grimpy

My Runner gets a whooping 13mpg right now... It sucks... I searched for possible solutions and so far I have replaced the spark plugs (denso iridium), fuel filter, pcv, and pre-cat 02 sensor. I also cleaned the MAF sensor, throttle body, and air filter... I also did the deckplate mod... I'm on 295/75/16's though right now with the stock 4.30 gears. I know this will effect my mpg but 13mpg just doesn't sound right... When I had 265/75/16's I was getting about 14mpg... Is this normal for daily driving in the city?

Anything else I should replace? My 4Runner is an auto and I keep the rpms usually at 2000-2500, and never go past 3000rpm...

I have been driving on 2wd... I do go over a few hills everyday... Would using 4wd help my mpg?

For the folks that live in major cities/encounter stop and go driving... what mpg are you getting? For the guys with 33's and regeared, how many mpg are you guys getting now and before the regear if possible?

grimpy

ok, I did a quick calculation check...

Stock tires are 265/70/16 and at 75mph, with the 295/75/16 the vehicle is actually going 81.89 miles. Last time I pumped gas, I filled 11 gallons at 150 miles. So the size difference will make the actual miles differ by appox. 14miles.

So at 11 gallons and 164 miles, that comes out to be 14.9 mpg... Does 14.9 actual mpg sound right?

02SE

In my experience, the auto tranny 3rd gens seem to do a little worse than the manual tranny 'Runners, for mpg.

My sister has an '01 auto, I have a '97 5 speed.

You have a lift, and bigger, heavier tires. Those will definitely hurt mpg.

Driving in 4wd on the road, will just add more friction (drag) form spinning the extra drivetrain components, which of course will hurt mileage too.

You also need to take into account the larger circumference of your tires. You are actually traveling farther with every revolution of your tires, than you were with smaller tires.

So unless you've factored that into your equations, you're actually getting better mpg, than you realize.

02SE

I see you posted about the tire diameter difference while I was typing.

With your current set-up, 15 or so mpg, is probably about what you can expect.

The lift, and tires, really do have a noticeable effect on mpg.

Doing what I mentioned in the other mpg thread, will make the vehicle more efficient, which would have a positive effect on mpg.

Bob_98SR5

hey grimpy!

yeah, your mileage, even with the 32s, is on the low end. sounds like you've done a good preventative maintenance shedule too. and DONT drive in 4wd. you will be getting ford "OJ simpson" white bronco gas mileage

yes, those big tires are gonna hurt your mileage. my advice is to baby the gas pedal. the advice i've always heard is to pretend you have an egg between your foot and the gas pedal. see what happens in a month driving like that

also, do you make a lot of short trips? that will kill your mileage too.

about your plugs= is there a reason why you went with those vs stock plugs? I dont konw much about them but there are some plugs that do worse than stock plugs.

bottom line: its an SUV to begin with and you added big tires on your original gearing!

bob

grimpy

darn, thanks for the info guys... I was hoping there was something I missed so I can get up to around 17 or 18mpg...

I sometimes take some short trips... 1 mile or 2 miles... Park then drive back... I drive approx 10 miles locally to get to my campus... The hill I am referring to is that sucker getting to Harbor.

I try to baby the pedal as much as I can... I will stay off the 4wd unless I need it...

I went with denso iridiums because that is what I had on my prev 4 cars, SC400, E39 528i, MRoadster, and E39 528i... I guess I just got use to the iridium thing...

I guess with my current situation, my mpgs are pretty normal then? I hate my fuel light POS... I always get gas when it comes on even though I know I have about 5 gallon left...

deathrunner

Might want to check into gearing your truck. Also run at a deecent tire pressure...it can actually make a 1mpg difference.

grimpy

I set it at 40 psi right now. What do you think about it at that psi?

spacewrangler

i would think 40 psi is a bit high. ....how does it ride with that much air pressure?

grimpy

it still rides pretty good... I may end up going down to 38psi's though.

99_Runner

The best way to find out how much your speedo is off is to follow one of your friends that has a stock car. Have them do 60 and you follow to see how fast you have to go to keep up. Your calculations sound about right. If you slow down to where you are only really doing 70-75 then that might help your milage as well instead of doing 82.

MTL_4runner

I would also suggest looking into a regear.....those are very large tires for that vehicle. You might also want to verify that you do actually have 4.30s and not 4.10s (there has been dicrepancy lately)

For that combo, @15mpg is not bad at all....the engine rpms gives you a hint as to why mileage is not so good. With those tires, your engine should be higher in the rpm range where it makes maximum torque when driving on the highway.

Higher tire pressure will help mpg and the irridiums should do fine as well. Sounds like you also did the rest of the suggested maintenence too so it seems gearing would be the issue (you can counter that a bit with a supercharger but how you attack the issue is up to you).

RebuiltRunner

Has anybody noticed an MPG difference with synth tranny/diff oil yet?

ebelen1

Grimpy,

Same issue here. '99 w/ 265's and getting about 14-15 mpg w/o making up for the difference in tire size. I've done the same type of maintenance including a BG flush (similar to Seafoam) and tranny fluid replacement (not a flush).

My mileage actually got a little worse the first tank and was about 13.5 mpg. I figure if the only way to get better gas mileage is to baby the gas pedal, I'll just eat the higher gas prices. It's my fault for swapping my '97 accord, fully paid for for this truck. It used to get 20+ mpg. Then yotatech came and $4k seemed to have disappeared from my wallet to make the mpg issue even worse.

BTW, I live in L.A. too so I understand the stop and go. The only good thing is that I only work 5 miles from the office. I get about 220 - 240 miles off a 16 - 17 gallon fillup.

JGM

This is another one of those topics that comes up about 3 times a week. There are a million little things you can do to "try" to improve gas mileage. Really, the bottom line is when you go an put on lift, big tires, yadda, yadda, yadda, those hurt mileage a heck of a lot more than you will ever get back with new plugs, cleaning your filter, etc. Not that you shouldn't do those, but that is the reality of it.

Make sure your math is right, and keep an eye on your numbers. It has become second nature to me. I have 35's with 4.88's. I make mostly highway trips as this is my DD. My truck gets about 14-16 in the summer (need AC in AZ), and about 17 in the winter. Not too bad. I do know those numbers would be much lower if I made mostly short trips.

jacksonpt

FWIW...

I have a 96 - 33/12.5-15 MTs, stock 3.90s, 3" SL, 2" BL and get about 16 in town (though not a major city).

99runner4me

That's how much I was getting with the old Bridgestone Dueler 285's. I wasn't getting more than 15 mpg on the highway. Since I've changed to 265's, looks like I'm back to almost normal gas mileage and bottom-end torque. I'm glad I went back down a size.

MTL_4runner

How does yours do on hills?

jacksonpt

It's not going to win any races, but I've gotten used to it. I keep the RPMs up and have no problems. Normal use on hills is fine, towing on hills is a bit, um... takes some patience.

ebelen1

During my recent maintenance, I swapped regular fluids for synthetic in the diff and put long-life fluid in the tranny. No change in mpg. I gotta think it's all in the gearing...