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Discussion Starter · #1 ·
hey, i am still haveing a huge problem with gas mileage on my 98 2.7. last time i checked, the thing was getting around 10-12 mpg. this is horrible! im running 32 11.50s with a 3in cornfed lift. any ideas on this one? i had my exaust re welded on that that gave me a little better mileage but not much. This thing is really raping me on gas and its a 4cyl!! i did replace the oxygen sensors a while ago so they are new. i have noticed a huge buildup of black carbon stuff in the tail pipe. it is so bad that it is starting to get on the outside of the pipe, weird.... :mad:
 

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Just a thought, the fact that you're running 32's would kill it significantly... unless you've regeared to match em that might be your problem... Seafoam could help you a little... cleaning your engine.. but that's just my .02
 

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Regear man, i'm running 33x12.5's and 4.88 gears w/my 2.7l 5spd and i get 18-19 mpg.
 

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So if you dont use your truck for hardcore offroad and you use it for light hauling (couple of motorcycles) could you regear a stock V6 to get better mileage? If so would it be worth the cost? My truck also sux as far as mileage, 16-17mpg with a V6 its 50:50 city highway
 

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I have 2 questions before my scenario: What trans and gear ratio do you have?

I have an '03 2wd prerunner w/autotrans and a 2.7 4 banger.

Supposedly, I have 3:91 gears, according to the codes that I have read others have here. I am runnung stock tires that are of 16" fare, and I was getting 15 mpg.

I say was because now, I am getting 18, due in part to not using the over-drive on the freeway, or at all for the most part.

After doing many things to increase my mpg, I finally came upon the fact that whenever I did use the O/D, I was constantly bogging and losing road speed, however; I was still keeping my foot placed on the accelerator in the same spot, and slowing down, thus using more fuel to go slower, if that makes sense?

So, in conclusion, I do not use O/D unless I am going down hill.

I will be installing 32 x 11.50 x15's soon, and re-gearing when funds permit.

I hope this has helped you.

Later, Ritchie
 

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Discussion Starter · #6 ·
thanks for the advise but i forgot to mention that it didnt get much worse when i put the 32s on, its about the same as it got when it had the stock 31s on it. any more ideas?
 

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You didn't mention which trans you have.
 

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Discussion Starter · #8 ·
its got the 5 speed in it. i dont know what gears are in it, i dont remember what i looked up a few years ago....
 

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new plugs,distributer cap, and distributer rotor could help. check air and oil filers, also, tire air pressure. also, how do you drive?? are you easy, or hard on the gas pedal, also, do you do a lot of riding around town on the weekends?? i know how you feel. gas is gettin expensive, and it hurts the wallet. it makes me physically sick when i get a bad tank, with low mpgs. good luck man.
 

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Discussion Starter · #10 ·
ive replaced all the plugs and wires but my engine doesnt have a distributor, just those electric ignition coils. im not to heavy on the gas in my opinion but who knows, thanks for the advice
 

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go get a can of BG 44K and run it through the engine and see if it helps it out.
 

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im getting about 345-355 miles per tankfull on my 2.7l 5speed with 2" lift and 31x12.5s and stock 4.11 gearing. not sure what that comes out to in MPG, but im sure its alot more than what you get
 

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98taco3 said:
ya, you are getting better than me, i getting somewere around 200-230 on a tank or so...
I was getting about the same to a tank, I replaced the fuel filter and I had a major leak in my exhaust manifold. Did you notice any lack of power? I would have the catalytic converter checked. :confused:
 

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Amber00Dak said:
im getting about 345-355 miles per tankfull on my 2.7l 5speed with 2" lift and 31x12.5s and stock 4.11 gearing. not sure what that comes out to in MPG, but im sure its alot more than what you get
NJtacoma said:
I was getting about the same to a tank, I replaced the fuel filter and I had a major leak in my exhaust manifold. Did you notice any lack of power? I would have the catalytic converter checked. :confused:
Quick question... I used to be getting like 330-355 like you, but recently this year, have seemed to notice a significant, and immediate drop in gas mileage... only getting about 225-240 max in a tank... could this mean a notorious... cracked exhaust manifold? If not I would contribute some of this to the small "warmup" periods i give it in the mornings... when it's 25* in the morning thats a little rough... but usually letting my truck idle for anything longer than 2-5 minutes is rare.

any ideas?
 

