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Thread: reasons for bad fuel ecconomy??

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    Default reasons for bad fuel ecconomy??

    hey guys, my cars been getting worse at the fuel finally its hit rock bottom,
    average of 19L /100km running BP ultimate 98RON,

    so far ive changed the
    Injectors and Fuel filter

    they helped but not much, i know for a fact the thermostat is rooted and the L/100km goes up when im idling replacing it tommorrow ($14) and ill pick up a spare housing incase i blow it up,

    i can also smell a faint smell of petrol vapours as if theres a leak in the inlet manifold, im gonna rip the injectors out and check that they're sealed properly and that might fix something aswel but yeah anyother sensors / misc things that i can use to make her use round 13-14L/100km becuase id be happy with that

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    The Oxygen sensor (top of the passenger side exhaust manifold) can die. And when it does it'll send your fuel figures through the roof.

    Worth looking at anyway.
    Gravity is proof that nature keeps getting us down.

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    geez dude i got a v8 and i get on average 14.5-15L/100km doing city driving ang thats also driving it hard
    "A life lived in fear is a life half lived"

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    When did you last check plugs,leads and air filter? Is it blowing black smoke or anything like that?

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    ok sorry forgot to mention

    o2 sensor was done 3 months ago
    plugs done last year
    air filter = pod = cleaned last week
    leads done december last year

    found the reason for the petrol smell, one of the injector seal washers was missing, wasnt holding the seal in, replaced injector and it goes soo much better, idles better yet still runs hot (thermostat)

    havnt had a chance to check petrol usage, reset it and i got it up around 25L/100km... lol lets say i was flat foot everywhere (using one of foams tunes of course)

    blows no smoke, and dosnt smell funny

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    LOL...depends on which of foamy's tunes you're running, but at least one of them was a complete fuel whore. Try running a stock memcal and see what you get. It might be a tad slower, but that will mean that you can compare the fuel figures to what everyone else is getting.
    Gravity is proof that nature keeps getting us down.

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    ran it with stock and got a crazy 22L to 100km

    not the memcal, ive got a burner so i change tunes alot, this ones good because untill map 80 theres no more extra fuel or spark really which suits me fine

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    Lucky you with your own burner, I can't wait to get mine. Hopefully sometime after the stereo, suspension and rims/tyres have been sorted LOL.

    Something else to think about would be compression...you noticed it running a bit rougher than normal? Could be that you've dropped a cylinder or one of them is considerably weaker than the others. That'll start to drink your fuel.
    Gravity is proof that nature keeps getting us down.

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    check your fuel pressure. also, another thing could be a blocked fuel return line which would also show as higher fuel pressure. where does it idle at?
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    usually 800rpm, how do u check fuel pressure???? (btw compression is @ 150 in all cyclidners)

    brought my self a 180deg thermostat today 82deg C
    about to fit it when the engine cools down see how it runs then

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    check also your fuel pressure regulator.
    i replace mine on my vs just as a stab in the dark as had change pretty much everything else, and that helped alot.
    VX SS - Twin 2.5 cat back - MAFLESS Tune - MCAI

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    GRR STUPID THERMOSTAT PIPING, sprung a leak, coolant everywhere car overheating GRR WORK IN 30 mins!!!
    gotta fix it cuz i gotta drive to tafe tommorrow

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    my fingers are burnt but its fixed, dammmit now i have to take my group A bumper in tommorrow

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    Haha, maybe your regulator is pushing 80psi instead of its recommended 40psi! Myne was doing that and cused my car to splutter like a cheap asian hoe, would also cause bad fuel consumption. Me not happy with the price I got charged tho, very bad.

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    well new thermostat in, stock memcal, runs nicely temp stays round a quarter

    right untill the housing pipe decided to start leaking, gonna add another 2 clamps onto it to stop the leak, other than that i averaged 10.5-12.5L/100km on a stock tune driving responsibly... so that im happy with, also the car runs nicely providing it has coolant GRRR

    and yes there is fuel pressure, to remove the inlet manifold i had to remove teh hose for the fuel drain, it shot off and got me in the eye... BP ultimate burns!!!!!!!!!!!!!!!!!!!!!!!

    think i nailed the issue, providing i can stop the coolant from leaking (its just a little trickle when pressure builds up)

    i was lucky with the thermo stat, the housing was in good condition not corroded so i could use the orignal housing

    fitted a 180deg F thermostat, costed me $16.99 from auto bahn not bad

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    averaging 15L per 100km using a chip foam made so im happy, fixed theromostat issues and hosing leaks

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    i wonder how i can make mine run better.. but all that car talk has jumbled my mind hahaha

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    I changed an oxgen sensor and the fuel economy increased much, from above 20 to 13 combined.
    I found a guy who sell o2 sensor on ebay. About 60 to 80 bucks. It is very easy to change it by yourself.
    Good luck!

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    Quote Originally Posted by protossw View Post
    I changed an oxgen sensor and the fuel economy increased much, from above 20 to 13 combined.
    I found a guy who sell o2 sensor on ebay. About 60 to 80 bucks. It is very easy to change it by yourself.
    Good luck!
    dude i paid $41 to have it at my door and did it ages ago :P

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