous area it makes a huge impact on FE. This is also by far one of the easiest hypermiling techniques to use.

Hypermiling is not about saving money though that is certainly a nice and tangible side benefit. It is about reducing our use of and dependence on oil (especially foreign oil) and reducing our emissions, thereby lowering our overall impact on the planet and its environment.

[Yaris Hilton]

Right. I'm not saying it doesn't save gas, only that the way most people drive, the DFCO feature usually won't make a big mileage difference.

[scape]

DFCO's not going to make a big difference in MPG for most folks. It's mainly a pollution control measure. An idling engine being spun faster than idle speed is especially dirty.

I'm so confused by that...do you mean when the engine and transmission are not engaged?

[2009Toyotoad]

DFCO only works with the gear engaged and the wheels rolling. However, as Bailout pointed out its most effective going downhill because on the flats the DFCO feature starts and stops very quickly because the driver is attempting to maintain speed, whereas, on the downhill slope the car's momentum will maintain speed without throttle inputs.

This brings Yaris Hilton and also my own arguments of the subject of DFCO into play. I argue that for every downhill there is an uphill. I believe that the two will ultimately balance each other out because while DFCO saves fuel on the downhill the need to maintain speed of the uphill section requires that more fuel is burned. In my argument I believe the the only real fuel saving that can be achieved is if the uphill section is traveled at reducing speeds going over the hill and that as a result the actual amount of time the DFCO operates on the downhill will be longer because the momentum and speed are slower coming off the hilltop.

However, This type of driving behavior is impractical, and a bit dangerous in the real world; unless you operate the vehicle in an area with light traffic. But even that assertion has caveats. If you live and travel in a light traffic area chances are you are traveling farther to get into the city to buy /sell goods and services. Which confuses the savings calculations even further.

[Yaris Hilton]

I'm so confused by that...do you mean when the engine and transmission are not engaged?

No. I mean when the engine and transmission ARE engaged. The coasting car spins the engine faster than idle speed. When an engine's just getting idle fuel and being spun faster this way, the fuel burns incompletely and hydrocarbon emissions go up.

As for the fuel economy effects of DFCO, it will vary depending on your circumstances. Going down a moderately steep hill, it will help to slow the car and it will save whatever fuel the engine would have consumed at idle power. The brakes will have to be used less. Anytime you're coasting to an eventual stop, cutting off the fuel will save the fuel that would've been burned during that coast at idle power. Not much, but every bit adds up. If you're doing something like pulse and glide in gear on level ground, the car will slow faster with DFCO, and you'll have to get back on the gas for a pulse sooner. You'll likely burn more than you would coasting in gear at idle power or in neutral or with the clutch disengaged with the engine idling. But I doubt that most people will really notice the difference under most circumstances.