4x4Lamm

Maybe its winter, maybe its gas, maybe its just me but my gas mileage has slowly moved from "it's worth it to drive such a sweet truck" to "unacceptable".

When I first got my 95 it had 28" tires and I got about 14-16 MPG.

After I lifted it and got 32"s it dropped to about 12-13 (unknown odometer accuracy), this is with 4.88 gears too!

Now I am just slightly above 10 MPG and except when I am making emergency runs to the fire station, I drive like my Grandpa on a Sunday.

I really am upset with this because my 92 with twice the miles constatly got 15 MPG with 33"s and I drove it like Mad Max (it was a stick, current 4Runner is automatic)

So, as of now I am going broke and gas is relativly cheap. I would like to perform as much maintainance and replace as much stuff as I can (save an engine or transmission swap) to boost my MPG and power because the easier it is for the engine, the less gas is used. As far as I know, my engine is in good timing as the head gaskets were replaced not to long ago by a great mechanic and I have no "check engine light" or noticable engine troubles. My spark plugs are also new. My MPG calculations may be a bit off, but since it was geared for 31"s and I am running 32"s, they can't be off by much.

Here is the plan then:
-Manual hubs
-New o2 sensor
-ISR mod with K&N intake tube
-Exhaust (flowmaster 40 and CatCo cat
-Clean throtle body
-Clean air flow sensor
-SeeFoam treatment (gas and intake)
-New cap and rotor
-Free flowing air filter (stock replacement, not open element)

After that if I still have a dime in my bank account:
-Jet chip
-Electric fan
-New wires (MSD?)
-Headers

So, I ask of you.
-What else can I do to help (please, no get a 3.4, etc. etc. etc.) I know there is no miracle mod, but I plan of having this a long time (body is cherry) so I don't mind on waiting for things to pay off over a long period of time.

-What may I have overlooked as a possible cause of a mileage decrese? Wheel bearings causing drag? Need to find a better preassure for my tires?

-How do my numbers compare to yours? How much worse is it?

-Anything else, I am serious about getting this to work for me.


Thanks, as always.
Lamm

regularguy412

I did a bit of research on tire sizes. The 28's you were running were about 10% smaller than the 31's the speedo / odo was calibrated for. If you didn't correct for the speedo / odo offset, the odo was showing that you traveled 10% farther between fill-ups than you actually traveled. Now that you are closer to an accurate tire size relative to your speedo / odo calibration, you are seeing a truer mileage figure. Some other things to consider: Bigger tires are heavier. Not only heavier, but more rotating weight that has to be spun up and slowed down every time you accelerate or decelerate. Carrying weight (of any kind) costs mileage. Automatic transmission vehicles are generally less fuel efficient than manual transmission vehicles.

I have a 92 3.0 w/ auto tranny that has 182,000 miles on the clock. I run 31's but the speedo was calibrated for 28's, so I correct for miles traveled by increasing the trip mileage figure by 10% after every fill-up to get a more accurate mileage figure. Recently my mileage was pretty bad around town. I was getting about 11 mpg , even with the mileage correction. I had been running some Bosch +4 plugs in it. The plugs work great in my 2002 Solara and in my daughter's 99 model Camry ( both 4-bangers ). But for some reason,, the 3.0 in my 4Runner doesn't like Bosch. So i changed back to some regular NGK plugs and cleaned the throttle body thoroughly. With no other changes, my around town mileage improved to about 13.5 mpg. The next day, I left on a 1300 mile trip. Best mileage on the highway was 20.25,,, worst was 17.89. I also found that fuel with 10% ethanol in it gets worse mileage. It was worse by ( you guessed it ) 10%, compared to the previous tank of 'normal' fuel. So be alert at what type of fuel you are running. That could cause poor mileage. Also be sure to have your tires inflated properly. I try to keep my 31's at 35 lbs.

Looks like you are on the right track with the mods you mention. Keep us posted as you go.

Mike in AR

93Toyota PU

You are on the right track...plugs, wires, rotor and cap plus cleaning injectors and top end can easily add a couple of MPG. I've read conflicting reports on the oxygen sensor. It stands to reason that eventually it will wear out although some have reported that cleaning it will work too. To save a few bucks you might want to try cleaning your old O2 sensor first. There are a couple of threads on here about cleaning the O2.
Your insight about gas is correct too. My experience with Ohio gas is that you always lose a couple MPG in the winter due to the winterization of the gas by the refinery. Regularguy412 is also correct in that ethanol additives in gas (usually 10 to 30 %) result in slightly worse gas mileage (usually 1-2 MPG). So check out the gas pump and look for a notice to that effect. Usually ethanol based gas is cheaper, but due to losing a couple of MPG you may not be saving much $ per tankfull. There is a lot of good info on the internet about ethanol based gas. A couple of tankfulls can help clean up your engine.
Be carefull with the air cleaner mods...experiment with it and keep track of the results. More air will make the engine more responsive and powerful but it can also use more gas. The engine computer controls the air to fuel ratio at a fixed rate, so more air could mean more fuel!! A less restrictive air cleaner and performance exhaust will add a few HP, but less us know how your MPG fairs. Doing these mods in steps with close monitoring of MPG will help you isolate the mods that have the greatest effect on MPG . Keep us posted on your results and good luck.

