Lexus GS300 - drinking too much fuel

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Mon 20 Feb 2006 08:01
Lexus GS300 - drinking too much fuel - nutty_nissan
Hi,

99 model, mk2 with 85k. Car struggles to get 18 in mixed driving, even when driving with light foot. Cruising on motorway at 60mph returns just 24mpg. I know from other owners of same car, that they can get around 25mpg in mixed driving, and up to 32mpg at a steady cruise.

Car has been serviced regulary. Oil and filter last done 6 months ago. Platinum tipped plugs were replaced at 60k service.
Changed air filter 2 months back, no mileage improvement. Have used fuel injector cleaner too. Was going to replace distributor cap and rotor arm, but was told these don't have them, being coil on plug.

Any ideas what I could try next, without necessarily visiting a main dealer? I suspect it may be worn oxygen sensors?
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Mon 20 Feb 2006 08:24
Lexus GS300 - drinking too much fuel - adam f
i have a bmw e36 and was getting awful mpg.initially thought it was rhe usual- air filter, oil etc etc, but my tyres were just a little bit off there full pumped up capacity. since i put in a little more air the mpg has almost doubled.
you probably have already checked all this but if not give that a try.
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Mon 20 Feb 2006 11:00
Lexus GS300 - drinking too much fuel - nutty_nissan
Thanks. Yes, tyres have always been at correct pressures.
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Mon 20 Feb 2006 11:24
Lexus GS300 - drinking too much fuel - Aprilia
Drive to local MoT station and get them to do an emissions check - this should highlight whether air-fuel ratio is correct and weed out any engine managment faults.

If all seems well then look for basic mechanical problems (binding brakes, bad wheel alignment etc).
Also check that the 'box is upshifting at the right rpm.
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Mon 20 Feb 2006 11:48
Lexus GS300 - drinking too much fuel - Collos25
Do not believe what other people tell you ,an aquaintance who has the same vehicle says thats all he gets and sometimes not that much but he is still a Lexus fan.
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Mon 20 Feb 2006 20:59
Lexus GS300 - drinking too much fuel - Railroad.
There's no screw you can simply adjust to improve fuel consumption. The best way to tell is to remove the spark plugs and check the colour and condition of them, or look at the exhaust tailpipe to see how black it is inside.

Spark plug gaps, valve clearances, tyre pressures, types of journey, engine temperature, use of electrical ancilleries, air conditioning, open windows and sunroof and a whole lot more all affect fuel consumption....
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Tue 21 Feb 2006 08:03
Lexus GS300 - drinking too much fuel - Collos25
One problem I forgot to mention ,plugs 3 and 4 get left because they are almost impossible to change.Main lexus dealer did not change we found out after a misfire started.
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