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wtf is up with my gas mileage?

Discussion in '80-Series Tech' started by Mr.Bryan, Aug 14, 2006.

  1. Mr.Bryan

    Mr.Bryan

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    Ok guys, I need a little help with this one. I've figgured out this much, the more worry that arises about global warming, the more my mpg's go down. So I think Al Gore is causing my problems.

    Serioulsy though, over the last like 2-3 months, my gas mileage has been going lower and lower. I used to be able to get about 16 cruising at about 65, now i'm getting about 10-11. If i do city driving, i'm down to 8 or 9 from maybe 12-13. I'm not hard on the throttle, usually keep it at 2 and if i really need to move, i'll get it up to 3k rpm, but thats it.

    The thing runs fine. I haven't noticed any power loss... besides the fact that its a landcruiser. Here's what the rig is. 3" lift, arb w/8274 warn in it, custom rear bumper, but nothing to it, sliders, and 305/70 bfg muds with about 35-40% tread left and 165k mi total on the odo. I havent repacked my front wheel bearings or birfs in about 2 years, but I think it should still be ok. It's only been about 35k mi. since it was done. I do have a check engine light on, but last time i checked it, it was still a code 420 which is just a bad o2 sensor. Could those bastards be doing it?


    AAARRRGG... ok any ideas?

    Thanks for any and all help.


    Thats the truck, nothin fancy.... cept the fender flares ain't there any more. [​IMG]
     
  2. landtank

    landtank SILVER Star

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    Seeing how you're in the rust belt, is there any play in the e-brake handle? So when you pull up on it, it takes some movement before you feel resistance.
     
  3. -Spike-

    -Spike-

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    Your o2 sensor tells the engine how much fuel to dump in. If it's not working, the engine computer won't know how much fuel isn't being burned, so it will give a default amount of fuel to the engine- more than enough to run. Not good for fuel economy.

    -Spike
     
  4. Mr.Bryan

    Mr.Bryan

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    Yea, i took my e-brake out. The cable is still there, but no handle. I put my cb in it's place. I'll check that though, maybe it is dragging.

    As far as the o2 sensor goes, would it really cause it to drop 5 mpg though? that seems like a monsterous ammount for just a little computer thing... but then again, i hate computers.
     
  5. MLX450

    MLX450

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    16 MPG with the lift and tires? Thats pretty good. (Before or after mods?)
    Could it be Ethanol in the gas (E85) since you live in IL?
     
  6. Mr.Bryan

    Mr.Bryan

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    Yea, i drive pretty conservativly, but I was happy with the 16mpg. I think the bigger tires made up for a little bit of it. I'm not running e85 though. there is like 10% in the gas, but its always been like that. eh come to think of it, it was probably about 15mpg with the 10% ethanol, and 16mpg with straight gas. But yea, that was with the mods and crap.
     
  7. Beowulf

    Beowulf

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    Yes.

    Replace your O2 sensors. I recommend OEM though you may pay slightly more. Check with C-Dan on the current price.

    -B-
     
  8. archie

    archie

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  9. CJF

    CJF

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    Guessed the answer before opening the thread: Count me in on the O2 sensors.

    Collect some good before/after mileage data and keep us posted.

    Curtis
     
  10. Mr.Bryan

    Mr.Bryan

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    hmm, well.... I guess I'll try it. The light has been on for a little over a year now, but I guess they'd just keep getting worse. I'll replace em, and let ya know what happens.

    Thanks dudes.
     
  11. Kalawang

    Kalawang

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    Do you buy all your gas from the same station ?


    Kalawang
     
  12. Gumby

    Gumby Supamod Staff Member s-Moderator

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    O2 sensors, air filter, vacuum leak, leaky injector, tire pressure.

    Any exterior mods since the fuel mileage dip? roof rack? Big giant spoiler on the back?
     
  13. Mr.Bryan

    Mr.Bryan

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    I'm tryin the o2 sensors, but i replaced the airfilter 2 weeks ago, i'll look for a vaccum leak, but i'm not to good at that, no fuel is dripping, and tire pressure does keep getting low, but I fill em up like once a week. I keep them at 40psi.


    I've been considering the big giant spoiler, but I just can't find the time to do it. Maybe next month.
    I should just sell the cruiser and get a harley. Then i'll get good reliable gas mileage! :D :D :D
     
  14. gnx7

    gnx7

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    O2 sensors for sure are contributing to the worse gas mileage. They have direct input for how much fuel to dump in based upon a/f ratio. If they are fouled/failing they go rich as a safety buffer.
     
  15. Capocaccia

    Capocaccia

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    I probably need to replace mine also since I just found out im getting 11.6 MPG with 33's and the air conditioner on 90% of the time.
     
  16. Panzer

    Panzer SILVER Star

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    could be both o2 sensors and the switch to ethanol. I have already posted a rant on the screwing we are all getting with the ethanol fiasco so I will stay off my soap box on that.
    OME 3" and 315's without regearing I was getting 14.5 "indicated" mpg.
    Now with ethanol I am getting about 12.1 mpg. Combined little city and mostly highway commute to work.
    Hope this helps.
     
  17. BROKEROB1

    BROKEROB1 SILVER Star

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    I took a trip 2 weeks ago (from PA to FL) with a roof top carrier, I averaged 12 mpgs. I ran down I95 at an ave speed of around 75mph. Last year on the very same trip with very similar circumstances, I averaged closer to 16.5 mpgs. I keep throwing the same code and I am also assuming that my O2's are bad. I know that they are still the factory originals per the PO.
     
  18. Brian Macgyver

    Brian Macgyver

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    Right. With a check engine light on your system is running on back-up. You will burn a lot more fuel in that mode. Correct the problem and you should be back to the wonderment of 15 MPG!:bounce:
     
  19. Mr.Bryan

    Mr.Bryan

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    14.8 mpg @70mph on hilly terrain!


    Thanks a TON guys!
     
  20. Arleaux

    Arleaux

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    I am assuming it was the O2 sensors only.
    Or did you find a vac leak as well?