Deathmage

If you had good results by upgrading/replacing parts, post here please.

- I just had my engine rebuilt and it didn't seem to improve my MPG at all.
- My alignment is slightly off.. would this effect the mpg? All I know is uneven wear on the tires and tire pressure being off would effect MPG
- o2 sensor - I read a lot of mixed results about this
- what gas do yall put in? I use cheap 87 arco gas and I'm going to try 89 mobile on the next fill and 91 after that
- I got 14.75mpg on the last fill with 75% highway 25% city

Deathmage

I've read about several people replacing everything in frustration with little or no results (replacing spark plugs, air filter). I'll try to clean out my o2 sensor to see if that does anything.

marko3xl3

Let's see...

Spark Plugs -> NO
Air Filter -> NO
TB Cleaning -> NO
Seafoam -> NO
Tire Pressure -> NO
Alignment -> It's fine, so, NO
o2 sensor -> NO (see below)

The deal with o2 sensors is that they can start to fail before they throw a code, in my case my old one was fine, but oh well, now I have a new o2 sensor .

Things I still have to check...

Fuel Filter?
Clogged Fuel Injectors?
Spark Plug Wires?

The two above are basically my last hope (unless I think of more), because I have obviously tried a lot with no success. My problem is that I cannot convince myself to think that I am getting a 3MPG difference from some others (15MPG city vs 17-18 MPG) just because of a heavier foot? Even then people with a pretty heavy foot are sometimes getting good results, while others still get crappy milage.

I am pretty sure it's SOMETHING, because engines don't just get born getting such a great difference in MPG. The only question is WHAT?!

Racer944

I don't know if this sounds ridiculous, but I got 33's on my 'runner, and get a lot better highway mileage, definetly a lot smoother, definetly feel a whole lot better. Also, did a FIPK and Borla exhaust and they seemed to improve the feel, but probably won't be worth the money. Oh well, sounds good at WOT...

914runner

Easiest way to improve MPG...Slow down! I just went on a 400 mile round trip in my new '98. I did 70-75 the whole way one way, got around 18-20 (didnt keep that good of track), on the way back I kept it at 68 the whole way (cruise control) and got 21.4!

grimpy

This is what I have done so far:
replaced spark plugs
replaced fuel filter
switched to royal purple oil
replaced 02 sensor
replaced tps
cleaned tb
cleaned maf
cleaned air filter
magnaflow exhaust
deckplate mod
isr mod


I got an average of 13.2 last fill up, approx 75% city 25% highway.

I usually average 13-14.

BTW: all the crap I did, no increase in mpg....

I'm on 33's and not regeared...

tps

914runner

Are you running 4.10's or 4.30's?

X-AWDriver

My mileage jumps around depending on how many hills I climb and how heavy my foot is so I get anywhere from 14-16 around town with at least 11 miles of highway each day.
My mom gets pretty much 17 all the time in her '99 Limited. I'm guessing my D load rated Nittos aren't helping.

MTL_4runner

The sweet spot so to speak on my 4runner (stock 4.10 gearing, 265/70R16 michelin LTX M/S tires, fill up with any 87 octane gas) is right around 65-70MPH (slower or faster are worse) which I verified with my OBD scanner (it has a gas mileage feature which shows you what the optimum speed is for best MPG on the fly). When I do that I get somewhere between 21 and 22 MPG consistently (if I encounter alot of hills, it goes down by 2-4 MPG).

.......city MPG is a totally different story.

Rick F.

Driving habits typically will give you your most dramatic "bang-for-the-buck". Unless you drive the same roads the same way in similar weather, your results will be skewed. I get 19.5-20 mpg in the summer driving 65 miles round trip to/from work on country back roads with about 12 stop signs/lights total, both ways. That drops to about 18 mpg in the winter, NOT including snow. I was off from work the entire month of December and most of my driving was around town which dropped me to 16.5-18 mpg. All-in-all, I'm typically a non-aggresive driver these days, and it's very apparent that my mileage drops when I get on it.

Mechanically, maintain a tuned engine with a clean air filter, increase your tire pressure (I prefer 34 psi in my Firestone Destination LT's and 32 psi when I had my REVO's) and by all means be sure your tires are aligned (the tire life outweighs the minor change in fuel mileage, IMHO).

ebelen1

I've tried everything (including synthetic everywhere) but an 02 sensor and all to no avail. At least the truck is well maintained.

I've also tried being gentle on the gas but this will maybe get you 1 mpg more, maybe 2.

The real test and has been super consistent for me is city vs. highway driving. If I drive all city (including a big hill daily), I get about 200 miles to a tank (about 12.5 mpg w/o factoring bigger tires). If I drive half city/half highway, my tank will go to at least 240, mostly 250 miles to a tank (a little over 15 mpg). If I do all highway, which is very rare for me, I've hit almost 300 miles to a tank (almost 19 mpg).

This has made me think that you don't have much control over mpg so I don't worry about it anymore. My numbers have been pretty consistent w/ others on this board based on driving habits so as long as she keeps runnin', I'm happy.

Roadtripr

Deathmage, do you still have your snowborad rack on the runner? That is bound to take some of your mpg

Deathmage

I do a lot of grandpa driving and I'm sure I'll be getting 11mpg ish, if I were to drive rough. Yes, I have the snowboard rack and I did hear about them taking a toll on the mpg. Maybe I'll take them out and test it.

Nobody post what kind of gas they used. I use cheap ol' Arco 87, but will try out 89 mobile, the 91 octane.

alotawatts

Same here as MTL 4Runner - 65-70 = best mpg

Roadtripr

I usually get 17 in the city driving and 19-20 on the hwy with 265/70/16 using 87 octane.

rimpainter.com

Rick F.

BTW, 87 octane in my 3.4L unless I'm towing. Going to 89 or 91 doesn't do squat for my mileage.

2000t4r

I'm getting around 20-21 mpg which is about 285-300 miles per tank. This is also with the faulty gas gauge that doesn't read correctly ever. I drive on the highway with the cruise control set at 70-75. I drive the same road everyday. I have stock tires, intake mod I always fill up with Chevron 87.

CynicX

I get better gas milage with brand name gas. I used to use BJ wholesale gas. I switched to brand name like Exxon, Shell and Mobile etc etc. I usually get 1-2 mpg better.

Just my personal experience. Although this is a big debate I've seen a ton of times I KNOW there is a difference because my WRX would NOT run on BJ's gas. I couldnt tune it and it would knock real bad. I thought it was a bad tank but didnt want to risk it. About a year later my girlfriend filled it up at BJ's and it did the same damn thing, I ended up having to drain the tank that time it was so bad. (I think she used 87 but even when I adjust the tuning for 87 octane it didnt help). Of course I had the car is tuned out it was very very finnicky about gas. But it ran like a raped ape on brand name 93-94 octane.

What I'm getting at is I know there is some sort of difference in the gas. Maybe its just additives but those additives make a huge difference.

Rick F.

Unless you don't have the standard 18 +change gallon fuel tank, that doesn't add up. 20 mpg x 18 gallons = 360 miles/tank. I still don't understand why people list their mileage as "per tank". It's meaningless unless you run the tank empty before every refill. Keep a monthly pocket planner in the car, log your mileage and # of gallons at each fill-up and the mpg computation is simple:

(odometer reading @ this fillup - odometer reading @ previous fillup)/gallons

I also suggest experimenting with your OD and ECT settings. I believe the combination of the 2 that gives you the best mileage vs. performance is based on individual driving habits and terrain.

Any changes you note should be based upon at least 3 fill-ups while under similar driving conditions.