Another gas mileage (mpg) thread. But with a COOL twist.

[shootmymime]

So I've been quite pleasantly surprised with a shocking new turn of events.

My current mpg is 13 city and 14 highway

Saturday I drove 86 miles. Mixed driving. Filled up with gas w/ 5 gal.
That equals 17 mpg. I thought it was a fluke

Sunday I spent the day in Yellowstone driving around then the hour and a half drive home. Today I filled back up with gas and was again surprised.

226 miles driven Sunday. And I put 12.7 gal of fuel in. That another 17 mpg in fuel. ABSOLUTELY AMAZING.

So I pose this question to all of you. What changed? Only one reason I can think of it my new radiator I just installed Friday for some preventative maintenance. Everything went smoothly and I'm happy.

So did my radiator kill my mpg and my new one fixed it?

 

[RedSled]

I'm gonna say probably not on the radiator thing, but did you adjust your tire pressure lately, or did your area switch to there summer gas blend?

 

[jhfleet]

Back in the day a fellow at work bought a new VW bug and constantly bragged about his great gas mileage. A few of us got together and would top his car off from a can of gas a couple of times a week. After a few weeks he happily reported that his already great mileage was getting to unbelievable levels as the car got broke in. Then we stopped adding fuel.

 

[shootmymime]

I'm gonna say probably not on the radiator thing, but did you adjust your tire pressure lately, or did your area switch to there summer gas blend?

no, i was going to add air before the trip got busy and didnt. the fuel has not changed, its been in the 70s -80s for the past 3 months.

Back in the day a fellow at work bought a new VW bug and constantly bragged about his great gas mileage. A few of us got together and would top his car off from a can of gas a couple of times a week. After a few weeks he happily reported that his already great mileage was getting to unbelievable levels as the car got broke in. Then we stopped adding fuel.

thats just down right mean!!! haha!

 

[3bears]

you sure you did nothing else ? How did it run before radiator change as far as temp. some engines are touchy when it comes to running temperature.

 

[7echo]

I think you need some more samples.

The Yellowstone trip was how much on the highway?

 

[shootmymime]

you sure you did nothing else ? How did it run before radiator change as far as temp. some engines are touchy when it comes to running temperature.

Temps view to be the same.

I think you need some more samples.



The Yellowstone trip was how much on the highway?

It was about 150 miles in the part taking multiple stops to get out and view attractions with long distances in between going about 35-50 mph

But the rest was the hour and a half driving home windy cross winds doing 70.

I'm going to keep doing some city driving this week and see if it changed.

 

[KainDrag]

jeebus I get like 20 mpg on the highway on a bad day avg. A bit higher 22-23 with good pedal control.

 

[shootmymime]

jeebus I get like 20 mpg on the highway on a bad day avg. A bit higher 22-23 with good pedal control.

mine is not aerodynamic as your tho.

<a href="https://www.flickr.com/photos/126279212@N03/18446679904" title="DSC_1246 by Patrick Mccole, on Flickr"><img src="https://c1.staticflickr.com/1/290/18446679904_4f26480755_b.jpg" width="1024" height="683" alt="DSC_1246"></a>

 

[KainDrag]

mine is not aerodynamic as your tho.

<a href="https://www.flickr.com/photos/126279212@N03/18446679904" title="DSC_1246 by Patrick Mccole, on Flickr"><img src="https://c1.staticflickr.com/1/290/18446679904_4f26480755_b.jpg" width="1024" height="683" alt="DSC_1246"></a>

Oh yea mines stock as hell lol

 

[Ed_C]

Do your normal drive,where you've been getting 13/14 and see if there's still an improvement in mileage.

Did you use a different brand/octane that weekend than the usual gas you've been using? In my case different fuel affected mileage. I've been driving a GX470 for the past month and always use Valero. Since last Thursday to Sunday I used Speedway (formerly Hess) and definitely lost some mileage. I would always out-do the indicated range display by at least 10-15 miles,now I've been getting 10-15 less driving the same route I've been doing. My '02 4Runner is also the same,I get the best mileage consistently with Valero.

