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Thread: mafless tune spark timing issue?

  1. #1
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    mafless tune spark timing issue?

    adrian6.hptadrian street log.hpl

    can somebody please explain why spark timing is going to 3.5* btdc after 4800rpm at wot in my mates a4 ls1 vy Calais? tune was done by a mate of a mate..
    thanks in advance

  2. #2
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    also not always 3.5 sometimes less as well
    theres a good 1st to 2nd full throttle run toward end of log that's a good example

  3. #3
    Need your congif file to see the log properly. Have you tried to disable all torque management and traction control? Looks like in the tune it still has some TM which will pull timing.

  4. #4
    Senior Tuner mowton's Avatar
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    Quote Originally Posted by UP2MISCHF View Post
    adrian6.hptadrian street log.hpl

    can somebody please explain why spark timing is going to 3.5* btdc after 4800rpm at wot in my mates a4 ls1 vy Calais? tune was done by a mate of a mate..
    thanks in advance
    That is what is known as decel fuel cutoff (DFCO). When the car enters deceleration (or coastdown) the tune reduces the fuel and spark values to save fuel and help brake the car. You can see it always ocurrs around the Fuel Trim cell (FTC) 21 whicg is coastdown. Perfectly normal. some people shut it off but leaving it on is ok as well. Youe certainly usually shut it off during tuning sessions thought.

    Note ... use the Default Imperial.cfg and you can see all the log information including the FTC.

    decel log example.png

    Ed M
    Last edited by mowton; 03-12-2015 at 11:08 PM.
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

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  5. #5
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    You've got torque management or traction control messing with your timing. Also looks like pcm is switching between high octane and low octane spark table. You can copy your high table to the low table so they are the same. But you need to figure out that KR and get rid of it. Determine if it's real or false, and if it's fuel or spark related. Probably getting your PE to come on sooner will help.
    2001 Z06 : 856/830 : Built LQ9 403ci : D1SC 17psi : Self-built , self-tuned.

  6. #6
    Senior Tuner mowton's Avatar
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    I didnt go deep enough into your log last night, sorry. I see what you are saying now.

    So the first question is what are your mods. You are pushing the IPW beyond 100% (>19ms at 6000 rpm). Your PE seems a bit late as stated above. I would cut the hot/cold throttle tables by 60% (x .4) and set the MAP enable to 85 kPa. The PE EQ ratio, onceMAF/VE is tuned correctly and wideband installed, should be like 1.15 for starters.

    I have included a new log .cfg file for you to use. Want to check out the torque data and TCS spark retard. You can try reducing the traction control spark retard tables Engine>Torque Management>TCS Method>Retard vs. and Agressive for a test.

    Up2mchf Default Imperial.cfg

    Need to get a wideband installed.....

    Ed M
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

    ERM Performance Tuning -- Interactive Learning ..from tuning software training to custom tunes
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  7. #7
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    thanks for the help guys
    wideband has been order and is on its way

  8. #8
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    so after fitting wide band and doing some logs found out car wasn't running lean so assumed last tuner had just put to much timing advance in
    so after using histogram to see where kr problem areas were I started to tune out timing 3 degrees at a time until got sick of it and just put all used main areas down to 20
    then logged it again and it was still getting knock retard so if its not lean and its not timing maybe its false knock?
    so I desensitized the knock sensors by changing the knock sensor global gain table all the cells that were around 1.000 I changed to 1.500
    then logged again and bang no more kr while logging so then I put a decent timing advance table back it too it and then logged again and still no kr
    and finally the car feels like it pulls good all the way through the revs. so unless changing the knock sensitivity by that much is unsafe?? problem solvered

  9. #9
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    Quote Originally Posted by UP2MISCHF View Post
    so after fitting wide band and doing some logs found out car wasn't running lean so assumed last tuner had just put to much timing advance in
    so after using histogram to see where kr problem areas were I started to tune out timing 3 degrees at a time until got sick of it and just put all used main areas down to 20
    then logged it again and it was still getting knock retard so if its not lean and its not timing maybe its false knock?
    so I desensitized the knock sensors by changing the knock sensor global gain table all the cells that were around 1.000 I changed to 1.500
    then logged again and bang no more kr while logging so then I put a decent timing advance table back it too it and then logged again and still no kr
    and finally the car feels like it pulls good all the way through the revs. so unless changing the knock sensitivity by that much is unsafe?? problem solvered
    As I can take sensitivity to knock sensors on or off?