2006 v8 4x4 with bad mpg

[Jasonredwood]

Just bought a 2006 sport v8 4x4, stock.
Not much records from the past but pretty clean and runs nice at 148k on it.
I have clocked 2 fill ups under my ownership.
12.5 mpg city and freeway was what the onboard comp was telling me.
Then I seafoamed and replaced the air filter, oil and filter, plugs, cleaned maf, and pcv valve(new enroute) and checked tire pressure.
Currently it says I'm averaging 14.8. Ugh
What else should I be looking at?

 

[super.secret]

I did the same with Seafoam and did regular maintenance. i went from 12.8MPG to 14.7MPG and now steady at 13.8 MPG, 2 months later. 2005 sport V8 4WD. I honestly dont think its going to get much better than this.

 

[swampdodo]

Just bought a 2006 sport v8 4x4, stock.
Not much records from the past but pretty clean and runs nice at 148k on it.
I have clocked 2 fill ups under my ownership.
12.5 mpg city and freeway was what the onboard comp was telling me.
Then I seafoamed and replaced the air filter, oil and filter, plugs, cleaned maf, and pcv valve(new enroute) and checked tire pressure.
Currently it says I'm averaging 14.8. Ugh
What else should I be looking at?

Well, since you've gone this far...what about greasing the u-joints and slip yokes, change the diff fluid, tranny fluid and x-fer case fluid (and coolant).

Should be noticeable, but you might check for a sticking caliper...4th gen are known for it.

But other than that...yeah, might not get any better. I think the highest I got on mostly hwy was right at 19mpg...according to the readout.

 

[techoguy]

How did you guys use the seafoam? The best I get on all highway driving is 15MPG calculated, and in town as bad as 11MPG. I hear other guys getting 18MPG and I keep wondering what I should do. Average, I get about 13MPG on average.

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[Jasonredwood]

Well, since you've gone this far...what about greasing the u-joints and slip yokes, change the diff fluid, tranny fluid and x-fer case fluid (and coolant).

Should be noticeable, but you might check for a sticking caliper...4th gen are known for it.

But other than that...yeah, might not get any better. I think the highest I got on mostly hwy was right at 19mpg...according to the readout.

Yeah that's the plan down the road.

The best I saw, calculated, was 18 mpg but that was right after resetting the system.

 

[Jasonredwood]

How did you guys use the seafoam? The best I get on all highway driving is 15MPG calculated, and in town as bad as 11MPG. I hear other guys getting 18MPG and I keep wondering what I should do. Average, I get about 13MPG on average.

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There's a couple threads on here that read about it. I went in through the pcv valve tube and some in the gas tank.

 

[HOJeepster]

There's a couple threads on here that read about it. I went in through the pcv valve tube and some in the gas tank.

I was getting 22mpg highway and about 18 in city when the truck was stock at sea level.

All built I get about 16 highway and 14 city at 5000 feet.

I'd imagine you should be getting better gas mileage at sea level

 

[Rishi3]

My 2007 V6 sport gets around 13 city... I also have a cornfed 3/2 and 275 KO2's. Cleaned MAF, throttle body, tire pressure, I think spark plugs.

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[Morphyne]

bad calipers (dragging) would hurt mpgs. so would bad wheel bearings and bad tires. or E-rate or oversized tires. non-stock rims (more rotating mass) will also hurt mpgs.

 

[Bossman]

You may also want to verify what the onboard computer is telling you, with regards to mpg, by also doing hand calculations.

http://www.toyota-4runner.org/4th-gen-t4rs/60516-reset-ecu-better-gas-mileage.html

http://www.toyota-4runner.org/4th-gen-t4rs/73896-mileage-computer-issues.html

http://www.toyota-4runner.org/5th-gen-t4rs/66138-accuracy-mpg-gauge.html

http://www.toyota-4runner.org/4th-gen-t4rs/92104-how-increase-gas-mileage.html

 

[Phils4th]

15 mpg combined doesn't seem too bad. The avg mpg is merely an estimate. Measuring how much gas goes in and how many accurate miles you drive is the only way to truely measure mpg. Different tire size from oem will alter distance driven. Best way to save fuel now that you did all that work is to keep your foot off the gas, and drive the speed limit. You restored some of the engines lost efficiency, so less throttle should mean the same power, so you use less fuel. It's all in the right foot.

With almost 1/5 less air pressure at 5000 feet, high altitude will most likely increase highway fuel mileage. Less air means less air resistance. T4R isn't the most aerodynamic SUV around... It's also the hills that don't help mpg at altitude. Since there is less air pressure, we must use more throttle to allow more air in to get the same amount of air/fuel in to make power, compared to sea level.

 

[Rishi3]

I am certain it is my flow master muffler as my mpg dropped 6 points after the install from 18 to 12 then stayed steady at 13.5. I am going to contact them.

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[duffdog]

I am certain it is my flow master muffler as my mpg dropped 6 points after the install from 18 to 12 then stayed steady at 13.5. I am going to contact them.

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If you are sure that the mpgs dropped then that simply means that the ECU detected more total airflow and added more fuel...giving you more power. It is not possible to make more horsepower without adding more fuel, so I'm not sure what your goal was by adding an aftermarket muffler specifically designed to increase power? Were you trying to get more power AND mpgs? Them dang physics and laws about conservation of energy will always getcha...

