kpar

I have a 94 toyota pickup with a V6 3.0L EFI engine with a 5spd manual transmission and 4wd. The truck is supposed to be getting 20 mpg and I am getting around 10 mpg....what could be wrong with my car to cause this...I did some research and found the knock sensor, head gasket, or throttle position sensor could be malfunctioning or bad; however, if it was the tps I would think that I would have rough acceleration or something like that... the only other question is that the truck comes with cruise control that will turn on but it will not set the speed...is this a relay issue or a computer issue?

thanks for taking the time to look

stormin94

Don't expect 20 MPG. More like 18-19... Do a tune up on it, and check MPG after that.

Also, does your cruise light blink when you try to set it?

kpar

no it does not...it stays constant

yotadriver42

check your airfilter my truck got real ty mileage and i changed the filter and it does alot better now

kpar

thanks I changed the air filter as well as the oil last week

buckz6319

these 3.0 if tuned right will get close to 20 miles per gal with 1 driver, and that depends on their weight, then you add the weight of other passengers and gear and you get really bad MPG

TNRabbit

It is also winter; cold start injector is running until the engine gets up to temp, and if you're using 4x4 in the snow, mileage drops to CRAP. I just got 15.75 on my last tank!

If you've never replaced your O2 sensor, DO IT. I'll practically guarantee an increase in fuel economy.

Greybeard LTD

"If you've never replaced your O2 sensor, DO IT. I'll practically guarantee an increase in fuel economy. "

Just what is the life expectancy of a O2 sensor in a 3VZE? Does it vary with vehicle weight/engine load?

TNRabbit

It is usually advantageous to replace the O2 sensor every 100k miles or so. They tend to go downhill after that; of course, that varies with other factors like fuel quality, method of operation, etc.

abecedarian

Nope. Cold start injector should only operate while cranking the engine to start. Once the engine starts, the ECU controls the cold fuel mixture via the normal injectors.

abecedarian

What size tires do you have?
Throttle position sensor could affect mileage without significantly affecting performance, so if you're comfortable with doing it, you could check it out- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml
If the cruise control isn't working, that could be caused by a speed sensor, vaccum leak or other issue that may also be an effect on your mileage.

TNRabbit

Good calls~

tried4x2signN

You could also get 10% more MPG by using Ethanol free gas...


Whatever the mix is, is the % in MPG you're LOSING with our latest boondoggle...

http://www.youtube.com/watch?v=kBzmmO-3Cdo

rossboy83

I changed the air filter and all fluids in mine and Im getting 19 around town probly more on the highway. Putting a cold air intake would also help thats my next project.

Jay351

yeah, that won't do anything

rossboy83

Yeah I dont know for sure that just what I heard that it would help. Have you tried it?

TNRabbit

Don't waste your money. Got to be one of the biggest ripoffs ever in the world of autos...

86tuning

not all cars, just ours.

remember that a cold air intake can allow your engine to make more POWER. doesn't mean that efficiency goes up, just power output. More power output = more fuel input. Simple math

As for the op's question, top ten items that affect fuel economy:

driving habits
tire size & pressure
driving habits
tire tread design, alignment
driving habits
altitude and terrain (hills!)
driving habits
poorly running engine
driving habits
heavy load in vehicle

valx18

I know that a few weeks ago my boyfriend had an o2 sensor go bad on his truck. He was getting literally 5-7 mpg. Once he changed it, the gas mileage went way up.

TNRabbit

Like I said....