MPG @ sea level vs mile high?

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Dkon82

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I have a 04 TR4 4x4 V8 and live right at an elevation of about 5200 ft, and average about 14 mpg (80% city & the rest highway). I have read many posts where other v8's are getting 2-3mpg better. Is this due to an elevation differences?
Side note: i consider my rig to be well maintained inside and out. Recently did the timing belt, water pump, seals and pulleys, surp belt and iridium spark plugs all at 92k (had 90k when I bought it, now @ 95k). For the most part I would consider myself to be a pretty conservative driver only getting on it from time to time.
Does this sound about right given my conditions? I know an engine has to work harder to keep the same pace as an identical one traveling at as sea level.
What do you all think?
 
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I live in the Denver area and frequently tow into the mountains and get 23.4 mpg. Granted, I have the V6, but doubt there is that much difference. You should be doing better than that. Injection system should be compensating for the altitude and I use 87 octain.
 
Wow. That's surprisingly good! So you think my fuel injectors need to be cleaned out?

Any other v8's with an opinion?
 
Sorry guys, just one last observation and rant regarding the issue!
I forgot to mention that the 14ish mpgs I was averaging included running the AC 100% of the time. Now that the weather has cooled down a bit, and not using the AC (only about 5% of the time) I've been averaging about 15.7 mpg.
Does anyone else fill their tank up all the way to the very top of the gas tank funnel, right to where the gas cap is (the absolute maximum)? Seems like that is the most accurate way to calculate the mpgs.
I know it seems like the topic of mpgs of the 4th gen T4R has been discussed many times, but I feel as though there is no general consensus on what people are really averaging. Some are getting 13 and others as much as 21 in the city with the v8? I have to question the methods and consistency of how these calculations are being done?
Don't all chime in at once now!!! :)
 
I have an 05 4x4 V8 w/75000 miles. I live in las vegas. With ac on 100% of the time I was getting 15ish mpg according to onboard computer. Now that its cooling down and I am only using the ac 20-30% of the time, I am getting around 16mpg. I do 90% city drving. Tires at 36 psi. This is also driving it like a normal human being, not stomping on it at all. I also just replaced the air filter, cleaned maf, changed all drivetrain fluids to synthetic (except for oil, coming next oil change, and I wanna do plugs too)

When I first got the 4runner and before I did the maintanance listed above, I was drving it like it was my M3 and was getting 11-12mpg.

To me it seems impossible to get 19-21mpg if you have a v8, 4x4, running ac all the time, and driving in the city (45mph limit). I call BS unless you drive in school zones all day.
 
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Your vehicle will use less fuel at altitude... less air means that your computer will adjust the fuel down to keep the correct air/fuel ratio. And, of course, less fuel means less power... the general rule of thumb is that you lose 3% power per 1000 feet of elevation increase. That's for normally aspirated engines.

I personally feel that there are way too many variables to compare fuel economy between vehicles. Everything from driving style, road surface, altitude, temperature, humidity, tire design, tire size, tire pressure, etc, etc. You'll be in the ballpark when comparing to a similar vehicle in the same area, but a few mpg off between the two is not unusual.
 
I like going down to Colorado. I run around 16mpg here in SD, but it always kicks up to anywhere from 20 to 23mpg down there.

*Calculated. Not the computer.
 
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Also, the mpg display in my 4runner is always about 2 mpg better than what I am actually calculating manually. For me, a/c on: 2mpg less. A/T tires: 1 mpg less. Driving 75-80 instead of 65-70: 3-5 mpg less. 4wd instead of 2wd: 1-2 mpg less. Tire pressures of 38 psi to 33 psi: 1-2 mpg less. Pulling a 4x8 trailer: 4-5 mpg less. These are just a few of the many variables and factors in determining mpg. I've calculated anywhere from 14 to 21 mpg.
 
