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Best Single MPG Mod?

stogen said:
gas weighs a lot especially a full tank if you don't drive far every day just keep the tank half full or even just above a quarter tank, it  got me a little better mileage
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gas weighs about 6-7lbs per gallon I forget actual number but is less then water @ 8 lbs per gallon...

so 15 gallons which is half a tank = using 7 lbs = 105 lbs...

Which for the 6000 pound truck is not very much... I bet it effects the mpg less then 0.01%

the best way tpo get better mpg... is to take off very very very slowly.... from stops.. as that is where the majority of the fuel is wastd getting this pig of a truck moving....

also anything ovr 50 mph is wasting huge amounts of fuel fighting the wind..
 
ygmn said:
gas weighs about 6-7lbs per gallon I forget actual number but is less then water @ 8 lbs per gallon...

so 15 gallons which is half a tank = using 7 lbs = 105 lbs...
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Yes, gas is roughly 6lbs / gallon. I know jet fuel is a little more at 7 lbs./gal.  (I used to be a sub-contractor working at an Air Force base, so we'd calculate these things.)

ygmn said:
Which for the 6000 pound truck is not very much... I bet it effects the mpg less then 0.01%
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My thoughts, exactly.  6 lbs * 26 gal = 156 lbs. 

If this were a Yugo, I'm sure that 156 lbs. would have a drastic effect. On an Avalanche - not so much.


ygmn said:
the best way tpo get better mpg... is to take off very very very slowly.... from stops.. as that is where the majority of the fuel is wastd getting this pig of a truck moving....
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I remember Sperry mentioning that he tried to keep his truck under 2000 rpm. Not sure how he did it where he lived but I do the same. For most of my drive, I can keep the truck under 2000 rpm, even on starts. That really helps out.


ygmn said:
also anything ovr 50 mph is wasting huge amounts of fuel fighting the wind..
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But it sure helps when you have an 18-wheeler on your tail!
 
Don't mean to  :jacked: but it's related to your question. The AV has now quit down shifting on hills and some were fairly small and milage is improving with 93 octane still not sure about the ethanol.
 
Tune it for 91 or 93 octane gas (which ever is available) and always fill it with that. The MPGs and added power will justify the higher priced fuel.
 
Loss of mileage is for me related to oil loss again  :E:
So I wake up to a check engine light this morning stop by auto zone number 7 misfire. Same thing I had last time. I have already scheduled a test for this next week. I plan to make a poll here to see who has had this is who hasn't. What milage apprx did it start? Has it reoccurred? If you don't have the is what do you typically dive city or highway and how many miles?
If I can't get a resolution a lawyer will be spoken to.
 
stogen said:
gas weighs a lot especially a full tank if you don't drive far every day just keep the tank half full or even just above a quarter tank, it  got me a little better mileage
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That's intersting. I've heard that having the truck less then 1/2 full will cause it to use more gas, which as I'm typing this makes utterly no sense to me now. I just got 16.8 from my 2004 with some rather agressive driving. I'm a teacher and I've been really agitated after school >:D Can't  :beating: the students, so I took it out on my gas pedal and really  :drive: this last tank. I also had to put 31 gallons into it and was terrified I wouldn't make it a gas station, but I did.
 
Z66Modder said:
Tune it for 91 or 93 octane gas (which ever is available) and always fill it with that. The MPGs and added power will justify the higher priced fuel.
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So I am planning on the diablo that just went up for sale on this site. If I tune to 93 (only 93 or 87 available) will there be issues when only 91 is available?
 
misura said:
Why not use neutral down long hills? Out of my drive, I can coast for 6.3 miles. Adjusting RPMs before engaging tranny, what does it hurt?
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This actually uses more gas than if you just let it coast in gear...just saying.
 
I saw on top gear that coasting at speeds uses almost no fuel in modern cars, because the spinning of the tranny keeps it running while using less fuel. Don't know how true it is but I thought it was interesting.
 
