DFCO and Autos - Toyota Yaris Forums

MadMax · 11-08-2008, 11:35 AM

OK, this may have been discussed in the numerous other threads on DFCO and fuel economy; but I was hoping I could get some clarification on how to get DFCO to work with an auto.

In an earlier thread on DFCO, it was believed that you had to tap the brake lightly to get the auto to downshift and engage the DFCO. Is this still the case, or can you simply let off the gas and let it kick in? Or, do you have to manually downshift into 3rd gear to get it to work?

Right now I am "only" getting 35 MPG, but I do have bigger, wider tires (215/45ZR17 Riken Raptor ZRs) which will drop the fuel efficiency a bit; but I drive it very conservatively and mostly at highway speeds, so I was hoping for a little better (and yes, I do adjust my computations for the larger tires). I am hoping that I could utilize the DFCO capability better to improve my mileage.

Cheers! M2

voodoo22 · 11-08-2008, 02:03 PM

Keep in mind that your new tire circumference will also affect your numbers. If your Yaris came with 15" rims you'll be getting numbers 3.7% lower when calculating your FE, but if your Yaris came with 14" tires your FE readings will be 7.2% off.

If you haven't taken this into account and your Yaris came with 14" rims your 35mpg is actually 37.5mpg.

I don't know how much of a hit, but add that initial inaccuracy in calculations on top of the affect of your much bigger tires and rims and you could easily be hurting yourself by reduced FE b/c of the plus size setup and miscalculations by over 10%.

On DFCO; from what I've read; it engages as soon as you take your foot off the gas and your engine remains above 1100 rpms or thereabouts...

MadMax · 11-08-2008, 02:22 PM

Voodoo

I do add 7% for the added dimension of the larger tire (I had an earlier thread and someone provided a web site that gave me that number), and that is calculated into my figures.

It would seem logical that the DCO would kick in when you let off the gas, but I was wondering if anyone has ever tested it with a ScanGauge II on an auto...

Cheers! M2

PreciousPups4U · 11-08-2008, 03:43 PM

I have an auto and a scangauge. Like voodoo said it kicks in automatically when you take your foot off the gas. DFCO is just a fancy name for coasting seems to me. Course you get the most benefit when going down hill so as not to lose too much speed, but it works when approaching traffic lights and stop signs as well.

I am only averaging 34 mpg by the way with the stock 15" alloys that came with the car. Not much highway driving for me though. Pretty much all city or at least traffic area.

MadMax · 11-08-2008, 06:41 PM

PP4U

Thanks, that's the kind of info I was looking for!

Since I also have a Jeep Wrangler with an auto, so I am always trying to wrangle (pun intended) better mileage out of it. I get 15-16 MPG, another reason I wanted a Yaris to offset it!

Cheers! M2

drummerboy2004 · 11-11-2008, 02:45 AM

DFCO occurs in the auto whenever you are above 1100 RPMs with your foot off of the gas. I have a scanguage, and watch it happen every time. I am not sure about 1st gear though... I never see it happen when I am driving in my neighborhood less than 15 mph. It will read around 50 mpg when I am below 15 foot off the pedal. Hope this helps...
Any other questions feel free to ask.

Matt

voodoo22 · 11-11-2008, 07:13 AM

Thanks for the feedback about pedal off and slow moving scanguage numbers. I was wondering it foot off the gas and slowly rolling in parking lots and towards stop signs was worth it.

drummerboy2004 · 11-11-2008, 01:08 PM

Quote:

Originally Posted by voodoo22

Thanks for the feedback about pedal off and slow moving scanguage numbers. I was wondering it foot off the gas and slowly rolling in parking lots and towards stop signs was worth it.

I usually FAS to lights and home, but only do it below 30 mph and less than 100 feet. I have not had any problems, and am sure none will appear. If nothing else, yes, letting off the gas is what I do if I have to slow to light where I will not be stopped for more then 15 seconds (light about to turn green). It is a heck of a lot better than idling because my numbers went from 35 in the city to 45 most days.

Matt

voodoo22 · 11-11-2008, 01:38 PM

That's an amazing example about how much of a difference effort can make. Way to go.

I've started FASing to my parking space since I start work before nearly everyone. It's kind of fun when you screw it up a little and end up just crawling into your spot.

drummerboy2004 · 11-11-2008, 01:45 PM

Quote:

Originally Posted by voodoo22

That's an amazing example about how much of a difference effort can make. Way to go.

I've started FASing to my parking space since I start work before nearly everyone. It's kind of fun when you screw it up a little and end up just crawling into your spot.

