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Thread: Over 30% tps looses spark advance

  1. #1
    Fuel Injected!
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    Over 30% tps looses spark advance

    Hello ,
    I am reletively new to here the last year or so and have done some upgrades and havent tuned much due to other projects .
    I have had off and on lean spots just off idle but have been able to adjust timing some and get most of it to go away.
    My new problem is above 30% tps i loose spark advance to around 14-16 degrees .The blms are all within 125-135
    The truck is
    1993 c1500 350 tbi 4l60e
    vortec heads
    hi rise single plane w adapter
    46mm tbi with cop car injectors at 20 psi
    cam motion hyd roller 201/211 454 465 lift
    short headers 2/5 y pipe no cat with flomaster
    new timing set
    new ias
    new distributor including new cap &rotor
    newer o2
    new coil
    newer tps

    The strange thing is with the old original flat tappet cam it had much more oompf but i noticed today above 30% tps sa is dropping to 15 .i have a aggresive timing table as at 0 intial its a pig so much i pulled the timing cover back off to check if it was a tooth off at cam.it wasnt [i didnt have a puller for the gear or i would have advanced the cam 4 degrees ]its straight up
    .
    The initial sa at the distributor is 12 .i tried to raise and lower the initial to cheat the engine and it still wouldnt leave the timing in above 30% tps.
    At light throttle it seems to run ok it just looses all timing when you try to step on it .I know there may be qualifiers that reduce timing but i havent changed anything .
    I have tried suggested vortec timing tables from this site and at 20 through 1200 rpm it does the same even with as much as 27 in same ranges .
    I tried to search this but have came up empty .Its almost like the timing advance is backwards ?I have uploaded the data log before and if needed i can again but if anyone can help with suggestions id greatly appreciate it .
    It feels like if i can get about 35 degrees sa above 30% tps it will run very well .
    Last edited by zuk1972; 11-30-2015 at 02:58 AM.

  2. #2
    Fuel Injected! sturgillbd's Avatar
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    Look in the log to see if you are having knock retard. It may help if you post your bin and the log file. What mask are you using ($E6 or $0D)?
    Brian

  3. #3
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    It's $e6
    i think knock retard was replaced in mask for wbo2 on dashboard
    so I watch live parameter for kr in data log ?its not showing any kr except when I changed the initial timing 1 time in the log to 15 degrees in the middle of run once I switched it back to 12 it had no kr .
    Last edited by zuk1972; 11-30-2015 at 03:38 AM.

  4. #4
    Fuel Injected! sturgillbd's Avatar
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    Post your bin, the xdf and adx you use along with your latest log. I will take a look at it tonight or tomorrow eve.

  5. #5
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    The Bin is BDJY and thanks! i appreciate you guys
    Attached Files Attached Files
    Last edited by zuk1972; 11-30-2015 at 05:28 AM.

  6. #6
    Fuel Injected! sturgillbd's Avatar
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    Ok, Played your log file and checked your bin etc. You didn't update your adx file to reflect your 12 degrees of initial timing. You need to either update your adx conversion where it calculates spark advance or set initial timing back to 0 degrees and set the initial timing value in the bin back to 0. Your timing is actually 12 degrees more than what your datalog is showing. You also need to compare what the aldl data for spark advance to what the timing is at the crank using a timing light. I edited your adx file and replayed your log after editing the adx file and things look more sane. Try this adx and see what you think.
    Hope this helps.
    Brian

  7. #7
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    Ok my intial at the crank with light is 12 degrees .
    i had set the bin to 12 then to zero then 15 then back to 12 to try and get the timing to take .
    So i should consider trying it at zero it at balancer with light then crank it up in bin accordingly?
    I know this sounds like a dumb newby question[and it is] but i also need to save adx before i close the bin/tp5? .I had allways just saved the purple file near the bin before i closed tp5 and thought it kept everything updated ?

    Also if i just edit my original adx to reflect 12 degrees at crank i should i try that first ?When i tried to back down the timing to 0 it didnt want to run well - but again it sounds like it was contributing to my adx being off ?
    Last edited by zuk1972; 11-30-2015 at 06:39 AM.

  8. #8
    Fuel Injected! sturgillbd's Avatar
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    If it were me tuning this setup, I would set the timing back to 0 degrees at the crank with the bypass wire disconnected. I would set the bin back to 0 degrees initial advance and use the original ADX file. Once you reconnect the bypass wire and clear the stored code, the timing should follow what you have in the tables. Others may have a different view. To me, leaving these settings stock takes another variable out when trying to chase down a problem.

    Brian

  9. #9
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    That's what I'm going to try . The cam swap was just a few weeks ago and it really seemed weak down low until I set bin with aggressive timing . I have tried to up timing in bin and at crank and it did work below 50% throttle but I did have adx set at 0 incorrectly . I also want to advance the camshaft when I get a chance ( didn't degree it ) but have a feeling that it will help to advance cam .
    I will try to set it all back to zero and log again in a few days and check back in here . Thanks so much for your help

  10. #10
    Fuel Injected! JeepsAndGuns's Avatar
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    Quote Originally Posted by sturgillbd View Post
    If it were me tuning this setup, I would set the timing back to 0 degrees at the crank with the bypass wire disconnected. I would set the bin back to 0 degrees initial advance and use the original ADX file. Once you reconnect the bypass wire and clear the stored code, the timing should follow what you have in the tables. Others may have a different view. To me, leaving these settings stock takes another variable out when trying to chase down a problem.

    Brian
    I second Brians advice. Set base timing back to zero with the bypass unplugged.
    First drive it until engine is at operating temp. Shut engine off, disconnect bypass wire, restart engine and set base timing to zero degrees. Shut off engine, reconnect bypass, and disconnect the battery to clear the ecm. Now change your bin to match the zero degrees of base timing.
    For years on my fuel injection conversion, I ran 10 degrees of base timing and set my bin to match because of what someone else said. And also for years I fought with varying and unsteady AFR. After lots of long stories I finally set the base timing to zero and set my bin to match. It made a world of difference. I will no longer recommend setting the base timing at anything but zero.
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