Must be new record 8MPG

[T4Running]

I'd like to hear if anyone has mechanical input on how I could improve my MPG? I understand all the general things (driving style, 4wd, etc...) I have been getting at BEST 250km (155miles) per tank!!! I ran it almost empty last time to fill up a full tank of 93octance and so far have done 100km (62miles) on half a tank! This can't be normal

I have done my research and was looking into a complete driveline service, flushing all fluids, changing filters, belts, but what is really needed and has improve mpg for you.

 

[gamefreakgc]

Three thoughts:

1. Our gas gauges are inaccurate. How many gallons did you put in? My gas light comes on when I've got 5 gallons left so I usually only put 13-14 gallons in it.

2. Search is your friend here, looks like you've done some but missed the big ones. MAF cleaning is the biggest. Then spark plugs and wires if they have not been done recently. Look into replacing your front O2 sensor (only use DENSO!).

3. Any check engine lights? Are you running oversized tires?

 

[JimG]

Is that just city driving?

 

[JBurt]

Here's some things to check: http://www.toyota-4runner.org/3rd-gen-t4rs/159942-bad-mpgs-things-check.html

Depending on what you've done to your truck, 8 might be expected. Do you have 35's, SAS, 5+ inches of lift etc.

For stock that is pretty low. I'd just make sure everything is in good condition. How many miles are on your 4runner?

 

[BrandonF]

Here's some things to check: http://www.toyota-4runner.org/3rd-gen-t4rs/159942-bad-mpgs-things-check.html

Depending on what you've done to your truck, 8 might be expected. Do you have 35's, SAS, 5+ inches of lift etc.

For stock that is pretty low. I'd just make sure everything is in good condition. How many miles are on your 4runner?

LOL if he has 35's and an SAS, I doubt he'd be here on t4r.org complaining about his gas mileage.

And even still, 8 mpg is absolutely horrible. No matter how modded his truck is, there is definitely something wrong. Mine has 33" MT's and a lot of extra weight and I'm still getting well over 400 km per tank (17-19 mpg). Not to mention, I have over 350,000 km and nothing has ever been rebuilt.

 

[gamefreakgc]

The funny thing about larger tires is that it doesn't really lower your gas mileage, it makes your miles "longer".

If stock wheels say, have a circumference of 50 inches (throwing out a number here) and you swap those with tires that are 2 inches higher, you've added 6.28 inches to the circumference, which is now 56.28. So now a wheel rotation is roughly 12% longer and your odometer count is going to be 12% lower, hence your MPG's went down by 12% (i.e. 17 MPG mixed would drop to 14.96).

That's not taking account any extra wind drag from being higher off the ground though or tread design.

 

[Illicitdream]

Correct if me if I'm wrong but running lower octane might help as well. I don't think the 5vz-fe N/A is set up to run 93 octane. If you were SC that would be different.

 

[gamefreakgc]

Correct if me if I'm wrong but running lower octane might help as well. I don't think the 5vz-fe N/A is set up to run 93 octane. If you were SC that would be different.

In my experience, it has been the opposite. I'm no chemist, but a higher octane is a higher fuel efficiency. I used to run 91 as opposed to 87 in my Pickup and gained a whole MPG from it (offset the fuel cost in gas savings). There might be a point in which that efficiency levels out (running racing gas probably will not net me 30 MPG), but I don't think it would lower MPG's.

Though it's pretty pricey and like you said, unless your engine has forced induction or some crazy air intake mods it's unnecessary.

 

[Ed_C]

I have done my research and was looking into a complete driveline service, flushing all fluids, changing filters, belts, but what is really needed and has improve mpg for you.

Biggest improvement was changing my driving style. Second improvement was from doing a "tune-up" consisting of the air filter,spark plugs,and PCV valve (gained 20 miles from the usual distance the fuel light turns on). Search my posts using the keyword "mileage".

But man,your mileage is horrible OP. Posting your truck's setup would help,and if there are any issues like check engine light etc.

 

[animator]

The funny thing about larger tires is that it doesn't really lower your gas mileage, it makes your miles "longer".

