A few people recommended I change the upstream air / fuel sensors so last week I had both upstream sensors replaced and I had Toyota do a fuel injection cleaning and a 4wheel alignment. I filled up with a full tank of gas and and removed both battery leads overnight. Normally on a full tank the miles till empty says 280, this time it said 369 so I though the sensors / cleaning did the trick but NOPE its back to shi*y gas mileage and the miles till empty corrected itself over a few days.

I filled up last night and divided the number of gallons it took to fill up by the miles of my tripometer and Im still getting the same exact mileage as before? All fluids (except trans) have been changed within the past 10K miles. Within the last 1K miles I put a new air filter, cleaned the MAF sensor / throttle body and did a Mobil 1 oil change. When Toyota did the injector cleaning I had them check the brakes for dragging and they said theyre fine. I havent changed the spark plugs yet but theyre good for 120K miles, I barely have over 100K.

Anyone have any other ideas?

 

tires and wheels? you are pushing more air and weight with your tire/wheel set-up and your speedo is likely off by a few percentage points. those two factors combined could be costing you a few MPG, couple that with a slightly off speedo/odo and that might account for what the computer and your hand calculations are finding.

just one hypothesis.

 

well, my average in town is 12 so I'm not too surprised you're only getting 11. I don't really expect more from my V8, 2-ton truck to be honest!

I live at 5800 feet though. Not sure if that has a positive or negative effect.

 

Unfortunately thats not the problem. I was getting the same mileage with the stock 17" wheels and tires (265/60/17). Also since getting new tires I tested my speedo against several speed traps and a iPhone speedo app and its the same as my GXs' speedo.


I expected more. I had a '06 Tundra DC (same V8 engine) and by the time you factored in the larger gas tank of the Tundra I was as heavy if not a little more heavier than the GX AND I had larger 33" M/T tires and I got better gas mileage than the GX and I drove my Tundra like I stole it!! I try not to get to 3K RPMs in the GX and I still cant improve gas mileage?

There are some guys on other forums with lifted GXs, 33" tires, tons of heavy gear that are getting better gas mileage than me. Im not the one to b*tch and complain about MPG but at 11 MPG something isnt right.

 

Well the spark plugs look great and my engine definitely isnt running too rich......

 

try changing your route... I changed the way I go to work and I get 3mpg better.

 

Clogged fuel filter? I think they are inside of the tank... it sounds like you covered everything else.

You could also hook up an OBDII data logger and try to get A/F information from the ECU. You can get them as apps for an android phone now.

 

Since you've done almost everything, I would recommend replacing the PCV valve and see if that makes a difference. This is cheap and easy to replace.

 

I dont think it's your engine, but you could run up to a 4 wheel dyno and do some pulls to see power and air/fuel. Shouldnt cost more than 100 bucks.

 

That does sound low for sure! I get about 14-15 in town driving and I dont take it easy either lol. A full tank of gas I can get about 300-330 depending in the summer. Now winter time is a different story

 

I have an 03 GX with 120,000 miles on it and am getting 18MPG using the miles into gallons method of calculating. I get 19.8 on the same tank of gas using the in car computer. Either way this is far better than 11 or 12 you are getting. I don't track the MPG all the time but it has been pretty consistant for the life of the car.

 

I drive all city NO highway what so ever, so I expected at least 13-14mpg.

The 18mpg you're getting is mixed city / highway.

I'm moving as I type this so hopefully where I move to Ill have a better route.

 

I suspect that you may actually be getting better than 11. The mileage you actually travel, shows less on the odometer, if you have larger tires/ diameter. You must be in the Texas heat cranking on the air conditioner. You might loose a mile per gallon. I have an 08 with 60,000 miles. Can get 19 or 20 mpg on only freeway, keeping it at 65 to 70. I get 18 combined, but it is fairly driving on flat roads. Going into the city and buring up a tank, waiting in traffic (killer), I go to 13.5.

I think you have done more than most, to solve your problem and certainly have the technical skills.

 

+1 Same here,

Maybe RC could change the fuelling from a another gas station and then check. And have the fuel pumped early morning. As the gas would be denser. Try it.

 

We all know this is just a part of owning the best vehicle on the road...Continue to follow the maintenance intervals religiously- as you are doing.
Also, you can go easy on the throttle when driving- keeping your PWR/ "ECT" button in the off position.