Help ! I Get Really Bad Gas Mileage. Only 10 Mpg !

[billy hoang]

i have a 1993 lexus ls400 and it has about 155,000 miles on it . i changed both front o2 sensors and air filter . and i only get 10 miles per galllon . is there anything else i could do to try to improve my gas mileage . if it stays like this i might as well get a SUV . i am planning on changing the fuel filter and pcv valve . would that help ?

[ED.]

How's the pressure in your tires?

[billy hoang]

its at like 40 psi

[SRK]

If the engine has not popped a code, and you drive at less than full throttle all the time, I would take the mileage again over several tankfuls. I can't think that a good running LS could get so few MPG. Mine does 22 MPG in town, imperial gallon, so about 18 US.

[billy hoang]

i had it for about 2 monthes already . at first i was hoping that it was the oxygen sensor since it was throwing a code . replaced it . nothing . then did the air filter which was reallly reallly dirty . words cant describe how bad it was . and i swore that i got 20 mpg . but i might have calculated wrong . but i just calculated again and i think its still doing 10 mpg.

[VBdenny]

I get a pretty steady 18 or 19 mpg in town and about 24 on Interstates. You must have something wrong to get that bad. I would almost suspect a cylinder not firing correctly with it being that bad but that would certainly send a code. I put a K&N airfilter on and it seemd to help a little but nothing like what you need. You sure someone isn't doing a little siphon job on you?

[akewlguy]

I get about 19-20 with my 93.

Anyone have any different MPG with different fuel companies? Texaco? BP? Mobil? Shell? Hess?

I have been keeping my receipts to compare, but not enough miles yet to have a solid conclusion.

[VBdenny]

I never noticed much difference between brands although I'm not to good at checking milage on a regular basis since I don't want to know how much I spend on gas. I just close my eyes and put it in. Oil hit $64 a barrel today. Ouch!

[alsalih]

Visually inspect each brake rotor for signs of discoloration (blue) as a sign of a sticking caliper or calipers (if more then one rotor shows this then you have a bad brake master cylinder). Also, lift the back end of the vehicle and try to turn the wheels, hopefully the emergency brake is not misadjusted and grabbing. If nothing there then I would start to look at possible catalytic converter problem. Hit the converter lightly with a mallet and see if sounds like a can with "rocks" in it. If it does then your cat is shot!

[billy hoang]

i dont think its the catalytic convertor cause i passed inspection . but i do know that one of the calipers is like stuck . my friend was trying to pry it out so that it could move back and forth when applying the brakes but all it does is stay like in a locked position . but not on the rotor . like away from the rotor . could that be it ?

[dcfish]

i dont think its the catalytic convertor cause i passed inspection . but i do know that one of the calipers is like stuck . my friend was trying to pry it out so that it could move back and forth when applying the brakes but all it does is stay like in a locked position . but not on the rotor . like away from the rotor . could that be it ?

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You mentioned that the air filter was really bad, That leads me to beleive the car has been neglected. I would start with a full tune up , plugs, wires, all fluids, clean the MAF, motorvac, all the filters on the car, Like it has been mentioned check all the calipers and E-brake. Only use premium fuel and see how it runs after that. Good Luck

[alsalih]

Any indication of a sticking caliper is not good, even if it's stuck in the retracted position. Personally I would do as dcfish has recommended, the complete tune up on this vehicle in addition to replacing all four calipers. Rebuilt calipers are not too expensive and given the age of the vehicle (and abuse) it would be cheap insurance and very likely the cause of your problem. Also while your at it check the brake master cylinder for signs of a brake fluid leak.

[bartkat]

I think you should reset the ECU, then get an accurate check for mileage on a couple tanks of gas. See what you are actually getting and then go from there.

Of course, the brakes need attention, whether it affects mileage or not.

[billy hoang]

can anyone help me ? or what could i do ? would having 20" rims contribute to this 10 mpg problem ? its driving me nuts . i dont want to trade the car

[dcfish]

can anyone help me ? or what could i do ? would having 20" rims contribute to this 10 mpg problem ? its driving me nuts . i dont want to trade the car

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A good mechanic, Buy a brand new LS, Rim size will not kill your mpg, Don't go nuts, This should not bring you to a trade. Try the above mentioned suggestions on this topic and if there is no difference we'll take it from there. Patience and understanding go a long way. ;)

[billy hoang]

anyone else might have a solution ? please help me . filling up $10-$20 everyday sucks !

[billy hoang]

my next step is to change cap , rotor , spark plugs and spark plug wires . any more suggestion ? please help .. im beggin !

[vyhanh]

Do you smell gas? Is there a leak ?

[billy hoang]

nope . no smell and no stains in driveway

[mason]

I recently had my fuel-injection system serviced, and that helped my mileage. I get 17-19 in the city and 25 on the highway. ('94 LS) Try that, along with all the other suggestions.

[daying]

is the car equiped with standard 225/60-16 tyre? non-standard tire size may result in misleading odometer reading.

[dcfish]

anyone else might have a solution ? please help me . filling up $10-$20 everyday sucks !

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After all above recomendations have been performed post the results and we'll go from there. ;)