Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-27-2010, 09:06 PM   #11 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Silly-Con Valley
Posts: 1,471
Thanks: 191
Thanked 257 Times in 194 Posts
As to why your car drops out of DFCO after a while, there are almost always RPM limits for DFCO. After all, if they left the injectors off all the way down to 0 RPM, you'd have to use the key to start again and that wouldn't be so great.

It is also possible that Ford engineers decided that running in DFCO for more than X amount of time ran some risk they didn't want to run. I'm not sure what sort of risk that could be, though. You should still be pulling a vacuum so the brakes should keep working; with no fuel and no spark you shouldn't be putting a thermal load on the engine (just compression heating which isn't nearly as much as combustion heating); the field coil on the alternator should still be energized so the charging system should still be charging... No, no idea why they'd do that.

-soD

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-27-2010, 09:17 PM   #12 (permalink)
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,864

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 529 Times in 356 Posts
some_other_dave -

Quote:
Originally Posted by some_other_dave View Post
As to why your car drops out of DFCO after a while, there are almost always RPM limits for DFCO. After all, if they left the injectors off all the way down to 0 RPM, you'd have to use the key to start again and that wouldn't be so great.

It is also possible that Ford engineers decided that running in DFCO for more than X amount of time ran some risk they didn't want to run. I'm not sure what sort of risk that could be, though. You should still be pulling a vacuum so the brakes should keep working; with no fuel and no spark you shouldn't be putting a thermal load on the engine (just compression heating which isn't nearly as much as combustion heating); the field coil on the alternator should still be energized so the charging system should still be charging... No, no idea why they'd do that.

-soD
My car usually exits DFCO around 2500 RPM in 3rd or 4th gear. I wish it was around 1000 RPM, but maybe that's too close for comfort because idle RPM is about 850.

If the Ford has unheated oxygen sensors, then a long period of time would cool off the sensor and it wouldn't read correctly. A cold oxygen sensor would encourage the ECU/PCM to switch from closed-loop to open-loop mode, which is not good for MPG.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society

Last edited by cfg83; 08-27-2010 at 09:58 PM..
  Reply With Quote
Old 08-28-2010, 04:27 AM   #13 (permalink)
Master EcoModder
 
euromodder's Avatar
 
Join Date: Jul 2010
Location: Belgium
Posts: 4,683

The SCUD - '15 Fiat Scudo L2
Thanks: 178
Thanked 649 Times in 514 Posts
Quote:
Originally Posted by cfg83 View Post
Yes, but I think DFCO has a strategic purpose for us.
However, if I can get engine-braking + DFCO on the downhill, I can avoid using my brakes and risking dangerous speeds.
Going down a rather steep incline, you obviously have no choice but to remain in gear and use engine braking.

If gravity is propelling your car, DFCO is better than coasting with the engine on as there is no fuel use at all using DFCO.

But on the near-flat terrain where I live, engine-on coasting is definitely better for FE than DFCO and trying to brake as little as possible.
__________________
Strayed to the Dark Diesel Side

  Reply With Quote
Old 08-28-2010, 11:06 AM   #14 (permalink)
Master EcoModder
 
comptiger5000's Avatar
 
Join Date: Feb 2010
Location: CT, USA
Posts: 544

RaceJeep - '98 Jeep Grand Cherokee (ZJ) 5.9 Limited
90 day: 13.62 mpg (US)
Thanks: 1
Thanked 26 Times in 23 Posts
Exactly as Euromodder said. DFCO is best used for when you have no choice but to bleed off momentum. At least you can keep the engine from using fuel while doing so, plus it saves wear on your brakes.
__________________
Call me crazy, but I actually try for mpg with this Jeep:



Typical driving: Back in Rochester for school, driving is 60 - 70% city
  Reply With Quote
Old 08-29-2010, 11:12 PM   #15 (permalink)
EcoModding Lurker
 
Join Date: Dec 2008
Location: Aurora, CO
Posts: 45
Thanks: 2
Thanked 11 Times in 6 Posts
The beauty of many of the roads I drive, I suppose, is lots of time to watch the guages.
My DFCO cuts off at ~2000 rpm regardless of time.
Coming down a hill, the water temp will drop to ~192 with engine-on coasting, temps hold ~198 with RPM's in the mid 2000's and no fuel, temps climb to ~206 with RPM's in the mid 3000's during prolonged no fuel engine braking. An 8 mile down grade of consistent 6 or 7% (I-70 tunnel to Silverthorne) will have me cycle between DFCO and engine-on coasting several times. Pulling a trailer I can't really coast out of gear though or I'll melt my brakes.
I'll bet the exhaust gas temps are the reason for cutting off the cut off. Too bad, most of those descents transition into climbs, and temps will jump right back up with hardly any wait at all.
__________________
  Reply With Quote
Old 09-02-2010, 12:29 AM   #16 (permalink)
Legend in my own mind
 
trikkonceptz's Avatar
 
Join Date: Apr 2008
Location: Homestead, Fl.
Posts: 927

Evil Pumpkin - '08 Scion xD RS 1.0 #1633
90 day: 35.45 mpg (US)

Silent Silver Killer - '10 Honda Insight EX
90 day: 51.5 mpg (US)
Thanks: 2
Thanked 13 Times in 12 Posts
Understanding its purpose and use how come DFCO reads 9999 on the scangauge while EOC reads somewhere in the ball park of lets say 2800 mpg's, why not 9999 as well?
__________________
Thx NoCO2; "The biggest FE mod you can make is to adjust the nut behind the wheel"

I am a precisional instrument of speed and aeromatics
If your knees bent in the opposite direction......what would a chair look like???





  Reply With Quote
Old 09-02-2010, 08:57 AM   #17 (permalink)
Master EcoModder
 
Join Date: Jun 2010
Location: scotland
Posts: 1,423

The Mistress - '88 Bmw 320i Touring SE
Team m8
Last 3: 27.17 mpg (US)

Germany Beadle - '91 Mercedes 300td (estate, N/A)
90 day: 24.63 mpg (US)

The Bloodylingo - '05 Citroen Berlingo Multispace Desire
90 day: 39.77 mpg (US)

Shanner Scaab - '03 Saab 9-5 estate Vector
90 day: 26.19 mpg (US)
Thanks: 88
Thanked 86 Times in 72 Posts
In my daily commute, I've started adding a DFCO phase to the endo of my EO(n)C sections..

this presents the ideal opportunity to slow the car for the ROundabout/junction

Using no fuel and being in the right gear for picking away again!

The OBC shows its a positive step..

fingers crossed it works on this tank!
  Reply With Quote
Old 09-02-2010, 02:15 PM   #18 (permalink)
Master EcoModder
 
euromodder's Avatar
 
Join Date: Jul 2010
Location: Belgium
Posts: 4,683

The SCUD - '15 Fiat Scudo L2
Thanks: 178
Thanked 649 Times in 514 Posts
Quote:
Originally Posted by 320touring View Post
In my daily commute, I've started adding a DFCO phase to the end of my EO(n)C sections..
If you can't start coasting from further out, DFCO is the way to go for the last part of the glide.

I've done the opposite, adding E-On-Coasting to a long habit of DFCO
__________________
Strayed to the Dark Diesel Side

  Reply With Quote
Old 09-02-2010, 02:24 PM   #19 (permalink)
Master EcoModder
 
euromodder's Avatar
 
Join Date: Jul 2010
Location: Belgium
Posts: 4,683

The SCUD - '15 Fiat Scudo L2
Thanks: 178
Thanked 649 Times in 514 Posts
Quote:
Originally Posted by trikkonceptz View Post
Understanding its purpose and use how come DFCO reads 9999 on the scangauge while EOC reads somewhere in the ball park of lets say 2800 mpg's, why not 9999 as well?
As you're not using any fuel anymore, both should see "infinite" mileage ...
It's got to be a software thing.


Driving my sister's Skoda Fabia 1.4 Diesel, I've noticed its fuel consumption indicator switches to the hourly fuel consumption when you're stopped.
(I got 3,6 L/100 km or 65.3 mpg BTW, without even trying hard)
__________________
Strayed to the Dark Diesel Side

  Reply With Quote
Old 09-02-2010, 02:45 PM   #20 (permalink)
NightKnight
 
NachtRitter's Avatar
 
Join Date: Dec 2008
Location: Placerville, CA
Posts: 1,594

RippinRoo - '05 Subaru Legacy Wagon 2.5 GT
Subaru
90 day: 21.16 mpg (US)

Helga - '00 Volkswagen Jetta TDI
TEAM VW AUDI Group
Diesel
90 day: 53.91 mpg (US)

Olga - '03 Volkswagen Jetta Wagon
90 day: 46.24 mpg (US)
Thanks: 303
Thanked 311 Times in 186 Posts
Quote:
Originally Posted by trikkonceptz View Post
Understanding its purpose and use how come DFCO reads 9999 on the scangauge while EOC reads somewhere in the ball park of lets say 2800 mpg's, why not 9999 as well?
When you say EOC, do you mean Engine On Coast or Engine Off Coast?

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
ScanGauge II does not show open loop under DFCO? Pappnese Instrumentation 6 09-06-2010 05:47 AM
Manual DFCO, EGR, accessory belt "clutches" usergone EcoModding Central 11 05-24-2010 11:14 PM
Civic DFCO Conditions ben98gs EcoModding Central 9 04-30-2010 09:26 PM
Is DFCO bad for fuel pumps?? thatguitarguy EcoModding Central 5 03-02-2010 06:30 PM
Help identify and explain... SirKeats Off-Topic Tech 6 05-28-2008 06:34 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com