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Thread: LMM: Strange defuel

  1. #1
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    Default LMM: Strange defuel

    I'm having a weird defuel with my dad's LMM. I don't know what is causing it, and I can't find any tables that might be contributing to it. It is pulling up to 30 mm3 of fuel. I am having trouble correlating it to anything other than the transmission, but I can't log any transmission PIDs to be sure if it is transmission related. I do know for a fact it is not pulling tq ref numbers down; it is only pulling fuel quantity.

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    When I go WOT. LOL

    Actually, it seems pretty good until the converter locks, but since I can't log any TCM functions, I can't verify if it is just doing it when the converter locks or not. Also seems to be somewhat related to RPMs. Here are some logs.

    A little info on the logs from a post on McRat's site:

    I did some modifying to the tune and found out the problem is something is pulling fuel. Based off my last logs I saw that I was running around 85 to 90 mm3 when the odd problem was happening, so I changed my tune so that 80 mm3 and up was the same amount of fuel and set the tq to fuel tables to call for 85 mm3. Boy did that show me what was up. I could barely get more than 60 mm3 of fuel. Based on that I set 100 mm3 and up to the same pulse, and set my tq to fuel tables to 120. That really woke it up. I was still dipping down into the 95 mm3 are so I set 90 and up to the same pulse, and backed the pulse down to 2200. I may go back and see if I can set the max mm3 to 150 and use the whole pulse table, but for now this is a crude yet effective fix.
    Attached Files Attached Files

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    Why cant you log TCM functions? To tune the LMM you need a V2 which can do both the ECM and TCM at the same time...have to use BBL though.

    This is a weird issue though, does it do it with different OSs too or just this particular one? I honestly have no idea, just trying to throw ideas out there.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

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    I don't know why I can't log the TCM. I can select it and connect to it, but when I do, there are no TCM PIDs to select.

    I have not tried any other OSs, and this problem didn't start until a few weeks ago when I put in a bigger tune. It was working fine up until then. I put the tune that was in before I put the big tune in it, and the original tune was doing it too.

    One thing that may be of note, when I put the bigger tune in, I had recently updated to a new version of EFI. Don't know if that could be part of the problem, but I thought it might be worth mentioning. I have since updated to the most recent build, and the problem is still there.

  6. #6
    Lifetime Member vortecfcar's Avatar
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    Without seeing the ECM tune it's hard to say for sure, but my guess would be the issue lies in the intake air temp or barometric fuel modifiers. I doubt it's an issue with the TCM.

    Just my $.02

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    Lifetime Member LBZoom's Avatar
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    I was going to suggest IAT but like Nick said without seeing the tune itself it's hard to say

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    Have you gone in and configured the BBL PIDs correctly in the Options.txt file? You have to do that before you can log to setup the TCM PID selection just like setting up the ECM PID selection.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

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    Senior Member camcojb's Avatar
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    Quote Originally Posted by ScarabEpic22 View Post
    Have you gone in and configured the BBL PIDs correctly in the Options.txt file? You have to do that before you can log to setup the TCM PID selection just like setting up the ECM PID selection.
    I don't remember doing anything to log ecm pids; just picked the ones I wanted and saved them as a separate pid file. I also cannot get any of the tcm pids to work. Could you briefly explain where to find this options.txt file for the pids?

    Jody
    07.5 4X CC 2500HD, EFI Live, MBRP exhaust
    new updated website!

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    Quote Originally Posted by vortecfcar View Post
    Without seeing the ECM tune it's hard to say for sure, but my guess would be the issue lies in the intake air temp or barometric fuel modifiers. I doubt it's an issue with the TCM.

    Just my $.02
    Quote Originally Posted by LBZoom View Post
    I was going to suggest IAT but like Nick said without seeing the tune itself it's hard to say
    Here's the two tunes. One is the tune from the first logs, and the other is the modified tune from the last logs. I don't think it is IAT related as I have the multiplier zeroed out until it gets to 140 degrees, and the only baro modifier I can find only pulls 4 mm3.

    Quote Originally Posted by ScarabEpic22 View Post
    Have you gone in and configured the BBL PIDs correctly in the Options.txt file? You have to do that before you can log to setup the TCM PID selection just like setting up the ECM PID selection.
    I'm using the laptop to log not BBL.

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