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Yes, it can be cleaned using MAF air sensor cleaner. Unplug it and remove it from the intake and spray it over a rag or some container to contain the drippings, being sure it's dry before reinstalling. Don't touch the wires inside the sensor with the tip of the sprayer. Don't use compressed air that isn't filtered for water or oil to blow dry it either. Your FJ sounds like it's getting the normal mileage, so it may not need cleaning anyway.

My 2011 AT FJC gets 16-17 mpg around town in the winter. It does closer to 16 if it's really cold. I did get 24 mpg on the highway once, but that was downhill with a stiff tailwind. Hwy is usually around 19 or 20 mpg and yes, a tailwind does make a huge difference with the mileage on this vehicle. I also have the newer engine, so that is indicated in my slightly higher numbers.

No one has mentioned to the OP that perhaps his FJ's injectors may be really dirty? I know someone mentioned pouring in some fuel system cleaner, but if they're dirty enough, they may require being removed, checked and cleaned on a stand. If they can't be cleaned, and I've seen quite a few that refused to spray properly even after a cleaning, they have to be replaced. Dragging brakes could be another possibility, although not as likely since you'd probably notice a smell after driving.
 

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Wow, great info. Can you clean the MAF sensor yourself ? Mine in a manual '14 with roof top tent and Titan tank mounted on rear gate. I get 18 on highway 15 in town if I go 74 or less and do not have the rooftop tent mounted. With it mounted 15 is about as good as it gets. BUT ... it's a lot more fun to rev it up more in between shifts...
Easy to clean the MAF sensor yourself.

Here's a simplistic YouTube vid showing the basic process on a dual-VVTi 1GR-FE engine in a 4Runner, but he spends as much time cleaning the external, match-head shaped intake air temperature sensor as he does spraying solvent down into the actual MAF sensor elements. More importantly, he never even looks at down into the housing to view the MAF sensor elements to verify if they are clean.

Here's a web photo of the two tiny, extremely delicate little ceramic sensing elements deep within the housing ... these must be surgically clean. If just spraying MAF cleaner on them, soaking for a moment, and then spraying again doesn't get them clean, you need to VERY DELICATELY wipe them with a cotton swab. They are extremely delicate and can be destroyed if any force is applied while cleaning, or if the nozzle of the MAF cleaner can touches them. Don't swab across them, swab parallel to the leads. Apply as much force as you would if you were wiping a cotton swab across your eyeball.

Automotive tire Wood Electric blue Door Gas


18 MPG with a manual at 74 MPH is pretty good ... is your RTT a streamlined hard-shell model, or a big non-aero rectangular box?

I guarantee you will pick up another 1 or 2 MPG if you limit your speed to 65.

I've got a '14 AT with hard-shell RTT, under-armor, awning, fridge, on-board air, E-range tires at 45 PSI, etc. and I can achieve 20 MPG on the freeway IF I limit speed to 65-70 and drive very conservatively WRT acceleration, etc.
 

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I've discovered the joys of using these little micro brushes for doing all sorts of very fine detail and cleaning work. Much nicer to use, they have smaller heads and leave nearly zero lint. You can find them in different head sizes too.

 

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I just knew somebody was going to throw in litres and confuse me badly. Someday I'm going to plug in that obdII reader that has been in the console for two years and see how bad it really is....
27.5 mpg unloaded and 19.5 mpg pulling the trailer , i always use 98 octane petrol
 

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I usually get 10KLMs to the litre , i towed 3 tone of firewood in a large heavy tandem trailer 125 KLMs the other day and got just over 7 KLMs to the litre
27.5 mpg unloaded and 19.5 mpg pulling the trailer , i always use 98 octane petrol
That works out to 23.5mpg and 16.5mpg as both the volume of fuel and distance traveled are different. But that’s great gas mileage on your FJ either way, congrats. I get around 17mpg to 19mpg on average with my driving style.
 

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I don’t come here much anymore (sold my FJ’s) but I recall this issue coming up frequently in the past. Many suggested changing the thermostat. FWIW
 

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Ethanol is making it almost impossible to get to epa specs.
While the maintenance items mentioned are more important, when I run 100% gasoline the mileage always surprises me.
On a New England trip where I tracked my mileage and I bought pure gas whenever I could; I was consistently in the the low to mid-20's with 2 adults, 2 dogs, the back packed and the top loaded. OEM suspension and tires.
 

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The factors that have the greatest affect on fuel consumption are:
1. By far the greatest affect is the driver's driving habits: hard on the accelerator and hard on the brakes, little or no coasting up to stop lights and stop signs, consistently running up to 3,500 RPM or higher, etc.
2. Condition of the engine's fuel-feedback system: clean mass airflow sensor and correctly functioning fuel-air sensors;
3. Average cruise speed on the highway: you'll need to limit that to around 65 MPH for decent fuel economy;
4. Ratio of highway driving to stop-and-go city driving;
5. Modifications that add weight and aerodynamic drag: larger/heavier than stock tires, roof rack, roof-top tent, heavy steel skid plates, etc.
6. Tire inflation pressure: the higher the pressure, the less rolling resistance there is. The recommended tire pressure shown on the door jamb label is only applicable to the original tire type and size that the vehicle was delivered with.
7. Condition of the engine's ignition system (primarily spark plug condition).
8. The 2010 and later dual-VVTi, higher compression engines are capable of a few more MPG than the '07-'09 models with single VVTi engines.

