Any guesses why I am getting 13mpg?

[RiverMan]

I have a 1990 s-door 4runner with a newly, completely, rebuilt 3.0.

http://www.cardomain.com/ride/2213670

I have just burned one full tank of premium gas thru it (200 miles) and discovered the horrible mileage.

What should I be getting?

And also... does anyone know the largest tire size I can use on a stock, unlifted, 4runner?

Thanks.

-=] River [=-

 

[yotatilla]

The 3.0 has a great reputation for being slow and eating gas like a 350. 13 mpg isnt that far off. As for tires, I wouldnt go bigger than 32x11.50's, but you can fit larger, but you will sacrifice too much in acceleration due to gearing.



Sam

 

[regularguy412]

I just got back from a road-trip in my 92 , 3.0 4Runner. Prior to this trip, I was getting about 12 mpg around town and about 15 mpg on the highway. I decided to put in new NGK plugs and I cleaned the throttle-body thoroughly ( it was pretty gummy). I have a relatively new rotor cap and button, so I didn't change those. On the trip, my highway miles jumped to an average of 19 mpg. I didn't do much around town driving, so I don't know how that will be. The best mileage i received on any one tank was 20.24 mpg. The worst was 16.98.

What I 'DID' notice was that fuels with 10% Blended Ethanol caused me to have WORSE mileage than fuels with no ethanol. One tank with all 'REGULAR' gas in it produced almost precisely 20 mpg. The very next tank with 10% Ethanol went down to 17.86 mpg -- a difference of (you guessed it ) 10%.

It also helps to make sure your tires are aired up to the proper spec. Two days before I left, I made sure the 31 x 10.50 Michelin LTX M/S tires I have on were all up to 35 lbs. Low air pressure can rob you of 1- 2 mpg.

Mike in AR

 

[RiverMan]

Thanks for the input.

I have top quality plugs that are gapped to 31
New plug wires
new belts, hoses, etc
I only use Chevron premium gasoline

I was thinking that maybe it was the oxygen sensor? Ever heard of that causing bad mileage?

Thanks,

-=] River [=-

 

[mikes4runner]

Fuel filter....tire pressure....air filter.......


Mike

 

[gohawks444]

I have a 1988 3.0 and auto transmission. I have slightly larger than stock tires.

I have a new air filter, new plugs, new plug wires, new fuel filter, new cap and rotor.

I get horrendous mileage

I may get 16 purely highway
I may get 12-13 half highway/half in town
I may get 10 in town in warmer weather
In the winter in town only...ughhhh 8 mpg maybe

The O2 sensor is next on my list, I don't get a CEL however.

 

[RiverMan]

I have a 1988 3.0 and auto transmission. I have slightly larger than stock tires.

I have a new air filter, new plugs, new plug wires, new fuel filter, new cap and rotor.

I get horrendous mileage

I may get 16 purely highway
I may get 12-13 half highway/half in town
I may get 10 in town in warmer weather
In the winter in town only...ughhhh 8 mpg maybe

The O2 sensor is next on my list, I don't get a CEL however.

I find this very odd. I have a 2000 Tacoma V6 (I think it's a 3.2L) and I typically get 20mpg. I wonder whats wrong with these engines?

 

[regularguy412]

I find this very odd. I have a 2000 Tacoma V6 (I think it's a 3.2L) and I typically get 20mpg. I wonder whats wrong with these engines?

After a little research, I believe the correct displacment is 3.4L for your pickup. It is good to note that a pickup is somewhat lighter than 1988 model 4Runner -- 3,430 lbs unladen pickup vs. 3,740 unladen 4Runner. It costs mileage to carry weight.

Additionally, the 3.0 V6 is not known to be either fuel efficient nor exceptionally powerful. In my opinion, however, it is a very reliable powerplant.

Automatic transmission vehicles are notoriously less fuel efficient than manual transmission models. You did not mention whether your pickup is standard or auto.

Probably the most striking difference is that the 2000 Tacoma you drive has the advantage of the myriad advances in computer and engine technology that have taken place in the 12 yrs since the 1988 4Runner was produced.

I say this because my 2002 model Solara with a 2.4L 4-cylinder engine makes more horsepower ( 157 hp) than my 3.0 V6 1992 4Runner engine makes (150 hp). The Solara seems noticeably more 'powerful' but it is a front-wheel drive car and not a rear-wheel drive, 4 wheel drive, 4Runner. My car routinely gets 34 mpg on the highway , even at 70 mph. My 4Runner does well to get 20 mpg on the highway.


Mike in AR

 

[RiverMan]

My 4Runner does well to get 20 mpg on the highway.


Mike in AR

I have a 1996 dodge conversion van that gets better mileage...

What are the chances that it is an O2 sensor? I am asking this because they cost about 89 bux for OEM at autozone and the guy said there are three.

 

[gohawks444]

Update.

Not to hijack, just providing some more data.

I filled up yesterday, I had 100 miles on the odometer and used 12 gallons to fill

 

[regularguy412]

Update.

Not to hijack, just providing some more data.

I filled up yesterday, I had 100 miles on the odometer and used 12 gallons to fill

No worries. Looks like a good piece of info for this thread.

You said you had slightly larger than stock tires on. How much larger are they? Your odometer is still registering the distance traveled based on stock tire dimensions. I put 31 x 10.50s on mine. Stock for me were the P225's. I looked at the chart at Michelin for revolutions per mile of my new tires vs. my old tires. The new , larger 31's travel approximately 10% farther per revolution than the old 225's. So when I figure miles traveled on a tank of fuel,I always increase the trip meter mileage by 10%. Then I use that figure to calculate MPG.

I'd see how far off your odometer is, based on the difference between your old tires and new ones. It may not make a lot of difference, but you may not be getting 'quite' as bad mileage as you think you are.

Additionally, larger tires do reduce your effective axel ratio gearing. This 'can' cause the 3.0 to lug around and not work in an optimum rev range. I noticed a little better mileage when I had the P225's on.

Mike in AR

PS- with these 31's on, I'm also traveling 10% faster than my speedometer shows, too.

 

[STRAP22]

1990 4Runner automatic 33x12.5 regeared to 4:88's manual hubs. I just got 14mpg loaded. I use to get low 20's when I ran smaller tires and 4:10 gears.

 

[Schooler]

Have you checked your timing lately? That can have a huge effect on your gas mileage if it's off.

 

[gizmo]

Thanks for the input.

I have top quality plugs that are gapped to 31
New plug wires
new belts, hoses, etc
I only use Chevron premium gasoline

I was thinking that maybe it was the oxygen sensor? Ever heard of that causing bad mileage?

Thanks,

-=] River [=-

If it is the oxygen sensor, basically this monitors the burning process and if required through the ECUs actually add/subtract more fuel so if the sensor is faulty then the ecu will be getting incorrect readings and voila your mpg goes down.

also fuels with ethanol in also can contribute to lower mpg once again to the burning of the fuel mixture. Whilst it may provide a little more power it will drink the stuff