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 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

[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

[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