A well-tuned, minimally-modified '07, conservatively driven, can achieve 18-19 MPG or better on the highway.
A well-tuned, minimally-modified '10 or later can achieve 20-21 MPG on the highway.

If you don't know when the last time the MAF sensor was cleaned, do it now. If the air-fuel sensors have more than about 85,000 miles on them, replace them now. Check your tire pressures. Try upshifting at 2,000 RPM for one tank of gas and see how that affects fuel consumption.
I can echo the above, my 2011 with 62,000 miles on the clock averages 20.7mpg, urban and on a measured 540 mile highway journey averaged 24.8mpg. Well happy with that. :)
 

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2013 FJ Cruiser TT #885/2500
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100% agree that not all premium gas is made the same. On top of that, the gas quality you have been getting from that same gas station all these years may be getting worse as well.

Recently I had my MPG drop from 15-17mpg to 12.4mpg & my check engine light went on.
With the help of another post in this Forum I was instructed to look for LOWEST ETHANOL content possible.

Im in Vegas & I was shocked at what I found out.

it doesn’t matter the Octane Number as much as it matters if the gas is PURE. You want 0% Ethanol & yes the gas cap says nothing higher then ETH10 But the lower you go the better.

I switched to SHELL PREMIUM & my MPG jumped back up to 15.5Mpg. (It’s inconvenient for me because there isn’t many SHELL STATIONS around, but it runs SOOOO MUCH BETTER now.)

The world Is changing and poor quality gas may be the simple answer.

Here is One article: (Maybe someone else can find even more recent info on this because the Gas Quality that caused an issue was me filling up at a SINCLAIR DINO station where the ETH can get up to 15%, and even that is listed at Shell. That’s why you need SHELL PREMIUM.

 

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Ethanol has 30% less energy per unit than gasoline, but E10 is only 10% ethanol, or net -3% energy. Your own driving style can make far more difference in MPG than that. It is more likely that you either got some very bad quality fuel from that gas station, or there was something else that caused your mileage to drop so much, that one time.

Thoughts on E10:
Ethanol absorbs water, so if some condenses in the fuel it will be burned along with the fuel. If you have a tank with pure gas the water that condenses will pool at the bottom. Either rusting out the inside of a steel fuel tank, or freezing in the fuel lines in winter. This is why "dry gas" ("ethanol") used to be something we added to our fuel tanks in winter, back when all we had was pure gas.

It is a good idea to drain off the bottom of a fuel tank which has pure gas in it, once a year, to get rid of any liquid water condensed there. This is what is done with alcohol free fuel tanks at airfields and marinas

When E10 came along there was the usual hysteria but I've found that on my various classic cars, even when stored 2 years, putting some Sta-Bil fuel stabilizer in, and making sure the tank was completely full, it ran fine next season. I've never seen a measurable change in mpg when running either pure gas or E10 gas. Since pure gas costs several $ more/gallon, and is hard to get, I just run the easily available E10.


Norm
 

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This conversation has come up more than a few times in the last couple of years I've been on the forum. I've tried to pay attention because fuel efficiency should be near and dear to all our hearts. Even if you don't care about the environment or any of that other "liberal BS", fuel costs money, and the more money you're pouring into your tank, the less money you will have available for FJ mods! Right?

I remember talking about this to a coworker who was young Mechanical Engineer just a couple of years out of school who had taken more than a few classes on internal combustion engines and really knew his stuff overall. He told me that as RPMs went up, engines typically became starved for air. That means that at high RPMs there will be more unburned fuel going out with the exhaust. His recommendation was to shift at lower RPMs whenever possible.

I tried it, and sure enough, my MPGs went up more than anything else I had done at that time, more than better gas, more than conservative driving, etc. Of course, I don't remember the exact numbers off the top of my head, but I've adjusted my driving habits so I shift below 2000 RPM on the regular, usually at about 1500. Sure, she's still a brick, but now she's a less thirsty brick (y)
 

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Ethanol has 30% less energy per unit than gasoline, but E10 is only 10% ethanol, or net -3% energy. Your own driving style can make far more difference in MPG than that. It is more likely that you either got some very bad quality fuel from that gas station, or there was something else that caused your mileage to drop so much, that one time.

Thoughts on E10:
Ethanol absorbs water, so if some condenses in the fuel it will be burned along with the fuel. If you have a tank with pure gas the water that condenses will pool at the bottom. Either rusting out the inside of a steel fuel tank, or freezing in the fuel lines in winter. This is why "dry gas" ("ethanol") used to be something we added to our fuel tanks in winter, back when all we had was pure gas.

It is a good idea to drain off the bottom of a fuel tank which has pure gas in it, once a year, to get rid of any liquid water condensed there. This is what is done with alcohol free fuel tanks at airfields and marinas

When E10 came along there was the usual hysteria but I've found that on my various classic cars, even when stored 2 years, putting some Sta-Bil fuel stabilizer in, and making sure the tank was completely full, it ran fine next season. I've never seen a measurable change in mpg when running either pure gas or E10 gas. Since pure gas costs several $ more/gallon, and is hard to get, I just run the easily available E10.


Norm
I think it was really bad gas ya. It dropped to 12.5 for 2 months before putting better gas in it and it immediately jumped back up
 

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2014 FJ Cruiser
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I have just bought a 2014 FJ and it has some mods like steel bumpers front and back, winch, large tires. I’m trying to determine whether I’m on target with my gas mileage. I got 18.5 mph off my first tank and I drove it very conservatively.
Is that about right for gas mileage?
 
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