If stock wheels say, have a circumference of 50 inches (throwing out a number here) and you swap those with tires that are 2 inches higher, you've added 6.28 inches to the circumference, which is now 56.28. So now a wheel rotation is roughly 12% longer and your odometer count is going to be 12% lower, hence your MPG's went down by 12% (i.e. 17 MPG mixed would drop to 14.96).

That's not taking account any extra wind drag from being higher off the ground though or tread design.

I may agree with part of your post, but the other thing to consider is the efficiency of moving the vehicle down the road is also less, due to large tires. The gear ratio was decided based on overall engine output vs desired speed vs acceptable gas mileage, trading one thing for another until we got what we have in these vehicles. If you put larger tires on without regearing, your engine is having to work harder to get and keep the truck moving at a desired speed, therefore, gas mileage suffers.

I know because I have a truck (not a toyota) that had 3.88 gears, and when I moved up to 35" tires, the mileage went from a 16mpg average to less than 10. After 4.56 gears, it's back to 15-ish.

 

[gamefreakgc]

I may agree with part of your post, but the other thing to consider is the efficiency of moving the vehicle down the road is also less, due to large tires. The gear ratio was decided based on overall engine output vs desired speed vs acceptable gas mileage, trading one thing for another until we got what we have in these vehicles. If you put larger tires on without regearing, your engine is having to work harder to get and keep the truck moving at a desired speed, therefore, gas mileage suffers.

I know because I have a truck (not a toyota) that had 3.88 gears, and when I moved up to 35" tires, the mileage went from a 16mpg average to less than 10. After 4.56 gears, it's back to 15-ish.

Yeah totally. I was looking only from a calculation perspective. Small wheel size changes usually don't put too much stress on the gears/engine (like going from a 31" to 32" like many do) but there's so many other factors that could also affect it. Like how road tires get better mileage than All Terrain, and All Terrain get better mileage than Mud & Snow, etc.

There's almost too many factors once you start changing your setup from a stock setup to say what may or may not be stealing your MPG's.

 

[nevada]

I'd like to hear if anyone has mechanical input on how I could improve my MPG? I understand all the general things (driving style, 4wd, etc...) I have been getting at BEST 250km (155miles) per tank!!! I ran it almost empty last time to fill up a full tank of 93octance and so far have done 100km (62miles) on half a tank! This can't be normal

I have done my research and was looking into a complete driveline service, flushing all fluids, changing filters, belts, but what is really needed and has improve mpg for you.

how much fuel are you adding from empty?



I don't see how it would be possible to get 8mpg. unless you have a leak, I suspect it would be running terrible if it really is burning 8mpg worth of fuel...

 

[T4Running]

I may agree with part of your post, but the other thing to consider is the efficiency of moving the vehicle down the road is also less, due to large tires. The gear ratio was decided based on overall engine output vs desired speed vs acceptable gas mileage, trading one thing for another until we got what we have in these vehicles. If you put larger tires on without regearing, your engine is having to work harder to get and keep the truck moving at a desired speed, therefore, gas mileage suffers.

I know because I have a truck (not a toyota) that had 3.88 gears, and when I moved up to 35" tires, the mileage went from a 16mpg average to less than 10. After 4.56 gears, it's back to 15-ish.

I definitely agree with you, and what most people are saying, modifying anything from factory can mess things up. Theres an insane amount of engineering that goes into design the entire vehicle set up to work in harmony.

The sad thing is that mine in completely stock apart from a K&N intake (recently cleaned) and overall she seems to be running great. I see no indication that its running super rich or the fuel ratios are off. This has been pretty much all city with some idling in the cold morning, but very sensible driving even with theses factors I should get somewhere around the average 16mpg.

 

[T4Running]

Three thoughts:

1. Our gas gauges are inaccurate. How many gallons did you put in? My gas light comes on when I've got 5 gallons left so I usually only put 13-14 gallons in it.

2. Search is your friend here, looks like you've done some but missed the big ones. MAF cleaning is the biggest. Then spark plugs and wires if they have not been done recently. Look into replacing your front O2 sensor (only use DENSO!).

