Another MPG... IM STUMPED

M

MichaelFuller

New member
Heres what ive got;
2000 Limited V6 4x4
OME 3" HD Lift
265/75-16 BFG A/T's
Warn style front bumper w/ winch
Custom skid plate
Snorkel

My gas mileage is horrific.
Im on a good tank getting 200 to the tank and this time around I got 160.
I dont have a lead foot, and I do about 50/50 city highway.

Ive done;
Plugs, wires, PCV, fuel filter, oil change, air filter, injector cleaner, MAF clean, Throttle body clean, greased all greasable joints on driveshafts.

The truck feels sluggish when driving compared to my 98 SR5... But not hugely different.

Im stumped!
Ive got a friend with the same mods and bigger tired that sees 17mpg city average and I would be stoked if i saw anything near that..
11-13 for me :-x


Thoughts?
 
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My mileage went DOWN after I changed the plugs, wires and and cleaned throttle body. Not sure why.
 
Did you guys disconnect your battery? Have you been driving it alot since??? My mechanic friend says that the computer has re-learn the fuel consumption rate after the battery has been disconnected. I have the same issue, but he told me to give it a couple of weeks of daily driving, and it should get better....

On a related note.....

The real meaning of MPH- The Original - YouTube
 
You can also pull the EFI fuse out for 10-15 minutes.

It's the yellow 20 AMP fuse.

fuses.jpg
 
fightman80 said:
Did you guys disconnect your battery? Have you been driving it alot since??? My mechanic friend says that the computer has re-learn the fuel consumption rate after the battery has been disconnected. I have the same issue, but he told me to give it a couple of weeks of daily driving, and it should get better....

On a related note.....

The real meaning of MPH- The Original - YouTube
Click to expand...

Im not sure i believe that this will cause extreme issues, i disconnect the leads all the time for an extended period (enough so that the clock needs to be reset), and i have had no issues at all with fuel consumption, power or anything.
 
fightman80 said:
Did you guys disconnect your battery? Have you been driving it alot since??? My mechanic friend says that the computer has re-learn the fuel consumption rate after the battery has been disconnected. I have the same issue, but he told me to give it a couple of weeks of daily driving, and it should get better....

On a related note.....

The real meaning of MPH- The Original - YouTube
Click to expand...

Yes I did. However even if you didn't it shouldn't take the computer long to realize there is a problem. I am guessing the computer works through a sum of difference of error squared to figure out how much fuel needs to be used compared to how much is being sent. Like making a best it to abhyperbolic decline line. This would hone in very quickly. However, in agreement it would happen even faster if you reset the computer.
 
Weight and aerodynamics are killing you. If you drove more on flat highway than in town, you'd probably help your gas mileage by getting BIGGER tires.


That said, replace your upstream O2 sensor. That sucker controls everything, and if it's original, it's due for a replacement. Buy on amazon.com. If your truck has two cats (Cali spec) you'll need a 234-9002. If you just have a 49 state emission truck with one cat, you need a 234-4162.
 
Haha, I have it worse I think. Not lifted, stock size tires, stock bumper, etc. I did all the things you did and replaced the O2 sensor, I'm only getting on average less than 15 MPG.

BUT, I had an exhaust leak. Just fixed it and although I haven't filled up or anything yet, the gauge is moving A LOT slower than it was before. Once I refill and start a new tank I'll monitor it and see where it's at.
 
I've been contemplating doing the o2 sensor and have read a lot about replacing them even though no codes are being thrown...
Thanks for the info on the right sensor, I may go ahead and do that because my fuel costs are ripping me a new one.

Something I did forget to mention is that I do have an exhaust leak somewhere near the front passenger side.
I haven't got out the little stethascope yet to try and locate exactly where.

Is a *very small* exhaust leak (pre-sensor) going to effect fuel economy as much as I'm seeing?

Hadn't thought about that until someone else mentioned exhaust leak...
 
It will definitely effect the fuel economy, especially pre-sensor. The sensor isn't getting a correct reading so it's probably making it run very rich. I'd almost guarantee you that's the culprit.
 
