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Thread: Fuel Rate issue

  1. #1
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    Fuel Rate issue

    I'm having an issue with not hitting commanded fuel rate and it dropping off as RPM climbs. Everything else is working great for me, trans etc... I cant find any other limiters to turn off that i think would affect this that i can find anyways, but i could simply be over looking something. Anyone willing to check out the file see if im missing something? I can email it to you. HPT support directed me to the forums for this question , so here it is! BTW the truck is an 05 auto.

  2. #2
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    Have you tried logging any of the enhanced PIDs from the logging patch to see if they will point you to a cause? They may give you some insight as to the events taking place during the defueling.
    Jaime

  3. #3
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    Ill give it a try. What do u suggest logging?

  4. #4
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    PM you my email address.

  5. #5
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    Thanks superwagon! File sent.

  6. #6
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    Is the truck heavily modified? You may be running out of rail pressure up top. Would be cool to see a log!

  7. #7
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    I have been told that the 04.5 -05's still have a few limiters that haven't been located and will prevent full fueling at RPM, but HPT would have to confirm that.

    Where does the fuel rate start to drop? (RPM only or RPM and load related?)

    Have you tried rescaling the axis on the commanded and duration tables down a bit? That is a common issue I've seen with other packages. Seems like 125mm3 was a magic number for some, stay below that and no problems, any higher and they would pull fuel early.

  8. #8
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    Fuel rate comes up to around 150 when i got WOT and then as rpm climbs it goes down from there to 138-140 at shift point. Also when i disabled the limiters i found the load % gets messed up... Instead of reading around 99.8% at WOT it reads about 40% and drops right with fuel rate at an even slope to shift point around 3200RPM.

    The Smarty tune will hold 156 fuel rate after about 2-2200RPM and hold it until shift point and load also maintains at 99.8%
    Last edited by Blevins; 12-22-2015 at 11:26 AM.

  9. #9
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    Quote Originally Posted by 757performance View Post
    Is the truck heavily modified? You may be running out of rail pressure up top. Would be cool to see a log!
    Rail pressure top of 3rd gear is at commanded. Its acting just like on my smarty tune when comparing logs as far as rail pressure is concerned.. Truck has 50hp injectors, FASS 150, FMIC, high ram... Nothing too serious.

  10. #10
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    looking for a stock 05 cummins file in the repository with no luck, can you post your stock file here?
    15 C7Z M7

  11. #11
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    Quote Originally Posted by Tiffo60 View Post
    looking for a stock 05 cummins file in the repository with no luck, can you post your stock file here?
    Here is the stock file it gave me for my 05 auto.
    Attached Files Attached Files

  12. #12
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    Quote Originally Posted by Blevins View Post
    Here is the stock file it gave me for my 05 auto.
    thanks bud!
    15 C7Z M7

  13. #13
    Kind of off track, but you were able to log your truck with a smarty tune loaded? When I tried logging my UDC tune only the SAE pids like speed and rpm were available to me.

  14. #14
    Tuner in Training Matt@HPTuners's Avatar
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    We'll be back to work on this issue after the holidays. It looks like it's only affecting the 04.5+. Look for an update in the first or second week of January! Thanks for your patience.

    -Matt

  15. #15
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    Quote Originally Posted by Matt@HPTuners View Post
    We'll be back to work on this issue after the holidays. It looks like it's only affecting the 04.5+. Look for an update in the first or second week of January! Thanks for your patience.

    -Matt
    I hope you are talking about my fuel rate issue??? If so that's GREAT! Its been driving me nutty lol.

  16. #16
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    Quote Originally Posted by Kill View Post
    Kind of off track, but you were able to log your truck with a smarty tune loaded? When I tried logging my UDC tune only the SAE pids like speed and rpm were available to me.
    Yes i am able to log my Smarty Revo software and TNTR logs.

  17. #17
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    Im seeing the opposite issue, I see commanded as 23k psi, It eventually gets there.. but it starts at 17-18k then drops right on WOT, catches up around 2900... Im sure i can figure it out, just wondering if you guys are playing with the Fuel Duty cycle to hit target?