Phil676

New to me car. Dash showing 13.2 mpg, which I'm reading may be innacurate. The vehicle history extends to Lexus for timing chain and jiffy lube for all fluid changes. Therefore, sparks plugs are on my list .

I have an OBDii scanner that links to an app on my android. It is capable of providing a lot of information. The problem is I don't know what information to pay attention to and what range it needs to be in at what time. How can I use the OBD diagnostic tool to check fuel-economy sensors (O2, MAF, etc)

I realize if something is far out of range, the engine light would turn on. My thought is checking for sensors that are on the edge of failing.

IanB2

I've been tracking my fuel economy manually since I got our GX, and I'm getting about 13mpg as well, which sucks. When the weather warms up a bit I'll be putting in some time and replacing:
-air filter (aftermarket washable dry filter, AFE or similar)
-front & rear diff and transfer case fluids with synthetic
-lubing driveshaft
-cleaning MAF
-maybe change sparkplugs
-maybe have some of the resonators cut out of the exhaust

Hoping to get a bit better than this, I expected bad but not this bad. The best tank I've seen on this truck is worse than the worst tank I got with my '91 turbo diesel Land Cruiser by a few MPG!

06isDriver

I dont know why there is such a a range difference in vehicles. Our GX, before being lifted and all, was getting about 17.5-18mpg mixed driving.

Now we've got 33" tires, lifted 3 inches, steel bumper front and rear, rock sliders, and roof rack, and we're still getting about 15.5-16mpg. And this is calculated mileage, not relying on the computer.

I actually found that the computer calcualted mpg got MORE accurate after the larger tires. It is within .1-.2 mpg always now. I dont even have to do manual calculations anymore after 5 in a row yielded incredibly accurate results.

06isDriver

I'm thinking its a combination of environmental factors and gas blends. I hate to burst your bubble, but I doubt lubing anything or replacing fluids will change anything. if your engine is getting up there in mileage, a good spark plug change and maf/throttle body clean, with maybe a sea foam treatment in there could help.

IanB2

It may not make a diffrence, but it's something I like to do to all vehicles that are new to me. Our GX only has 135,000kms on it, so not what I'd call high mileage, and I did put 32" Duratracs on it 1st thing when we got it so that won't help either, but I'm hoping to get the mileage a bit better than 13mpg mixed driving, which I don't think is unrealistic. I should also mention that I'm using a 1.05 correction factor to compensate for the bigger tires, determined by using the roadside odometer calibration signs we have along some highways here in Canada, so my figures should be dead on accurate.

Matsui

Can you please elaborate on "sea foam" - like what it is and how it is used?
At 100k miles, my MPG has dropped significantly - from 18.5 to 14 MPG which I manually calculate every time after refilling. My car has gotten scheduled services done at every 5k miles. I did not ask them to investigate this issue last time I was there since I knew they would shoot in the dark and it would end up costing more.

I want to start looking for the cause myself. I have replaced the gas cap and also used Chevron fuel injector cleaner in last two fill ups but have not noticed a difference. I think I'll start with checking the tire pressure and air filter next. MAF/Throttle body clean sounds complicated.

Is the tire pressure mentioned in the manual the optimal in terms of ride comfort and MPG? If not, what would you recommend? I have stock wheels and tires.

06isDriver

sea foam is a name brand intatke/combustion chamber cleaner. It can be poured into the fuel or oil itself as a cleaner, or the more traditional method, is to have it injested through a vaccumm hose while the engine is running.

if you look on youtube for how to seafoam your car you'll see instructional videos and the signature plumes of white smoke. This is the cleaning proce3ss and does a very good job of breaking up all the deposits that you normally cant get to with cleaners in the fuel. Sea foam has been around for decades and is good for a little spring cleaning in a higher mileage engine.

Matsui

I vaguely recall seeing an article long time ago about it. I think they opened the throttle body, sprayed in this stuff and started the engine to let it all out through the tail. The process seems complicated top open the throttle so I might seek an indy to do it.

cssnms

Fuelly.com is a great site to use to calculate your mileage and compare it against other GX's.

http://www.fuelly.com/car/lexus/gx470/gas%20v8/suv

IanB2

X2, I've been using Fuelly to track my fuel economy on all my vehicles for years, very handy tool.

jstarmark

I would like to purchase an OBDII scanner also. Can you please post or send the type that you are using, and where you purchased it from.

Thanks,
v\r
Mark

mrblister

Hi I tried the link it wont work ?

ALAN553

New O2 sensors are usually the cure for aging....

chiph9

This one worked for me:

http://www.fuelly.com/car/lexus/gx470/

You can then narrow in on the year.

Or just click on my signature image to see just my vehicle.
Chip H.