help with fuel mileage

Discussion in 'International Forum' started by s.hitt, May 18, 2013.

  1. s.hitt

    s.hitt Bobtail Member

    3
    1
    May 18, 2013
    dallas ga
    0
    I have a 2006 9400i eagle that I just got a few months ago. I got it cause every one has told me how good the isx is. when I got it it had a life time average of 6.4 on the ecm. I have just had to replace the ecm a week ago. I have only got 6.4 one day! it has been in the shop more than on the road! what can I do to get it back to 6.4? right now im getting anywhere from 4.8 to 5.7? I rarely haul more than 45,000lbs with a grvw of around 68,000 lbs. I have had to put a butt load of money in this thing. it has just about drained me. I have it in the shop about once a week cause of the codes it was giving me til we found out the ecm was bad. I have put 2 injectors in it a egr valve all new filters delvac oil the over head ran 3 times fuel valves turbo speed control sensor boost sensor. the egr cooler is new turbo accuator is new also. Since we have swapped out the ecm no more codes and no more derating. but now I can only get 5.7! it has a 500hp isx 13speed 342 rears 22.5 wrapped in half woren good year 11r's! I #### at about 1600rpm's and cruise at 1400 rpms witch puts me at 66mph! what am I doing wrong? and what is the best rpm to cruise at! this is my first isx and could be the last. everone I talk to is getting anywhere from 6.4 up to 7.8 hauling the same thing I am and most of the time heaver than I am! any help would be great!
     
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  3. WorldofTransportation

    WorldofTransportation Heavy Load Member

    702
    577
    Sep 20, 2009
    Your mother
    0
    About 4 years ago I was about to sign the papers on a truck.. just about like this one... It was a KW though.. but exact same setup.. It was 3 years old and had 300k on it... About an hour before I was to sign the papers I walked in the office of KW in Dallas.. and the salesman came over and said lets go outside a minute.. We did and he strongly advised me against the ISX engine.. So I went to cummins and talked to the resident ISX man there and he told me those motors are hell... So I called another mechanic that works for a dealer in dallas and he said don't walk away from it RUN AWAY... So I did.. I did buy from that dealer and have been happy with the same truck with a cat in it.. I avg..6.3 with it and don't have much to complain about.. but your problem may very well be the ISX... My suggestion is after this trade it off and get a detroit.. put an egr tuner on it and run... I am very scared of ISX after being told what I was by these 3 men.. Good Luck my friend..
     
    s.hitt and nabil1127 Thank this.
  4. s.hitt

    s.hitt Bobtail Member

    3
    1
    May 18, 2013
    dallas ga
    0
    well thanks for the info. but just as my luck has been going lately just a little to late for that to help!lol! I just need to do something befor I lose whats left of my butt! Whats left from my wife getting threw with it!!! I just need to get it to run it to get something out of it! The folks I talked to love this motor! and the mechanics I have had working on it love this motor and say that once I get the thing running right that I will love it too!
     
  5. eeb

    eeb Heavy Load Member

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    267
    Mar 24, 2013
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    How's your driving style? I don't know what you do now, but maybe you can ease up on the throttle, take a little longer to get to speed, maybe lower your cruising speed. Pleny of other mileage and driving for mileage threads on here, check 'em out and see if you can apply any techniques or upgrades.
     
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  6. Heavyd

    Heavyd Road Train Member

    7,625
    6,025
    Feb 4, 2009
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    We have a good customer with a moderate size fleet, mostly ISX. He claims he gets the best mileage with the trucks running at 62 mph. 65 or higher it really drops off.
     
  7. freightlinerman

    freightlinerman Road Train Member

    1,287
    535
    Mar 4, 2011
    Florida
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    Maybe consider getting a tune?
     
  8. sdaniel

    sdaniel Road Train Member

    5,511
    4,416
    Sep 7, 2011
    Pelham N.C.
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    Boost leak ? Mix up some soapy water, or glass cleaner. Set to high idle, and soak all intake hose connections , gasket , flanges, and the charge air cooler. Any bubbles is a leak. Get any leaks fixed. Guessing there is a leak some where ? Good luck!
    My brother is buying one of ISX next week. He just will not take my advice ! Do not by any thing from 04 till 2011 ! No matter who made it !
     
  9. osumike33

    osumike33 Light Load Member

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    Jun 10, 2011
    Middletown, OH
    0
    I was just going to start a thread asking about an '06 IH 9400 with the ISX 450 in it. I think you may have just answered my question...seems like a nice truck, maybe just the wrong engine. Cannot afford the problems....
     
  10. jinxutoo2013

    jinxutoo2013 Bobtail Member

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    3
    May 12, 2013
    0
    I have a 2003 Int 9400 with a 450 cummins. I am happy with mine. my mpg is in the high 7's, I usually run around 60mph. With some new low rolling resistant tires I could break into 8.
    Since you have a 13spd try dropping to 12th gear at 60 for a month. I think 12th would be in direct drive. someone will correct me if I am wrong on that.
     
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