 

[rooost]

If you are sure that the mpgs dropped then that simply means that the ECU detected more total airflow and added more fuel...giving you more power. It is not possible to make more horsepower without adding more fuel, so I'm not sure what your goal was by adding an aftermarket muffler specifically designed to increase power? Were you trying to get more power AND mpgs? Them dang physics and laws about conservation of energy will always getcha...

Yea and more sound = more foot = more sound

I wonder if you are actually seeking scientific solutions, why you would not take the most care to determine scientifically the actual mileage. The dash is know to be off.

Really what did you expect from a V8 steel box cutting through the air, you can spend all you want on maintenance and mods but driving style and condition will have more effect

 

[MSRP.]

Have been averaging 13-15 mainly loaded up to the gills since I purchased it with almost at 160k miles. Mostly road trips fully loaded, sometimes with boards/skis on the roof.
Sometimes get 17mpg on the rare occasion. Winter tires are 265/65/17's.

Just this past weekend, pulled 19mpg, hand calculated, just me, and and 50lbs of camping gear in the back, nothing on the roof, travelling mostly between midnight-4am, and 8am-noon, weekend traffic, interstate going there 75 miles an hour, and coming back through country highways at a steady 65 mph, finally back on summer blend gas.

Still need to check tire pressures and get new plugs in too.
Shocked me for sure!
255/75/17 Goodyear Wranglers from Jeeps.

 

[RonJR]

Depends somewhat on the gas you're using, as well. Burning 10% ethanol will drop mileage by ~5%. Using mid-grade gasoline instead of the lowest grade will increase mileage by a few %, because the ECU can advance timing further.

Hard braking is a mileage killer in city driving. Anticipate stop lights and slow down in advance, as much as you can without being a traffic nuisance.

Air resistance is a big deal at higher speeds. I can average 19-20 on a 55-65 mph trip through the Colorado mountains, but only about 16.5 on a 75 mph trip across Kansas.

Finally, as has been said, don't take the onboard mileage computation as truth. Verify your odometer with a GPS, and then hand calculate mileage over several tanks to get the true picture.

 

[Phils4th]

If you are sure that the mpgs dropped then that simply means that the ECU detected more total airflow and added more fuel...giving you more power. It is not possible to make more horsepower without adding more fuel, so I'm not sure what your goal was by adding an aftermarket muffler specifically designed to increase power? Were you trying to get more power AND mpgs? Them dang physics and laws about conservation of energy will always getcha...

Wrong information right here ^

We can make more horsepower without adding more fuel. This is done through engine efficiency. The faster, more complete, more efficient way to burn fuel and convert it to torque will always make more power and use less fuel. Conservation of energy tells us we cannot create or destroy energy without it being transferred to something else. We're not creating or destroying energy, we're using energy for torque. It's all about how efficiently we can make the transfer.

Engines today are way more powerful, cleaner, and use less fuel than engines from 30 years ago. This is because today, we have much better design that contributes to airflow, machining processes that are more precise with better materials, better technology to control fuel, spark and valves to provide more consistency across the board. We can burn less and gain more if you know what you're doing.

 

[spc54]

Mines not too much better. 4.7l v8 limited.... Premium fuel for now...

 

[roadsterboy85]

In regards to my 4x4 v8 I get about 15.5 mpg calculated at each fill up. That's with mixed driving, stock t4r with 2.5/1.5 daystar spaced lift.


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[duffdog]

Wrong information right here ^

We can make more horsepower without adding more fuel. This is done through engine efficiency. The faster, more complete, more efficient way to burn fuel and convert it to torque will always make more power and use less fuel. Conservation of energy tells us we cannot create or destroy energy without it being transferred to something else. We're not creating or destroying energy, we're using energy for torque. It's all about how efficiently we can make the transfer.

Engines today are way more powerful, cleaner, and use less fuel than engines from 30 years ago. This is because today, we have much better design that contributes to airflow, machining processes that are more precise with better materials, better technology to control fuel, spark and valves to provide more consistency across the board. We can burn less and gain more if you know what you're doing.

Actually, you are completely wrong. When ANY engine makes its peak horsepower, its fuel economy essentially drops to 0. Show me ANY high performance engine that gets better fuel economy at full throttle made now vs 30 years ago that has the same power. There aren't any and you don't have any data to prove otherwise. What may be confusing you is that engines do not always make their peak horsepower and it is VERY difficult to test the complete system efficiency of a vehicle while including all parameters. Wind resistance, rolling resistance, transmission drag, lubrication viscosity, gearing, powerband, temperature, fuel type, emissions restrictions and testing method all contribute to determining the system efficiency of a vehicle.

The "parameters" you mentioned are cursory at best and do not actually relate to anything you claim they do. For instance, pintle valve spring rate simply determines the maximum valve float rpm and not the maximum power. Similarly, "better technology to control fuel", shows that you do not understand fuel injector pulse width. Full throttle is full throttle, period. There is no "control" of the injectors at full throttle, they are simply open all the way for the longest duty cycle possible, in some cases 100%.

Please show me 2 motors of identical power that get different fuel economy at their maximum power whose only difference between them was the year they were made. It can be any engine of similar design and displacement from any manufacturer.