I have been fighting this MPG thing for almost a year now and as of today have given up and realize that I am not ever going to get better than 12.6-12.8mpg PERIOD for city driving.

First thing I did was replace the 02 sensor and that did nothing whatsoever and it was original from 2002.

I cleaned the MAF, Nada.

My tires are properly inflated, every grease zerk is greased, I just a week ago replaced the water pump, timing belt thermostat and all other belts.
Cleaned the throttle body, replaced the PCV valve, replaced the spark plugs and wires, I use Amsoil performance improver/injector cleaner.
All fluids were changed to 100% synthetic the day after I bought the truck.

I have done basically everything that can be done that would affect fuel mileage and have gotten absolutely zero improvement, not even a 1/2mpg better.
So this truck gets about 12.7mpg city PERIOD and right around 19mpg highway.

I am running a 3" lift, 255 75R17 tires.
 
A lift on a vehicle such as ours with the V6 that is not exactly powerful will kill mpg's. I drive my buddies 96 4R with a 2 in lift and only 225 tires and i can feel a huge difference from mine. He even has the deckplate mod which is supposed to give a improvement in low end...

Going from 225's to 265's on my truck i could definitely feel a difference in pickup but im still getting about 16-17 city. I can thrown 40 bucks in my tank which around here gets me 10 gallons, drive it until the light comes on and im reading 175 miles on the trip, add about 10 to that because of tire size. I figure i would easily get 240 miles out of a tank of gas. It doesnt bother me much because i only drive 20 miles a day.
 
33 inch tires 3 inch lift and i get around 13-15 in city 15-19 on freeway, and its usually at the low number so yeah not so great. but then again you dont buy a 4runner to get good MPG you buy one to get you from point A to point B safe and comfortable.
 
I used to get an average of 18 mpg on my 2002 2x4 V6 4Runner. After a tune-up at the dealer, it dropped quickly down to 16 mpg. When I confronted them with it, the lead tech said there was NO WAY I could get 18 mpg on my truck. When I told him I was getting roughly 330 miles per tank he blew me off.

Since then, things haven't gotten better. In fact, today I measured only 14 mpg...the worst so far.

I replaced both O2 sensors last year but experienced no change. I've got new plugs and wires coming in the mail next week. I've never reset the EFI (pulling the fuse) but will attempt that too. Any other suggestions?
 
snorkel

Does adding a snorkel add any restriction? You may want to try and bypass it for a tank and see if it makes a difference.
 
I got 24 mpg once, but I was driving through Yellowstone so the speed limit is 55-60. and hwy tires stock 5 spd.

upped to 265 75 16 duratraks and its gone down. if I keep it around 70 or below I can get 18 tops.

oh well. still gets me where I need to go
 
YarSmythe said:
I used to get an average of 18 mpg on my 2002 2x4 V6 4Runner...
Click to expand...
Replaced my air filter with a K&N model and adjusted the air in my tires (265/70/16) to 31 psi cold (becoming 35 psi hot). On a full tank I drove 190 miles on the highway and 120 miles in the city. Ended up getting 19.5 MPG! Sure hope I can keep it that way. Will change the plugs and wires out next week.
 
tbst said:
My mileage went DOWN after I changed the plugs, wires and and cleaned throttle body. Not sure why.
Click to expand...


Did you use Toyota / OEM parts? Sorry had to ask...

Usually MPG goes up when one changes the plugs, wires and cleans the intake system.

:artist2:
 
My setup is pretty similar to OP's (ARB bumper, Warn winch, 265/75-16 Cooper AT3s). I am getting right at 18 ave (about 1/2 city, 1/2 highway). It was down to about 16.5 so I checked the tires. 2 were at 40 (where they should be) and the other 2 were down around 25. I aired up the tires and the mileage went up. I have load range C tires and they run at 40-45 psi. (I did notice the mileage drop when I added the bumper and winch - 170 lbs on the front end affects the mileage.)
 
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