DFSO (deceleration fuel shut off) strategies and explanations - Ford Focus Forum, Ford Focus ST Forum
Ford Focus Forum
HomeContact UsAbout UsGalleryDiscussion ForumsMarketplace


Go Back   Ford Focus Forum, Ford Focus ST Forum > Ford Focus Third Generation > MK3 Focus

MK3 Focus The place to chat about general questions, window tinting, exterior body, interior and lighting upgrades for the third generation 2012-Current Focus.

Search This Forum | Image Search | Advanced Search    
Ford Focus Tire & Wheels FocusFanatics Merchandise

Reply
 
Thread Tools Display Modes
Old 03-06-2012, 08:38 PM   #1
GoShockers
Focus Enthusiast
 
Join Date: Mar 2012
Fan#: 95869
Location: Air Capitol, KS
What I Drive: 2012 Ford Focus SE Sport 6-Speed PS

Posts: 121
FF Reputation: 2 GoShockers Good Standing Member
Buy-Sell-Trade Rating: (0)
DFSO (deceleration fuel shut off) strategies and explanations

Hey friends,

I'm looking to find out every thing I can about the DFSO system in my new Focus. I have done some searching on this forum and have found bits and pieces, but perhaps a single thread on the topic can combine all the knowledge this forum holds into one place.

I am trying to create some hypermiling strategies and would like to know the speeds at which DFSO turns on and when it turns off. Also, I like manually turning on the AC button when I am coasting to the light and turning it off when the light turns green. I want to know if having the AC on as I am coasting down to the light will keep the DFSO from activating.

Thanks in advance!


GoShockers is offline  
    Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 03-06-2012, 09:14 PM   #2
csvt2060
Focus Addict
 
csvt2060's Avatar
 
Join Date: Mar 2011
Fan#: 84122
Location: Northwest Indiana, IN
What I Drive: 2013 Ford Escape Titanium

Posts: 772
FF Reputation: 2 csvt2060 Good Standing Member
Buy-Sell-Trade Rating: (0)
Best way to do this is with a scangauge and look at the closed/open loop status. On mine the DFSO would work with or without A/C and it would stay activated upon coast down until ~25MPH.
csvt2060 is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 01:24 AM   #3
GoShockers
Focus Enthusiast
 
Join Date: Mar 2012
Fan#: 95869
Location: Air Capitol, KS
What I Drive: 2012 Ford Focus SE Sport 6-Speed PS

Posts: 121
FF Reputation: 2 GoShockers Good Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by csvt2060 View Post
Best way to do this is with a scangauge and look at the closed/open loop status. On mine the DFSO would work with or without A/C and it would stay activated upon coast down until ~25MPH.
Thanks for the data point. And I realize that owning a scangauge is the way to go but not all of us have one of those. I was about to purchase an ultra-gauge until I learned of the battery drain problem.

Perhaps those with scanguages and technical knowledge on the DFSO system could share their knowledge in here so we all benefit. Can a person "feel" when the DFSO is activated?
GoShockers is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 08:46 AM   #4
Visioned
Focus Enthusiast
 
Join Date: Jan 2012
Fan#: 93729
Location: RSVL, AR
What I Drive: 2012, Red Candy, Focus SE

Posts: 322
FF Reputation: -1 Visioned Poor Behavior Needs Improvement
Buy-Sell-Trade Rating: (0)
I have a scangauge, if you tell me what to look for I can get the data for you.
Visioned is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 10:25 AM   #5
Altis
Focus Addict
 
Join Date: Sep 2011
Fan#: 89540
Location: Ottawa, ON, Canada
What I Drive: 2012 Sterling Grey SEL Hatch 5MT

Posts: 936
FF Reputation: 1 Altis Good Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by GoShockers View Post
..........Also, I like manually turning on the AC button when I am coasting to the light and turning it off when the light turns green. I want to know if having the AC on as I am coasting down to the light will keep the DFSO from activating.

Thanks in advance!
Just a heads up, doing this very frequently is actually quite hard on the actuator for the A/C. Whatever money you're trying to save on brakes by doing this, you may end up paying 10x for new A/C parts. Rather than using cheap brake pads, you're using an expensive climate control component to slow the car down.
Altis is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 12:59 PM   #6
DarinS
Focus Enthusiast
 
Join Date: Jul 2011
Fan#: 88257
Location: Portland, OR
What I Drive: 2012 Titanium hatch, BMW E30 335iC

