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Thread: 63.5 limit best solution please

  1. #1
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    63.5 limit best solution please

    Trying to program new 80lb injectors into a 2008 g8 e38 ecm. Since ithere is a 63.5 limit what is the best and simplest way. (vehicle will later be supercharged).

    Been reading of a couple of options:

    method 1: "double stoich, halve IFR and halve IVT" - but this:" http://injectordynamics.com/wp-conte...SteckScale.pdf " seems to say that then a whole bunch of more tables will need to be modified including transmission tables...? sounds complicated. especially for a newb like me.

    method 2: reduce the flow table by a multiplier and add that multiplier at multiplier flow vs volts-whole range.- will this be a simpler and not affect any other tables?

    or is there any other way. looked at calibrations for other supercharged g8 with claimed large injectors and i can't see either of these methods used (in fact can't figure out what they are doing ).

    any help very much appreciated.

  2. #2
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    Ive been struggling with getting my deka 80s lined up for a little bit but i think I have them going well now. I used the double stoich method. I am running 10psi of boost and havent run out cylinder airmass in my spark tables so unless you are actually exceeding 136g/s then the tables you need to modify are simpler. And from my experience the less you have to modify the better. If you are running dekas then i will say that there are multiple sources for "correct" injector data and to get my setup to run correctly i used a mishmashed combination of the multiple data available by trial and error. The struggle was real because like you, no 2 tunes i found looked alike in their data

  3. #3
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    use the double stoich and half IFR and halve IVT terms and ur done, the steck scale way is the airflow way and its much more involved and can be better if u also want to expand the timing table if ur locked at 1.36g but u dont have to go that way if u do the double stoich way

  4. #4
    Senior Tuner Ben Charles's Avatar
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    Sometimes I have to double stoich and 50% scale

  5. #5
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    After reading comments and re reading that article- realized that article was about double air and not stoich ...oops so now three methods?Decided to try double stoich-half-half.
    Populated my tables with shipped data from injectors manufactor- fingers crossed- will try installing injectors tomorrow. hopefully wont be pushing car out of shop!
    all went great thus far
    I notice that the "short pulse adder" copied tables values changed slightly when pasted into tune- is this normal? The axis value on recieved data did have more decimal values then in the tune and even switching axis from ms to microseconds the values still changed slightly. The graph image on shipped data and the tuned generated one did look similar when both compared.
    Last edited by goodwrenchdave; 03-08-2020 at 04:44 AM.

  6. #6
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    Quote Originally Posted by Ben Charles View Post
    Sometimes I have to double stoich and 50% scale
    does it still work good doing both ? and does flex fuel still work ?

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    I had a similar issue. The program will automatically round in the spa values. Still worked

  8. #8
    Senior Tuner Ben Charles's Avatar
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    Still works just fine!

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    On Gen3 computer I simply reduce VE, make up the difference with PE values richer than commanded, and for the spark I use the table "afr advance" its right above the iat spark adjustments, it lets you define spark adder based on PE desired a/f ratio. So for example when I peg the spark table at 15* it it able to pull 4* (or whatever) of timing because I command a 1.3 boost enrichment which references the advance table.

    If you only needed 20 to 30% headroom and didnt want to scale 50% this is sort of like my bandaid. It seems like so few people know about that timing table.

  10. #10
    Senior Tuner Ben Charles's Avatar
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    Gen 3 has huge IFR limit at 256

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    Installed injectors. Wrote the new data- (double/hald/half). Since I'm more at home with a tech2-Plugged that in to monitor data.
    Started right up and seem to idle pretty darn well, smooth no misfires but as soon as o2 came online I noticed stft started removing fuel... let it run and seemed to stabilize around -21 but O2 still rich at 800 to 875 mv. so definitely still a little rich even with this much fuel removed. (not so much as to misfire). raised rpm to around 2000-2500 and monitored- same value (-21, 850mv) stabilized both stft and o2. let it run 10 minutes to see if it would set code but never did (needs more time i guess). stft still at -20ish reset fuel trims and repeat-same.

    Anyways- can i remove 10% (actually 5% as it is halved) across flow rate vs press table (as a start)? is this a proper way to lean out system? I realize -21 stft means it is taking 21% fuel but going 20% right of the bat seems a little radical.
    like i mentioned- everything else is stock and nothing changed except injectors for now so my flow tables likely wrong
    Last edited by goodwrenchdave; 03-10-2020 at 12:31 AM.

  12. #12
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    Quote Originally Posted by Ben Charles View Post
    Gen 3 has huge IFR limit at 256
    Oh, what the heck is IFR. Injector size limitation? I am new to hptuners but not to tuning in general. I am a bit confused what table is being maxed out on the Gen4 ecu I guess.

    Are you saying that Gen4 Ecu has an injector cap which puts a hard limit on the VE tables ability to add fuel?

    And if so, why can't one simply use the Power enrichment strategy to overcome that?

    I never tuned a gen4 yet, interesting to understand what is happening here.

  13. #13
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    Injector flow rate. On some of the early gen 4 ecm is has a limit of 63lb/hr. meaning you have to compensate for the flow if you have injectors bigger than that

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    Oh I am starting to remember this now. You can't just ignore the difference because the computer uses it for all kinds of other calculations.

    thanks I think i remember the issue now. And fudging it won't work if my memory serves because the values in some of those tables are very precise.
    I'll never forget that time it wanted right at .056g of fuel, not .052, and not .062, neither at 185*Fcts 99*Fiat would fire the engine quite the same
    Last edited by kingtal0n; 03-10-2020 at 10:03 PM.

