if your rear diff fluid was "out," and your mechanic was good, and honest, you should check your axle seals, usually can just look inside wheel for oil spatter without taking anything off, or you can take a wheel (and drum) off and check for seepage

 

i just bought a 02 4runner sport and before i bought it the guys said I would need a upper engine clean ( i think by that he meant a throttle body and MAF sensor clean) and i think the check engine light was going off. any pics/procedures showing how to do it? i'm keen to learn how to service it on my own

 

http://www.4runners.org/writeups/throttle/index.html

 

here in mo. they recently passed a law that all gas must contain 10 or 20% ethnaol i cant rember which but its to make it cheaper lol 2.89/gal today anyway once that happened everyones mileage whent to crap. i can tell a difference if i go to like oklahoma and get gas there i get about 30-50 more miles/tank so you might check your station or local govt. they still have the good stuff

 

also check your catalytic converter. wait til the exhaust cools off, then crawl under and bang on it with your fist. If you hear some rattle in there, it might be broken up and clogging your exhaust. a shop can check the temp and give you a better idea, but check it either way. a bad cat or a clogged muffler will kill your mpg

 

do you have a cold air intake and or use a self lubed air filter?? if so that may be the reason why your MAF keeps messing up.. dont use anything but paper filters bc those MAFs are pretty sensative

 

what that doesnt show you to do is to spray into the tiny hole just before the butterfly. spray liberally into and let it sit for a few mins.. then get in and crank her up with the gas to the floor.. run till the smoke clears and repeat..

 

I put my budbuilt skids back on for regular driving and the mpg went back up. I did seafoam the tank in let the engine ingest it from the pcv vac. line but no effects were evident over the last tank w/o the skids on. My theory was the skids add to the aerodynamics and therefore improve the mpg's I'll let you know what the overall is as soon as I'm out of gas.

Aaron

 

This thread reminds me of what i need to do to my 4runner.

clean maf and throttle boby
check spark plugs and wire
o2 sensors
replace fuel filter (180,xxx miles on it)

 

I could probably benefit from replacing my fuel filter though I think thy do it when she gets serviced every 50-75k.

Aaron

 

My friends O2 sensor went in his 99 Tacoma...I believe he was getting 10mpg at one point...your's doesn't seem to be as bad...so I donno if its that.

 

Ok I have something new to add to the theory pool. I know to reset the CEL light you unplug the batt. - or + and leave it off for a few minutes then re-attach the removed wire. This resets the ECU and the light goes off and the ECU re-learns the numbers from the o2's.

Enter theory 1. when the CEL is on and the VSC lights are on as well then your O2's have tripped it and you will get 1 of 2 coeds indicating front or rear O2. While the light is on your vehicle should have switch over and is now running in an open loop not conserving your fuel as it should be because your air fuel ratio is off.

Theory2. If theory 1 is true then when you disconnect the batt. terminal and then re-connect after proper elapsed time your CEL light is off and the vehicle is running normally in closed loop.

Theory3 . I have only had to disconnect the batt. a few times and after each instance the fuel economy soars to almost 19mpg. If this holds true then I will disconnect the battery every 2wks to see if I get an overall increase. While the only down sides are reseting the clock and proffered stations the upside is better fuel economy.

You'll notice in the upper right hand corner 162 MI. This is my actual mileage on the current tank of fuel as the needle just hits 1/2 tank/

There is a slight deviation I cannot even remove with the Super Lift True Speed calibrator. But after a full tank and highway/ city driving the GPS and 4Runner trip meter often only disagree by 1-3 miles.



I realize this sounds slightly absurd but hang in there I might have found a way to gain a few more mpg's or maybe not but only time will tell.

 

I too have experienced my own milage drop, and I'm not sure of its origin. I used to get 19-20 mpg, now I get 17 if I'm lucky. I probably need to do some cleaning and upkeep but I would agree with one of the previous statements: More companies are adding Ethanol to their fuel. It's renewable and cheaper but much less efficient than gasoline and could cause a decrease in your MPG.

My drop in milage happened back when gas was only about $2.50/gal and they werent adding as much ehtanol so I have some other culpret eating mine.

$4.00/gal... I hope I never meet any oil company CEOs, I'm scared of what I might do to them...

 

Down here they just started putting ethenol in the gas and that will get you about 20mpg less to a tank.

 

not only that, pick up some GM top end cleaner and use it like seafoam thru the PCV valve.. much better than seafoam. also look into doing a cycle of AUTO RX to clean the motor on the inside ITS THE ONLY MOTOR CLEANER THAT I WOULD RECOMMEND BC I KNOW FOR A FACT THAT IT WORKS AND WORKS GREAT... with that mileage it wouldnt hurt to do 2 cycles.. very simple to do. go to autorx.com i think

one more thing if you have not replaced your O2 then look into that.