If You Check Fuel Mileage Religiously, Inside....

06pvibe · Post by **06pvibe** » Sat Nov 13, 2010 7:43 am

I should justify first that this is my Mazda3 I am referring to here as my wife does not check her mileage very often. However, I feel if the problem is as I suspect, Vibe owners should also feel the sting and therefore this applies.We all know that in most places in the US these days our gasoline is laced with 10% ethanol. In fact there is discussion now that the EPA to allow the refineries to increase that to a max of 15%. (Be forewarned and aware people.) And we should know that alcohol of any kind, carries with it its own oxygen molecule causing a modern electronically controlled fuel injection system to richen up the mixture to compensate.My normal drive is 16.2-16.4 miles one way, depending on the route I take, or a total of 32.4-32.8 miles/day.I am one of those (removed) retentive guys that takes a receipt every time I fill up, and I rarely do anything BUT fill up. I check my mileage religiously and on the spot. Lately I have noticed a decline in my fuel mileage by between 2 and 3 MPG and am trying to figure out what might be causing it. I used to get between 24-26mpg during the summer months when the A/C is running all the time, and 27-29mpg when the A/C is off. In fact they were even on the rise after the car hit 35k miles!! My best was 30mpg in normal traffic during one tank full. My most recent "best" was when we took a day-trip to San Antonio and I managed only 27.37 for the tank. THAT's TERRIBLE compared to what I was used to.My last 9 fill ups show an average of 25.52mpg, where as last year during this same period the average was 27.89mpg. I highly doubt my driving habits or the situations I drive in have changed that radically during this time.Has anyone else (that regularly checks and documents their mileage) noticed a change, or this radical a change in mileage?

djkeev · Post by **djkeev** » Sat Nov 13, 2010 7:53 am

This isn't a new discovery. Maybe it is eye opening to you to feel the effects of the mix but it is well documented.It is a fact that by adding alcohol to gasoline, you increase the octane rating and lower tailpipe emissions. You also make the Fed's happy by supporting the corn growers of America!If I recall the average fuel economy drop with the 10 % mix is only 1 - 2 %. I don't keep accurate records like you so haven't any first hand knowledge. I do know that winter fuel mileage is less than summer mileage, even with the air conditioning on almost constantly. Cold air, winter fuel mix and longer warm up idling in the AM all play a part.Dave

keithvibe · Post by **keithvibe** » Sat Nov 13, 2010 9:44 am

I did notice a drop in my mileage. When I first got the car around town I would get 25-26mpg with it. Over the past year, it's dropped to an average of 20-22mpg.Yes I am (removed) about maintaining my car, tire pressure, maf cleaning, pvc cleaning, full syn oil for engine, trans and awd.I could never put my finger on what was causing the issue. I've alwasys filled up at the same station and the same pump.

kostby · Post by **kostby** » Sat Nov 13, 2010 9:57 am

I'm essentially retired, so I don't travel the same route daily.I chart the miles traveled, the gallons, air temp when I fill up, brand, and location, and I haven't noticed any significant drop in mpg, but my recent fillups have varied from 24 to 33 mpg. The higher numbers during a 160 mile round trip to my son's college. If I drive exclusively in my small town, mileage is closer to 22-23.I fill up with the same brand 95% of the time, and 90% of the time at one station.Conditions that could cause in a change in mileage:Road construction so you spend much time sitting in traffic idling at 0mpg (or road construction now finished, so you have a higher average speed?)Petroleum refiners switch to a 'winter' gasoline blend in the northern states. I don't know if they do the same thing in TX or not.Recent oil change to a different type or weight? For example, maybe the lube guy put in petro 10W30 instead of synthetic blend 5W20?New tires or different tire pressure?Changed the air filter recently?More passengers or equipment on board?Noticed any roughness at idle? Fouled sparkplug(s) or dirty injector(s)?

star_deceiver · Post by **star_deceiver** » Sat Nov 13, 2010 12:15 pm

Do any stations in your area sell ethanol free gas?

