Experiment for VXers - Fuelly Forums

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

Reply
 
Thread Tools Display Modes
 
Old 05-12-2008, 05:50 PM   #1
Registered Member
 
1993CivicVX's Avatar
 
Join Date: Aug 2007
Posts: 1,066
Country: United States
Send a message via AIM to 1993CivicVX
Experiment for VXers

Maybe some of us VX owners should perform a little experiment. That is, to avoid full enrichment mode for an entire tank. So, if we need more power, down shift rather than go into full enrichment mode. If you think this is a worthwhile experiment, let me know. I think it might be more valuable if more than one of us does.
__________________

__________________
three stripes the charm!

Car mods are overrated. Just gotta adjust that nut behind the wheel for best mpg.



Forget about World Peace...Visualize using your turn signal.
1993CivicVX is offline   Reply With Quote
Old 05-12-2008, 09:12 PM   #2
Registered Member
 
Danronian's Avatar
 
Join Date: Aug 2007
Posts: 652
Country: United States
This is something I always try to do (not go into vtec), but I'm always forced to mainly to merge into traffic.
__________________

__________________


On the never-ending quest for better gas mileage...
Danronian is offline   Reply With Quote
Old 05-13-2008, 06:58 AM   #3
Registered Member
 
GasSavers_TomO's Avatar
 
Join Date: Oct 2006
Posts: 1,108
Country: United States
Send a message via AIM to GasSavers_TomO Send a message via MSN to GasSavers_TomO Send a message via Yahoo to GasSavers_TomO
It's pretty hard for me to avoid it as well since I have to merge onto highways a couple times a day

I do have another experiment going that I will post results for us VX (and other Honda Owners) In fact I might get that thread going today.
__________________

Honda Civic VX Info/Links
Remember to use good Webiquette!
Quote:
Originally Posted by ezeedee View Post
controversy is an idea thought up by weak people who are too afraid to hear the truth.
GasSavers_TomO is offline   Reply With Quote
Old 05-13-2008, 07:09 AM   #4
Registered Member
 
Join Date: Apr 2008
Posts: 1,256
Country: United States
Location: wiliamsburg virigina
That is exactly what I have been trying to do since I read it was possible to climb a slight grade and stay in lean burn.

Does anyone know the approximate maximum throttle position where lean burn can be maintained?

If so I may rig up a throttle position sensor to make sure I am keeping it in lean burn.

regards
gary
__________________
R.I.D.E. is offline   Reply With Quote
Old 05-13-2008, 07:55 AM   #5
Registered Member
 
GasSavers_TomO's Avatar
 
Join Date: Oct 2006
Posts: 1,108
Country: United States
Send a message via AIM to GasSavers_TomO Send a message via MSN to GasSavers_TomO Send a message via Yahoo to GasSavers_TomO
It's not so much throttle position that determines Lean Burn but engine load. You can tap into the Throttle Position Sensor (TPS) with a Digital Multimeter (DMM) and watch the voltage. < .45VDC is 0% throttle >4.5VDC is 100% throttle on Hondas.
__________________

Honda Civic VX Info/Links
Remember to use good Webiquette!
Quote:
Originally Posted by ezeedee View Post
controversy is an idea thought up by weak people who are too afraid to hear the truth.
GasSavers_TomO is offline   Reply With Quote
Old 05-15-2008, 01:09 PM   #6
Registered Member
 
mkiVX's Avatar
 
Join Date: Dec 2007
Posts: 49
Country: United States
well i climb the cajon pass all the time.
it goes from 700ft to 4200 ft in 12 miles so its a high speed climb
i have to get in the truck lane to climb that pass if i want to stay in lean burn
it is tough to keep the car in lean burn.
its pretty much engine load like tom said.
you can get in to lean burn in second 3 4 5 gears.
to be honest with you it seems to coincide with the shift light.
if you are climbing a grade and you keep the shift light on it stays in lean burn.
when it shuts the shift light off it feels stronger and lean burn is not on.
i don't shift when the shift light advises me to any more.
i sometimes have to go 35 mph to stay in lean burn
and it still gets over 47 mpg. before i used to climb as far as i could in high gear and then when i needed o downshifted. ever since i keep lean burn on it really shines in the FE section
__________________
VX MASTER

SHWINN MOUNTAIN BIKE
GAS SAVER FAT BURNER

TOTAL MILES DISPLACED BY SHWIIN ON THE WAY TO WORK. 45 TOTAL MILES
mkiVX is offline   Reply With Quote
Old 05-19-2008, 02:03 AM   #7
Registered Member
 
Join Date: Mar 2008
Posts: 408
Country: United States
Quote:
Originally Posted by 1993CivicVX View Post
avoid full enrichment mode for an entire tank
I didn't see this thread until a few minutes ago. I didn't even realize there was an Experiments section! But I guess great minds think alike, because yesterday I did the experiment you thought of (not for an entire tank, but at least for an entire fill). I was prompted by discussion here: http://www.gassavers.org/showthread.php?t=7400. In particular I was thinking about the relative merits of maximizing lean burn vs. minimizing pumping losses. (My car is a '95 VX; eventually I'll get it into the garage.)

