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sowelldr

Gas Mileage

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Has anyone had a problem with a fairly sudden big drop in gas mileage? I have a 94 LS400 that was getting about 18 miles to the gallon and I'm now getting about half that. I don't see any signs of a gas leak, I occasionally smell gas but not constantly. Any ideas?

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Not sure. I know when I first got my 90 LS400- fuel mileage was terrible. I only got about 200 miles per tank. Now I am getting about 300-330 miles per tank of fuel- when mostly driving in city conditions. Not sure what happened. ??

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you might just need a tuneup. i'm pretty sure it will solve the problem. a guy in the office with 94 had this problem and his engine was running really ruff. tuneup solved both problems. he has 234k miles

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the gas companies have probably changed there formula and added alchohal, metonal or ether, none of these which are good for fuel systems, Drive out to rural areas out ther in Texas and see if the fuel doesn't contain those addatives. they do this at this time of year when the wheather changes.

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i agree with VMF. do a tune up. give her a new air filter and throttle body cleaning, along with some new plugs and wires, see if that helps. also always run premium fuel that will give u a little better gas mileage too.

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Replace the spark plugs, air filter, clean out the throttle body. And it will help improve your gas mileage.

JPI

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Spiller911 may be close. Reformualated gasoline, required by emission standards in control areas, often causes fuel consumption to increase by 10%-15%. In addition, it is not very good for your fuel system as alcohol is quite corrosive by nature.

A tune up would be in order especially if it has been 100K miles or more. Typically though, the fuel milage drops in a very slow, steady manner as the spark plugs wear. Nothing you should notice drastically, unless one has fouled.(which you would notice).

You also might give a check of your tires pressure. In my tires, I notice that cold weather seems to leech air from the tires.

The final though is this, in cold weather it takes a lot longer for your engine to get up to operating temperature, thus decreased fuel economy.

Either way, 8mpg is unacceptable. If worst comes to worst, play Lexus to put it on their diagnostic computer to determine what is wrong. They may soak you but at least you'll know whats up.

Good Luck

Denny

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.

I agree with Silvermate. Also, if your temperature gauge is reading lower than it used to then the cooling system thermostat could be stuck open and that will cause excessive gas consumption.

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How are members here cleaning the throttle body on their cars? I'm interested in doing this to my SC and LS and would appreciate some insights. I've cleaned throttle bodies before but I'm not sure if the "remove plastic intake tube, start engine, spray liberal amounts of cleaner into throttle body" is the appropriate procedure for these high dollar vehicles.

Thanks

:)

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How are members here cleaning the throttle body on their cars?

you can download the power point presentation by Curt Oberg (member 'obergc') for step-by-step procedure of throttle body cleaning (93 LS)

http://www.apaqdigital.com/ls400/throttle_body.ppt (1.5Meg; right-click and save target as...)

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i clean my throttle body with carbeurator cleaner, after you take off the intake manifold of course. my gas mileage sucks too, i'm getting about 200mi a tank, and every fluid has been changed, ignition (plugs, wires, igniters) been changed, throttle body cleaned, basically the whole works. just wondering if anyone has another idea.

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my gas mileage sucks too, i'm getting about 200mi a tank, and every fluid has been changed, ignition (plugs, wires, igniters) been changed, throttle body cleaned, basically the whole works.

well... like you, I had done everything (wires, plugs, tuneup, dist. cap/rotor, throttle...the whole 9 yards), but still only got 200miles per fill (about 19.5G when yellow light comes on).

however, since I stoped warming up car no more in the morning (widely suggested in the forum), it does improve to 240~250 miles per fill. that's a 20%+ improvement! like they said, you get 0-mile per G when car is sitting there warming up.....

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wow, that is very poor gas mileage. i wander what the culprit is. i just calucalated my gas mileage after my throttle body cleaning on a full tank and when the gas light came on i had already gotten 460 miles on that one tank of Exxon 93 octane. probably could have got a little better also, because i gave her hell a couple of times merging onto the bypass to check the throttle response after the cleaning of the throttle body. i could tell a HUGE difference. good luck guys

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Silvermate,

What type of cleaner did you use for throttle body? - I have to do Something with the LS once the weather warms.... :lol:

99

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hey 99. i did the cleaning about 2 weeks ago. and i used the STP fuel injection/throttle body cleaner, i got it at auto zone for i thing 2.99. it worked great. just sprayed and scrubbed with a tooth brush numerous times, then cleaned and dried with an old clean cloth.

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hey 99. i did the cleaning about 2 weeks ago. and i used the STP fuel injection/throttle body cleaner, i got it at auto zone for i thing 2.99. it worked great. just sprayed and scrubbed with a tooth brush numerous times, then cleaned and dried with an old clean cloth.

Thank you oh great one...... :lol:

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