06pvibe · Post by **06pvibe** » Sat Nov 13, 2010 6:07 pm

None that I am aware of, SD.Keith, you and I seems to have the same or similar habits. I too fill up at the same station whenever possible, usually in the early morning on my way to work and always the same pump. At that time of the morning, I usually have the whole place to myself. DJ, I am aware of the affects of alcohol in gasoline. Since it is almost exactly 1/3 less efficient than 100% gas, and carries a BTU rating of 76,100 compared to 114,000 (BTU's) for straight gasoline. The calculated difference should only be -3.32% running E10, or about 1 mpg from 28, not 2-3.This is why I am asking others. I'm curious if other people have noticed this much of a reduction or is my Mazda (2004 w/60,000 miles) on the verge of a breakdown that hasn't yet caused a CEL?Another factor I just thought of (and forgot to mention before) is that I run Shell almost exclusively and up to now been very happy with the quality of the fuel. But it occurs to me that Shell engineers have been "playing around" by adding nitrogen into the mix. (well documented in their TV ads) and wonder if this is the difference?

Entelodont · Post by **Entelodont** » Sat Nov 13, 2010 8:04 pm

Last summer using Shell 10% ethanol three consecutive tank fulls, the MPG ranged from 24 to 25.5. The usual straight gas yields form 25.5 to 27 MPG. No more E-10 for me.

Esteban · Post by **Esteban** » Sat Nov 13, 2010 8:04 pm

I am an " (removed) gas mileage checker . "Here is a link to ethanol free gas. I buy it whenever I can. I have a gas saving Ford Focus that I drive the most. When gas swithched over to 10% corn likker,, my mileage on my first tank && every one since, has dropped 5-10%. Ethano content can vary a lot. http://pure-gas.org/

keithvibe · Post by **keithvibe** » Sat Nov 13, 2010 8:04 pm

i've been burning nothing but shell 93... not because I want to waste money. It's been because I was getting ready to have the correct gas in the tank for the turbo build. I've been getting the same results.

Entelodont · Post by **Entelodont** » Sat Nov 13, 2010 8:09 pm

My results were roughly a 6% drop in mileage from both the high and low MPG readings.

06pvibe · Post by **06pvibe** » Sat Nov 13, 2010 8:22 pm

Thanks for the link, Esteban. There are absolutely none listed in the greater Austin/Manor/Pflugerville/Round Rock/Georgetown area. In fact for the size of the state of Texas, there are very few listed at all.I would also caution you (as you may already know) is that just because there is no sticker on sign on/near the pump does not mean it does not have ethanol in it. Thanks to the Bush admin, sellers are no longer required to post the "warning" label and haven't been for several years now.Also, these stations are listed by other regular people, so there is no scientific evidence that the listing is complete or correct.Many of those station I saw listed in the several states I checked would be in question in my own mind. And New Jersey is not even on the list.

djkeev · Post by **djkeev** » Sat Nov 13, 2010 9:50 pm

I've yet to do this but have read that it can affect MPG is service the VVT filter.There is a filter in the head that filters the oil?? that controls the valve timing. I've read it is little known, the filter screen clogs up and comes out in pieces and that is should be serviced. When this filter clogs, the efficiency improving aspect of VVT is pretty much not working.http://forums.genvibe.com/zerothread?id=42494Dave

jake75 · Post by **jake75** » Sun Nov 14, 2010 1:42 am

Quote, originally posted by Entelodont Â»Last summer using Shell 10% ethanol three consecutive tank fulls, the MPG ranged from 24 to 25.5. The usual straight gas yields form 25.5 to 27 MPG. No more E-10 for me.1.It is almost impossible to find 100% gasoline around here.2. That may be in part due to the fact that Ohio is one of the handful of states that do not require disclosure of the 10% alcohol content. My prediction is that while the EPA is going to permit E-15, few gasoline companies are going to market it. My second prediction is that if the gasoline marketers do start using 15% ethanol they will do that only in "regular 87 octane, forcing those of us who want to avoid the 15% ethanol to buy more expensive and higher profit premium gas even though we do not need it.Wouldn't it be nice if the govt. did something for us instead of to us for a change?

star_deceiver · Post by **star_deceiver** » Sun Nov 14, 2010 2:15 am

Quote, originally posted by 06pvibe Â»But it occurs to me that Shell engineers have been "playing around" by adding nitrogen into the mix. (well documented in their TV ads) and wonder if this is the difference? Try Chevron!!! I can't speak for how they blend their fuels down there but up here, their supreme plus 94 has no ethanol. Also maybe pull the neg batery cable and reset the ecu after you fill up at a diffrent station.Quote, originally posted by 06pvibe Â»or is my Mazda (2004 w/60,000 miles) on the verge of a breakdown that hasn't yet caused a CEL?Ever checked the plugs?

jake75 · Post by **jake75** » Sun Nov 14, 2010 2:16 am

"And we should know that alcohol of any kind, carries with it its own oxygen molecule causing a modern electronically controlled fuel injection system to richen up the mixture to compensate."My organic chemistry is a little rusty, but I don't see how a bound oxygen molecule is going to have any effect on the fuel injection system.

