Trying to get my MPG back...

[Erick Lihme]

Just follow the maintenance schedule... fuel filter too.

Yep, lower gearing doesn't seem to effect mpg badly. On a 2wd 22RE auto, stock with 3.40's the thing was a dooooog! 21 to 26 MPG with stock gears was about the same as the MPG with 4.30's at normal speeds! This preserves the trans, and provides power to pull trailers used in construction with the stock 195/75R14, and gain ground clearance in the winter with 235/75R15. The effective ratio with the large tire is then 3.70. The 4WD has the 5 spd and I also am setting it up with gears, but the better example is the 2WD with the AUTO with the tall final OD ratio of .70(.688) verses .85 (5sp), and the dual purpose the vehicle serves with radically different tire sizes, and treads.

As others have commented, it does seem that converter lock up could be stronger with the lower gears and it doesn't kick down to 3rd with it's 1.00 ratio very often. Speaking for the 22RE, the RPM at 60 mph is now in line with the 5 speed, putting it into the original design and natural power band.

If you don't plan on off-roading during trips as you've planned, investing in a highway tire for the purpose could be cost effective in several ways. 235/75R15 Michelin LTX M/S are fantastic on my 85', super long life, plenty of bite and top mpg. With lower 4.30's, the pair out of an auto which cost only $400.00, is a sensible compromise as 32" inchers, a 235/85R16 should run comfortably sans trailer, the equivalent of running 31x10.5's with stock 4.10's. The tall tires will only be used occasionally. With stock size tires (28.9"), with the grades around here, will be more comfortable, and with less down shifting needed, just as economical mpg wise. And 7.00R 15's Yokohama's (dia. 29.8") will be used in the winter for pushing snow, and off roading in the mountains in muddy conditions. Off road performance can be improved by rebuilding the transfer case with 4.70:1 gears. I'll get there slow, yet do just fine on the trail.

On paper anyway, it seems it could be a well balanced approach in many regards. Running large tires all of the time with stock brakes is a safety concern for me, and getting in and out of the truck on any day and especially in the winter with bulky boots on short legs is a hassle.

 

[crawler#976]

Well, I did a test run today - went down to Phx and back with the truck in "economy mode". Drove the whole way with the AC on and totaled 218 miles traveled and 10.5 gallons gas used. That works out to 20.7 MPG - an increase of 4.3 MPG from the trucks previous mileage. That brings fuel cost down to $815.00 from $1035.00 - a decrease of $220.00.

My cost to get that 4.3 MPG was:

Remove Yakima rack, shovel and high lift jack relocation: $0.0, just my labor since I already had the shovel/HL mounts previously installed on the tailgate.

Used stock alloy rim: $30.00

New Dominator A/T tire: $93.00

Total: $123.00 plus tax.

Fluids/tranny fluid exchange costs were not counted, the truck was due for a 90K service anyway, but they totaled up to $60.00 in synthetic gear lube (only 4 quarts!), $31.00 for 6 quarts of 5W30 Mobil 1, and $89.00 for the tranny fluid exchange at a local shop.

So, was it worth the trouble? Yeah, the extra $100.00 bucks pays for one nights lodging in Gardiner, WY. on our trip.

A secondary benifit is a much quieter and smoother ride - the MT/R's are loud and not quite round...

Mark

 

[Erick Lihme]

At $3.25/gal over the next 100,000 is $4,000 in savings:arabia: . And like you said, gas ain't gonna get cheeeeper!

 

[kcowyo]

4.3 mpg is substantial. Darn roof racks....

Congrats, sounds well worth the effort to battle the rapidly rising cost of fuel. :clapsmile

......and for the record, Gardiner is in Montana, not Wyoming.

 

[Martinjmpr]

I wouldn't worry about the AC either. AC has come a long way in recent years. Modern AC units are pretty efficient and any additional load on the engine that you get from having the AC on is probably offset by decreased wind resistance from having all the windows closed.

I've always been a mileage fanatic since I got my first vehicle in 1979 (during the Iranian oil embargo.) Back in the old days I shunned AC as being both unneccessary for Colorado and unneccessarily draining in terms of fuel economy. I based this assumption on the fact that when I was a kid we had an old Ford station wagon and running the AC would typically cost us 2-3 mpg. So to me AC always = worse MPG, which was true for the vehicles of the 60's and 70's.

