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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 10-02-2013, 04:15 PM   #21 (permalink)
The PRC.
 
Join Date: Oct 2009
Location: Elsewhere.
Posts: 5,304
Thanks: 285
Thanked 535 Times in 384 Posts
Quote:
Originally Posted by christofoo View Post
Am I wrong in believing the OBD-based-MPG-gauges are calculating fuel rate primarily from the MAF sensor? OBD-II PIDs - Wikipedia, the free encyclopedia.
Possibly - you may be right or wrong.

My point is that the SG2 is pulling the data from the OBD port at regular intervals, so if you acclerate fast and it has fewer data points to average from, accelerate slowly and it can more or less log every change and be more accurate.

IMHO based on this idea I suspect the overall result between fast and slow acceleration is equal in terms of real fuel cost.

The real way to test this is to top the tank from a can, do some runs with sharp accel, top it again and measure the fuel used. Then top it off and repeat with slow accel for the same number of runs on the same circuit.

Otherwise this data doesn't really mean much IMHO.

__________________
[I]So long and thanks for all the fish.[/I]
  Reply With Quote
The Following 2 Users Say Thank You to Arragonis For This Useful Post:
ECOHondaOdyssey (10-02-2013), pgfpro (10-03-2013)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 10-03-2013, 01:34 PM   #22 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,579

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 66.29 mpg (US)
Thanks: 3,362
Thanked 6,155 Times in 3,189 Posts
Quote:
Originally Posted by Arragonis View Post
My point is that the SG2 is pulling the data from the OBD port at regular intervals, so if you acclerate fast and it has fewer data points to average from, accelerate slowly and it can more or less log every change and be more accurate.
Confirmed by Linear Logic just now:

Quote:
The RATE adjustment is both for the ScanGauge display update, and the sampling rate.

Accelerating slower would give a more accurate average based on having more data points to compute the average with.
Also note: RATE is user-configurable to update "Fast" about every half second, compared to "Normal" about once per second. "Normal" is the default rate, and it resets to that every time the SG goes to sleep (on my release).
__________________
Latest mods: 3-cylinder Mitsubishi Mirage. EcoMods now in progress...
Ecodriving test:
Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
The Following 2 Users Say Thank You to MetroMPG For This Useful Post:
Arragonis (10-03-2013), pgfpro (10-04-2013)
Old 10-03-2013, 01:39 PM   #23 (permalink)
Master EcoModder
 
mechman600's Avatar
 
Join Date: Jul 2008
Location: Langley, BC
Posts: 1,226

Fusion - '16 Ford Fusion Hybrid SE
Thanks: 190
Thanked 272 Times in 166 Posts
Mine is set to "Fast". If the screen refresh rate is the same as the actual data sample rate, that's about one sample per second.
  Reply With Quote
Old 10-03-2013, 03:08 PM   #24 (permalink)
In Lean Burn Mode
 
pgfpro's Avatar
 
Join Date: Apr 2009
Location: Pacific NW
Posts: 1,427

MisFit Talon - '91 Eagle Talon TSi
Team Turbocharged!
90 day: 41.03 mpg (US)
Thanks: 1,031
Thanked 483 Times in 315 Posts
Normal sample rates for todays ecu's are over 1000 per second.
__________________
Pressure Gradient Force
The Positive Side of the Number Line

  Reply With Quote
Old 10-03-2013, 03:14 PM   #25 (permalink)
The PRC.
 
Join Date: Oct 2009
Location: Elsewhere.
Posts: 5,304
Thanks: 285
Thanked 535 Times in 384 Posts
Quote:
Originally Posted by Linear Logic via MetroMPG
Accelerating slower would give a more accurate average based on having more data points to compute the average with.
This is what I meant.
__________________
[I]So long and thanks for all the fish.[/I]
  Reply With Quote
Old 10-03-2013, 03:24 PM   #26 (permalink)
The PRC.
 
Join Date: Oct 2009
Location: Elsewhere.
Posts: 5,304
Thanks: 285
Thanked 535 Times in 384 Posts
Quote:
Originally Posted by pgfpro View Post
Normal sample rates for todays ecu's are over 1000 per second.
Do you have a source for that ? I think you are right but I would like to know. I remember reading stuff about ECUs in the late 80s and the computers even then (8bit "industrial" CPUs) had to be underclocked to even know that an engine was connected.

The on board displays are just as bad - the one in Hermann is hopelessly optimistic by as much as 10% more or less all the time.
__________________
[I]So long and thanks for all the fish.[/I]
  Reply With Quote
Old 10-03-2013, 03:45 PM   #27 (permalink)
Master EcoModder
 
mechman600's Avatar
 
Join Date: Jul 2008
Location: Langley, BC
Posts: 1,226

Fusion - '16 Ford Fusion Hybrid SE
Thanks: 190
Thanked 272 Times in 166 Posts
Quote:
Originally Posted by pgfpro View Post
Normal sample rates for todays ecu's are over 1000 per second.
Everyone here knows/assumes that. But we are not talking about ECU sample rates at all. We are talking about ScanGauge sample rates, which seems to be one per second.
  Reply With Quote
Old 10-03-2013, 04:56 PM   #28 (permalink)
The PRC.
 
Join Date: Oct 2009
Location: Elsewhere.
Posts: 5,304
Thanks: 285
Thanked 535 Times in 384 Posts
Quote:
Originally Posted by mechman600 View Post
Everyone here knows/assumes that. But we are not talking about ECU sample rates at all. We are talking about ScanGauge sample rates, which seems to be one per second.
With respect you are confusing the rate at which the SG2 refreshes it's display with the rate at which it samples data behind the scenes.
__________________
[I]So long and thanks for all the fish.[/I]
  Reply With Quote
Old 10-03-2013, 06:08 PM   #29 (permalink)
Master EcoModder
 
mechman600's Avatar
 
Join Date: Jul 2008
Location: Langley, BC
Posts: 1,226

Fusion - '16 Ford Fusion Hybrid SE
Thanks: 190
Thanked 272 Times in 166 Posts
Quote:
Originally Posted by Arragonis View Post
With respect you are confusing the rate at which the SG2 refreshes it's display with the rate at which it samples data behind the scenes.
Are they not the same? I cannot find any published information about display vs data sampling rates.

I assumed by your original argument that the data sampling rate also must be quite slow if it is inaccurate during fast acceleration.
  Reply With Quote
Old 10-03-2013, 10:02 PM   #30 (permalink)
EcoModding Lurker
 
Join Date: Oct 2013
Location: Maryland
Posts: 16

Amelia Pond - '13 Honda CR-Z Base
Thanks: 0
Thanked 1 Time in 1 Post
Awesome information! I will have to look and see how this reflects in my Auto CRZ

  Reply With Quote
Reply  Post New Thread


Thread Tools




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