Smw

Hey folks, so I recently purchased ls430 w/ ultra luxury package. Its has 124k miles
I Live in a suburban neighborhood and drive mostly city very little highway. So no real heavy stop and go traffic roads are fairly open. I am getting 11mpg!! and this is without the a/c on. I live the car and I know it isn't a gas saver but that's horrible mpg. Is this normal because of age or is something wrong?!?! I am hoping something is wrong
Timing belt and spark plugs changed @86k
average 17 mph
Air filter is clean
Cleaned maf sensor
Cleaned throttle body
Premium top tier gasoline
tires are inflated properly
I drive like a grandpa
The car is super smooth and hardly any vibration at idle and acceleration.
Most of the time it is only 2 people in the car me and the kid. Please help I don't know what else could be causing this!

jharris400

Do you have a OBD2 scanner that can read live data? I would pay attention to long term and short term fuel trim. The numbers will never be perfectly at 0 but the closer they are the less suspicious you should be of your engine not running correctly. I would also look at that coolant temperature sensor value, if your coolant doesn't get up to temp and stay there the ECU will add extra fuel to try to get the temperature up.

BigBoomer

If your average speed is 17Mph then you ain't gonna get good gas mileage.
Did you reset the averages when you bought it? If not, may be worth doing a reset and see what you get over the next week or 2.

The LS will do 25Mpg at a constant 70Mph and a bit more if you stay at 55Mph but any kind of stop-go traffic slaughters the gas mileage.
Most seem to average around 20Mpg according to Fuelly.
https://www.fuelly.com/car/lexus/ls430

This is still a 4.3litre (262CI) V8 in a 2+ ton car so gas mileage is going to be poor.

Smw

Thanks. I know she isn't a gas saver, but 11 is horrible even for city driving. I am not expecting even 17 mpg. But 15 mpg I would be happy with.

Smw

I do have an obd2 scanner. Not the fancy kinds. So all the fuel trim values should be close to 0? What would be a bad value? Thank you

Striker223

That's normal for city driving if you aren't employing any hypermileing tricks.

Smw

I checked ECT with scan tool (engine coolant temperature) at idle but the car was very warm as it was on for a long time. It was 93°. Do I need to check this while driving or idle??

Fuel trims @ idle
Long term b1 6.3
long term b2 9.4
short term b1 fluctuate between 3 to -1.6
​Short term b2 fluctuate between 1.8 to -.8

Fuel trim @ 2400 rpm
Long term b1 8.6
long term b2 11.7
short term b1 fluctuate between 2.3 to -4
Short term b2 fluctuate between 1.8 to -.8

TominPT

Do what BigBoomer suggests and see what your instantaneous gas mileage is at a steady 55 on level ground, no wind, and report back. If it checks out you can attribute your poor gas mileage to environmental factors, driving habits, red lights, ideling, 2 tons of inertia, etc etc. and not the engine per se. (I get about 30 at 50-55 on level ground, steady speed, and I know my city mileage is really awful because from tank to tank with mostly highway miles my average is currently in the low-mid 20s.