I have had to push my car into the spot like three times... I WILL NOT turn the car back on

... The thing that gets me is the wind, so beware. Oh, and I also try to keep my speeds between 30-40 (19tps)... but not 18 because unless you are on a downgrade you will slow quick. Hope that helps too...

Matt

GeneW · 11-12-2008, 02:55 PM

Quote:

Originally Posted by drummerboy2004

I usually FAS to lights and home, but only do it below 30 mph and less than 100 feet. I have not had any problems, and am sure none will appear.
Matt

If some one else doesn't say it I will - do not FAS with an AT. The AT relies upon a pump to maintain internal lubrication, and that pump needs a turning engine. Shut off the engine and you're basically exchanging gasoline savings for transmission repair money.

Gene

drummerboy2004 · 11-12-2008, 05:02 PM

Quote:

Originally Posted by GeneW

If some one else doesn't say it I will - do not FAS with an AT. The AT relies upon a pump to maintain internal lubrication, and that pump needs a turning engine. Shut off the engine and you're basically exchanging gasoline savings for transmission repair money.

Gene

Thanks for the heads-up Gene

... I have the lifetime powertrain on mine (perk from Toyota when I bought it), but still has a 100 deductible after the original warranty... I guess I will have to rethink my game plan. Doesn't NICE-on coasting essentially do the same thing? I have found mixed answers on the subject.

Thanks,

Matt

voodoo22 · 11-13-2008, 06:56 AM

Quote:

Originally Posted by drummerboy2004

Thanks for the heads-up Gene

... I have the lifetime powertrain on mine (perk from Toyota when I bought it), but still has a 100 deductible after the original warranty... I guess I will have to rethink my game plan. Doesn't NICE-on coasting essentially do the same thing? I have found mixed answers on the subject.

Thanks,

Matt

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

voodoo22 · 11-13-2008, 06:59 AM

Quote:

Originally Posted by drummerboy2004

I have had to push my car into the spot like three times... I WILL NOT turn the car back on

... The thing that gets me is the wind, so beware. Oh, and I also try to keep my speeds between 30-40 (19tps)... but not 18 because unless you are on a downgrade you will slow quick. Hope that helps too...

Matt

Hehe, yeah, I almost didn't make it to my spot today because of all the rain water in the parking lot. Thanks for sharing.

drummerboy2004 · 11-13-2008, 08:30 AM

Quote:

Originally Posted by voodoo22

Hehe, yeah, I almost didn't make it to my spot today because of all the rain water in the parking lot. Thanks for sharing.

No prob bob

, and thanks for all of the info... Keep on FASing... well partially

Matt

MadMax · 11-13-2008, 09:09 AM

OK, I'm a noob...what is FAS and NICE-ON coasting?

Cheers! M2

voodoo22 · 11-13-2008, 10:27 AM

Quote:

Originally Posted by MadMax

OK, I'm a noob...what is FAS and NICE-ON coasting?

Cheers! M2

For the best list of different techniques and acronyms I've found, check out:

http://www.cleanmpg.com/forums/showthread.php?t=1510

Revsson · 11-13-2008, 10:37 AM

I had to look them up myself.

Another explaination is at their glossary page:

http://www.cleanmpg.com/forums/glossary.php

FAS = Forced Autostop
ICE = Internal Combustion Engine
NICE-on coasting = Coasting with the car in neutral while ICE running

Whew....learn something new everyday.....hmmm didn't my parent's tell me that?

11-08-2008, 11:35 AM	#1
MadMax Drives: 2008 Yaris Liftback (Sprocket) Join Date: Oct 2008 Location: San Antonio, Texas! Posts: 2,799	DFCO and Autos OK, this may have been discussed in the numerous other threads on DFCO and fuel economy; but I was hoping I could get some clarification on how to get DFCO to work with an auto. In an earlier thread on DFCO, it was believed that you had to tap the brake lightly to get the auto to downshift and engage the DFCO. Is this still the case, or can you simply let off the gas and let it kick in? Or, do you have to manually downshift into 3rd gear to get it to work? Right now I am "only" getting 35 MPG, but I do have bigger, wider tires (215/45ZR17 Riken Raptor ZRs) which will drop the fuel efficiency a bit; but I drive it very conservatively and mostly at highway speeds, so I was hoping for a little better (and yes, I do adjust my computations for the larger tires). I am hoping that I could utilize the DFCO capability better to improve my mileage. Cheers! M2

