Extremely Poor Gas Milage

[Manj]

Hi All,

I am new to this forum and I drive a 98 4Runner.
I've had the truck for 5 years now, but in the past year the truck has been giving extremely bad gas milage. I've got to the point where $20 of gas only gives me 120-140 kms.
I have changed the spark plugs and changed all the fluids (engine oil, transmission oil, diff oil).
Any suggestions would be helpful.
Thanks,
Manj

 

[oh6SR5]

Did you try changing the air filter? Also, make sure your tires have the correct amount of air.

 

[drake3]

Did you try changing the air filter? Also, make sure your tires have the correct amount of air.

I changed the air filter in my '93 the other day and the idle went up about 400 rmps in neutral! It was only in there for about 30K miles and only road use.

I think the computer has adjusted now because the idle is almost back to normal. I only saw marginal fuel economy improvement though.

 

[Pirate VI]

it might be the oxygen sensor, usually if it was bad your check engine light or maint light or something would come on though.

 

[Manj]

The air filter has been changed, and the original oxygen sensors are still in there. The service light is not on, and the 4Runner has approx 225,000Kms on it.
Is it time to change the oxygen sensors, and how many sensors are there?

 

[Manj]

bumpity bump..

 

[Northof49]

Hi All,

I am new to this forum and I drive a 98 4Runner.
I've had the truck for 5 years now, but in the past year the truck has been giving extremely bad gas milage. I've got to the point where $20 of gas only gives me 120-140 kms.
I have changed the spark plugs and changed all the fluids (engine oil, transmission oil, diff oil).
Any suggestions would be helpful.
Thanks,
Manj

Since you're in Canada, that means roughly $1 per liter gas prices for the last year. So it'll take rouhgly $70 to fill that tank from empty....so by this extreme approximation, you'd be getting 420-490kms out of a tank. With some city driving in the mix, that's about all she's good for with everything working properly....you're not too far off the mark.

 

[Her4Runner]

FWIW, you might also try cleaning the MAF sensor... Easy job & doesn't cost much outside of time & a $5 can of elelctrical contact cleaner.

Her4Runner

 

[Manj]

I'll clean the MAF sensor over the weekend.
As for O2 sensors, if they go bad, should the Service Engine light display. My Service Light is not displayed, does that mean the o2 sensors are fine.

Northof49: As for the price of gas, I understand your concept, but in my case lets say for example:

Cost $50 to fill up and mileage = 450kms
Cost $70 to fill up and mileage = 350kms

Why would there be a big difference in mileage?
The trucks idles find and drives OK.
I do find it slower though and less power on acceleration. After changing the plugs, I thought I would regain more power back, but I didn't

Any thoughts.

 

[Manj]

bumpity bump..

 

[Chenango21]

Extremely poor gas mileage

I had a 4runner with a burnt cylinder head and got terrible gas mileage (and a rough ride). Hope it is not that!

 

[toyoboy]

o2 sensors are like little batteries...with in time the sensor starts to react weak and slow...so i would recommend replacing every
100,000 miles...some car manufacture recommend at 90k. there is a way to test it but since your 4run has over 225,000 km (what is that in miles) i would replace it....but keep in mind that all these guys inclueding myself are just suggesting..the o2 sensor may or may not fix your problem...

and also there are time when the o2 sensors are bad and reacting slow and will not through a code..

 

[Manj]

o2 sensors are like little batteries...with in time the sensor starts to react weak and slow...so i would recommend replacing every
100,000 miles...some car manufacture recommend at 90k. there is a way to test it but since your 4run has over 225,000 km (what is that in miles) i would replace it....but keep in mind that all these guys inclueding myself are just suggesting..the o2 sensor may or may not fix your problem...

and also there are time when the o2 sensors are bad and reacting slow and will not through a code..

Its roughly 135,000 miles.

Does anyone know the cheapest place to buy the sensors.
The dealership prices are just waaaaaay to expensive for my pocket.

 

[NViejeP]

Ya let me know how it goes.

I just did like 5 hours of straght homework so I dont really want to do any calculating.

But I roughly get 10-12 miles per gallon if i drive all city.
I took a long road trip and I got no more than 270 miles in a tank on all highway driving averaging 75 mpg.

and i think thats pretty bad

 

[RunnerUp]

try changing your fuel filter also, i did a tune up on mine a couple months back that included new plugs and wires, cleaned my air filter, replaced my fuel filter, new battery, new synthetic oil, changed my diff fluids, seafoamed the hell out of my engine before i put the new plugs in, and a couple other basic maintenence items and gained a few MPGs.

as far as where to get the o2 sensors search for URD on google, should be underdog racing development, they have them for around 80$ a piece iirc.