MrFuel

iTrader: (3)

First off I'll list all the things I replaced already and info on the car.
Yr: 1991 LS400
Miles: 180,000

I've done:
-spark plugs
-water pump/timing belt with all the pulleys and seals.
-new starter
-all the temp sensors are new.
-I just changed the O2 sensors in front of the cats. Should I change the O2 sensors after the cats?

I've been getting poor gas mileage lately. Do you think It can be the other two O2's after the cat? Or the spark plug wires? Also what about the fuel filter?
The car runs and drives great with no problems and there is zero codes. I just changed the oil and always use premium gas. Can someone help me?

PointABE

iTrader: (2)

What exactly is your MPG, as of now?

LJBSJB

Sorry for the newb question - what milage should we expect?
1992 LS400, just put 1000 km on it in my first week with it.

PointABE

iTrader: (2)

I believe it's 16 City and 20 or 21 for highway. Personally, I usually get 20 MPG.

FrankReynoldsCPA

On pure highway, I average 23-24. In town, you're looking at the neighborhood of 10-12 mpg. My last fillup was 9 mpg.

deanshark

Everyones mileage will be different b/c every car runs different but the average should be 16/20 city/highway give or take a few. Personally, I get alot lower then average. Check your AFM to see if it's in spec b/c sometimes it will not set a code b/c it still has electrical to it but the ECU will go into "failsafe" mode, which will give you less mileage.

FrankReynoldsCPA

How do you check the AFM(air flow sensor right? the one right after the air filter?)

MrFuel

iTrader: (3)

I'm getting about 10-13 city and not much better on the highway.

LJBSJB

Just checked my last 2 tankfulls, mostly highway driving: 23 and 25 MPG US (27 - 30 MPG Imperial, or 9.5-10.3 l/100 km).

curepunx

iTrader: (3)

I get about 16 mpg if its mostly city driving while mostly highway driving i get up to ~24 mpg and mixed driving will give 19-20. Note: I do try to stay on top of the maintenance.

deanshark

Like this; https://www.clublexus.com/forums/sc-...on-issues.html

Patsum

I drive 100% city and get about 280-300 miles per tank ( 20-21 gallons )
this is with my a/c comp off 100% of the time
I also tend to be an aggressive driver
I use 91 octane gas

1991 LS400

13-15 mpg city for my car in 100% city. I have never gone on a full highway trip with her so I cannot comment...but I think I could get 20 mpg going 70 with cruise

This is not the car to own for getting decent gas millage

Someday I will have myself a hybrid accord for that.. or a Civic and just bask in the fact I could get 600 miles on a tank.

New plugs and plug cables really helped my MPG go from 9 to 14-15

emarknot

I get 67 miles for every $10 bucks i put in.
Meaning...gas light on, i put in 10 bucks. Get 67 miles driving very carefully. 50 miles if i feel the need to get on it from time to time. All city.


An $10 bucks is 2.8 gallons of 91 octane....and i have 308,xxx miles on a first gen. The most i get from a full tank is 474 miles, city/hiway combined

Raddison

Jealous. With combined driving, the most I get is about 300...

emarknot

Dont be, it takes alot of effort to drive this car to maximize mpg.
My loaded idle is 500 rpm, 40 mph is 1100 rpm. I watch my tach more than the spedo.