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Ritchie said:
I have 2 questions before my scenario: What trans and gear ratio do you have?

I have an '03 2wd prerunner w/autotrans and a 2.7 4 banger.

Supposedly, I have 3:91 gears, according to the codes that I have read others have here. I am runnung stock tires that are of 16" fare, and I was getting 15 mpg.

I say was because now, I am getting 18, due in part to not using the over-drive on the freeway, or at all for the most part.

After doing many things to increase my mpg, I finally came upon the fact that whenever I did use the O/D, I was constantly bogging and losing road speed, however; I was still keeping my foot placed on the accelerator in the same spot, and slowing down, thus using more fuel to go slower, if that makes sense?

So, in conclusion, I do not use O/D unless I am going down hill.

I will be installing 32 x 11.50 x15's soon, and re-gearing when funds permit.

I hope this has helped you.

Later, Ritchie
you should have 4.30s in that '03 prerunner AT. 3.91s never got into an AT that I've ever heard of.
 

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Discussion Starter · #17 ·
that cracked manifold sounds right, i keep hearing an exaust leak, maybe thats it and the cat is now plugged up, good ideas!! i would never have thought of that.
 

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hytenor said:
you should have 4.30s in that '03 prerunner AT. 3.91s never got into an AT that I've ever heard of.
Thanks, I will double check the window sticker. 3:91's are what I supposedly have according to the code on the door jam too, but that doesn't mean that is correct either. Heck, for all I know, that could be a standard Toyota door jam sticker.

One thing is for sure, and that my truck is a toad with OD activated.

I am running 70 mph @ 3300 rpm in 3rd, and with the push of a button, 2300 in OD mode. The truck bogs terribly!

Do you have any ideas as to where I can confirm my gear ratio?

Thanks.
 

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Ritchie said:
Thanks, I will double check the window sticker. 3:91's are what I supposedly have according to the code on the door jam too, but that doesn't mean that is correct either. Heck, for all I know, that could be a standard Toyota door jam sticker.

One thing is for sure, and that my truck is a toad with OD activated.

I am running 70 mph @ 3100 rpm in 3rd, and with the push of a button, 2050 in OD mode. The truck bogs terribly!

Do you have any ideas as to where I can confirm my gear ratio?

Thanks.
that would be odd that you have 3.91s with the AT. 4.10s are common, however which is pretty close. If in fact you do have that ratio you'd be the first I've ever seen ;) with that low an rpm @ 70 you have quite a mystery there. 3.58s maybe? the plot thickens...
If you had an earlier model v6 I might suspect 3.15s. What are your door codes, OE tires size?

other than using the 'count the driveline revolutions to wheel revolutions' for the actual ratio the only other way to 'confirm' your gears is to pull the 3rd member and read what's stamped on the ring gear. Jack up the rear of the truck; make an easily seen mark on your drive shaft; turn the rear wheel 10 revolutions while counting the # of DS revolutions. DR revs:wheel revs is your ratio. Ex: 41 DR revs to 10 wheel revs = 4.10 gears.
 

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The exhaust manifold is notorious for cracking but I doubt it is your problem. I also got 300+ when it was new. I now get 240-250. Mods will hurt you. The tires most likely add some serious weight. A lifted truck is less aerodynamic. The more CV angle you have the more resistance they put on the motor. And the harder you go with these the worse it gets. If by any chance you find a way to get 300+ back post it like there is no tomorrow. There are a lot of us out there. My guess though is it that the mods are to blame. Mostly the tires. The stock tires are very light and roll very easy. Anything but, won't.
 
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