confusing mileage numbers?

Discussion in 'Injection Tech' started by Brandon A., May 12, 2019.


  1. Brandon A.

    Brandon A. Binder Driver

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    Hello everyone, I am hoping Bill has time to show me the way on this one. I have 1980 scout II Nv4500 5 speed with 3.73 gears and 33" tires 304 IH v8 stock camshaft. Running Bills GM TBI setup custom tuned chip per all of his how to's online. I have had this system for close to 9 years now. It works great except for one thing my mileage varies wildly and makes no sense at times..... I tuned the timing curve for maximum mileage so I thought and have the lean cruise mode enabled which added 1 more mpg overall. Here is my struggle:
    1. I can get phenomenal mileage if I stay around 60mph on a flat grade Or slightly declining in altitude drives (I have run 2 routes where I get 18-19 mpg every time at about 2600rpm) **However on the way back it drops to 12 or 13 mpg as I go back up slightly in altitude. I live in Wisconsin its not that big of a change. Where talking 1473 feet down to 1200 feet on one drive and the other is 1473 feet down to 900.

    2. Here is where I get confused: When I pull a trailer with this same vehicle weighing 3000lbs the worse mileage I get is around 11-12 mpg. Now when adding 3000lbs shouldn't my mileage be worse than unloaded???????? More often than not I get 12-13 without pulling anything.....This has me very confused???????

    3. P.s I always check my mileage with the odometer and GPS device to make sure my mileage is correct......

    4. I am wondering if Bill could look into the tune I have on my chip? OR what I would need to do to figure this out. I tuned it years ago with a wide band LM-1 and logged lots of data until I hit my highest mpg runs and stayed there.....I don't remember all the specifics as it was years ago. But I spent about 2 years off and on adjusting the tune until I found the best mileage I could get..... All mileage checks are done in 4th gear. as with 5th gear I always lose 2mpg and the motor can hardly maintain speed,

    Thanks for any ideas. Just wondering what I may have missed or did wrong..........
     
  2. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    You can email me the bin and I'll take a look.
     
  3. Brandon A.

    Brandon A. Binder Driver

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    Thanks will do next week. Ran into a few unexpected issues....
     
  4. Brandon A.

    Brandon A. Binder Driver

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    Here you go Bill. I should mention the base timing on the distributor is set at 5-6 degrees not 0. Also the timing curve was seriously tweaked at my cruising rpm around 2400 to 2600 rpm that's around 60 mph with 33" tires and 3.73 gears in 4th gear with nv4500. That is how I was able to increase my mileage. You will also see in 5th gear timing was dropped as it was pinging in WinALDL probably around 2000 rpm (I made all of these adjustments years ago so I am going by memory). You may also see random points were timing was dropped due to seeing pinging in WinALDL. It has the highway mode enabled. That gained me 1mpg. Most of the adjustments where done in tuner cat but highway mode was tweaked in tuner pro if I am remembering correctly. This is the only bin I have ever done so maybe I missed something I don't know. Otherwise it runs perfectly. Not the happiest with power in 4th gear climbing hills but I feel that is due to tire size...... I can provide logs sometime later on if that would help...... Hopefully I upload the bin correctly? It's my first time uploading a bin..... Thanks for taking a look!!!!!!
     
  5. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    Got it.
    Removed the file so it's not copied.
    Attach the logs and BLMs when you can.
     
    Last edited: May 21, 2019
  6. Brandon A.

    Brandon A. Binder Driver

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    Sounds good my plan is to save a log and BLM on the way to my parents house 2.5 hours worth. I usually get 12mpg on this run and get 18 mpg on the way back. Then I will take another log & BLM on the way back to my house another 2.5 hours worth. That should give a comparison between what is happening on 12mpg runs v. 18mpg runs...... However I don't know when I will get a chance to do this. Hopefully in the next few weeks....... Thanks!!!! excited to see what you think.....
     
  7. Brandon A.

    Brandon A. Binder Driver

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    Hello Bill just checking in to let you know I have not forgot about sending you some data. I plan on making a run to my parents hopefully in next few weeks. Today I drove around the neighborhood paying attention to using a light throttle with some idling time for about 30 minutes. According to gas gauge I used about 4 gallons a whole quarter of a tank! That just does not seem correct.... I looked for a fuel leak but can't find one and don't smell anything.... I checked my fuel line pressure and it is set at 15 psi at idle and stays there as I rev the motor up. That is where it has been set since I installed the TBI years ago. Is that a good number to shoot for????? *Also I was wondering if you had a chance to look at my Bin? Did you find anything interesting? I really want to nail this down as I want to use this vehicle for trips with my family but need to figure out the mileage.....
    Thanks for your time!!!!!
     
  8. Brandon A.

    Brandon A. Binder Driver

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    Well finally made a trip to my parents house close to 3 hour trip one way. I usually got around 12mpg driving north to my parents house and 18 mpg's on the way back south. Well this time I got a shocking 16mpg's on the way north and the drive back was ruined by traffic being stopped on the interstate so I could only get an accurate reading one way. I am happy with the mpg's on this trip but I'll send you the blm's and log from the trip north getting 16mpg's. I am happy with this mileage it's the 13mpg's and under that I don't like. I will try to record more trips and send them to see if you see any areas to improve on....... Wondering if anything on my bin could use work?
    Thanks Bill...
     

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