06pvibe · Post by **06pvibe** » Sun Nov 14, 2010 6:09 am

Gasoline in the traditional sense does not carry with it any O2 molecule so by bringing additional air into the combustion chamber through the fuel acts the same as if it were taken in through the intake. The optimum 14.7% of air is compromised... the ratio is increased, so the ECU controlling the FI must try to adapt. It does that by adding more fuel and along with that more O2 also so it has double duty to do trying to bring the mixture back to 14.7:1.Just yesterday I saw an episode of Horsepower on Spike TV that dealt with this issue. (2010, episode #297, orig airdate: 11/13/2010) In their case it was a 383 stroker small block Chevy. The carb chosen was a Holley 950... a little big for a normal small block the usual being closer to a 750-850cfm. But in addition they had to change the main jets from 0.79's to 1.44's to compensate for the oxygen carried by the alcohol they planned to run in it.

DressedInBlack · Post by **DressedInBlack** » Sun Nov 14, 2010 8:30 am

there are a lot of stations that sell gas without ethanol around me...the catch is that they are in marinas and for boats only, unless you barge your car to the pump. the ethanol kills boat engines and the boaters here on the coast raised hell. marina gas station owners listened to the people and many of them sell "gas only" gas.i don't like this ethanol scenario at all.

06pvibe · Post by **06pvibe** » Sun Nov 14, 2010 9:22 am

Terrific. But not very useful in this situation, Geoff. LOL

DressedInBlack · Post by **DressedInBlack** » Sun Nov 14, 2010 10:16 pm

i just wish, as well as boaters, that more "regular" gas stations would do the same. the marinas charge so much money for gas...if a regular station sold the good stuff, they could make a killing. filling up a boat and the truck that is pulling it could easily take 100+ gallons.as far as my mileage, i have been using the Shell brand only. ive been having a consistent 25-26mpg city. your 2mpg drop over the 9 tanks is really suspect. it makes me wonder what ELSE they are throwing into the gas. maybe a "watering down" type scenario going on here...?

jake75 · Post by **jake75** » Sun Nov 14, 2010 11:53 pm

Quote, originally posted by DressedInBlack Â»there are a lot of stations that sell gas without ethanol around me...the catch is that they are in marinas and for boats only, unless you barge your car to the pump. the ethanol kills boat engines and the boaters here on the coast raised hell. marina gas station owners listened to the people and many of them sell "gas only" gas.i don't like this ethanol scenario at all.Seems to me that the prices I've seen at Marina's are through the roof. For that reason many boaters have a lot of 5 gal cans and buy their gas at land stations.

jake75 · Post by **jake75** » Sun Nov 14, 2010 11:58 pm

The Shell "Nitrogen" story is advertising hype. Moreover, since Nitrogen is an inert gas I don't understand why that would have any appeal.

jake75 · Post by **jake75** » Mon Nov 15, 2010 12:06 am

Quote, originally posted by 06pvibe Â»Gasoline in the traditional sense does not carry with it any O2 molecule so by bringing additional air into the combustion chamber through the fuel acts the same as if it were taken in through the intake. The optimum 14.7% of air is compromised... the ratio is increased, so the ECU controlling the FI must try to adapt. It does that by adding more fuel and along with that more O2 also so it has double duty to do trying to bring the mixture back to 14.7:1.Just yesterday I saw an episode of Horsepower on Spike TV that dealt with this issue. (2010, episode #297, orig airdate: 11/13/2010) In their case it was a 383 stroker small block Chevy. The carb chosen was a Holley 950... a little big for a normal small block the usual being closer to a 750-850cfm. But in addition they had to change the main jets from 0.79's to 1.44's to compensate for the oxygen carried by the alcohol they planned to run in it. Any expert chemists here? My opinion is that the oxygen that is bound as part of the organic chemical we call ethanol (C2H5OH) could not have any effect on the oxygen sensor. Even when ethanol is burned that oxygen ends up as water (H2O)Combustion: Complete combustion of ethanol forms carbon dioxide and water: C2H5OH + 3 O2 → 2 CO2 + 3 H2O