4runnermax

ahh!!! don't use bosh plugs (+4 especially) unless you have a tuner car, even then stay away from bosh (plugs anyway) I'm a commercial manager @ Advance Auto and I steer people away as much as possible, Reason--> they over genralize plugs vehicle to vehicle, so... vehicles on each extreme have very poor performance. So i usually steer them towards autolite, champion, acdelco, (domestic) or ngk (japanese) depending on the vehicle. I've heard conflicting stories on NGK Iridiums any body know if there worth the 6.50 a plug???

F0RSAKEN

This is something I have been considering as well. I dont know why you are getting such terrible gas milage, because I do a mix of city/highway every tank, and I AVERAGE 17.5+ mpg. My best was a little over 20 I think, still with a city/highway mix. My truck is a stock '94 with the 3.0, new wires, plugs, rotor, cap, fuel filter.

One thing that I was thinking about getting was the MSD ignition Amp. A hotter spark will create a better combustion, which will result in a slightly more efficient usage of the fuel dumped into the cylinders.

Something else to consider, do you have any driveline lag? I.E is your ebrake not fully releasing?

To regularguy412: What were the bosch plugs doing to your truck? I have them in mine, and it seems to run fine, other than part throttle hesitation, which I have been trying to figure out how to cure. Could the plugs be causing this? Because it did it before I switched them out....

metalhed

I will respond to the NGK Iridium plugs. I put them in my 3.4 S/C motor and noticed a 2 mpg drop. I went with the 2 step colder plug, no knock but decreased mpg. I pulled out Bosch +4, (came in the truck when I bought it) which were getting 18 to 19 mpg in the city. They did knock under hard acceleration.

just a slight hi-jack sorry

tc

Lamm - I am seeing about the same mileage. You should really check your speedo either with a stopwatch against mile markers or GPS. Going from 31's to 33's, my speedo is only off like 1 MPH at 70 - not enough to worry about! Also, how often do you fill up? I seem to get much better mileage on the last 1/2 the tank than I do on the full 1/2...Here's what I've seen with my truck and read on here:

TIRE PRESSURE! It's free and it makes a HUGE difference. I document my mileage every tank, and you can tell when I've been wheeling and haven't filled them up as usual. I need to do the chalk test to see what my pressure really should be, but I'm running a little higher than stock (about 32 IIRC). I would imagine with the wider tires, you may need to go up a little more.

TIMING: It's free. It's easy. It made a HUGE difference in my truck. Factory says 10 BTDC, you can safely go a touch more.

AUTOMATIC: Driving Molly's truck with 35's, 5.71's and auto, she tachs MUCH lower RPM in OD than I do in 5th. Lots of people around here say you'll get better mileage with the 3.0 running higher RPM's. Make sure you're not kicking into OD too soon driving like "grandpa on Sunday". (Not advocating return to MadMax style - just hit the little button to kick it down)

TPS: Your Throttle Position Sensor may need adjustment. Seems to cure a variety of woes, including mileage. Do a search on "TPS" for all the details.

If your goal is MPG, be careful about the "performance" mods, especially if you do a lot of "highway" driving. Since the computer is going to equalize the air/fuel ratio when in closed loop mode (mostly highway), more air = more fuel. Especially the headers, as they promote scavenging of the cyclinder, more effectively removing any unburned fuel instead of giving it another chance...

regularguy412

I liked the longevity factor regarding the Bosch plugs, since they have a platinum electrode. Reason being: Changing plugs in the 3.0 is not the easiest thing to do -- especially number 5 and number 6 plugs at the back of the motor. I ran them for about 30,000 miles before making the change about a month ago. I had noticed a consistent drop in fuel economy. The last thing I wanted to do was change plugs. So about two months ago, I changed plug wires. Nothing fancy, just stock-type replacements. I figured with nearly 180,000 miles on the old wires,, they may have been going south. When I changed the Bosch plugs out, I noted some ash deposits on them. That is generally a sign of the remnants of the burning of fuel addititves. These plugs may be a bit more prone to fouling in this motor, than others. I had a bit of a stumble from off-idle, as well, with the Bosch plugs installed.

