Bad gas mileage. Fix problem but still bad mileage.

I am happy to get between 10 and 12 but then I always have at least 800 to 1200 pounds of payload adding to the wind resistance as well. If I was worried about fuel mileage I would not drive a 4x4 Truck.

Could the 23mpg been from a math error or reading the figures incorrect that much of a drop would seem to be a major problem??

 

Alright so, I changed out the temp sending unit with an OEM one from toyota for $60. Still not fixed. Still getting 15 mpg. So now I've bought 2 of those, an o2 sensor (good to change anyway), a new cat, and spark plugs.

Based on everything I have read, I know for a fact I should be getting 20-25 mpg.

I'm running out of ideas. I'm going to check to see if the egr valve is not closing all of the way today.

Any one have any ideas? I was getting 23 average, part went bad light came on. Got 12-13 mpg. Ran really rich for a while. Changed part, ran way better, now I'm getting 15 mpg.

btw I also did a compression test, 150 in all four cylinders...

 

Wish I could get 20 mpg. I have two reg cabs with 2.7 4x4 5 speed. If I totally pussy foot it with lots and lots of coasting while watching the scan gauge like a hawk I can get maybe 19 mpg on a 40 mile one way commute with two stop signs. The other truck is built up a bit, 15 to 17 is what she gets no matter what.

 

Have you tried resetting the computer? Or wiping the codes?

 

Yeah, I resetted the computer. Battery cable off and efi fuse out...

I live in FL, it's very flat and at sea level where the air is dense. There is a huge thread around here about 2.7 gas mileage. I read through almost the entire thing and I should definitely see a 2 as the first digit. Makes sense, because again, I was averaging 23 mpg before.

 

Your 1st post says you got 23 for 1 tank, and then you didn't. That's not really 'getting' that's 'got'. The average for that truck is 17, 15/20 town and highway and 'average' driving style. The driving style is pretty arbitrary imo, since what one person considers normal is pretty abnormal to the next guy. And there are both sides to an average, every guy that gets 10 there's another guy that gets 30 etc etc etc. My 2000 2.7l 4wd, 5spd, I *might* have gotten 20mpg once or twice but it would be pretty unusual for it. 17-18 is the norm for just driving around, it's been in the low low teens while in the mountains.

"Averaged 23 mpg first tank. Mix of highway, city, off road. Awesome!

Check engine light comes on. Temp sending unit. 12-14 mpg.

Changed part, light stays off, truck runs way smoother."


15 is a little low, but not knowing your driving style I can't say it's significantly low. There's a reasonable chance, that's what the truck will get with 0 issues.

With the computer reset, that takes everything to default settings and it should start learning from there. 500 miles isn't an unusual number of miles before the computer has basically adjusted to your driving style. I have known people that had an issue and just reset reset reset rest ad nauseum and could never get back to 'normal' until they finally stopped doing that.

and, the previous owners may have been a hypermiling sob at 3k below sea level, and you're not. If the computer was adjusted to him, and reset to you, you may never see the same results.

 

It is questionable because it was only one tank of gas. The thing is though, when I first get a vehicle I drive the shit out of it out of excitement. That should have been my worst tank. I tried to find the thread I was talking about, but could not. Mpg is one reason I bought a Tacoma and not a Jeep (other than Jeeps being garbage). I'm becoming convinced that I had two problems go wrong at the same time that are unrelated. I have not given up yet. There are plenty of other people I've seen on here that also live at sea level with no hills that are averaging much higher than I am, easily in the 20's.

I'm testing my fuel pressure next. I disconnected the fuel line and NO fuel came out. NO pressure. This was odd because it had been running 10 minutes prior... Aren't these EFI systems supposed to hold pressure when off?

 

New guy at my work has the same truck as me. 98 single cab 5 speed 4wd 3 inch lift. Only he has 33 inch all terrains and I have 32 inch all terrains. he's averaging 20-22. Makes perfect sense. Clearly something is wrong with my truck and I'm not just getting bad mileage due to tires/location. Somebody please help...

 

Just curious, anyone know if an O2 sensor is something to change only when it goes bad. Or does anyone recommend them being changed as a part of regular maintenance? I have around 150k on original O2's... FWIW I average 15/17 mostly hwy some city.

 

Subed

 

What kinda speeds are you running on the hwy.
My 4.0 gets 20 on the hwy. doing 55-60. 17 or less on the hwy. doing 70+.
I also always use ethanol FREE fuel.
All other things being equal, MPG has more to do with driving behavior.