11-08-2008, 03:43 PM	#4
PreciousPups4U I really LOVE this car!!! View User's Garage Drives: 08 Bayou Blue LB AT Join Date: Oct 2008 Location: Lexington, SC USA Posts: 887	I have an auto and a scangauge. Like voodoo said it kicks in automatically when you take your foot off the gas. DFCO is just a fancy name for coasting seems to me. Course you get the most benefit when going down hill so as not to lose too much speed, but it works when approaching traffic lights and stop signs as well. I am only averaging 34 mpg by the way with the stock 15" alloys that came with the car. Not much highway driving for me though. Pretty much all city or at least traffic area. __________________ Cindy “If there are no dogs in Heaven, then when I die I want to go where they went.” - Will Rogers

11-11-2008, 02:45 AM	#6
drummerboy2004 Drives: 2008 Yaris LB Auto Join Date: Nov 2008 Location: Tampa, Fl Posts: 166	DFCO occurs in the auto whenever you are above 1100 RPMs with your foot off of the gas. I have a scanguage, and watch it happen every time. I am not sure about 1st gear though... I never see it happen when I am driving in my neighborhood less than 15 mph. It will read around 50 mpg when I am below 15 foot off the pedal. Hope this helps... Any other questions feel free to ask. Matt __________________

11-08-2008, 02:03 PM	#2
voodoo22 Drives: Yaris Sedan (auto) Join Date: Jun 2007 Location: Toronto, Ontario Posts: 545	Keep in mind that your new tire circumference will also affect your numbers. If your Yaris came with 15" rims you'll be getting numbers 3.7% lower when calculating your FE, but if your Yaris came with 14" tires your FE readings will be 7.2% off. If you haven't taken this into account and your Yaris came with 14" rims your 35mpg is actually 37.5mpg. I don't know how much of a hit, but add that initial inaccuracy in calculations on top of the affect of your much bigger tires and rims and you could easily be hurting yourself by reduced FE b/c of the plus size setup and miscalculations by over 10%. On DFCO; from what I've read; it engages as soon as you take your foot off the gas and your engine remains above 1100 rpms or thereabouts...

11-08-2008, 02:22 PM	#3
MadMax Drives: 2008 Yaris Liftback (Sprocket) Join Date: Oct 2008 Location: San Antonio, Texas! Posts: 2,799	Voodoo I do add 7% for the added dimension of the larger tire (I had an earlier thread and someone provided a web site that gave me that number), and that is calculated into my figures. It would seem logical that the DCO would kick in when you let off the gas, but I was wondering if anyone has ever tested it with a ScanGauge II on an auto... Cheers! M2

11-08-2008, 06:41 PM	#5
MadMax Drives: 2008 Yaris Liftback (Sprocket) Join Date: Oct 2008 Location: San Antonio, Texas! Posts: 2,799	PP4U Thanks, that's the kind of info I was looking for! Since I also have a Jeep Wrangler with an auto, so I am always trying to wrangle (pun intended) better mileage out of it. I get 15-16 MPG, another reason I wanted a Yaris to offset it! Cheers! M2

11-11-2008, 07:13 AM	#7
voodoo22 Drives: Yaris Sedan (auto) Join Date: Jun 2007 Location: Toronto, Ontario Posts: 545	Thanks for the feedback about pedal off and slow moving scanguage numbers. I was wondering it foot off the gas and slowly rolling in parking lots and towards stop signs was worth it.

11-11-2008, 01:38 PM	#9
voodoo22 Drives: Yaris Sedan (auto) Join Date: Jun 2007 Location: Toronto, Ontario Posts: 545	That's an amazing example about how much of a difference effort can make. Way to go. I've started FASing to my parking space since I start work before nearly everyone. It's kind of fun when you screw it up a little and end up just crawling into your spot.

11-13-2008, 09:09 AM	#16
MadMax Drives: 2008 Yaris Liftback (Sprocket) Join Date: Oct 2008 Location: San Antonio, Texas! Posts: 2,799	OK, I'm a noob...what is FAS and NICE-ON coasting? Cheers! M2

11-13-2008, 10:37 AM	#18
Revsson View User's Garage Drives: 2009 Meteorite Metallic LB MT Join Date: Oct 2008 Location: Southeast Wisconsin Posts: 810	I had to look them up myself. Another explaination is at their glossary page: http://www.cleanmpg.com/forums/glossary.php FAS = Forced Autostop ICE = Internal Combustion Engine NICE-on coasting = Coasting with the car in neutral while ICE running Whew....learn something new everyday.....hmmm didn't my parent's tell me that?