 

[good2go]

After the lift with bigger tire rim and combo, I was getting about about 15.4 mpg, down from about 18.8 mpg stock. I recently checked the tires and they were under inflated at about 32-35 psi. I inflated them to 45 psi and during trip to Vegas, I was getting 17.2 mpg - kudos!

 

[Riceye]

Two things come to mind:

-Did you disconnect the battery when changing your radiator, rebooting the engine control? That may account for some differences.

-Driving through Yellowstone/Grand Tetons is a stretch of 35-45 mph roads. I recall my best ever gas mileage in my 1987 VW Westfalia was there - 23 mpg!!!. The reason? Reduced wind drag. The Westy has a profile very similar to a brick. Once I get over 50 mph, I can feel and hear the mileage drop. Your 4Runner sits pretty high, and catches lots of air, especially at higher speeds.

The answer is probably not one or the other listed above, but a combination of the two, and perhaps a few other unidentified factors.

Ambient buffalo methane increasing stoichiometric efficiency?

 

[sportscarfan]

I'm going with the yellowstone speeds -
Last time we were in yellowstone (over 10 years ago) we were driving my wife's '92 Integra GSR (high reving motor, short gears). We filled up in Jackson Hole, spent the week in the park and made it back to Jackson (barely) to fill up again. On that tank we got 44MPG.

 

[shootmymime]

Do your normal drive,where you've been getting 13/14 and see if there's still an improvement in mileage.



Did you use a different brand/octane that weekend than the usual gas you've been using? In my case different fuel affected mileage. I've been driving a GX470 for the past month and always use Valero. Since last Thursday to Sunday I used Speedway (formerly Hess) and definitely lost some mileage. I would always out-do the indicated range display by at least 10-15 miles,now I've been getting 10-15 less driving the same route I've been doing. My '02 4Runner is also the same,I get the best mileage consistently with Valero.

Not with grade. I am now committed to 91 with a supercharger. Kinda like a love hate relationship.

After the lift with bigger tire rim and combo, I was getting about about 15.4 mpg, down from about 18.8 mpg stock. I recently checked the tires and they were under inflated at about 32-35 psi. I inflated them to 45 psi and during trip to Vegas, I was getting 17.2 mpg - kudos!

I want to fill my tires back up. I think they are around 35

Two things come to mind:



-Did you disconnect the battery when changing your radiator, rebooting the engine control? That may account for some differences.



-Driving through Yellowstone/Grand Tetons is a stretch of 35-45 mph roads. I recall my best ever gas mileage in my 1987 VW Westfalia was there - 23 mpg!!!. The reason? Reduced wind drag. The Westy has a profile very similar to a brick. Once I get over 50 mph, I can feel and hear the mileage drop. Your 4Runner sits pretty high, and catches lots of air, especially at higher speeds.



The answer is probably not one or the other listed above, but a combination of the two, and perhaps a few other unidentified factors.



Ambient buffalo methane increasing stoichiometric efficiency?

Haha I think your right. Damn buffalo. How can I find one to put under my hood. No I didn't disconnect my battery. Had the radio on the whole time rocking out!!

I'm going with the yellowstone speeds -

Last time we were in yellowstone (over 10 years ago) we were driving my wife's '92 Integra GSR (high reving motor, short gears). We filled up in Jackson Hole, spent the week in the park and made it back to Jackson (barely) to fill up again. On that tank we got 44MPG.

You might be right. The slow speeds might have something to do with it. I sure hope not tho.

Time will tell if it truly was Yellowstone or something on my part.

 

[farmerjon]

I got really good MPGs in Yellowstone driving 45 most of the time, that's where our trucks really shine in terms of engine load and RPMs, that's their perfect speed, about 50 MPH. Along with lots of up and down and coasting, it makes sense. Higher elevations get better MPGs as well, gas runs leaner, and YELL is very high, especially in the passes. I've gotten 23.8 MPG there, lots of coasting.

