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Thread: Injector duty cycle Pulse spikes

  1. #21
    are you changing your maf during stoich operation? because that should be done with fuel trims if you arent forcing open loop. and if you are gonna force open loop and go that route, you need to shut off dfco.

    set ramp in much lower than 2.0 during tuning as well. im assuming your wideband at the end of your downpipe. because there is a lag time in the readings. look at the supplied pictures of your logs. goes from a commanded 14.7 to 11.6 immediately. the wideband cant keep up and it shows a lean condition of 30+ afr error. if your wideband is far downstream, its not receiving the pe burnt fuel and air yet. setting the ramp in lower will help this. does that make sense? im in class trying to focus on this as well. i apologize if it doesnt lol

    afr lean1.png

    afr lean2.png

  2. #22
    Ow, that WB reaction speed is something that I have to remember. I always try to be smooth with the throttle during tuning, but this will help too. Thxs.

  3. #23
    Senior Tuner cobaltssoverbooster's Avatar
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    if you lower it and it bogs out some when it goes through the transition then you need to put it back to an enrichment rate of 2 because having the sensor pushed back and adjusting this value is just a band-aid for the real issue of your sensor being in a not so optimal spot.

    in the supercharged ecotecs and the turbo conversions with the properly sized turbocharger (most usable range not a drag race twice over-sized turbo) the enrichment rate will need to be max because of how fast it builds boost and needs the additional fuel so it can get to its target ratio faster. when you lower this value the time it takes to get to the target pe ratio from stoich is made longer (aka the transition happens slower).
    the way i understand the enrichment rate the best is by comparing it to adjusting the linkage on the accelerator pump of a high performance carburetor. use the shorter fulcrum on the accelerator pump and more fuel enters sooner in the pedal travel (this would be like raising the value in the computer to make it push the acceleration enrichment fuel in as soon as it can.)

    there are a few different ways to understand this feature. just find the way that helps you understand it the best and don't perform band-aid tune corrections they only lead to problems in the long run.

    i will link the in depth pe description from the v8 section below
    Last edited by cobaltssoverbooster; 09-11-2013 at 05:35 PM.
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  4. #24
    Tuner in Training antonio321's Avatar
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    Quote Originally Posted by GM COBALT SC SS View Post
    are you changing your maf during stoich operation? because that should be done with fuel trims if you arent forcing open loop. and if you are gonna force open loop and go that route, you need to shut off dfco.

    set ramp in much lower than 2.0 during tuning as well. im assuming your wideband at the end of your downpipe. because there is a lag time in the readings. look at the supplied pictures of your logs. goes from a commanded 14.7 to 11.6 immediately. the wideband cant keep up and it shows a lean condition of 30+ afr error. if your wideband is far downstream, its not receiving the pe burnt fuel and air yet. setting the ramp in lower will help this. does that make sense? im in class trying to focus on this as well. i apologize if it doesnt lol

    afr lean1.png

    afr lean2.png
    The wide band is at the front of the down pipe maybe 12" aways from the stock 02, but i am running a pace setter mid length header so that dose place the wideband pretty far away from the exhasut ports.I didn't think about the delay and it makes a lot of sense.

    The last tune i uploaded i had finished with the maf calibration and re-enabled all of the open loop adders and dcfo to see how it all worked together.
    During the cal open loop was forced and all adders and dcfo and piston protection were zeroed or turned off.

  5. #25
    Senior Tuner cobaltssoverbooster's Avatar
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    this is direct from megasquirt and they put it exactly how i did but for some reason theirs just sounded better:
    AE Tuning Basics - What is acceleration enrichment?

    The standard AE under the Acceleration Wizard can be thought of like the accelerator pump on a carb, which shoots in some extra fuel when you suddenly hit the throttle to compensate for the massive influx of air when you open the throttle blades. The goal is to compensate for this influx of air for an instant during that transient until the the transient is over and the VE tables are again providing the proper amount of fueling. If your background is tuning carburetors, you can think of this as a very powerful fully adjustable/tunable accelerator pump that lets you compensate for more than one rate of throttle position change. Slow 'tip-in' can be adjusted with a certain PW adder, medium with another larger PW shot, mid-fast with another size PW squirt, and very fast throttle movements with another.

    had trouble finding the exact v8 post im still looking. edit: its buried deep in the v8 section, no luck
    Last edited by cobaltssoverbooster; 09-11-2013 at 05:57 PM.
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  6. #26
    it is a used to mask the problem. but on a car that is close to stock, and using it only while tuning is the next best option. the first being placing the 02 bung upstream. also, the guys with longtube headers will always have this issue regardless. their merge collector is far downstream

    and just easing into throttle doesnt help either. if ramp in is set to 1.0-2.0, youll go straight from 14.7 afr to 11.7 or w/e your commanding, no matter how slow you press throttle

    on the 07 gms2 file, ramp in is set real low. like .02. keep that in mind
    Last edited by GM COBALT SC SS; 09-11-2013 at 08:47 PM.