Thanks for the feedback gentlemen!
I guess the general consensus is that there are way too many variables to accurately compare the mpg of one rig to another unless it was done so in a controlled experiment where all variables were equal.
Side note: for those of you who believe what your dash display mpg is telling you, you are being lied to. Next time you gas up, I recommend filling it all the way to the top to where you can actually see the gas ( no longer funneling down). I found that this filling up process is much faster (less start and stop) if you pull the nozzle out and aim the gas straight down the hole. This allows you to really pinpoint the accuracy of your calculations because you know for sure that your filling up to the exact same level every time.
I know some of you may think I put too much energy into this, but I know there is probably at least a few of you out there that are just as meticulous about this as I am. The way I look at is: if your going to post up numbers, do so with as much accuracy as possible. Anyone even with a v8 can reset their on board mpg, ***** foot down the highway for 15 miles and say their getting 27 mpg.
Anyways, for those of you who try out my top off method or who already do it that way, let me know what you think about it!!!
 
Dkon, you are doing potentionally serious damage to your vehicle's Emission systems by overfilling the tank like that. All modern fuel tanks are designed to have some air inside of them for evaporation, expansion, and emission control. By over filling your gas tank like that you are saturating the charcoal canister and other emission related components that are designed to handle fumes and not liquid fuel.

That is also not 23 gallons when you overfill it like that which could through your calculations off. Also I do not know what the laws are in your state, but all gas stations in California are required to have evaporative recovery systems on the nozzles (those lovely rubber boots and crap) to recover as much of the fumes as they can. I am not sure (any confirmation one way or the other would be appreciated) if this could happen, but by bypassing that safety/emissions device you could be breaking the law. I just felt I needed to clarify that because it is potentionally damaging to your vehicle and could be a safety hazard.

That being said, at higher altitude you will have the trade off mentioned earlier about less power but potentionally better fuel mileage.
 
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Dkon82 - There was another guy on here with similar low MPG issues like you had. After about a year he finally figured out his caliper was dragging or frozen don't remember which. But something to look into if you have confirmed that everything else seems to be in order.

Also I do the 100% top off too.
 
Bad thing to do, kills your fuel pump; among other things.
Edit:
http://www.epa.gov/donttopoff/

I know some on here don't give two ****s about the environment, could care less about cat converters, but it has horrible effects. The main one you should take away is the need for expansion and air space in the tank. By overfilling, you are killing your fuel pump and vapor control system on your car. All for what? 1 more gallon?

Edited: As to not hurt feelings.
 
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Black: Oh wow, I had no idea about all that you mentioned above. In regards to the rubber boot, I'm familiar with what your talking about but I don't recall every seeing them here in the state of New Mexico; when it comes to environmental standards NM is a little behind the times (so probably not breaking any laws). As for the potential harm I may be causing, I'll simply take your word for it; If I remember correctly from previous posts, you mentioned being a master technician for Toyota right?
Q: from the way I have been filling up my tank, is it only harmful during the first 15 miles or so, until the gas level drops, creating the space needed for fumes etc.? Or will the tank be deprived of the proper oxygen mixture until I take the cap off?
So when filling up the tank, the first time the nozzle automatically shuts off flow, the level is exactly at 23 gal? Is the auto shut off activated from pressure and or fumes? Can you elaborate?
Thanks for the info!
 
No. That is the problem. The tank operates under a slight vacuum, which is why you hear the "SWWW" sound every now and then when you open the tank. When you overfill the system, pushing all the air out and the drive around... there is no air in the system.
 
DC: The helpful and informative info Black provided was educational, meaning I can learn from it and make changes. You telling me that what I'm doing is the dumbest thing I can do, and providing an "im stupid if" link is the dumbest way someone can offer advice to a fellow enthusiast.
 
Sighs. I will leave it like this, sorry I hurt your feelings. I was joking. The site is funny in a "you might be a redneck" sorta way. Also, I apologize, I guess I didn't realize that many car enthusiasts were not aware of that. Since the days when mechanical fuel pumps and fuel canisters, over filling has been what is called a "known known" bad. I apologize. At least you caught it before it killed a fuel pump or something else.

I have removed it, go about your merry way.
 
No hard feelings. I get that your intentions may be good, but your delivery came across as being snide. The rest of what you contributed was helpful. Thank you.
Chayos: thanks for the input, I'll have to research the caliper issue; are you referring to the brake caliper?
Lastly: my apologies to anyone for recommending to completely top off the gas tank. I understand now that it's not healthy for vehicles to be toped off as i was doing, and will stop pumping after the first auto stop.
 
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