ScanGauge tuning - Page 2 - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 11-17-2008, 09:14 AM   #11
Site Team / Moderator
 
Jay2TheRescue's Avatar
 
Join Date: Sep 2008
Location: Northern Virginia
Posts: 4,657
Country: United States
Location: Northern Virginia
That was probably a big part of your problem. It was overestimating the size of your engine and fuel usage.

-Jay
__________________

__________________






Jay2TheRescue is offline   Reply With Quote
Old 11-17-2008, 09:23 AM   #12
Registered Member
 
Join Date: Jun 2008
Posts: 256
Country: United States
Quote:
Originally Posted by Jay2TheRescue View Post
Yes, the computer knows what size everything is, but the SG is trying to calculate fuel usage based on the live sensor data it reads. Knowing what size the engine is, how large the fuel tank is, and how many gallons are put in the tank at each fillup helps it calibrate.

-Jay
Yes, I switched the SG between my 2 vehicles and forgot to reset and it seemed off a little......then I realized and reset it.
__________________

__________________
Dave
GasSavers_GasUser is offline   Reply With Quote
Old 11-17-2008, 06:47 PM   #13
Registered Member
 
Rick Rae's Avatar
 
Join Date: Jun 2007
Posts: 240
Country: United States
Jay has you headed in the right direction, but let me draw a parallel so maybe this will all make more sense.

Quote:
Originally Posted by vectorg View Post
Are you saying my car's computer doesn't even know the displacement of it's own engine?
It's not about your ECC, it's about your Scangauge. The ECC isn't calculating your fuel efficiency and just handing the numbers over; it's busy managing the engine. Your Scangauge is doing that job based on speed, injector pulse width, and similar things.

Here's the parallel.

When you buy a new TV and hook it up to your cable, does it automagically know what channels are available? Nope. And the cable company doesn't send any sort of message that tells it, either.

So before you use your new cable-ready TV, you go into the setup menu and tell it to scan for available channels. It stops briefly on every possible channel to see if there's a signal. If it finds one, it marks that as a working channel, otherwise it marks it to be skipped in the future.

Similarly, the Scangauge doesn't know anything about the vehicle/engine/etc. to which its connected.

So like the new TV, before you can use your Scangauge effectively you have to tell it certain things about the car you've hooked it to, like the size of the gas tank and the engine displacement.

Displacement will get you into the right range for fuel efficiency, but be aware that your Scangauge is calculating (estimating) your fuel usage. It can make really, really good estimates, but the default displacement setting might be off a little for your particular engine (maybe one of the injectors is a little clogged or something; who knows?) That's what the tank refill adjustment is for. When you refill, you tell the Scangauge how many gallons you put in the tank. It then compares what the car really used with what it thought should have been used, and works out a correction percentage. Usually a single tank will do it; if not, the second surely will. After that you'll just bounce around due to slightly different fill levels and other variables.

Once you have the adjustment factor set (or really close), you don't have to mess with it again. Just do a quick sanity check to make sure the refill is close to what the Scangauge was expecting, then hit the "fillup" button to tell it you're starting a fresh tank.

Does that help it make sense?

Rick
__________________
Rick Rae is offline   Reply With Quote
Old 11-18-2008, 06:57 AM   #14
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Quote:
Originally Posted by Rick Rae View Post
Your Scangauge is doing that job based on speed, injector pulse width, and similar things.
Actually, the ScanGauge doesn't have access to injector pulse width or duty cycle, which is not part of OBDII data. It estimates based on the MAF and O2 data, which tells it how much air goes in and what the A/F ratio is.

That's another reason you have to fine-tune it manually.
__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 11-18-2008, 09:29 AM   #15
Registered Member
 
Rick Rae's Avatar
 
Join Date: Jun 2007
Posts: 240
Country: United States
Quote:
Originally Posted by theholycow View Post
Actually, the ScanGauge doesn't have access to injector pulse width or duty cycle, which is not part of OBDII data.
I'm glad I disclaimed my comment with "and similar things" then.

Thanks for the correction.

The principle I cited remains the same.

Rick
__________________
Rick Rae is offline   Reply With Quote
Old 11-18-2008, 06:46 PM   #16
Registered Member
 
Join Date: Jun 2008
Posts: 33
Country: United States
Thanks, Rick, that was a good explanation. Changing from 3.0 to 2.2 liters made a big difference in my mileage reading. But now I understand that I need to enter some more info when I do my fillups. Got it.
__________________

vectorg is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Someone scratched up my car!!! AMX General Discussion (Off-Topic) 2 06-07-2008 12:43 PM
dead battery? lunarhighway General Maintenance and Repair 8 12-20-2007 02:07 AM
Saturn TDI for S-Series cfg83 Diesels 14 10-02-2007 02:24 PM
Anyone have experience making their own solar panels? MetroMPG Electric and Solar powered 17 08-29-2007 06:43 PM
Atlanta Auto Show GasSavers_DaX General Discussion (Off-Topic) 26 05-07-2006 06:02 PM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 01:51 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.