Joelg1980 said:
That's intersting. I've heard that having the truck less then 1/2 full will cause it to use more gas, which as I'm typing this makes utterly no sense to me now. I just got 16.8 from my 2004 with some rather agressive driving. I'm a teacher and I've been really agitated after school >:D Can't  :beating: the students, so I took it out on my gas pedal and really  :drive: this last tank. I also had to put 31 gallons into it and was terrified I wouldn't make it a gas station, but I did.
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As an engineer, I know where this comes from.... And in older cars, yes this is somewhat true. In an older car, the fuel systems were very, I mean VERY basic. They were actually exactly what you would imagine in your head right now. A simple fuel tank with a spout, or filler hose, that led up to an accessible hole where fuel could be added. In this gas tank was a basic fuel pump, which was somewhat easily accessible for a reason (always had to be replaced). Things were even worse before EFI came about. Anyways, back on topic. Fuel tends to evaporate relatively quick. Therefore, this claim has to do with the rate the fuel would actually evaporate from the tank whether it was actually in use, or just sitting over night. A smaller amount of fuel (i.e. 1/4 tank would obviously evaporate faster than a full tank, due to surface area etc). New cars have a lot more advanced fuel systems. They eliminated nearly all the evaporation issues (from the little flap on the filler spout to advanced gas caps, circulation hoses .. the list goes on).  But thats how that theory began and people have tended to continue believing it.  Trust me, you waste more money by making more frequent stops to refuel due to only filling up halfway, rather than filling up and not having to stop as often.
 
I apologize, I just re-read what I wrote and it probably doesn't make sense to some.  People used to think that a way to reduce loss due to evaporation would be to keep the tank full, which reduced the amount (volume) of space above the liquid (gasoline) in the tank.

 
hauselvaughn1 said:
I apologize, I just re-read what I wrote and it probably doesn't make sense to some.   People used to think that a way to reduce loss due to evaporation would be to keep the tank full, which reduced the amount (volume) of space above the liquid (gasoline) in the tank.
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I'm kind of an old school engineer too and I remember when we kept the tank full not because of evaporation but because of condensation. 

The theory was that when the tank had air space in it, the air contains water (humidity) and if the temperature changes then the condensation (translate water) would sink to the bottom of the tank and then on into the engine. the other theory was that it would also rust the tank bottom (I don't see that oxidizing effect happening when there is no oxygen under the fluid however).

There still may be some truth in this condensation theory today but with the complexity of the modern vehicles, I would think this would far down the list of things that could go wrong.

 
i know if im on my "budget tanks" where i am trying to save fuel i will adjust my pedals all the way forward... flooring it isnt near the same that way it cuts the acceleration down greatly
 
If you can draft off of a big rig, it saves a ton of gas. I'm not saying its safe but it does work. And the truck driver probably wont like it :beating:
 
AvyOwner23 said:
I saw on top gear that coasting at speeds uses almost no fuel in modern cars, because the spinning of the tranny keeps it running while using less fuel. Don't know how true it is but I thought it was interesting.
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The way the maps are written, high vacuum, no load, idle-ish TPS readings=no fuel. You end up with a giant air exchanger. They keep the converter locked in D and OD to maintain the pumping action.
 
You could try the UPS method - Adjust your routes so that you make alot of right turns and avoid stopping at traffic signals and left hand turns.

Seriously, there is no mod or upgrade that is going to improve your mpg drastically. Many of us are happy at 15-16 city and 19-21 hwy. Anything above that is a fantasy.  Depending on your wallet, driving habits and type of daily commute will determine your mpg. Do your research, upgrade the air filter to a K&N, upgrade your plugs to iridium, clean your MAF sensor, buy a tuner, change tires to city/hwy rated tires, drop the spare (keep the slime kit in the tool box), use fuel system cleaner with each tank fill up, change your oil every 3k, cut your vehicle warm-up time, etc. [flash=200,200]http://It's 7200 lb aerodynamic Brick. Built for those who love the option of fun and versatile daily hauler with room for 5 or full size drywall panels. Excellent towing capcity for our weekend toys and enough to enjoy a day off-roading.[/flash]

The wife and kids love it because of the styling, versatility and modifications for a day at the beach, in mountains, antique shopping, moving friends or a night on the town. Inaddition, they don't have to worry about filling up the tank, I do.