  15. #15
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    I give up, what am i missing or is my injector data all wrong?
    g8davedoublehalfhalfrevisedminimums.hpt
    lasttestdrive.hpl
    GM_-_80lb.xlsx
    IMG_4390.jpg

    nothing done to a perfectly running stock g8 except injectors swap. i know the single sheet flow does not seem to exactly match the excel file.... HELP.

    i realize that these arent the best injectors on the market- but not the cheapest and seems like a lot of people are buying them (so cant be all that bad? ) they arent decapped and have a nice capped tip on them- also called "new"

  16. #16
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    Quote Originally Posted by goodwrenchdave View Post
    I give up, what am i missing or is my injector data all wrong?
    g8davedoublehalfhalfrevisedminimums.hpt
    lasttestdrive.hpl
    GM_-_80lb.xlsx
    IMG_4390.jpg

    nothing done to a perfectly running stock g8 except injectors swap. i know the single sheet flow does not seem to exactly match the excel file.... HELP.

    i realize that these arent the best injectors on the market- but not the cheapest and seems like a lot of people are buying them (so cant be all that bad? ) they arent decapped and have a nice capped tip on them- also called "new"
    ecm 33392 make all 1.0, ecm 12303 halve it, ecm 13344 disable it, also adjust cat temp so it wont get high enough to use it as i think disabling it then causes the dod not to work, see if that helps at all it may smooth things out a little, dont adjust the fueling using the IFR leave it to suit your injector scaling size, then adjust and fuel error with the maf and vve, even if your tune is dialled in 100% if u change injectors u will always have the re check the fueling as they are all a little different in there characteristics

  17. #17
    Advanced Tuner mbray01's Avatar
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    the problem is that you were given no data. that isnt what we look for with data. there are voltage offsets, pressure offsets, and calculations for when the injector is ramping open and closed. the rest is going to have to be figured out, or your going to have to bake the discrepancies into the airflow models. im not saying the injectors cant be used, but for a plug and play setup, they will never be right. To my knowledge, i have only ever seen one company that offered plug and play data, that when you input their data, the fuel trims stay with 1 or 2%. Thats injector dynamics. Ive never seen anybody else offer data, that you didnt have to create your own data, or fudge something somewhere else. with an aftermarket ecu, that data would be fine, just not gonna cut it with a factory ecu. your gonna have to do the legwork, and tune it from here
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  18. #18
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    Fuel injector clinic supplies the hptuners injector data

    https://fuelinjectorclinic.com/HPTUNERS0775

  19. #19
    Senior Tuner Ben Charles's Avatar
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    Just Bc companies supply it doesn’t mean it’s right...

    Email Tunes, PM me for more info
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  20. #20
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    Quote Originally Posted by Ben Charles View Post
    Just Bc companies supply it doesn’t mean it’s right...
    hah. Well. First I'd like to say I used their injectors and their data. And that you can't just pull those numbers out of thin air.


    Next I'd like to point out that how would somebody even know if the data was wrong?
    A natural discrepancy exists because the temperature and pressure of fuel both affect injector behavior, there is no way to create a 'perfect' injector data, all you can do is get close enough. close enough.


    I almost made this comment earlier. but hey now thats it come up- I could point out a couple things
    1. hptuners afaik(gen3) uses a VE map and not an injector on-time table, the difference in averages across a range of low injector duty would be very difficult to notice unless the on-time was significantly high or low (say more than 25% 'wrong') to raise or lower the VE in those low-duty regions enough to be able to tell something was wrong.
    For example if the VE seems to 'creep up' near idle region, it could mean that the injector on-time delay is too low for that low of a pulse width.

    SO what is the consequence? The VE table is a bit high in those low pulse regions. For any typical stand-alone this might be the only consequence. For hptuners? I don't know all the subtle intricacies that tie together various maps so I can't say for sure.
    But I do know that we have a minimum pulse table which should really help.

    2. Injector data is not that important for the majority of stand-alone systems. I've tuned at least 100 cars without any data. It only really matters for low speed (<1200rpm) situation where injector on-time is very low (below 2ms for example) and every little .0005 to .0008seconds counts. And if you are wayyy off in the data, it shows on the injector on-time map.

    3. large injectors are easy to find in their 'dead zones' by simply turning down the fuel pulse until the injectors have a fit(misfires near idle).
    Add a little back and there is your minimum- there is your data. Simply extrapolate low speed data and thats a very basic map technique.

    I think the injector data thing is way overblown and not very important for the majority of stand-alone systems.
    HPtuners is quite different in that many tables work together off of known variables from other tables, so many that I cannot even begin to understand the consequences of poor injector data. However, we are talking a descrepancy of .001~ seconds of fuel (1ms or so) which doesn't leave a very wide margin for making mistakes (error). In other words, if you 'try' some random numbers and 'see' any of the effects at the level of the VE table, you would know instantly to adjust the injector data within a very minimal margin of error (It won't be .002-.012ms, it will be .0001 to .0009ms, a much smaller target and easier to predict and hit that target).