Posts: 260
FF Reputation: 1 DarinS Good Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by Altis View Post
Just a heads up, doing this very frequently is actually quite hard on the actuator for the A/C. Whatever money you're trying to save on brakes by doing this, you may end up paying 10x for new A/C parts. Rather than using cheap brake pads, you're using an expensive climate control component to slow the car down.
I think he's trying to save on fuel, not brakes. But this is a very good point. You could never in a million years save enough fuel by activating/deactivating the A/C on decel to make up for the $1500 it will cost to replace the compressor and/or EM clutch.
DarinS is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 01:24 PM   #7
BetaDnB
Drum n Bass Lover
 
BetaDnB's Avatar
 
Join Date: Jul 2011
Fan#: 87466
Location: Buffalo, NY
What I Drive: 2012 Silver SE Sport

Posts: 2,010
Points 2,244, Level 28
Points: 2,244, Level: 28 Points: 2,244, Level: 28 Points: 2,244, Level: 28
Level Up 63% Completed
Level up: 63% Level up: 63% Level up: 63%
Forum Activity 3%
Activity: 3% Activity: 3% Activity: 3%
FF Reputation: 13 BetaDnB Great Standing Member
Buy-Sell-Trade Rating: (0)
The way I understand this system is the fuel system shuts down any time you're coasting in gear with no accelerator use. Since it's in gear the rolling of the tires keeps the engine cranking.
__________________
Sedan Revolution #249 - 2012 SE Sport - ╠╬╝ - Ingot Silver - 201A - K&N w/ snorkel delete - Blox Type R Knob
BetaDnB is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 01:36 PM   #8
kam327
-----<M>-----
 
kam327's Avatar
 
Join Date: Feb 2012
Fan#: 94700
Location: Tampa, FL
What I Drive: '14 Ruby Ti w/ Handling Pkg

Posts: 2,435
Points 6,210, Level 51
Points: 6,210, Level: 51 Points: 6,210, Level: 51 Points: 6,210, Level: 51
Level Up 30% Completed
Level up: 30% Level up: 30% Level up: 30%
Forum Activity 7%
Activity: 7% Activity: 7% Activity: 7%
FF Reputation: 12 kam327 Great Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by BetaDnB View Post
The way I understand this system is the fuel system shuts down any time you're coasting in gear with no accelerator use. Since it's in gear the rolling of the tires keeps the engine cranking.
The thing I can't wrap my head around with this is that if there's no fuel being injected then there's no combustion in the cylinders while coasting - wouldn't the engine sound be much different while coasting? Even no engine noise at all or just some kind of mechanical whirring sound?
kam327 is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 01:58 PM   #9
GoShockers
Focus Enthusiast
 
Join Date: Mar 2012
Fan#: 95869
Location: Air Capitol, KS
What I Drive: 2012 Ford Focus SE Sport 6-Speed PS

Posts: 121
FF Reputation: 2 GoShockers Good Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by Altis View Post
Just a heads up, doing this very frequently is actually quite hard on the actuator for the A/C. Whatever money you're trying to save on brakes by doing this, you may end up paying 10x for new A/C parts. Rather than using cheap brake pads, you're using an expensive climate control component to slow the car down.
I always heard that turning the AC button off and on was the same as the compressor cycling which it does continually when in use. Did I receive incorrect information? I did it a million times in my 2001 Focus and the engine died (thrown rod at 150k) before the air conditioner ever did.
GoShockers is offline  
    Reply With Quote Quick reply to this message
Old 03-07-2012, 02:03 PM   #10
GoShockers
Focus Enthusiast
 
Join Date: Mar 2012
Fan#: 95869
Location: Air Capitol, KS
What I Drive: 2012 Ford Focus SE Sport 6-Speed PS

Posts: 121
FF Reputation: 2 GoShockers Good Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by Visioned View Post
I have a scangauge, if you tell me what to look for I can get the data for you.
Thanks!

Do you notice the DFSO activating only at particular speeds; for example, only after decelerating from 50mph but not 40mph? Or does it turn on as long as your foot is off the gas and you are over 25mph? Also, have you ever seen it on under 25mph? And have you found the 3 second delay after lifting off the gas to be true in your experience?
GoShockers is offline  
    Reply With Quote Quick reply to this message
Reply

Bookmarks & Social Networks

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Focus Forum, Ford Focus ST Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 12:29 AM.


Copyright 2002-2014 FocusFanatics.com. All Rights Reserved : Privacy Policy : Advertise Information

Focus Fanatics Ford Focus Forum offers many fun ways for you to engage with other Ford Focus Owners from across the world. Whether it be about the aftermarket performance modifications, technical how-to's, European tuned suspension or awesome fuel economy similar to the Cadillac ATS-V, Ford Fusion and Acura TLX. You can find all Ford Focus and Focus ST related information here. Join our Ford Focus discussion forums and chat with local Focus enthusiasts in your area.