25% increase in MPG

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Joined
Oct 29, 2008
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In the valley of the Great Salt Lake.
Most of the two years I have had my FJ62 it has been all torn apart--paint, suspension, repairs, etc. Now that I have been driving it consistently, I decided to try to do something about the 10 MPG I have been getting. I mean 150 miles out of a $50 tank of gas is painful. My rig is a stock 3FE and drive train except for the ARB suspension and 31 inch tires. I have not been compensating at all for the 31 inch tires, I just drive it and do my MPG calculations right off the speedometer/odometer. So, I figured I should at least be able to get the 12 to 14 miles per gallon that the window sticker claimed it would get when it was new.

So, I started down the Poor Gasoline Mileage troubleshooting chart in the Repair Manual. I pretty quickly eliminated the simple things like fuel leak, dragging brakes, dirty air cleaner, incorrect ignition timing, idle speed, spark plugs and tire pressure. That left the more involved items. So I pulled the EGR valve off to take a look. It has a long pipe with a hole at the end that sticks into the intake. The hole and the pipe were almost completely plugged with carbon. AH-HA I thought! A smoking gun. So I ordered up a new EGR valve and modulator from Cruiser Dan (it's an expensive sucker). After installing these new parts, I ran through a tank of gas. It seemed to have a little more power, or should I say it seemed to be a little less gutless. I mean, I can now actually accelerate going up the freeway on-ramp and hit freeway speed by the time the on-ramp ends! But, at the end of the tank of gas, I had still only gone 150 miles. Rats. Well, OK, on to the next item. I bought a new PCV valve and rubber grommet (the old grommet was hard and brittle). I wouldn't be surprised if the PCV valve was original. I compared the old one to the new one. The old one still rattled, but it wasn't a clean sounding rattle like the new one. So I installed the new parts and started driving. Driving included some highway driving, a couple of hours of wheeling in 4 LO, and driving around town. I got 200 miles out of this first tank of gas following the PCV valve replacment. I calculated MPG and I got 12.5 MPG out of this tank of fuel! Yes, positive improvement. I'm not the guy to explain why, and I plan on running through a couple of tanks of fuel before I declare positive success, but the initial results look promising. PCV valve and grommet are just a little over $10, so I almost paid for it with the first tank....And you might also want to check your EGR system.
 
Have you ever checked the valve clearances? I've helped several friends set their valves for the first time and have found that the majority of the trucks' exhaust valves were set to .008" - same as intake spec - instead of the factory spec of .014". In each case, a small but noticeable gain in power was felt by the owners. Another thing you might try, if you haven't already, is bumping initial ignition timing a degree or two from the factory 7* btdc. Have you checked compression #s? 31" tires with the stock 4.11 gearing nets about a 10% increase in calculated fuel mileage so, instead of 10 mpg you have been getting 11 mpg. Wow!! If compession #s are within factory spec your efforts should get you closer to 14-15 mpg on the hiway.
 
So are you guys talking something in the 9 or 10 degrees neighborhood?

Every engine is different which seems logical enough, factory tolerences being what they are. Since adjusting timing on the 3FE isn't as easy as a sbc with a degree wheel, you might try a big bump right off, say 10 or 11, rather then sneaking up on your engine's timing happy place one degree at a time. You can play with timing and octane rating to your hearts content. I've read here of others going all the way to 13* btdc with the 3FE but taking your time with this process is worth it and easy does it. Better pep AND a SMALL gain in mpg can be realized with optimized ignition timing.
 
I got big gain out of cleaning the throttle body, new plugs, air filter seafoam in the gas and another right into the oil, driving it about 200 miles before an oil change, vaccum hoses- valves and timing next year
 
The 3FE is just abysmal around town. It's the nature of it. I have move to acceptance on that one. I was pleasantly surprised with an 800 mile trip to Southern California and back--17 mpg, all freeway at 65 mph.

I think the torque converter is just not efficient, because once it's locked in high gear, it actually does pretty well. When it's shifting all the time, the fuel economy goes in the toilet.

Doubt the PCV had anything to do with it. Kind of like how it runs better after you wash it.
 
with a flat belly pan that is dimpled like a golf ball, you can expect to increase your highway millage by another 20%
 
The 3FE is just abysmal around town. It's the nature of it. I have move to acceptance on that one. I was pleasantly surprised with an 800 mile trip to Southern California and back--17 mpg, all freeway at 65 mph.

