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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-23-2009, 09:11 PM   #61 (permalink)
PokÚmoderator
 
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 528 Times in 355 Posts
Christ -

Quote:
Originally Posted by Christ View Post
Woot for better mileage! I'm sure there's lots of places that you drive that would allow you to do this as well!
I did this last week on a steep downhill on the freeway (405 North on the way to the 101 East). I had to put it in 4th gear. I felt like a "sinner" because I was over 3100 RPM, but lo and behold the AFR gauge went lean so the fuel savings is there to be had.

CarloSW2

__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-23-2009, 09:33 PM   #62 (permalink)
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Quote:
Originally Posted by cfg83 View Post
Christ -



I did this last week on a steep downhill on the freeway (405 North on the way to the 101 East). I had to put it in 4th gear. I felt like a "sinner" because I was over 3100 RPM, but lo and behold the AFR gauge went lean so the fuel savings is there to be had.

CarloSW2
Carlos -

Next time, wait till the indicator goes lean, then quickly shift into a higher gear without letting the engine idle at all. You might stay in DFCO at a lower RPM that way. Worth a shot, I'd think?
__________________
"┐ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

  Reply With Quote
Old 08-23-2009, 09:35 PM   #63 (permalink)
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Of course, redline at WOT and redline at NoT are two completely different things. The engine isn't under anything close to as much stress while you're decelerating, so it's not as big a deal to rev it up a bit higher. (I used to downshift at or near redline on purpose, but upshift at 2500-3000)
__________________
"┐ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

  Reply With Quote
Old 08-23-2009, 10:27 PM   #64 (permalink)
PokÚmoderator
 
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 528 Times in 355 Posts
Christ -

Quote:
Originally Posted by Christ View Post
Of course, redline at WOT and redline at NoT are two completely different things. The engine isn't under anything close to as much stress while you're decelerating, so it's not as big a deal to rev it up a bit higher. (I used to downshift at or near redline on purpose, but upshift at 2500-3000)
Ok, I'll try the quick upshift next time. It would be cool if I can fool the ECU/PCM in this manner. It's just funny that 3100 RPM "feels" like a high RPM to me.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Old 08-23-2009, 10:43 PM   #65 (permalink)
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
When considering average range of operation, 3100 actually is high RPM. Most engines that aren't designed for spirited driving redline between 5500 and 6500, and you're halfway there... of course, you idle 1/6 of the way there.

Imagine you're driving a large diesel - you're engine braking at or near redline. :P

So, just to clarify - make sure that you shift somewhat abruptly, so that the RPM don't have to go back up while you're letting the clutch out. Try shifting without the clutch, if you're comfortable doing so.

I'm thinking that the ECU will think that you're just slowing down, and keep it in DFCO mode, unless it's still taking info from the VSS - at which point it may think you're crazy and:

Attached Thumbnails
Click image for larger version

Name:	RRoD360-1.jpg
Views:	70
Size:	108.3 KB
ID:	4045  
__________________
"┐ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

  Reply With Quote
Old 08-24-2009, 12:08 AM   #66 (permalink)
herp derp Apprentice
 
Join Date: Oct 2008
Location: Lawrence, KS
Posts: 1,044

Saturn-sold - '99 saturn sc1
Team Saturn
90 day: 28.28 mpg (US)

Yukon - '03 GMC Yukon Denali
90 day: 13.61 mpg (US)
Thanks: 43
Thanked 322 Times in 229 Posts
Quote:
Originally Posted by Christ View Post
Imagine you're driving a large diesel - you're engine braking at or near redline. :P
i believe gm got rid of the redline on the tach for the duramax after a couple years because of customer complaints of engine overspeed when decelerating or braking, because it was being used for engine braking far beyond where the engine makes useful power.

from bulletin #02-07-30-004C

For the LB7 diesel engine, maximum engine speed immediately following a preselect or grade braking downshift can be as high as 4,000 RPM. After a grade braking downshift, if vehicle speed continues to increase, an upshift will occur at 4,800 RPM engine speed.
  Reply With Quote
Old 08-24-2009, 12:11 AM   #67 (permalink)
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Quote:
Originally Posted by 2000mc View Post
i believe gm got rid of the redline on the tach for the duramax after a couple years because of customer complaints of engine overspeed when decelerating or braking, because it was being used for engine braking far beyond where the engine makes useful power.

from bulletin #02-07-30-004C

For the LB7 diesel engine, maximum engine speed immediately following a preselect or grade braking downshift can be as high as 4,000 RPM. After a grade braking downshift, if vehicle speed continues to increase, an upshift will occur at 4,800 RPM engine speed.
But this only happens at 0 throttle input, correct? If you touch the throttle, that signals the TCU to upshift the transmission immediately, which lowers the RPM - at least as far as I can remember from driving my boss's old diesel Chebby.
__________________
"┐ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

  Reply With Quote
Old 08-24-2009, 12:18 AM   #68 (permalink)
herp derp Apprentice
 
Join Date: Oct 2008
Location: Lawrence, KS
Posts: 1,044

Saturn-sold - '99 saturn sc1
Team Saturn
90 day: 28.28 mpg (US)

Yukon - '03 GMC Yukon Denali
90 day: 13.61 mpg (US)
Thanks: 43
Thanked 322 Times in 229 Posts
yea, just chiming in that even manufacturers use engine braking on diesels at such high rpm
  Reply With Quote
Old 08-24-2009, 01:02 AM   #69 (permalink)
PokÚmoderator
 
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 528 Times in 355 Posts
Christ -

Yup, my ECU/PCM is always messing with me :



CarloSW2

__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Reply  Post New Thread


Tags
hypermiling transmission

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Some Hypermiling techniques denounced by AAA Lazarus Hypermiling / EcoDriver's Ed 135 04-17-2011 04:07 AM
are there race style driving techniques for hypermiling? spyghost Hypermiling / EcoDriver's Ed 12 08-07-2008 11:16 AM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com