this kind of freaked me out.....29 mpg. on my way back from the mountains, 87 mile trip, 80% highway at 70-73 mph, up and down hills, using the a/c every once and a while. i just put a taurus fan in it and was curious what effect that had on it. this is also with an on and off code for my 02 sensor.

heres what i am wondering, i filled up in the morning. got home and filled up, it was pretty hot. maybe the gas in my tank expanded some and gave me somewhat of a false reading? i anticipated somewhere around 26 mpg, going with what i had gotten before with this truck, i was a little suprised to see 29.

my truck is a 93 p/u 4x4 22re. stock tires, gears, etc.

 

Well the hotter it is the more you're getting riped off at the pump. The fuel has less density than when its cool so that should have had an negitive effect on your miles.

 

o2 sensor throwing a code?

Probably running lean...

In 1983 I had a Nissan Sanza that got 45mpg on a CARB.
By 1992 the VW golf got 32mpg with EFI.

What happened?

Clean AIR.

Running lean can give huge bumps in efficiency.
It also runs "hot" and thus emits alot of NOx....

To cut NOx emissions, the EFI is designe to scroll back and forth between rich and lean. The RICH cools the temps down. The Cat then cleans up the excess HC emissions.

 

that does sound pretty good...geez i just got my best mileage today on a 400 mile roundtrip to ohio. I got 21.5 with about 1,000 lbs in the bed and i turned the a/c on for the ride back. But thats with a 4x4 3.0

 

Yes and no. Most pumps are calibrated to about 15*C. At lower temperatures, yes you have greater density, but it's because of a a decreased volume, higher temps give greater volume but less density. Kind of hard to justify "being ripped off" because of higher temperatures.

 

the fuel will have the same density as it comes out,
the temp of the gas year round will stay 50 to 55 degrees below ground.
it will expand a little that is why when the pump stops the first time don't continue to try to pump gas.

 

In my 85 Celica GTS one year I made a trip starting in Los Angeles topped off in Las Vegas and topped off again in Ely, Final destination was Twin falls, We calculated almost 45+mpg, 90 mph average to.
If I remember correctly, Thats the year I had a load of fur, Chewed grass and alot of other gross stuff plastered under my hood.

 

Well, the best I've gotten with a '94 4Runner 5 speed, with the 3.0 was about 21 MPG, and I was HAPPY . But now, I've been getting bad gas mileage, batman. Average is usually around 15 now. I don't know why.

 

Are you certain your speedometer is correct? That's the usual issue when you're getting REALLY good fuel mileage!

 

yep - speedo is correct, checked it with a gps.

 

BTW - if you are talking the trip down from the Poconos to Philly via the NE extension - Ive logged some amazing MPGs on that leg.
-- all highway
-- downhill
-- steady pace
-- warm engine

 

thats excactly the roads i've been traveling. have you ever noticed that even coming home its still not really "downhill" all the way home? i used to be doing this trip in my bronco....my toyota easily doubles the gas mileage on the bronco.

 

i have a 94 3.slo and i am happy when i get 18 unloaded.
pretty stock: k&n air filter, camper shell, stereo....oh and the flame stickers i removed from the side of my treuck really slowed my top end a bit so i expected some mileage in return....shouldi put back on the stickers?

 

Myst be a mystery spot or something...
I have gas logs from that leg and its amazing - 23-24mpg is not uncommon (thats with a roff rack and everything)

I always thought that there was less MTBE or whatever in the gas up in sticks so ya got better MPG...