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Thread: Mileage Increase on Trucks

  1. #11
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    Quote Originally Posted by cmitchell17
    I can't figure out how the closed loop modes range? Do the low ones like 0,8 just the light loads and then the 16-24 seem like they control about the same load levels?

    How should the switch points ramp up to 14.7? Should it be 250-300mv for just like 0,8,16 then quickly go up to 14.7 from there. Becuase you want it close to 14.7 going up a hill in a low gear right?
    That's something that you'll need to figure out. The closed loop mode airflow is defined in the PCM. What you'll need to do is figure out what your airflow is at cruise, look up the corresponding closed loop mode and go from there.

  2. #12
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    I've been looking at some tunes on holdencrazy.com, and they started putting the O2 switch points at 450mv across the board starting in 2003 for the LM7 engine.
    That seems like the best route to go.
    The way I came up with my O2 switch points is to go out and log some data, and then highlight the HOSS11 V and HO2S21 V in the cruise and idle sections to get an average. (This is after the AutoVE/MAF tune to make sure my commanded AFR equals my LC-1 wideband AFR)
    Don't know if this is the best way, but seems like the logical way.
    I'll be doing some more research on this to find the correct way.
    I love this stuff. It gets very addicting!!

  3. #13
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    The 450mv switch point is where the O2 sensor is most precise and represent stoich. If you want to achieve slightly less fuel consumption, then you can lower the switch points in low load regions.

  4. #14
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    Would lowering the O2 switch point be something that should be done if running a Custom Operating System. Specifically, You can command your A/F ratio in B3647, so would you want to drop the Switch Points.

  5. #15
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    Quote Originally Posted by Lextech
    Would lowering the O2 switch point be something that should be done if running a Custom Operating System. Specifically, You can command your A/F ratio in B3647, so would you want to drop the Switch Points.
    The only benefit to doing so in a custom OS would be to retain closed loop operation in those particular cells. Otherwise, you'll have no need to adjust the switch points.

  6. #16
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    hey guys i am trying to tune a friends 2007 5.3 and i read about you closed loop stuff and cannot figure out how to relate it to the 07's....and suggestions on simple things to do in the new operating systems to gain some power and milage???

  7. #17
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    Welcome to the forum deadsquirrel!


  8. #18
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    Quote Originally Posted by TAQuickness
    Welcome to the forum deadsquirrel!
    thanks just tryin to learn the ins and outs of the gasser world of tuning

  9. #19
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    Quote Originally Posted by cmitchell17 View Post
    With my 2000 5.3 ext cab Since Ive lowerd O2 switch points and added some timing based off the optimal timing table I can get about 21-23mpg crusing at 45-60 and about 17-20 avarage city/hyw.

    So far Ive probably got on avarage about 2-3mpg more especially on cruises.
    When you say you added timing, what do you mean, could you help me out a little. I am tuning my step dads truck for better economy.

    Tony
    Last edited by horsehaulin; May 8th, 2008 at 02:11 PM.

  10. #20
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    So far I havent noticed anything from adding timing in part throttle non pe.

    You can experiment with it but I don't think it will help.

    I think the factory timing would be the best timing, except the timing in PE high throttle beucase the stock tune is always consiveritive in the high load regions.

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