Glad you got to visit! Was probably really crazy this time of year.

Edit: 02SE and shootmymime clarified this a little further. Basically, the engine doesn't run lean or rich so much as it uses less fuel as a result of the thinner air. A slight difference, since our trucks can tune for altitude - it's just a matter of them using less.

Your 4Runner won't run rich or lean based on altitude. If all the pertinent sensors and the ECU are working properly.

The ECU will gather the data from the pertinent sensors, and adjust the amount of fuel injected in real-time, so the air/fuel ratio stays as close as possible to the pre-programmed value, at any elevation.

Rich or lean no. So you are correct. But what they are saying is with less air you use less fuel in order to keep the afr in check. Thus better mileage.

 

[atalarico]

I got really good MPGs in Yellowstone driving 45 most of the time, that's where our trucks really shine in terms of engine load and RPMs, that's their perfect speed, about 50 MPH. Along with lots of up and down and coasting, it makes sense. Higher elevations get better MPGs as well, gas runs leaner, and YELL is very high, especially in the passes. I've gotten 23.8 MPG there, lots of coasting.

Glad you got to visit! Was probably really crazy this time of year.

Waittt a second, I was under the impression that MPG worsens in higher elevations. Seriously, for the last 5 years since moving to Denver, that's what I thought I had read. Mind=blown.

Also, this thread rules because for the first part of it I kept thinking, "Jesus Christ, that's terrible mileage!" but then I saw his rig and said "Well, actually, that's not too bad at all!". Haha! Sick rig, though.

I've experienced this phenomenon before, and it was after a large combination of regularly scheduled maintenance tasks. I never did figure it out, but I just rolled with it and was happy to get better mileage.

Good luck!

 

[farmerjon]

Waittt a second, I was under the impression that MPG worsens in higher elevations. Seriously, for the last 5 years since moving to Denver, that's what I thought I had read. Mind=blown.

Also, this thread rules because for the first part of it I kept thinking, "Jesus Christ, that's terrible mileage!" but then I saw his rig and said "Well, actually, that's not too bad at all!". Haha! Sick rig, though.

I've experienced this phenomenon before, and it was after a large combination of regularly scheduled maintenance tasks. I never did figure it out, but I just rolled with it and was happy to get better mileage.

Good luck!

Yep! This is why higher elevations sell 85 grade gas, whereas most other places sell 87 minimum. You can get away with the lower octane at higher elevations because it is leaner, not as much air. It's not running richer like it would at low elevations with much more oxygen.

My rig stock with an ARB can get 20ish going about 60-65 on flat ground. It's a matter of acceleration and how much wind drag you have from mods, like lightbars, as well as weight/gearing.

Good explainer here in simple terms:

Octane is the ability of a fuel to resist knock, and high-compression engines tend to knock more. The obverse of that is that lower-compression engines can run on lower-octane gas. Air is thinner the higher above sea level you go. Less air going into the cylinders means less pressure at top dead center when things go bang. It's a lot like lowering the compression ratio in the engine, reducing the need for high octane. Cars will run just fine on lower-octane fuel when they're well above sea level--and all of those states are. Hopefully, by the time you get back down to denser air, you've burned off most of the low-octane stuff, and can refill the tank with higher-grade fuel.

Source (at bottom of page): http://www.popularmechanics.com/cars/how-to/a5308/4345737/

 

[Jaketino]

Are you kidding me? I got 12 the other day and you have a supercharger. That's crap.

 

[02SE]

Yep! This is why higher elevations sell 85 grade gas, whereas most other places sell 87 minimum. You can get away with the lower octane at higher elevations because it is leaner, not as much air. It's not running richer like it would at low elevations with much more oxygen.

Your 4Runner won't run rich or lean based on altitude. If all the pertinent sensors and the ECU are working properly.

The ECU will gather the data from the pertinent sensors, and adjust the amount of fuel injected in real-time, so the air/fuel ratio stays as close as possible to the pre-programmed value, at any elevation.