I think the torque converter is just not efficient, because once it's locked in high gear, it actually does pretty well. When it's shifting all the time, the fuel economy goes in the toilet.

Doubt the PCV had anything to do with it. Kind of like how it runs better after you wash it.

So it would be the A440 tranny that is abysmal, not necessarily the 3FE! Once I got my 3FE set up right, I am very pleased with it around town. It is coupled to a 4 speed manual.
 
Doubt the PCV had anything to do with it. Kind of like how it runs better after you wash it.

I'm still dubious that the PCV would make that kind of difference, which is why I'm going to go through a couple of more tanks of fuel before I believe it. It is on the troubleshooting chart for poor fuel economy however.......
 
I really have no problems with our 62 s. The 80 with full time 4 wheel drive is another thing .I need to get the Australian kit and make it part time. Mike
 
I felt a small improvement in low end peformance when I installed my PCV catch can (with new valve and grommet). No immediate change in economy though.

I haven't messed around with my timing since I Seafoam'd my engine really good last summer. I should give it another shot. It pinged like crazy when I tried to do it before, but I got a s*** ton of carbon out with my last Seafoam treatment, so I'm curious to try again. I have no EGR equipment installed, so I think that might make my engine a bit more apt to ping under load when the timing is advanced.
 
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with a flat belly pan that is dimpled like a golf ball, you can expect to increase your highway millage by another 20%

Bwahaha! Who's been watching MythBusters?

Try a tank at 55mph and see what it does. I drove that all last week in Eastern Oregon and went from 19mpg to 22mpg over 2300 miles. I wouldn't be surprised if you can get it to 15.
 
There are really three knowns to supper fuel economy. One, is to radically reduce the air drag at highway speeds. Weight is not a issue for the energy "hp and torqe" when driving at highway speeds. The physics formula for grad is

Coefficient of drag

Fd = Pv2.Cd.A/2

Drag coefficient - Wikipedia, the free encyclopedia


Fd is the friction drag in pounds I suspect. The land cruiser because of its body style, has a large surface area that creates alot of drag. A very turbulent under carriage, Steeply raked windshield, A flat front grill area, and flat back area with large open wheel wells plus less then efficient engine contribute to the less then desirable fuel economy on the highway.

The old fj60 also suffers from GVW fuel economy numbers. It takes considerably more Force. In physics its called F=ma. To get this beast up and running to speed which takes more fuel to make this happen. When its weight and drag are substantially reduced, you can put a smaller engine inside the vehicle and still get the same amount of performance with less Force F with less Mass m. This is why small light aerodynamic cars get such high fuel economy numbers.

I should bring it on my self just for fun to design a truck with Superior aerodynamic drag numbers to see what it would look like :)

Also, take a look at this web site on the most aerodynamic trucks on the road. http://fueleconomy.net/feg/best/bestworstEPAtrucksNF.shtml

Seems the smaller hybrids win fuel economy marks for great fuel economy. BTW, semis are now experimenting with these numbers with more radical fuel economy numbers.

With the land cruiser, some how having it lowered for in city/highway speeds with increase fuel economy numbers. Some radial suspension design would have to work in this case. But, you can on the cheap, change the way the drag is reduced on the truck without a whole lot of money and....driving habit.

If you see a light turning red down the road, take your foot off the throttle. Coast to the stop. If you are lucky, the light will turn green and you wont stop, thus requiring LITTLE force to get back up to speed. Baby your throttle if possible. Alow the truck to catch up to the throttle position, not the other way around.

I believe in the future, to get super good fuel economy numbers from trucks, there suspensions could extend out like landing gear similar to jet aircraft, then extend in and tucked to the body with some suspension moments for better fuel economy numbers.

Here is a good site on Cd Drag 101 http://www.recumbents.com/car_aerodynamics/

http://www.recumbents.com/car_aerodynamics/

one more :) http://ecomodder.com/blog/diy-aero-fairings-honda-125cc-motorcycle-214-mpg/
 
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That would be cool to see! Come up with a good benchmark approach so you can see if you achieve any measurable differences.

But start with a 60 as a platform!
 

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