horrible MPG in my 98 4runner

[onesojourner]

I am trying to gear up for driving 100 miles round trip to the lake and back towing the skis this spring/summer. I have a 98 6cyl. around town right now we are getting 14-15 mpg. The 02 sensor went out shortly after We got the truck and I replaced it hoping to see a significant gas mileage improvement. So far I have not seen and improvement and it has been about 2 months. I disconnected the battery to reset the ecu after I replaced the sensor. I am planning on cleaning the MAF sensor with some electrical contact cleaner tonight. Is there anything else that could be causing such horrible gas mileage? The 4runner is getting worse MPG than the jeep...

[corax]

How's it run otherwise?

check the basic maintenance items first: air filter, fuel filter, spark plugs / wires, pcv valve. You could run Sea Foam through the intake to clean any carbon or residue build up out of the engine. make sure your tires are properly aired up - go by the sticker on the driver front door jamb, not the tire sidewall - if you go ~ 5 psi higher you may see some slight improvement. if you have a lot of heavy junk in the back that you don't need, take it out - it takes gas to move all that stuff.

[Henrythewound]

I was going to post a new thread but this is right in line w/ my question as well (not intended as a hijack). I keep track of my mileage for each tank and have noticed a drop from an average of about 19 mpg to ~17 mpg overall. I used to have some street tires on the 4Runner and now have BFG ATs. Could these tires have such a dramatic effect on mpg. I have corrected for the difference in circumference between the 2 in my calculations. I have also added a SS #7 and sliders, so I suppose there is a tiny bit more weight as well.

Just another mpg-related question, sorry if it clutters this thread.

[glenyoshida]

Just in case you took your initial readings in warm weather, winter weather may decrease mileage by a couple of miles per gallon in a 3rd gen

[onesojourner]

How's it run otherwise?

check the basic maintenance items first: air filter, fuel filter, spark plugs / wires, pcv valve. You could run Sea Foam through the intake to clean any carbon or residue build up out of the engine. make sure your tires are properly aired up - go by the sticker on the driver front door jamb, not the tire sidewall - if you go ~ 5 psi higher you may see some slight improvement. if you have a lot of heavy junk in the back that you don't need, take it out - it takes gas to move all that stuff.


It runs great. it had a full tune up by a toyota dealership at 100,000

[4runnerchevy]

14 or 15 mpg (:rofl: if I am lucky)! I wouldn't split hairs over 1 or 2 mpg. Get a tune up !

[BruceTS]

I keep track of my mileage for each tank and have noticed a drop from an average of about 19 mpg to ~17 mpg overall. I used to have some street tires on the 4Runner and now have BFG ATs. Could these tires have such a dramatic effect on mpg.


The simple answer is YES...... same happend to me when I went from street tires to BFG at's.... you lose an average of 2-3 mpg........

[4LowLocked]

You guys are all REALLY LUCKY!!!! I would LOVE to have your numbers...

Currently, I am getting 9.05 MPG - yes thats right NINE. ZERO FIVE. In real numbers, thats 65 Litres of fuel and 250kms til empty :(

This weekend I am putting new plugs in with hopes that it helps! And I am running HT tires at the moment. The engine runs VERY smooth and I also have a K&N

Ambient Air temperature at the moment is between 25-50 F

I pulled this off the government of Canada website
http://oee.nrcan.gc.ca/transportation/tools/fuel-trip-calculator/fuel-calculator-input.cfm


Fuel Cost
$1.10

Distance travelled
250 km
155.35 miles

Fuel Amount
65 litres
17.17 US gallons
14.3 Imperial gallons
Cost of Fuel
$0.02 per litre
$0.06 per US gallon
$0.08 per Imperial gallon

Fuel Economy
26 litres per 100 km
9.05 miles per US gallon
10.86 miles per Imperial gallon

Mileage Costs
0.44 ¢ents per km
0.71 ¢ents per mile

[04 Rocko Taco]

.06 per US gallon?
Fuel cost $1.10?

WTF?

[4LowLocked]

.06 per US gallon?
Fuel cost $1.10?

WTF?


If you notice my location, I am in Canada so gas charged by the litre. 1.10 for regular 87 octane at the moment :(

[04 Rocko Taco]

okay, forgive my conversion math... $1.10 a liter... how many liters are in a US gallon?

[corax]

one liter is close in size to one quart, so about 4 liters per gallon - if you don't need to be exact

to be precise - 1 Gallon = 3.78541178 liters

[4LowLocked]

3.79 Litres in a US Gallon

[paddlenbike]

Do a tune up, ensure your tires are properly inflated and keep a consistent speed on the freeway. I just completed a 1,400 mile trip with three 4Runners traveling together and we recorded some very good mileage. All of us were filling up at the same time and recorded 21 mpg on two fillups, one at 20 mpg and another at 19 mpg, which included mostly 4-wheeling and a lot of idling with the A/C running.

The suprising thing is the supercharged automatic 4Runner with 32" tires, ARB bull bar, BruceTS rear bumper, sliders and a ton of skid plating was getting the exact same mileage as the bone-stock 5-speed on the trip and also the same as my 5-speed truck with 32" BFG A/Ts, sliders and a 2.5" lift. It is possible to get really good mileage, even when modded.

The mileage drop from adding BFGs to my truck was somewhere between not noticeable and 0.5 mpg. Not sure where it falls in that range since I stepped up tire size AND added a lift on the same day.

[QSVeilside]

Might want to run a compression check. Saw a post on another forum - valve was burnt crispy.

[mastacox]

Currently, I am getting 9.05 MPG - yes thats right NINE. ZERO FIVE. In real numbers, thats 65 Litres of fuel and 250kms til empty :(


That's about the mileage I got last weekend. But I was towing a 2000lb trailer. And I was driving into a 30mph headwind. When I went with the wind I got about 12-14mpg.

Seriously though, 13-14 mpg isn't completely out of the realm of possibility depending on your elevation and a host of factors like winter fuel or weight in the back. You can replace some of the prime suspects like TPS, MAF, plugs, etc. but if no improvement is seen that's probably just the mileage you're stuck with...

[corax]

Coming cross country in an '88 4runner, 3.0L 7MGE Supra engine conversion, 4.56 gears, and 31" tires in 4th gear the entire way & towing a 3,500 lb 5x8 enclosed trailer the wife got about 17mpg. Highway I get 19-20mpg, city 19 mpg - with the 4 cylinder I got 19-20 mpg. Offroad is another story, I haven't run enough of a tank out to accurately calculate that.