Enjoy the vehicle for what it was designed for and not it's limitations.
 
#1 way to improve MPG is to instal skinny light weight wheels. 

Guaranteed double digit percentage increase if you go skinny enough. And it would look so cool  (y)
 
 
Realistically if you are worried about gas mileage on a full sized truck that weighs almost 1000 lbs more than a standard pickup truck you have the wrong vehicle...

Having said that unless you get your PCM dyno tuned and maybe spend some money getting your engine running more efficiently you REALLY can't do anything much from stock to make your truck get better mileage. The tuners that are mentioned really are guesses and are going to be of very limited value. Going to a premium gas does absolutely nothing for you unless your engine is changing its timing to take advantage of it. And realistically you should NOT be getting better gas mileage from higher octane gas because it burns faster. It MAY help with in town driving but it is more for performance and should have a negative affect on your long range mileage.

CAI... Stock already is...

You can try a pseudo forced air intake but it does minimal actual improvement and generally may degrade performance if you can't keep the air cooled off. (Ram air)

If you are worried about the cost of fuel you could look into going to Propane or CNG either of which is not only far cheaper than Gasoline but also help to extend the life of your engine and are zero emissions. Actually much cleaner long term than an electric car that generally depends on coal generated fuel to produce power. Company I talked to told me to expect a 3 year return on a system in my truck if I drive 12,000 miles a year and gas is $4 a gallon. So a little longer if gasoline is less. At the time the CNG was available for the equivalence of $2 a gallon. They also mentioned that the CNG actually got better mileage due to the fact the engine stayed cleaner and it is a gas so it doesn't have an issue mixing.

Otherwise the only thing you can do is get good road tires and maintain your vehicle replacing worn components. GM did a pretty bang up job trying to get as much efficiency as possible out of the truck from the factory so most anything you do will have a negative effect even if initially it seems to be a positive effect since the PCM will learn around it.
 
Best mod for MPG is a tune...right foot tune, that is

I've read a lot about never coming to a complete stop...may be tough for the city guys but for me in the suburbs if I see a light change red from a ways away I can try to anticipate when it's going to change back to green and keep it above 15-20MPH or so and thus have to accelerate less.  The worst MPG is when you're accelerating from a stop so in theory this should help a lot

And as previously mentioned keeping the RPM below 2000 and limiting highway speed (tough for me, ~50 miles each way) does in fact help.  Pumping up tire pressure helps too.

Anybody tried an octane booster or a fuel injector cleaner?
 
misura said:
Why not use neutral down long hills? Out of my drive, I can coast for 6.3 miles. Adjusting RPMs before engaging tranny, what does it hurt?
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You use less gas going down hill in drive with foot off pedal (fuel injectors are turned off) than putting into neutral (fuel injectors are flowing fuel to keep engine running).

Best single mod for MPG? - Keep off the brake unless really needed.  I gain speed going down hill & lose a little speed going uphill, I let off the gas when I see a stop light ahead avoiding the brake as much as possible.  I see using the brake as lost gas mileage.

I'm a big fan of K&N drop in filters with over 500,000 miles of use.  I little oil goes a long way, too many over oil their filters which causes problems.

I've also found I get more miles/$ by running a 93 tune with premium fuel than a 87 tune with regular fuel if I keep my foot out of it.

I enjoy my jackrabbit starts & get to speed quickly which is also where I get my best MPG.  Some take way to long to get to their best fuel efficiency speed which actually hurts their MPG.

My typical mixed MPG is 17-18 & hwy is 22-26 depending on elevation changes.
 
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