But that was the old days. I got my first AC equipped vehicle in 1999 (Ford Ranger) and after I did I wanted to kick myself for all those years I'd spent without it.

The worst was the time in 1993 that I drove from Southern Arizona to North Carolina in 2 1/2 days in a non-AC equipped Mitsubishi Montero in late July! It was so brutally hot that the only way I could stay even remotely comfortable was to drive at 70mph with all 4 windows open wearing only shorts and flip flops - needless to say I couldn't hear the radio. By the end of the day I was still soaked in sweat. It was miserable.

In 1999 I got the Ranger in the middle of Summer, primarily because I was sick of not having AC. In 2002 I took a similar trip from CO to NC, again in the middle of July, and I was cool and comfy the whole way. I also did not notice even the slightest difference in MPG.

 

[devinsixtyseven]

Couple more tricks you can do to help the A/C.

Shop around auto audio shops, see if you can find the sound deadener that's felted strings and such. It's very lightweight and a good insulator. Anywhere you can add it, do so...doing the headliner will make a huge difference.

Make sure your heater valve is completely closed. The one on my Tundra sticks open a little, so does the one on Katie's Stratus. You'll need to go under the hood or in the dash to check/fix this.

For raw mileage, assuming the outside of the truck is as good as it'll get, keep your speed between 55-70mph. That for me is a difference of as much as 3mpg.

Make sure your alignment is good...good meaning caster is identical both sides so you're not always holding the wheels in a partial turn, and toe is also identical and minimal on both sides to reduce scrub and wear when moving in a straight line.

You'll get better mileage picking the right gear for the situation and letting the Yota engine rev high on the uphills than you will trying to keep it low and lugging it...just like the old Roos. What you use on the uphill you'll get back letting the truck run where it wants going downhill.

With a large vehicle, V8, toys, etc. I just got 17.5mpg crossing the Rockies on I70 with stock gears and 35" tires in a truck rated 13/17. Don't forget why the speed limit was lowered to 55 back in the day .

-Sean

 

[dirtysouth]

According to the mythbusters show, running the ac has no more effect on gas mileage than riding with the windows down.

 

[DaveInDenver]

According to the mythbusters show, running the ac has no more effect on gas mileage than riding with the windows down.

That seems intuitive. Windows up is better aerodynamics with engine power sucked off to run the compressor, windows down ruins the aerodynamics of the car with less energy required to run the compressor. Probably a wash more or less over a road trip. OTOH, not having A/C in my truck until last summer I can tell you that driving through St. George, UT when it's 100+ without A/C is pretty much what Elijah's Chariot must be like in the 8th circle of Dante's Inferno. IOW, worth every penny in lost efficiency!

 

[Martinjmpr]

According to the mythbusters show, running the ac has no more effect on gas mileage than riding with the windows down.

I've often wondered why this is so. Seems to me it's either because designers have gotten more serious about aerodynamics (our 71 Chevy wagon was build like a brick!) or because AC compressors have gotten more efficient, or more likely a combination of both.

With a pickup, especially, because it has such a small interior area to cool AC can be remarkably efficient. In the trip I referred to above going to NC in 2002, even on the hottest days I could only leave the AC on for 15-20 minutes before I had to switch it off or start mixing heater air in with it. The inside of the cab got to be like an icebox!

I spent most of 2004 in Kuwait and we drove a number of different vehicles including quite a few Toyotas (everything from little Corollas to Prado SUVs) and the locals that we worked with actually referred to the best air conditioners as "Toyota air conditioning." Anything that can make a vehicle comfortable in 125 degree heat has got to be pretty good!

 

[DaveInDenver]

Seems to me it's either because designers have gotten more serious about aerodynamics

I think it's mostly this, that the shape and air flow over a car is very much based on the windows being closed. Compressors are probably a little better now than 25 years ago, but mostly I think it's the aerodynamics.

