[ale] [OT] - Ethanol-free gas in the Atlanta area? - and gas saving tips

[Ron Frazier (ALE)]

"Ron Frazier (ALE)" <atllinuxenthinfo at techstarship.com> wrote:

>
>
>"Ted W." <ted-lists at xy0.org> wrote:
>
>>On 09/17/2013 07:40 PM, Ron Frazier (ALE) wrote:
>>> Hi All,
>>> 
>>> I just experienced something fascinating in my car.  We've got two
>>car related threads going, but this one is also fuel related, so I'll
>>put it here.
>>> 
>>> In the UltraGauge manual and in that Popular Mechanics article, I
>>read that many cars occasionally turn their fuel injectors off to save
>>fuel.  I sort of said yea, yea, all well and good.  But I also assumed
>>that my 2005 Hyundai Santa Fe and my wife's 2007 Hyundai Sonata didn't
>>have this feature.  Surely, I would have noticed it.
>>> 
>>> So, I took the Santa Fe out to go have supper.  I had torque running
>>beside me on the android tablet.  When I was cruising down a pretty
>>steep hill, I took my foot totally off the gas pedal.  I kept one eye
>>on the fuel flow gauge on the tablet.  Of course, you'd expect instant
>>mpg to go up, which it did.  What I DIDN'T expect, and could hardly
>>believe, is that after a few seconds, the fuel flow went to ZERO.  It
>>didn't go down.  It went AWAY!  I was totally amazed.  So my car does
>>have this feature.  There was NO discernable difference in the feel of
>>the car versus when the injectors were on.  The momentum of the car
>>keeps the engine turning and the accessories running.  I don't know if
>>they have a way of removing cylinder compression or something.  When I
>>got to the bottom of the hill and tapped the gas pedal, the fuel flow
>>resumed and I got power exactly like I expected to and went up the
>>other side of the hill.
>>> 
>>> This was totally fascinating.  Note that you have to be on a pretty
>>steep hill and going at a decent speed for this to work, at least in
>my
>>car.  If the ECU thinks it's losing the ability to keep things
>running,
>>it will re engage the fuel.  Now that I know what to look for, though,
>>I want to see how often I can make this happen while maintaining
>>safety.  Burning NO FUEL, and getting infinite MPG, even for a few
>>seconds, is very enticing.  I have a theory that touching the brake
>may
>>make this happen sooner, but I haven't confirmed this.  I have to
>>research that.
>>> 
>>> If you have an addon gauge system for your car, either torque,
>>scanguage, ultragauge, or other, definitely turn on the fuel flow
>gauge
>>and watch it coasting down hills.  Ultragauge has configuration
>screens
>>specifically for dealing with injector cut off.  I don't know about
>the
>>others.
>>> 
>>> I thought this was way cooler than dirt, to paraphrase the cliche,
>so
>>I'm passing it along.
>>> 
>>> Sincerely,
>>> 
>>> Ron
>>
>>Ron, I would have been thoroughly surprised had you found your car, as
>>new as it is, /didn't/ have this feature. I drive a '99 Subaru
>Forester
>>and I use a ScanGaugeII to monitor my fuel consumption. When I leave
>it
>>in gear (it is a manual 5-spd) going down a hill the MPG reading
>>instantly jumps (and stays) at 99999MPG which leads me to believe the
>>fuel injectors are not in use.
>>
>>Cheers,
>>Ted W.
>
>
>Hi Ted,
>
>I guess the feature has been around for a while.  It's just not
>something I've ever known about.  And I've certainly never tried to
>make it happen, since I didn't know about it.  I'd usually keep a light
>foot on the gas all the way down the hill.  Now I'm trying to make it
>happen when practical.  Seeing the fuel flow read zero was very neat. 
>Your ScanGauge might do that if it has a fuel flow gauge in the menu. 
>But, since it's reading 99999 MPG, I'd also agree that you're achieving
>fuel cutoff.
>
>My wife's car has it too, but hers freewheels down a hill so fast,
>while still having minimal engine braking, that you have to downshift
>her automatic transmission from 4th (D) to 3rd to get the injector
>cutoff, as going down in 4th doesn't keep the engine spinning fast
>enough to cut the fuel.  I doubt she'll be messing with the gear shift.
>Her Sonata has a 2.4L engine and it only weighs 4000 Lbs or so.  So it
>gets pretty good MPG anyway, around 24 MPG.
>
>My Santa Fe has a 2.7L engine and weighs 5000 Lbs or so, so it doesn't
>do so well on MPG.  With my prior driving habits, I get around 17 MPG
>if I don't let it idle in parking lots and such.  I'd like to improve
>that a bit.  It's fairly easy to get that one to cut off it's fuel on a
>medium sized hill even in 4th gear.  It also has an automatic
>transmission.  Lesser hills make the car decelerate too rapidly to run
>for any substantial period of time.  You can also use the technique
>when cruising up to a traffic light some distance away.
>
>In testing my cars going down hills at say, 45 MPH with the cruise on,
>sometimes even if the car is gaining speed above the 45 MPH, it will
>not cut off the fuel.  Not sure why.  One time, it appeared to work,
>and others not.  It may be only possible to reliably use the technique
>with manual throttle control.
>
>I have conflicting data on what the brake pedal will do.  I thought it
>might trigger the cutoff.  But, I read on a forum somewhere that it
>kills the cutoff, ie re engages the fuel, because it may unlock the
>torque converter.  It may vary by vehicle.
>
>I read that on a manual transmission, pushing in (or disengaging) the
>clutch will re engage the fuel so the engine doesn't choke down.
>
>For some interesting reading, you can:
>
>Google dfco and the name of your car.  DFCO means deceleration fuel
>cutoff.
>
>https://www.google.com/search?output=search&sclient=psy-ab&q=dfco
>
>Google hypermiler - a person who always tries to beat the EPA MPG
>rating on their car.
>
>https://www.google.com/search?output=search&sclient=psy-ab&q=hypermiler
>
>Apparently, it's not too hard for some people to exceed EPA ratings by
>30%.  For the Santa Fe, since it's rated at 18 MPG, I'd just like to
>get to the EPA rating.
>
>Sincerely,
>
>Ron
>
>