3. Any check engine lights? Are you running oversized tires?

I do watch to see how much fuel I put in, can't remember right now but I keep receipts and will check. I have also noticed the inaccuracy of our gauges, is there a fix for this? On certain long road trip it would be nice to have a better reading, and have have seen mine fluctuate during acceleration, braking or being on a decent slope

 

[gamefreakgc]

I do watch to see how much fuel I put in, can't remember right now but I keep receipts and will check. I have also noticed the inaccuracy of our gauges, is there a fix for this? On certain long road trip it would be nice to have a better reading, and have have seen mine fluctuate during acceleration, braking or being on a decent slope

Not really a good fix for the gas guage. It's a problem with the float sensor and assembly that is in the gas tank itself. It's a bit of work to do so almost all of us just live with it. A few daring souls fork out the cash for a new assembly and drop the tank to do it.

Weird that you're almost stock and having such bad issues. Do you ever smell fuel? You won't see it on the ground if it leaks since it evaporates quickly but you can sure smell it.

If not then you've got a bad sensor telling it to max out the fuel trims as high as possible when it doesn't need to. MAF and O2 are the places to start to see if they need cleaning/replacing.

 

[THatfield]

Not really a good fix for the gas guage. It's a problem with the float sensor and assembly that is in the gas tank itself. It's a bit of work to do so almost all of us just live with it. A few daring souls fork out the cash for a new assembly and drop the tank to do it.

I fixed mine for less than $100 and an afternoon working on the truck with my pops. Worth it to me, things damn accurate now. I didn't think that was too much money to know how much gas is in the tank. :shrug:

 

[scrap metal]

Are you using US gallons or Imperial gallons in your calculations?

Imperial gallons are larger, so it would equate in lower mpg... does Canada use imperial in MPG calculations?

What we really need so we can rule out speculation is how many gallons you fill up when you "think" your empty

 

[animator]

I definitely agree with you, and what most people are saying, modifying anything from factory can mess things up. Theres an insane amount of engineering that goes into design the entire vehicle set up to work in harmony.

The sad thing is that mine in completely stock apart from a K&N intake (recently cleaned) and overall she seems to be running great. I see no indication that its running super rich or the fuel ratios are off. This has been pretty much all city with some idling in the cold morning, but very sensible driving even with theses factors I should get somewhere around the average 16mpg.

Yep, 16 should be a bare minimum without towing something or driving up mountains or in head winds all day.


First thing I'd do is jack the truck up and spin the wheels by hand and feel if anything is binding or rubbing. If the brakes are sticking, this will let you know.


Next I'd check the exhaust system to see if they're flowing freely. May be necessary to remove the cat(s) to see if they're clogged, although I suspect you'd get a code if there was a problem with them.


Next I'd check the plugs and see what condition they're in. Also check the gap.


I'd probably also run some fuel injector cleaner just for good measure. I've never put in 93 octane, so I have no idea how that would affect mileage, but with the cheap stuff, 16-19 is my average on a stock engine.


If all of that (easy-to-do stuff) checks out, next step is a compression test. If one or more of your cylinders has low or no compression, that will contribute to poor gas mileage, and an overall loss in power.

 

[Grenvilleter]

I'm going to take a stab at cold weather causing your poor mileage.

Never owned a vehicle in over 40 yrs that outside temp plays such a huge role in fuel consumption.

Temps in my area are -30C to -5 C right now and my mileage is deff halved and 250km on a tankful that gets over 400km in the summer time. The colder it is, the more fuel I burn.

This year I put a cardboard in front of the rad but I don't think it helped much but getting absolute numbers is next to impossible without diligent recording of conditions environmental as well as mechanical.

 

[T4Running]

Are you using US gallons or Imperial gallons in your calculations?

Imperial gallons are larger, so it would equate in lower mpg... does Canada use imperial in MPG calculations?

What we really need so we can rule out speculation is how many gallons you fill up when you "think" your empty

All calculations done using US gallons, measurements in Canada are normally liters and kilometres. Correctly me if I'm wrong but we have 70L tanks = 18.5 US gallons and the last time I filled up I put in 16 US gallons. Not quite empty but still works out to horrible mpg