 

[LaOutbackTrail]

A few things I'd like to add:

• 2001 Nissan Xterra 4wd. 13-21mpg has been my best and worst mileage. 13mpg ********************** on the interstate to the hospital with baby about to be born (50 mile trip) with A/C on. 21mpg, 150 miles on easy dirt roads. No major accelerating, no hwy, etc. ~45mph.
• I know you said you are removing your roof rack etc. For my Xterra, if I remove the 4 offroad lights on top, I gain about 2mpg
• Driving characteristics help greatly. Light on the gas, good gas mileage. Plan where you are going and the less the gas pedal moves and the better mpg you'll get.
• I keep my tires aired about 2psi above manufacturer's suggestion. Mainly to help compensate for the fluctuations in tire pressure, and tires have less rolling resistance.
• DO YOU REALLY NEED MUD TERRAINS???? I have a strong belief in a good all terrain. Sure you may need a little more technique and might get stuck... but if most of your time is going to be on the hwy... even if you do get offroad often.... the extra price of mud terrains doesnt pay off, espcecially if they wear quicker.

I'll shut up now.

 

[LaOutbackTrail]

According to the mythbusters show, running the ac has no more effect on gas mileage than riding with the windows down.

Mythbusters concluded that running without AC sucked much more gas than windows down. I seem to recall the vehicle going 15+ more laps with the windows down? But that was going 45... not 55.

I have ear problems (and my 1 year old daughter gets ear infections easy also) so I dont like running my windows all the way down at hwy speeds, but all 4 windows down half way is as effective in cooling the interior as both front windows fully down.

I definately get better mileage without the AC on. I check my MPG every time I fill up.

 

[DaveInDenver]

The rule of thumbs I think are A/C will reduce your fuel economy by 10% due to the load it puts on the engine. But the drag introduced by rolling the windows down reduces your fuel economy by about 10% at 45MPH and 20% at 55MPH. It goes up from there as speeds increase, too. So under 45MPH fuel economy is best with windows down, around 45MPH it's a wash more or less and above 55MPH you will do better with windows up.

 

[LaOutbackTrail]

The rule of thumbs I think are A/C will reduce your fuel economy by 10% due to the load it puts on the engine. But the drag introduced by rolling the windows down reduces your fuel economy by about 10% at 45MPH and 20% at 55MPH. It goes up from there as speeds increase, too. So under 45MPH fuel economy is best with windows down, around 45MPH it's a wash more or less and above 55MPH you will do better with windows up.

Try half down... works great for me... Id say maybe 2-5%

At 45 my engine runs at probably 2200 rpms. 60 i think is 3000rpms. 70 is close to 3500.... maybe more.... 5th gear needs to be a lot higher....

I mean hell, my dad's Chevy 2500 hd (I know... totally different vehicles) at 70 is running like 1500 rpms or so.... and he gets 23mpg.

 

[Grim Reaper]

had a couple tanks since this thread started and getting my gears broken in and I have been keeping a close eye on my MPG. Thought I would add my experiences and add some other factors.

Information about the truck:

86 4Runner with 22RE.
My truck is running 33x12.5's BFG AT's with about 27 psi to keep the tread wear even (skinny 7 inch rims).


Recent rebuild on the engine and transmission. Synthetic in tranny.
The truck has been regeard to 4.88 and that adds about 1 mile for every 100 traveled and confirmed with a GPS.

One tank had a fair amount of hwy and I live in Atlanta and travel the Atlanta Autobahn so 65-70mph is the norm. At those speed truck alone I am getting right at 21mpg. That actually has about 15 miles of trail riding. Considering the tire size and the associated rotating weight I am quite pleased with the millage. One straight run on the hwy I think It would get 23-24.

I have recently picked up a little 4x6 enclosed trailer that I have been getting a lot of use out of recently. BIG hammer on the MPG. It is down to 17.5 with about 60% of the tank pulling the trailer and a quick trail ride. The trailer is light but had a couple loads that probably had the total extra weight around 1,100lb.

Trailer has a very short tongue so I was hoping it would draft the truck and not put a big bite on the MPG. I have noticed with the trailer on I can roll down the back window and not smell the exhaust so it is drafting. I think where it is killing me is the shape of the rear with the vertical drop. I am thinking about putting a wedge on the back door sometime in a few weeks to try to smooth out the airflow and see if the MPG comes up.