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Thread: spark advance

  1. #1
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    spark advance

    Hi everybody,
    is there a tool like trimalyzer for the spark advance table?

    I could convert my amc 304 engine to tbi.When I used the original spark advance table from BPSA.bin the car didn`t run right. I have set the table according to the spark advance curves from the jeep-manual. Now it runs good when rpm is higher than 2000.At lower rpm and when accelerating i have to do that very smooth otherwise engine is bogging and trends to stall.I raised up spark advance in lower rpms slightly but no success up to now. When I take an other bin (bhmc) from a 5ltr engine, engine will not accelarate at all.
    Attached my last logfile where ve tables are not yet set by trimalizer.
    Attached Files Attached Files

  2. #2
    LT1 specialist steveo's Avatar
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    trimalyzer does have a knock analyzer built into it but knock analysis is as good as it gets, no tool will automatically tune spark (too dangerous, needs a practiced hand)

    spark advance is tricky for sure

    keep working on your custom table based on the jeep manual and don't forget that timing isnt' everything, maybe fuel has something to do with it too. where it bogs, add a few more degrees and see what happens. in areas of light load and low rpm its harder to cause damage.

  3. #3
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    Hi Steveo,
    thank you for the quick answer.
    Yes i have already realized the Knock table in your trimalizer.I have 4 big knocks in there.When I analyse the log.csv in excel, there are 5 knock retards.
    Do I have to decrease my spark advance or increase it at those cells?
    When I have the history running in tunerpro-rt I can see the knock retards in those cells but they are overwritten next time when no knock was detected.
    Is there some manual about spark advance?
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  4. #4
    LT1 specialist steveo's Avatar
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    if it's knocking definitely remove some spark advance. if it still knocks there remove some more. if it still doesnt' go away you might have false knock (mechanical noise or knock filter no good for engine) or it's lean knock.

    i'd focus on the areas with groupings of knock events, those are probably real.

    honestly i can't imagine your knock sensor and its filter are proper for your amc engine so you might not be able to trust it? you'll find out when you try to tune it back a bit

  5. #5
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    Hi Steveo,
    thank you for the quick answer.
    Yes i have already realized the Knock table in your trimalizer.I have 4 big knocks in there.When I analyse the log.csv in excel, there are 5 knock retards.
    Do I have to decrease my spark advance or increase it at those cells?
    When I have the history running in tunerpro-rt I can see the knock retards in those cells but they are overwritten next time when no knock was detected.
    Is there some manual about spark advance?
    As well i saw that my park brake switch is on all the time. I know I havent connected the pins because I could start the engine with and without connection.Does that matter on the behaviour of the engine?

  6. #6
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    Hi steveo,
    your answer was too quick, I wanted to add this question: As well i saw that my park brake switch is on all the time. I know I havent connected the pins because I could start the engine with and without connection.Does that matter on the behaviour of the engine?

  7. #7
    LT1 specialist steveo's Avatar
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    park brake or transmission park/neutral?

    they're very different things.

    i've never seen an oldschool GM ecm where the park brake switch does anything

    park/neutral or shift position switch definitely could if you're running an automatic bin.

  8. #8
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    Hi steveo
    it is an 16196395 and my bin is set to manual transmission! In the csv it was the park brake. So I think this signal will not work on the programming.
    In the meanwhile I had a look to John Wilson`s "How to tune a GM EFI System" He wrote he has an excel sheet what calculates spark advance based on spark advance out of the manual given at 100% MAP.He would sent it on demand.
    Unfortunatelly he is no longer reacheable on the internet.Does somebody have his spreadsheet or his new email adress and is willing to provide this to me?

  9. #9
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    I'm noticing the same spark retard in the same 100 kpa area usually when I stomp go pedal rolling or from a dead stop. Took some spark out in that area but won't know the results until next play time (not my car). Don't own a wideband but do notice on the tip in that the O2 starts way down low and works it's way up to ~.950mv. When that occurs, knock retard diminish until gone. Idk if it's me expecting instantaneous feedback from the log or log is really lagging. I'll fatten it up if reducing spark advance doesn't help.
    Last edited by stew86MCSS396; 06-17-2019 at 04:31 AM.

  10. #10
    LT1 specialist steveo's Avatar
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    if your o2 voltage is below switch point at anything but cruise or closed loop, you're lean. need to add some more fuel.

    maybe spark isnt your problem at all?

  11. #11
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    Thanx for the insight! Trying to keep this on topic, went back two weeks ago and watched some wot datalogs that didn't exhibit any knock retard in the 100kpa area, so two steps back (bin) compared to what I changed. Definitely took out fuel where it matters! I got too caught up in seeing 1000+mv and pulled some fuel out.

  12. #12
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    @steveo
    which tables do I have to observe ? Engine is running good over 2000rpm but on accelerating spark advance falls back to zero.In open loop this is not that much but in closed loop engine is nearly stalling.I have to accelerate very smooth when rpm gains ,spark advance gains again and engine gets power.
    Or should I increase spark advance generally in spark advance at idle table?

  13. #13
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    who may analyse my xdl?
    Here I have the monitor at a certain point where knock retard occurs. In none of my spark tables this stellation occurs
    MAP about 100
    rpm about 1000
    spark advance 15.8
    what can cause this spark advance?
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  14. #14
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    Watching this log and the previous posted, something seems amiss. Take it you're not running vss as I don't see any movement for mph. Some have alluded that this pcm needs vss but I don't know what negative impact it would have. Couple of observations, certain areas tps cycles up and down rapidly within a span of seconds. 1st log seen rpms go from 4500 to 0 jump to 6300 back to zero w steady tps. When it's wonky seen bpw go as high as 20.0 way beyond static then drop to 0 along with idc. Iac pegs to 150. Also yes there's periods of times spark would be hovering at 31* then drop to 0*. Suspect grounds? I would check tps ground and w key on engine off operate throttle while observing tps operation. Make sure volts within idle/wot specs and increase smoothly.

  15. #15
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    Hi,
    yes I changed some parameters between first log and this one.Mostly in the spark advance tables and had run trimalizer a few times for the ve tables.I have only connected the DRAC but no speed sensor. The speed sensor I could get has three pins red, black and white but the DRAC has only two input lines.I checked TPS signal while engine wasn`t running today , TPS and throttle angle reacted both in tunerpro. But I could find these abnormalities you mention when I examined log file in excel too.Will continue my search .
    Thank you for your comments.

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