From all the threads I've read on this and a couple of other boards, the 3.0 has never been a mileage or horsepower king. Combine that with the fact that these older 4Runners are heavy vehicles, on the order of 4,000 lbs. They sit up high and catch more wind. They have lots extra parts turning ( if you have ADD hubs ). And with an automatic transmission,, it's really a prescription for bad mileage. However, I just love to drive my 4Runner with the 3.slow. It won't win many drag races, but it's peppy enough to suit me.

When the weather gets nicer in the spring,, I plan to put my other set of wheels on ( the 7-spoke). These have smaller tires on them ( 28") and a more normal tread. Then I'll see how my mileage fares.

Mike in AR

sandcrawler

if this makes you feel any better, i've done all the items noted above and my MPGs have been sagging a lot lately. i'm still trying to figure out what's up, but my truck miraculously got better mileage before i started fixing it up.
go figure...

AZrocktoy

iTrader: (1)

Hi Lamm,

Above is what I have done to my 89 pickup V6 with 220,000 miles on it. I also have a jacobs ignition system in it. I am currently getting around 18 miles to a tank. I have 33s on it and have not corrected for the bigger tires (old tires were 31s). Before all the mods, I got about 18 mpg.

You made a comment "I am going broke and gas is relativly cheap." Well going through most of the things that you want to do, It is going to cost you well over a thousand just for the mods. That will buy you a lot of gas. Things like new plugs, wires, distributor cap will help and are usually replaced because of normal maitanance. My muffler and cat were replaced because the old ones were rusted out. I put the e-fan and jacobs ignition in for more power (what little that can be gotten out of the 3-slows) when I am on the rocks.

So you will have to ask what you are doing the mods for. If it is just better gas milage, than you can do them and see. If it is to save money, you may end up spending more doing the mods and not gaining a whole lot in the mpg. The mods such as jet chip and ignition system are mainly after power. Another note these mods will usually need a higher octane fuel. I am currently running 89 since I put the jacobs system in due to pinging.

Good luck with what ever you decide... Nate

sandcrawler

i agree in principle with AZrocktoy that you can do a lot of modding/upgrading chasing a few extra MPG and still come out way behind where you'd be if you just dealt with the extra $ for gas...

...still, i'm trying to get mine buttoned up. durned gremlins!

89macrunner

Winter gas and recent cold tempeatures destroy your mpg...and dont forget when you use 4wd it destorys your gas even more.

Remeber spending all that money is it really worth the little savings youll get in gas?..hate to be the pickle but i guess someone has to say it

4x4Lamm

First off, thanks for the great replys, this is very helpful.

Secondly, a lot of the parts I mentioned I have already, sitting around (stripped from old 4Runner) so the inital cost of the mods is not as high as it would seem. Also, like I mentioned, I am planning to keep my 4Runner indefinetly (not always as my only vehicle however) so a long term pay off is acceptable. I'm not actually going broke on gas, but I just hate to spend so much on it just to drive thr 4x4 I love.

I suppose the first thing to do will be a tire preassure test week. I will experiment and try the "chalk test" as well.

The idea of getting better milegae on the second half of a tank is interesting too. I always fill up 3 times a week or so (about 5 gallons or so) so this may be a factor.

I am going to borrow my Dad's GPS and do a mileage/speed check ASAP, then I can have some solid numbers to work with.

A new fuel filter is also going to be added to the list. I remember when I changed mine on my 92 it weighed at least 5 times as much as the new one due to all the crud in it.

Would everyone agree that manual hubs are a great investment for MPG and otherwise?

Thanks and I will keep you all updated.
Lamm

AZrocktoy

iTrader: (1)

Changing to manual hubs does help. There will be less things to turn and less frictions. It will also help lessen the wear on the front drive shafts if you have cranked the torsion bars a little.

rngrchad

i have a 97 tacoma 4.10 gears and 33's.. I get about 10 to 12 mpg with low test. a gallon or 2 higher with high test gas. My TRUCK HATES CHEAP GAS.

RustBucket

iTrader: (1)

Try some of that "Upper Cylinder Lube" additive they sell at autoparts stores. Sometimes it helps alot.

NRM

i've got an auto 95 runner and am running 32"s as well. i've done all the above mentioned mods and i get about the same mileage. anywhere from 12-16 depending on what kinda driving and what time of year(winter gas). my odo's still calibrated for 31"s and i really didn't notice much of a change in mileage since i moved from the 31"s to 32"s but then again i've got 4.88 gears so that was kind of expected.

Radyota

I experienced an extra mile or two per gallon after switching to manual hubs. I can understand getting better gas mileage on the last half of a tank because you've lost the weight of half of the fuel that was in the tank. Have you ever looked into threads on adjusting the AFM to run 1 click leaner?

4x4Lamm

No I have not. Its a possibility, but It makes me a little nervus as well as I have never messed with that type of thing.

Lamm

tc

Holy shnikes! I hope you're doing 0-60 in 3 secs now!! 18 miles/tank is what - 0.75 MPG?

:lmao: