Go Back   EcoModder Forum > EcoModding > Hypermiling / EcoDriver's Ed
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 04-22-2011, 08:22 PM   #1 (permalink)
EcoModding Lurker
 
Join Date: Feb 2011
Location: Florida
Posts: 13

Van - '00 Chevy Astro 2WD Passenger
Thanks: 8
Thanked 0 Times in 0 Posts
Hypermiling Question

One of the Hypermiling tips, number 76 to be exact, says to switch to neutral when stopped (in an automatic vehicle) to avoid the car trying to creep forward. This makes sense to me, but I've noticed (in 2 cars, an Acura TL and a VW Beetle), that when I am stopped and shift to neutral, the RPM's climb ever so slightly. That got me wondering if that climb in RPM's offsets the amount of fuel saved in shifting to neutral in the first place. Any ideas?
Thanks guys, I'm just curious :P

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 04-22-2011, 08:48 PM   #2 (permalink)
UFO
Master EcoModder
 
UFO's Avatar
 
Join Date: Sep 2010
Location: Denver, CO
Posts: 1,300

Colorado - '17 Chevrolet Colorado 4x4 LT
90 day: 23.07 mpg (US)
Thanks: 315
Thanked 178 Times in 138 Posts
My Scangauge tells me fuel consumed idling in neutral vs in drive is roughly half. I bet that is common to most automatics. It's the engine load that consumes fuel, and a small rpm spike does not take much.
__________________
I'm not coasting, I'm shifting slowly.
  Reply With Quote
Old 04-22-2011, 10:56 PM   #3 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,746

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,573
Thanked 3,517 Times in 2,201 Posts
Plus if there's brake lights on vs off...
__________________


  Reply With Quote
Old 04-23-2011, 02:22 AM   #4 (permalink)
Master EcoModder
 
metroschultz's Avatar
 
Join Date: Dec 2007
Location: Norfolk, Va. USA
Posts: 869

CPT SLO - '93 GEO Metro plainjane
90 day: 53.91 mpg (US)

SilverHairBeauty - '01 Toyota Avalon XL
90 day: 24.06 mpg (US)
Thanks: 14
Thanked 33 Times in 28 Posts
Send a message via AIM to metroschultz
Quote:
Originally Posted by UFO View Post
My Scangauge tells me fuel consumed idling in neutral vs in drive is roughly half. I bet that is common to most automatics. It's the engine load that consumes fuel, and a small rpm spike does not take much.
My wife and I had this same discussion in her Avalon.
I was able to show her on the SGII that at idle, in neutral fuel consumption is .4 gph. In drive, at idle fuel consumption was .75 gph.
Almost twice as much fuel burned per hour at idle in drive v neutral.
Even though the idle went up by 100 rpm.
__________________


When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity.
Albert Einstein
  Reply With Quote
The Following User Says Thank You to metroschultz For This Useful Post:
JohnnyRun (04-26-2011)
Old 04-23-2011, 04:33 AM   #5 (permalink)
Wiki Writer
 
Join Date: Jul 2010
Location: Melbourne, Australia
Posts: 236

bugler - '91 Mazda 626
90 day: 35.89 mpg (US)
Thanks: 15
Thanked 25 Times in 22 Posts
It seems to depend how your car controls its idle. In my relatively old auto mazda 626 91 year without any modification it would use up the same or a little bit more fuel if i put it into neutral. This was because the idle went up with the reduced engine load.
If the car actively controls the idle RPMs then the car will use less fuel when idling in neutral compared to drive.
The best way you can tell is to use a scan gauge or similar device.

As a general rule of thumb (that i am making up right now) if your idle goes up by more than about 50 rpm its likely your car will use the same or more fuel when idling in neutral compared to drive.

Note: some cars can be put into a "idle tuning" mode where the idle control will be turned off or set to a particular level. If your able to do this you can manually tune the idle with the set screw so that when you turn off the engine idle control, the car will idle as low as you set it. This works only when you can place a switch for this in the engine cabin otherwise the engine might stall with low RPM when in drive at the lights
  Reply With Quote
Old 04-23-2011, 05:24 AM   #6 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,746

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,573
Thanked 3,517 Times in 2,201 Posts
Why do the mfg's set the idle the way they do, when they have complete control of it?
__________________


  Reply With Quote
Old 04-23-2011, 02:44 PM   #7 (permalink)
EcoModding Apprentice
 
Join Date: Apr 2011
Location: Orange Country, CA
Posts: 102

Fiesta - '12 Ford Fiesta SE
90 day: 31.45 mpg (US)
Thanks: 36
Thanked 3 Times in 3 Posts
My check engine light came on and its cuz the idle throttle is too high, made a big difference in my mpg. when i put it in neutral at a stop it went up about 300-400 rpm. Getting that fixed thursday! so much wasted gas >X(
  Reply With Quote
Old 04-24-2011, 06:13 PM   #8 (permalink)
EcoModding Lurker
 
Join Date: Feb 2011
Location: Florida
Posts: 13

Van - '00 Chevy Astro 2WD Passenger
Thanks: 8
Thanked 0 Times in 0 Posts
Woah, thanks for all the responses guys! I'm definitely looking into getting a ScanGauge or something similar. Which would you guys recommend? I'm taking price and function into consideration because ScanGauge's seem pretty expensive to me, and I saw an ad on this site for one (I forget the name), but was like 50 dollars. Any tips from people who've used both?
  Reply With Quote
Old 04-24-2011, 07:36 PM   #9 (permalink)
Master EcoModder
 
vskid3's Avatar
 
Join Date: Jun 2008
Location: Utah
Posts: 975

Civic DX (sold) - '97 Honda Civic DX
90 day: 34.15 mpg (US)

GTO (sold) - '04 Pontiac GTO
90 day: 22.62 mpg (US)

Green Brick (sold) - '06 Ford Escape Hybrid
90 day: 31.93 mpg (US)
Thanks: 193
Thanked 311 Times in 220 Posts
Ultragauge is probably what you're thinking of. I have one and I like it. If cheap is best for you and there isn't something specific you need from the scangauge (like a certain x-gauge), I would highly recommend it.
  Reply With Quote
The Following User Says Thank You to vskid3 For This Useful Post:
JohnnyRun (04-25-2011)
Old 04-25-2011, 06:02 PM   #10 (permalink)
EcoModding Lurker
 
Join Date: Feb 2011
Location: Florida
Posts: 13

Van - '00 Chevy Astro 2WD Passenger
Thanks: 8
Thanked 0 Times in 0 Posts
That sounds really good, I just wanna be able to raise my mpg's haha. Does the Ultragauge allow me to see trip MPG and best MPG? Thats what I think is most important, right?

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com