joatmon · Post by **joatmon** » Mon Nov 15, 2010 2:25 am

I see a definite seasonal variation in MPGs, always better in summer than in winter, but you said you are seeing a drop compared to this same time last year, so it sounds like something outside a normal seasonal drop. It seems unlikely that it is related to ethanol, unless they are using ethanol in gas this year and they didn't last year. They have been using it here in MD for several years, I don't know about Austin. Here they switch to some "oxygenated" gas for the winter, and I blame that for my winter MPG drop. Maybe there in Austin they started doing something like that this year.viewtopic.php?f=17&t=6088&#p65128 has an excerpt from a 2003 service manual on things to check if gas mileage has dropped or is lower than expected. Fairly generic, those things probably also apply to your mazda as well. It could be a tune up issue.Quote, originally posted by jake75 Â»Any expert chemists here? Charlievibe, but she hasn't posted for a couple of years

tribalman · Post by **tribalman** » Mon Nov 15, 2010 7:02 am

i read about 1/2 of the thread and i didn't notice if this was mentioned, since it is colder the car takes longer to warm up. when it isn't at operating temp it does idle higher and run at a slightly higher RPM. i'm not sure the temps in your area, but i have also noticed a drop in my fuel efficiency related to the weather. happens because of the winter gas and the longer times not at operating temp. if you want i can scan or shop in my records for gas fills including dates, quantity of gas put into tank, cost, overall mileage, and trip mileage and you can see that every fall the MPG drops.

DressedInBlack · Post by **DressedInBlack** » Mon Nov 15, 2010 8:31 am

being a South Floridian where "winter" is when it dips into the 50's for a week, i have to ask: what is winter gas?

Old Tele man · Post by **Old Tele man** » Mon Nov 15, 2010 10:22 am

..."winter gas" is gasoline formulated to have a lower Reid Vapor pressure so that it'll evaporate better in cold weather...something that Alcohol doesn't do well at all.

jake75 · Post by **jake75** » Mon Nov 15, 2010 12:05 pm

We do a lot of short trips so in winter our '09 Vibe 1.8L mileage often dips into the high teens. Still better than the low teens we get at that time with our 3.3L V6 T&C.Sometimes I wonder why I keep that second vehicle - but it is comes in handy to have a 2nd car with its different attributes, it's paid for, and the additional insurance is not that much. When I was poorer a good reason to have two cars was to better the odds of having at least one that worked.

FaithHopeLove · Post by **FaithHopeLove** » Thu Jan 20, 2011 11:40 pm

Hi folks...new to the forum...recently purchased 2004 Vibe AWD w/ moon & tunes. I'm VERY happy to have found one, and it only has 48K mi.!!!...one owner, local...I even know her and where she purchased it new...what a "find"......BUT...I've discovered that over the first 2 fill-ups, I got 22 and 20 mpg. Checked the tire pressures, they were low...bossted them up to about 38 psi...just bought LucasOil fuel system cleaner and put in with this (3rd) fill-up. Also, have been using the O/D OFF button when traveling hilly and small town roads, here in PA. Checked air filter...clean as a whistle, looks new. Can't understand why the mpg is so low. I do not have any "check engine" light warnings or anything else. Checked with the dealer and he said that this is nothing really unusual for the winter months, here in PA. Is it possible that my MAF could need sprayed clean and the car computer rest?...or is this a symptom of the winter months...Is there ANYTHING I can do to improve this issue , such as octane booster, dry gas, Lucas fuel additive or anything else? This is driving me nuts, as the mpg was one of the "selling points" for me and the Vibe...especially this year and package. Please advise.

Salsa Guy · Post by **Salsa Guy** » Fri Jan 21, 2011 12:04 am

Winter gas, OD off and hilly travel can be the main reason. You drive highway or stop and go? Also when possible keep revs below 2500 rpms. The AWD is heavier and more power loss to the wheels (AWD system again). I have an SC on my AWD and get about 26 mpg on mostly highway driving. Keep the OD on when possible and it should improve as winter gas goes away. If you run the defroster you are also running the AC.

