LS400 High fuel consumption

Discussion in 'Diagnostic & Repair Tech' started by Bali26, Sep 28, 2007.

  1. Bali26

    Bali26 New Member

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    Hi,

    I'm a new owner of a 91 LS400 in large part due to this forum. I'm very happy with it so far. There are some things that the car needs done but I just don't have the money to have a lot done, I can barely afford gas. I prefer to buy tools than pay a mechanic. Here are my questions:


    Biggest problem: The car's giving me only 13 mpg in city. Tyre preasure is maxed out 38 psi but it feels like i'm pulling a trailer. Using 91 octane. What do you think is wrong? Check engine light is ok. Can the Oxy sensors be bad and not show up in check engine? How do I find out if they are bad? I have ramps and can buy oxy sensor socket. All four may need to be replaced? Or front more important than rear? What else can i do to decrease consumption? Alternator?


    Other problems:
    TRAC light comes on after a couple minutes of driving and periodic humming sound. Is it ok to ignore it?

    Very Minor oil leak around oil pan, PS rack area. Oil level stays high.

    Very minor oil leak around PS pump, area barely moist. Oil level stays high... ok to ignore?

    Sometimes car blows white smoke when started. Not always.

    Upper control arm joint a little loose. little play. Ok to ignore for now?

    Your advice is much appreciated
     
  2. Lextreme

    Lextreme Just call me "Lex"

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    Gotta fix the PS pump before anything. Your valve seals are bad.
     
  3. Bali26

    Bali26 New Member

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    Thanks Lextreme,
    Since I will be doing it my self, what do you think is the best way to fix it? Buy remanufactured? Used? Repair existing? Kit?

    Any advice on the fuel consumption?

    Thanks a lot.
     
  4. Deuce

    Deuce Member

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    Could the TRAC control be activating the brakes and causing drag? I would be de-activating it to eliminate it as a possible cause.
     
  5. SCV8

    SCV8 New Member

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    Dirty air filter perhaps...
     
  6. Bali26

    Bali26 New Member

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    Thanks,

    Air filter is new. Today I checked out throttle body and it was very clean. MAP was also very clean not a spec of dust.

    I put a blockage in the vac hose that goes from PS to intake manifold. Did I do good?

    Should I try to replace the leaking seals in the power steering or just buy a refurbished one? Whats the best way to go for DIY?

    Thanks :)
     
  7. Cobber

    Cobber New Member

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    PS pump is pretty easy to fix yourself. The best way is to get a repair kit.

    Don't block the hose from the ps to the manifold. Done bad.
    Check the oil level in your transmission as well to make sure all is good there.

    Check the cold start injector is switching off. The plug is at the top back of the inlet manifold and goes into the valley, Pull the plug off for a few days and check your economy.

    http://www.lextreme.com/parts/kit.html

    Oh and welcome to the forum, you won't find a better place to learn about your car and engine.
     

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