Ironmike4x4

This just raised a red flag to me... I believe you guys in the mountain/cooler climates have a change in fuel iirc as a lot of members have said once the fuel station switch over to "winter fuel" they often get a drop in gas mileage. Apparently we don't have that problem here in SC so I'm assuming it depends on where you live. Odd thing is if this didn't happen last year then that may not be the root cause.

Have you had someone check the O2 parameters yet? From your earlier posts you have not yet changed your plugs/wires. Try that first anyways if it's due in mileage. As said before ONLY use NGKs or Denso. You will regret it if not and pay twice for it. I'm consistently getting 15.2 MPGs but I'm running 31's and have not calibrated for the larger tire sizes so I'm actually getting a false record in MPGs. Also my driving habits are much more aggressive (jack rabbit starts, in a hurry to get home, etc) so I'm creating my own low MPGs.

Parker Runner

Check your speedo/Odometer with a GPS to make sure it is accurate. It may or may not be. My speedo is a consistent 5mph off. My accord is 3 percent off on odometer.

Anyway, I get about 13 in the city and about 18-20 on the freeway below 65. At 75 it drops to 15. At 85 it drops to 13.

I am a lead foot and don't really care about mileage between 13 and 18.

I wouldn't get crazy about replacing parts unless you can prove their is a problem. Spark plugs are cheap, but coils are not. Coils can be tested.

You can spend hundreds if not thousands to chase down a bucks in gas.

Kiroshu

If you live in the moutains and its bellow freezzing alot then thats prob about right..... sadly...

Smallwood0507

something is definitly not right my last tank was 11!!!!

Kiroshu

..... i mean i've said just about everything and you have claimed an ok on everythign so yea..... i dunno what to tell you. do a tune-up or somethin check into it further.... unless you got something freakin crazy wrong like a bent rear axle or something....

84truck

when i had my 84 pickup with a 22RE i had a straight back exhaust with no cat and a glasspack under the bed and untill i put an 02 sensor in, i was getting the same results. even with resetting the computer, it was just going off the default mode and just dumping fuel needlessly. i'd check the 02 sensor if you haven't already.

JWaldz

iTrader: (1)

so smallwood, did you ever get your mpg up? I'm barely getting 200 miles per tank these days and it's killing me. I need to know if it's just a desperately needed tune up or if something is seriously wrong. I wanna get back up to about 16 and 17 range. What size gallon tank is on the 3rd gens.. 16 or so?

A2B in a TLC

You have probably thought of this, but here's my $.02:

How about this: Bigger tires = greater circumference. That would mean you actually travel further per tire revolution. Your speedo has been calibrated for stock tires.

Here are some numbers: http://www.tiretrends.com/pdf/BFG/AllTerrainKO.pdf

Have a look at revs/mile.

265/70-16 = 678
265/75-16 = 654

That's a 3.6% difference. If you were getting 19 mpg, without doing the conversion, your speedo would show you only getting 18 mpg.

If your old tires were worn out, the difference would be greater than 3.6% because the revs/mile will increase as the tread wears out.

Bruce in Tsawwassen
A2B in a Toyota Land Cruiser

JWaldz

iTrader: (1)

I have no doubt my tires/lift/roofrack play a role in the loss of my mpg but something else is wrong to go from 300 mpg to not even 200.

Smallwood0507

hey sorry it took so long for me to get back to you but i did find out what was wrong i had a vacuum hose unpluged. im back to about 16. oh and on my 3rd gen my gas light comes on at 13.5 gallons and the most ive been able to put in is 15.5.

SnowRunner98

Thats SO crazy, those are such a small differnce on tires, and it MAKES that big of difference! good find.

JWaldz

iTrader: (1)

well I think my gas gauge sensor is messed up because I can be on 'e' turn it off and back on and it be close to half. But thats not my problem cus It can show half after being on 'e' all day and I can still fill up to around 16 gallons. I still need to find out why I'm only getting 10-12.

kawicowboy

So how did you figure out it was a vacuum leak.

ALTN8R

Where did you find the vacuum leak? Which hoses do you check? I'm having the same issue with bad gas mileage, even after some new sparkplugs. With normal driving I'm only getting about 250 kilometres or 155 miles per tank.

brian2sun

You can find vacuum leaks by opening a propane bottle so it lets out just a little gas and moving it around the engine while it's idling. If the idle changes, the leak is going to be in the area of wherever your propane bottle is at the time.

I had a miss for a long time on my truck and was getting about 10-11 mpgs for the last couple months so I did an machine-based induction cleaning and my mpgs have gone back up to 16-18 and my engine runs much smoother now. My write-up is a little long, but it may help you. I know you're not talking about a missing cylinder and our problems aren't exactly the same, but this could (and most likely will) restore your fuel mileage...

http://www.toyota-4runner.org/3rd-ge...hopefully.html