FaithHopeLove · Post by **FaithHopeLove** » Fri Jan 21, 2011 12:25 am

not very much "highway" miles...a bunch of start & stop, i suppose...small towns area in PA, hills and red-lights all over the place...thought OD OFF would help in these conditions as long as RPMs stay below 3000 or so. Considering cleaning my MAF, throttle body and PCV valve...but this Vibe's only got 49000 on it with no signs of being beaten-up...whadday' think...or should I just wait it out until winter-gas is used up...into Spring?

Salsa Guy · Post by **Salsa Guy** » Fri Jan 21, 2011 12:47 am

The driving conditions you are describing is stop and go. So with that being said and winter gas (they change the formula for winter) I don't think it's a concern at this time. When you get a chance and take it on a trip then see how it works out. Being from western PA I know what you are talking about. Keithvibe is getting about the same mileage as you (he lives in PA also).

ou.grizzly · Post by **ou.grizzly** » Fri Jan 21, 2011 1:02 am

Quote, originally posted by FaithHopeLove Â»Hi folks...new to the forum...recently purchased 2004 Vibe AWD w/ moon & tunes. I'm VERY happy to have found one, and it only has 48K mi.!!!...one owner, local...I even know her and where she purchased it new...what a "find"......BUT...I've discovered that over the first 2 fill-ups, I got 22 and 20 mpg. Checked the tire pressures, they were low...bossted them up to about 38 psi...just bought LucasOil fuel system cleaner and put in with this (3rd) fill-up. Also, have been using the O/D OFF button when traveling hilly and small town roads, here in PA. Checked air filter...clean as a whistle, looks new. Can't understand why the mpg is so low. I do not have any "check engine" light warnings or anything else. Checked with the dealer and he said that this is nothing really unusual for the winter months, here in PA. Is it possible that my MAF could need sprayed clean and the car computer rest?...or is this a symptom of the winter months...Is there ANYTHING I can do to improve this issue , such as octane booster, dry gas, Lucas fuel additive or anything else? This is driving me nuts, as the mpg was one of the "selling points" for me and the Vibe...especially this year and package. Please advise.20-22 mpg for an AWD in the winter and with short stops is NORMAL. Summer, you may be able to obtain 30 highway. Welcome

FaithHopeLove · Post by **FaithHopeLove** » Fri Jan 21, 2011 1:02 am

should I mess with the MAF, etc.?...or just continue to wait it out?

ou.grizzly · Post by **ou.grizzly** » Fri Jan 21, 2011 1:11 am

Quote, originally posted by FaithHopeLove Â»should I mess with the MAF, etc.?...or just continue to wait it out?Sounds like there isn't an issue to me. An AWD is going to get that kind of mileage. What were you expecting?

Salsa Guy · Post by **Salsa Guy** » Fri Jan 21, 2011 3:31 am

Cleaning the MAF, Throttle body and check this out http://forums.genvibe.com/zerothread?id=42494You can do this stuff yourself but only if you are confident in you skills. Otherwise take it to a trusted shop and discuss the issues with them. Goodluck!

KITT222 · Post by **KITT222** » Fri Jan 21, 2011 8:55 am

Personally, I think an MPG gauge is invaluable. The instant display on my Kiwi MPG lets me find the throttle sweet spot where I can get mid-high 30s at almost 60-MPH. My tires need to be filled, and I am (according to the gauge) maintaining 28MPG. The gauge can help you tune your driving style for the best FE you can get.