Hi all,

I wanted to pass along a bit more information about saving fuel, and some tips as to what not to do.

One technique I'm experimenting with that has the promise of both saving some fuel and being safe (if done properly) is called DWB, which stands for driving without brakes.  You don't literally do that, but you try to manage the momentum of your car and, whenever possible and safe, never touch the brakes.  If you press the brakes, that's an indication that you've burnt too much fuel to build up momentum in the car and you have to turn that momentum back into heat with the brakes and waste it.

Of course, in the real world, there are many times that you cannot just coast for 1 mile to come to a stop.  Also, if you're decelerating without touching the brake, the people behind you may not realize this.

This also relates to getting the fuel injectors to cut off.  In my car, if I'm going down a pretty steep hill, above 45 MPH or so, I can achieve DFCO by taking my foot of the gas.  Sometimes, touching the brake briefly triggers DFCO, but it usually does that on its own.  In my wife's car, however, you'd probably have to be going 55 MPH or so to achieve that, and that is probably unsafe.

What I'm about to say is controversial, and there is a big debate with proponents on either side of the fence on the internet.

Note that I'm only talking about automatic transmissions here.  One alternative with a car with P N R D 3 2 1, etc. on the shifter or cars with the "sport" mode and +/- shift controls is to shift the car from D to 3 (assuming a 4 speed gearbox).  This will cause the engine to rev up, decelerate the car, and allow you to get into DFCO or maintain it longer, and save wear and tear on your brakes.  Some people will shift to 2 and even 1 as the car decelerates and not hardly touch the brakes.  The consensus on shifting to 1 seems to be never above 5-10 mph and some say not unless you're stopped, in which case, the automatic goes to 1 for you.

I will go ahead and point out that the manual for most cars SAYS to do this downshifting in mountain terrain to avoid burning out your brakes.  That's not what I'm talking about.  I'm talking about just average driving, on moderate hills, at traffic lights, turns, and stop signs.

So, the controversy is: should you do this downshifting in average driving or not and does it harm the transmission.  I spent hours yesterday reading blogs and forums which advocated each side of the fence, do it and no harm, or don't do it and it will harm.

The consensus, for whatever that's worth, seems to be biased toward the don't do this, it can harm your transmission, and brakes are much cheaper to fix than the transmission.

I decided to go and ask my mechanic, whom is very knowledgeable and whom I trust.  It turns out that he agrees with the consensus.  He said that if you do the procedure just right, at just the right rpm, and under just the right conditions, it is theoretically possible to be OK.  (Side note - if you fee the car lurch when you downshift, you didn't get it right.)  But, he said  that's almost impossible to do.  He said there is a really good chance you WILL harm the transmission routinely downshifting except under specific conditions, like mountains, that require it for safety.

His advice, under normal conditions, and for average driving, is just leave it in D and let the computer figure out when to switch gears.  So, I'm not going to be doing any manual shifting on my car's automatic unless I have a specific need to do so.  And, that doesn't include trying to save a few dollars on gas.  The other time I'll probably just shift into 3rd and leave it there is when I'm going on a road where there are hills every half mile or so, and the transmission would be shifting up on the downhill and then shifting down on the uphill and repeating over and over.  Leaving it in third will lessen the shift cycles it has to go through.  Other than that, and mountain driving, I'll leave it in D and just pay the price in gas and brake maintenance.

I've also seen things that say change the ATF fluid every 30K miles, etc.  I asked the mechanic about that.  This is a used car, and I don't know the service history.  He said, that if I knew the service history, and knew that it had new fluid periodically, to continue that pattern.  However, he said that if I didn't know that, just leave it be.  He said that putting new fluid in a transmission with 100K + miles on it that's not showing problems can do much more harm than good.  Don't ask me how or why.

So, that's what I'm going to do, drive it in D(rive), leave it be, and let it figure out when to shift the gears.  I'm still trying to only touch the brake a minimal amount when practical.  I think I can eke another MPG or so out of it.  I don't seek out hills to use DFCO, because, even if I can be using no fuel going down the hill, I'm only going to be getting 8 MPG or so going up the other side in 3rd gear.

Just thought I'd pass it along.

Sincerely,

Ron



--

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Ron Frazier
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