DFCO and Autos

[voodoo22]

CleanMPG is a great resource full of an extremely mature group of helpful people.

Visit that place enough and you'll be surprised what rubs off on you.

[drummerboy2004]

Originally Posted by voodoo22

CleanMPG is a great resource full of an extremely mature group of helpful people.

Visit that place enough and you'll be surprised what rubs off on you.

He's right...

This is where this magician got all of his tricks

Even better than going to the site... try to find videos of Wayne talking hypermiling with reporters... It is 90% acronyms.

Matt

[yarswiss]

To answer the OP, DFCO can be engaged whenever the RPS are sufficiently high, the ratios of which (according to my Scangauge estimates) are 2nd:1700rpm, 3rd:1800rpm, 4th and Overdrive: 1800rpm. As a general rule of thumb, though, DFCO will engage whenever the rpms are significantly high and your car uses engine braking to slow down. For example, I live on top of a steep hill, so whenever I driver down in the morning, I go into 2 and the rpms will be around 2400, and DFCO will kick on, even though I'm only in 2nd gear.

Sometimes when I'm cruising about town, my DFCO will not engage, so I find giving a quick, light tap on the gas and then taking my foot off again will "force" the car into DFCO. This works best when you are on a long, smooth downhill where momentum keeps you between 30-40mph.

At freeway speeds, if you drive a hilly commute with steep enough downslopes that won't slow you down too much with engine braking, use DFCO whenever you go downhill. DFCO is also great to use whenever taking an exit, slowing to a traffic light on a slope, stopping at a stop sign, and coasting down any steep slope.

[GeneW]

Originally Posted by voodoo22

Nice on coasting causes no damage at any speeds in our cars.

My Scanguage indicated that NICE uses more fuel than DFCO. I agree with you that keeping the motor on keeps the pump turning but I didn't see any advantage to doing coasting while the motor is running.

Originally Posted by voodoo22

Some cars require you to rev match when shifting back to D, but as long as you shift back into D before you are going back up a hill(You don't need to, but it works better), the Yaris transmission will smoothly choose the correct gear. The Yaris manual states that our AT is flat towable for short distances at low speeds on flat surfaces. FASing to your parking space will cause no damage either, but FASing at hwy speeds or for long distances will cause you future transmission issues.

The manual says it pretty explicitly - "No Dinghy towing". I am not sure what "short distances" mean, but as best as I can recall the manual suggests using the rear wheels to tow or use a flat bed. I suspect that towing on the front wheels is used because the car must be removed rather than as a preferred towing option. Especially if the car was struck in the rear and cannot be towed any other way.

Not to be a smart ass, but you can also run your motor without oil for brief periods of time too. There is enough residual lubricants to keep things good for seconds worth of total operation, at least until one of the cylinders seizes or one of the bearings seize. An AT is a bit different in that it doesn't have as much heat generation as an internal combustion engine.

The AT uses the fluid for several purposes - lubricant, to operate the torque converter and to remove heat. Don't run that pump and you're letting the parts conduction cool. You will accelerate wear doing this.

I do not recommend FAS for any AT. I think the trade off of lowered reliability isn't worth the marginal fuel savings.

Best way to save fuel is to drive at "optimal" highway speeds, avoid heavy acceleration, reduce vehicle weight and keep the car in good working condition. Pulse and glide is also a good idea. I think many of the advanced techniques are almost in the domain of "diminishing returns", good when gasoline is horribly expensive or scarce but otherwise not terribly practical (though they are fun to do, as a challenge).

I live in a state where FAS is illegal. I drive at times of the day when the bars close and the drunks and hooligans are out and about. A car the size of a Yaris survives because of its maneuverability and agility. You cannot maneuver or be very agile in FAS.

I treat my Yaris as a motorcycle with a sheet metal skin, as I did with my CRX. So I don't use techniques that reduce maneuverability or require vigilance that takes away from my primary need of avoiding collision or losing control of the car. So even if I could FAS I would not do so on the road.