06pvibe · Post by **06pvibe** » Fri Jan 21, 2011 9:08 am

Quote, originally posted by FaithHopeLove Â»should I mess with the MAF, etc.?...or just continue to wait it out?Sometimes, and in the case of a very delicate MAF sensor, you shouldn't try to fix what ain't broke. In other words, I would leave it alone till you got nothin' to lose.I have a question for the general public here: For years I have heard and bought into the "winter mix gas" theory. But, does anybody actually know what the winter mix is?Remember now, this winter mix business started at least 30 yrs ago, and that's that I know of. Perhaps earlier than that.But today's fuels, not to mention the science behind them, while business driven (RE: $$$), we have such chemicals/elements as 10% ethonal which is now pretty universal, and added nitrogen to our commercially produced fuels. With that in mind, are winter mixed fuels still necessary, or is this nothing but a modern day myth? Seems to me that a winter mixed fuel would have some ethonal in it to combat condensation, yes? Since we now have ethonal 24/7-365 why would we need a special winter mix?And an update: My Mazda3 continues to lose 2-3 mpg from where it was several years ago. That hasn't improved or become worse, and this is not based on where or how I happen to be driving it. The best I have achieved since ethonal additives became std is 26.9 mpg... best before that was 30, and average was 28.5mpg.

torker · Post by **torker** » Fri Jan 21, 2011 10:49 am

I am not sure about the fuels but the poster that made comment about Reid Vapor pressure seemed to know. Part of the problemmay be that 99% of the gas they sell is 86-87 octane these days instead of 91-92 being the norm. Maybe with lower octane and using ethanol just to reach 87 it is making it to where they have to reformulate just to get it to burn decent when it gets cold. We need a chemical engineer to chime in. Also I remember a few years ago I used to run around with a buddy that had an 8 to 1 350 chev and he could get the same octane at 2 different stations and one would ping bad and one would not. I think quality varies a lot and mostly bad these days.

tpollauf · Post by **tpollauf** » Fri Jan 21, 2011 11:28 am

Quote, originally posted by KITT222 Â»Personally, I think an MPG gauge is invaluable.I totally agree with you on this one My ScanGauge II is an awesome little analyzer and I have one of the four displayed views SPECIFICALLY on instant MPG all the time. You'll be amazed how just a few changes in your driving habits equate to better mileage & performance

Old Tele man · Post by **Old Tele man** » Fri Jan 21, 2011 11:52 am

+1 for the ScanGuageIIâ„¢ use it religiously...have gotten consistent highway milage up into 40+ mpgs (EPA is 31 mpg), but not in city in the winter.

star_deceiver · Post by **star_deceiver** » Sat Jan 22, 2011 8:12 am

Welcome to GenVibe!!! Quote, originally posted by FaithHopeLove Â» Also, have been using the O/D OFF button when traveling hilly and small town roads, here in PA.Don't use this... keep overdrive on unless you're towing or need a quick downshift!

waveresponder · Post by **waveresponder** » Sat Jan 22, 2011 10:37 am

Quote, originally posted by star_deceiver Â»Don't use this... keep overdrive on unless you're towing or need a quick downshift!why shouldnt you use the overdrive off button on hills?this is some of the stuff i thought what you should be using it forhttp://www.ehow.com/how_442288....html

star_deceiver · Post by **star_deceiver** » Sun Jan 23, 2011 6:53 am

There are hills out there that are steep enough? And as I said "or need a quick downshift!" Using lower gears for better accelleration will use more gas...

Salsa Guy · Post by **Salsa Guy** » Sun Jan 23, 2011 8:14 am

I'm still trying to figure out how to Drive 40 mph is this car. It want's to upshift and lug (about 1500 rpms). I hate messing with the OD in this case but seems to be only option. Last mileage was 26mpg.

FaithHopeLove · Post by **FaithHopeLove** » Tue Feb 15, 2011 11:58 pm

just wanted to let everyone know, I posted my displeasure with "winter mix" gas blends, here in PA...I was only getting about 21-23 mpg, with mixed driving...but, cleaned my MAF sensor, and went to http://www.pure-gas.org to investigate pure gas, as opposed to methanol blends...there are VERY FEW pure gas retailers around...I went to the closest one, about 25 mi. away...it was a Shell station that has nitrogen added to their "pure gas"...no ethanol...WHAT A DIFFERENCE! I could tell almost immediately, and my mileage is MUCH better since cleaning the MAF, running LUCAS fuel system cleaner and switching to "pure gas"...VERY happy owner of recently purchased 2004 Vibe AWD w/ moon & tunes...48000 mi., one owner (know her for a long time)...I'm just ready for spring and summer, though...thanks, Ron.

hextavo · Post by **hextavo** » Fri Mar 04, 2011 4:44 pm

Huh, very nice that you could find a "pure gas" area, so you going to continue buying fuel from that area then, if so let us know how it goes!!