Yesterday I needed to visit a town about 100 miles away. Mostly highway. I haven't been doing much highway lately, so I thought this would be a good chance for an experiment. I had two passengers along with me (both ways).

I filled before leaving very early in the morning (call that the start of Leg A). In the afternoon I filled again, after I started back home (call this fill the start of Leg B). Then I filled again at home.

For Leg A, I used my normal P&G technique. This means alternating WOT with coasting in neutral. (Normally I use some EOC, but in this experiment I excluded that. I also excluded drafting.) When I'm doing this P&G routine, I try very hard to avoid any throttle setting other than WOT (and zero, of course). I used a speed range of 50-65 mph.

I'm using a DMM to monitor AFR. During WOT, there's obviously full enrichment. On my car, that means a reading of about -0.8v. So that's the reading I saw for pretty much the full trip (except when I was coasting, of course).

The duration of lean burn during Leg A was probably close to 0%. Aside from idling while coasting, of course. That produces a reading of about +0.2v.

For Leg B, I drove very, very differently. I tried to always use the smallest possible throttle opening. I never got anywhere near WOT. I had my eyes glued to the DMM, trying to maximize lean burn. I did this by using the smallest possible throttle opening that would maintain 57 mph. I would let my speed drop to 50 mph (which would happen going uphill, obviously), but not below (to create a fair comparison to Leg A).

Going downhill, I did some coasting in neutral, when the grade was steep enough to make it worthwhile. But mostly I tried to maintain a steady speed, with the smallest possible throttle opening.

Maximum lean on my car produces a reading of about +0.8v. For about 80% of Leg B I was looking at a reading of roughly +0.6v. Obviously there were a few moments of richness, but they were very brief, and I think never beyond -0.3v.

Leg A yielded 55.8 mpg. Leg B yielded 51.2 mpg.

I obviously would have done better (on both legs) without the two passengers, and if I had been willing to go slower. Maybe a maximum of 60 mph instead of 65.

I find the results interesting, even though it's only one trial, and even though 200 miles (round-trip) isn't a huge distance, and even though I used two different pumps. It was the same car, same driver, same passengers, same route, same day. And basically the same speed.

By the way, the ambient temp was about 20 degrees higher for Leg B.
monroe74 is offline   Reply With Quote
Old 05-19-2008, 02:03 AM   #8
Registered Member
 
Join Date: Mar 2008
Posts: 408
Country: United States
Quote:
Originally Posted by 1993CivicVX View Post
avoid full enrichment mode for an entire tank. So, if we need more power, down shift rather than go into full enrichment mode.
Quote:
Originally Posted by Danronian View Post
This is something I always try to do (not go into vtec), but I'm always forced to mainly to merge into traffic.
There might be some confusion here. VTEC-E and lean burn are not the same thing. The VTEC-E transition happens at 2500 rpm. By downshifting, you might be crossing that threshold.

Anyway, I think my experiment tends to show that you're probably better off with the higher gear and the higher throttle opening, even though this means no lean burn. It also means you haven't crossed the VTEC-E threshold, most likely. In a VX, 2500 rpm in top gear is about 70 mph.
monroe74 is offline   Reply With Quote
Old 05-19-2008, 02:03 AM   #9
Registered Member
 
Join Date: Mar 2008
Posts: 408
Country: United States
Quote:
Originally Posted by R.I.D.E. View Post
Does anyone know the approximate maximum throttle position where lean burn can be maintained?
My experience is that it tends to be quite low. Probably 10-20%.

Quote:
If so I may rig up a throttle position sensor to make sure I am keeping it in lean burn.
Your car already has a Throttle Angle Sensor, which you can read with a DMM (as Tom mentioned). But it would probably make more sense to simply read the O2 sensor directly.

Also, I think I have discovered that going out of your way to keep the car in lean burn has a negative payoff.
monroe74 is offline   Reply With Quote
Old 05-19-2008, 02:03 AM   #10
Registered Member
 
Join Date: Mar 2008
Posts: 408
Country: United States
Quote:
Originally Posted by TomO View Post
It's not so much throttle position that determines Lean Burn but engine load.
I'm wondering what you mean by that, since throttle position and engine load are so directly related that they're virtually synonymous.
__________________

monroe74 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
Incorrect mileage calculation? tonedepear Fuelly Web Support and Community News 6 04-04-2011 01:04 AM
No EPA Est for 2007 Chrysler Town & Country jklaiber Fuelly Web Support and Community News 1 08-23-2008 01:15 AM
Motocycle Data pb Fuelly Web Support and Community News 12 08-18-2008 07:06 AM
New to Site FormulaTwo Introduce Yourself - New member Welcome 15 09-20-2006 08:17 AM
WTB: HX or VX Wheels GasSavers_DaX Wanted to Buy 6 07-12-2006 10:50 PM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 04:45 PM.


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