My 98 Ltd has 135k on. I have replaced plugs, fuel filter, air filter and have a cat back system and a deck plate mod.

Mileage is a desperate 14 mpg around town.

I am running 32's but I am sure my 99 with a very similar set up was at least 16/17 mpg. I have taken the load basket off but that cannot be more than 0.5 mpg at best at sub highway speeds.

I have run the codes and so far all clear. I have a feeling its the Oxygen sensor. Anyone have any experience and /or a good place to get a new Oxygen sensor. At current gas prices, this is costing me around $500/year versus what I think I should be getting.

Thanks for your input..

David

EDITED TO ADD :

I have cleaned the intake and I use a fuel injection system cleaner every 3k.

 

www.urdusa.com has good prices on o2 sensors not sure what my in town mileage is but i do get around 21mpg on the hwy maybe its cause i have a 5spd

 

I really wonder if it is the type of gas you use. I filled up with Exxon this time and am seeing maybe 200 to the tank. I havent changed my driving style at all.

Now before that, I filled up with Shell and saw 250. Same exact driving style...what gives?

Anyways, for the o2 sensor, URD would be your best bet. I dont think it would be too hard to put in yourself either. Good luck

EDIT: here is a write up

http://www.4x4wire.com/toyota/4Runner/tech/O2_Sensor/

 

I think you are on the right track with the O2 sensor, given the vehicle mileage and the other maintenance items you have done. I have a 2" lift and 32s and can still pull close to 20 mpg on the highway.

 

Thanks for the link.

There may be something in the gas thing as I happen to know Shell was actually very strong in the Richmond area as they were trying a new additive system in all grades of gas and Richmond was a test market. I use nothing else in the Audi S4 I have.

However, it should not affect day to day mileage...

David

 

i did the same with costco gas, did much better with sheetz

 

My 1997 4 Runner with 141k, 33's, 5 speed and stock gears gets about 230-260 a tank and that's not even correcting for the speedo reading slow! How are you guys getting only 200?

 

front O2 sensor was going on my runner at about ~120-125k.

mileage dropped off to about 12 MPG around town. at that point, i ordered a new one from URDUSA for ~$100 and swapped it out. mileage immediately jumped back up to 16/17 MPG.

it never threw a code.

 

Sorry to bring back an old thread.

I think I am going to do that this weekend, I have been getting barely 200 miles with my lifted 4RUnner on 33's and have really bad pinging. Does the O2 sensor affect engine pinging?

 

I don't know about engine pinging but I do know on my Runner when my mileage started dropping off the CEL P0171 & P0133 were not too far behind. I went from 20 hwy to 16 hwy. Replaced the O2 sensor and my mileage immediately jumped back to 20-21 hwy.

Even did a tech write-up about it. It's a 10 minute job

 

I don't get it either, I just filled up at like 290 miles and put in 16 galons even, I run 32's also with an auto and do mixed hwy/city driving.

 

^^^^^290 ^^^^ to the tank that is so awsome I thought I was doing good with 250 miles mixed Hwy/city driving as well. Heck here in San Diego I just filled up with 91 octane @ $3.35 per gallon. alomost 50 bucks to fill her up. The 4 runner is fun to drive, but the gas tears my wallet up.

 

wow...im getting about 280 KM's not miles per tank! i know its bad...but is it something that a new 02 sensor will fix? i havent had any engine troubles (however i did get random CEL's but never stay on long enough for me to get codes pulled). tune up parts have been done, not recently, but not too long ago they require new parts.

im on 35's, auto, 4.88's and mostly city driving. is my mileage about right?

 

I get ˟˟˟˟˟ty gas mileage too, I average 15mpg. I can't for the life of me figure out why it's so bad. Mine is a 2000 Limited 4WD w/ 50k miles. I've tracked my fuel economy since 9/2005, it's always been bad. Could it be that an 02 sensor could help? Could they go bad at 50k miles and/or 7 years?

My economy...

 

Sorry to bring up an older thread, but I am starting to run out of ideas as to why my 4runner is getting crappy 12-13 MPG. I've read through all of the threads that I could find, and tried all of the recommended remedies (listed below). The only thing I haven't done is run seafoam through her, because I spent $90 dollars recently on new plugs and I'd rather not foul them up right away (and I don't have my old plugs any more )

So far I have replaced:
Front 02 Sensor
MAF sensor
Fuel Filter
Fuel Pump
Air Filter
Spark Plugs
Plug Wires
TPS Sensor
PCV valve
Timing Belt
Water Pump

and I've cleaned:
IAC valve
Throttle Body

absolutely no change in mpg... My tailpipe is black, so I assume I'm running rich, but my LM1 is showing a solid 14.7 AFR or thereabouts all the time unless I'm WOT. I ran a full tank without going WOT once, and got the same mileage that I would have if I was getting on the skinny pedal more. Also, this was an issue before I installed any fuel mods, so it's not my tune!

I'm just wondering if I'm missing something. Any suggestions would be greatly appreciated!

 

Just to chime in.....my '98 T SR5 4WD has nearly same profile, so far as performance -

PROFILE: SC 3.4L, URD fuel upgrade kit, aftermarket air intake, TRD ceramic-coated headers, IPT VB job, trans cooler, 265 series tires, (52 lbs just rubber-each). My FTC-1 is tuned nicely with no CEL history or ping. Tallest tires that fit on stock liftless truck, 52 lbs (rubber-only) each. All 93 octane and Amsoil fluids. 102K miles, SC, etc. since 60K.

Now to comment on mpg - 13.8 - 14 mpg no matter what, how, or where I drive - It sucks it down.

No sensor, filter, oil, or voodoo will help it. I have replaced my front O2 with no change.

Comments on Fuel: Fuel companies (brands) are all selling the same basic gasoline, since they are pumping from a common pipeline network. However, their proprietary additives do sweeten the tankers before they deliver to their pumps. But IMHO, I believe that end product "quality" between petrol vendors differs little - if at all.

Now, is the truck still fun to drive? Oh yes. Hard on the Wallet? You know it. I guess it has always been "Pay to play".

 

I am EXACTLY in the same boat minus the cat-back. I have a VORTEX.

I think I'm gonna get a new O2 sensor now...haha.

 

For the last two years I've bene averaging 16-17 around town witha bit of a leadfoot so I haven't been complaining but in the last month my average tank went form 250ish down to just over 200miles and I was throwing a CEL for the TPS but after cleaning a few things and resetting the ECU my CEL hasn't returned and there's nothing stored but I'm sure my TPS is still having issues so my mechanic is checking it over and should get back to me today and I also told him to check my O2 sensors.

I'm hoping it's just something simple and will be a quick fix.

 

Be sure to let us know!

 

for those that had the problems of bad mileage, did you guys change your O2's and see an improvement?