  7. #27
    Senior Tuner cobaltssoverbooster's Avatar
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    everyone in the ecotec world keeps road tuning which results in improper collection of transient data. the only proper way is to set the base tables up as i keep saying over and over on a solid state dyno. keep in mind im not the only one who tells people this...some big players in the v8 world here also keep putting it out. a solid state allows for proper calibration of the transient data by tuning the base tables to a preset condition. after the solid state you use the modifiers to correct any transient errors. if the transient didnt have to be corrected separately then there would be no reason for the tables to exist in the ecu as they would as most do now just tune the ve and maf and call it quits. if you tune your ve on the road your tuning it for a transient condition not a steady state. bottom line, everyone who road tunes and never pays for a proper dyno session has their enrichment rate tuned wrong along with a bunch of other stuff.

    the way i do it: leave it at 0 so it doesn't add fuel. enrichment rate is a modifier and the base calibrations should be adjusted without any corrections being applied. after done go back and make wot transitions from a roll at different rpm ranges. if it bogs raise the value. as soon as it stops bogging in your most commonly used ranges, add a tad for environmental conditions then leave it.

    the reason its set so high is because most users asking for help don't seem to have the time to set the finer parts of the tune up. better to have it slightly rich than lean out and cause problems. everyone seems to have time for wot and dyno pulls but never the whole file.
    Last edited by cobaltssoverbooster; 09-12-2013 at 12:30 AM.
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  8. #28
    Tuner in Training antonio321's Avatar
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    Quote Originally Posted by cobaltssoverbooster View Post
    everyone in the ecotec world keeps road tuning which results in improper collection of transient data. the only proper way is to set the base tables up as i keep saying over and over on a solid state dyno. keep in mind im not the only one who tells people this...some big players in the v8 world here also keep putting it out. a solid state allows for proper calibration of the transient data by tuning the base tables to a preset condition. after the solid state you use the modifiers to correct any transient errors. if the transient didnt have to be corrected separately then there would be no reason for the tables to exist in the ecu as they would as most do now just tune the ve and maf and call it quits. if you tune your ve on the road your tuning it for a transient condition not a steady state. bottom line, everyone who road tunes and never pays for a proper dyno session has their enrichment rate tuned wrong along with a bunch of other stuff.

    the way i do it: leave it at 0 so it doesn't add fuel. enrichment rate is a modifier and the base calibrations should be adjusted without any corrections being applied. after done go back and make wot transitions from a roll at different rpm ranges. if it bogs raise the value. as soon as it stops bogging in your most commonly used ranges, add a tad for environmental conditions then leave it.

    the reason its set so high is because most users asking for help don't seem to have the time to set the finer parts of the tune up. better to have it slightly rich than lean out and cause problems. everyone seems to have time for wot and dyno pulls but never the whole file.
    This is one of the reason i'm doing a MAF only tune and im not so much trying to squeeze power out as much as i'm tiring to bring things back into spec.I haven't touch timing yet ,but i might add some at wot once i switch to e85, I tried to do some VE on the street but its near impossible to get solid hits in all the cells. I don't plan plan on running VE and if i do it will be in all low range driving. I have a friend that knows a guy that owns a shop with with a loading dyno ,once i get every thing somewhat together and i can put together a plan of attack and what areas id like to address i'll be seeing him for steady state tuning of the ignition tables and maybe VE even tho i don't to use it for anything more than a way to limp home if the maf fails lol.
    Last edited by antonio321; 09-12-2013 at 05:25 PM.

  9. #29
    Quote Originally Posted by cobaltssoverbooster View Post
    everyone in the ecotec world keeps road tuning which results in improper collection of transient data. the only proper way is to set the base tables up as i keep saying over and over on a solid state dyno. keep in mind im not the only one who tells people this...some big players in the v8 world here also keep putting it out. a solid state allows for proper calibration of the transient data by tuning the base tables to a preset condition. after the solid state you use the modifiers to correct any transient errors. if the transient didnt have to be corrected separately then there would be no reason for the tables to exist in the ecu as they would as most do now just tune the ve and maf and call it quits. if you tune your ve on the road your tuning it for a transient condition not a steady state. bottom line, everyone who road tunes and never pays for a proper dyno session has their enrichment rate tuned wrong along with a bunch of other stuff.

    the way i do it: leave it at 0 so it doesn't add fuel. enrichment rate is a modifier and the base calibrations should be adjusted without any corrections being applied. after done go back and make wot transitions from a roll at different rpm ranges. if it bogs raise the value. as soon as it stops bogging in your most commonly used ranges, add a tad for environmental conditions then leave it.

    the reason its set so high is because most users asking for help don't seem to have the time to set the finer parts of the tune up. better to have it slightly rich than lean out and cause problems. everyone seems to have time for wot and dyno pulls but never the whole file.

    Makes sence, but can you specify this more to the (limited) tables of the LSJ-P12?
    MAF & VE tables are what you call the steady state tables, but which one does the transient part, because you're not talking about the PE ramp-in speed here, right?

  10. #30
    Senior Tuner cobaltssoverbooster's Avatar
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    Pe ramp in is a transient condition.
    Anything that causes a change when you take a solid state tune and run dynamic with it is a change that falls under transient condition.
    Transient means some thing that is of short time or not lasting very long.
    So when you get errors in the tune after solid state tuning the error that keep coming up are usually recurring but short in duration. The recurring part is why people think its a big change. since a cell can be effected many of times as it is driven through you have to look past the big change and go to minute modifiers. The minute modifiers are called transient control.

  11. #31
    I know the difference between transient and a steady state condition, but what HPT tables are you referring to for the P12 ecu?
    (I consider the PE ramp-in speed not really a transient modifier table... )

  12. #32
    Senior Tuner cobaltssoverbooster's Avatar
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    pe enrichment rate, and it is most definately transient
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  13. #33
    OK, getting confused here, so let's rephrase my question:

    What P12 tables, besides the PE ramp-in speed, influence the transient fuelling behaviour?? Or is the PE ramp speed the only P12 transient parameter we can access in HPT?
    (f.i. the E67 in the LE5 has a fuelling tab "Transient" with several tables and modifiers...)
    Last edited by Speedytec; 09-15-2013 at 06:53 PM.

  14. #34
    Senior Tuner cobaltssoverbooster's Avatar
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    if its any type of modifier chances are they are a form of transient.
    plus the p12 isnt fully unlocked so your not going to have a transient tab.
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