Gene

[GeneW]

Originally Posted by yarswiss

To answer the OP, DFCO can be engaged whenever the RPS are sufficiently high, the ratios of which (according to my Scangauge estimates) are 2nd:1700rpm, 3rd:1800rpm, 4th and Overdrive: 1800rpm. As a general rule of thumb, though, DFCO will engage whenever the rpms are significantly high and your car uses engine braking to slow down. For example, I live on top of a steep hill, so whenever I driver down in the morning, I go into 2 and the rpms will be around 2400, and DFCO will kick on, even though I'm only in 2nd gear.]

Laptops are getting cheap again.... I've so much wanted to plug one in and do a formal DFCO run. These aren't bad estimates though I think a laptop with logger software would do a better job.

Originally Posted by yarswiss

At freeway speeds, if you drive a hilly commute with steep enough downslopes that won't slow you down too much with engine braking, use DFCO whenever you go downhill. DFCO is also great to use whenever taking an exit, slowing to a traffic light on a slope, stopping at a stop sign, and coasting down any steep slope.

I tend to use DFCO this way too. I treat it as a "jake brake", which is used by truckers to reduce speed without consuming brake lining.

Gene

[drummerboy2004]

Gene,

Thanks for all of the insight. Oh, and I use NICE-ON coasting if I am going downhill or need to coast longer than the DFCO will allow. Yes, DFCO uses less gas, but you cannot glide for that long. There is a section when I am going to school... that if I time it right, I can NICE coast for almost two and a half miles into the school from the main road. DFCO would kill the speed about 3/4 of a mile into it. Then I would have to work my way through the gears again, which uses enough gas. They both have their advantages, and I use both when they are needed. I am not being a smart as when I say thanks for the insight either... It is people like you that help people get more from their cars, whether it be mileage or life... so thanks

Matt

[GeneW]

Originally Posted by drummerboy2004

Gene,

Thanks for all of the insight. Oh, and I use NICE-ON coasting if I am going downhill or need to coast longer than the DFCO will allow. Yes, DFCO uses less gas, but you cannot glide for that long. There is a section when I am going to school... that if I time it right, I can NICE coast for almost two and a half miles into the school from the main road. DFCO would kill the speed about 3/4 of a mile into it. Then I would have to work my way through the gears again, which uses enough gas. They both have their advantages, and I use both when they are needed. I am not being a smart as when I say thanks for the insight either... It is people like you that help people get more from their cars, whether it be mileage or life... so thanks

Matt

You're welcome.

Gene

[MadMax]

Here's a question for you automatic owners who have a ScanGauge, is it better to downshift from Drive into 3rd when slowing down to increase the RPMs and therefore keep the DFCO engaged? It may also come into play when slowing down on level surfaces where engine braking is more effective compared with coasting down an decline...

Cheers! M2

[Astroman]

Mine takes a bit to go into DFCO in D, while a quick shift to 3 and then back makes it immediately go into DFCO.

[mark2908]

Originally Posted by MadMax

Here's a question for you automatic owners who have a ScanGauge, is it better to downshift from Drive into 3rd when slowing down to increase the RPMs and therefore keep the DFCO engaged? It may also come into play when slowing down on level surfaces where engine braking is more effective compared with coasting down an decline...

Cheers! M2

It depends on how much "braking" you want. DFCO at lower rpm's is less engine braking than at higher rpm's.
DFCO will stay on as long as forward momentum is maintained, down to about 700 rpm in D. (warm engine) I try to keep in DFCO at the lowest rpm or the highest gear possible.
If I still have room and momentum at 700 rpm in D... I shift to 3rd to stay in DFCO a bit longer. I use DFCO on flat terrain and even uphill approaching stops if momentum and time allows.

Mark

[MadMax]

Thanks for the replies. The lack of a tach makes it tougher for me to know what my RPMs are, so I am doing this by the seat of my pants...

Cheers! M2

[GeneW]

Originally Posted by mark2908

It depends on how much "braking" you want. DFCO at lower rpm's is less engine braking than at higher rpm's.
DFCO will stay on as long as forward momentum is maintained, down to about 700 rpm in D. (warm engine) I try to keep in DFCO at the lowest rpm or the highest gear possible.
If I still have room and momentum at 700 rpm in D... I shift to 3rd to stay in DFCO a bit longer. I use DFCO on flat terrain and even uphill approaching stops if momentum and time allows.

Mark

I've seen the same thing. except I try to avoid DFCO approaching a hill. I figure that the momentum is like money in the bank which I did not wish to waste.

Gene