Results 1 to 6 of 6

Thread: LD9 help and questions

  1. #1
    Potential Tuner
    Join Date
    Oct 2017
    Posts
    2

    LD9 help and questions

    Hi,

    New to HP tuners but not new to tuning.

    I am working on a ld9 cavalier with GM supercharger. Big injectors and other mods have me re-mapping it. I have a AEM wideband logging on the mvpi port.


    Questions:
    1. Is there any way to make an AFR ERR graph inside VCM scanner when this particular ecu does not have a AFR commanded table? Or am I limited to some post processing in excel?

    2. Does anyone know what makes fueling switch from "idle" table to the main fuel tables? Is it load and rpm or either? High rpm table seems to be a straight forward switch at 3800RPM regardless of load.

    3 Am i correct in saying that there is no Injector dead time vs voltage compensation? Also no tip in enrichment? Am I missing it?


    I appreciate any help

  2. #2
    Senior Tuner cobaltssoverbooster's Avatar
    Join Date
    Dec 2008
    Location
    Nevada
    Posts
    3,674
    it may not have an afr command but you know from standardized techniques back then that it will have only been programmable for gasoline which is stoich 14.69 afr.
    so use your wideband and make a custom histogram with this pid function.... {(14.69-wideband afr)/14.69}*100
    if you decide to target a different afr then change the 14.69 number to whatever afr value you are targeting. i usually made 2 histograms and filtered them by pe enable settings to keep them from reading when i wasn't supposed to be tuning the listed target afr for the pid selected.

    idle switch is based on voltage of tps iirc. for the most part the cells that overlap should be identical between the tables.

    and you are correct there is no enrichment rate settings in the pe of the cav ecu
    rdrfabrication@gmail.com
    2016 GMC 3500 Denali Diesel
    2000 Ford Mustang - Top Sportsman

    Ecotec help can be found here:
    LNF-http://www.hptuners.com/forum/showth...357-LNF-Guides
    LSJ-http://www.hptuners.com/forum/showth...965-LSJ-Guides

  3. #3
    Advanced Tuner Dr. Nopps's Avatar
    Join Date
    Jan 2011
    Location
    I'm proudly a successfull stalker of an honor roll student!
    Posts
    365
    Sorry to chime in so late, but for some help with question 1 and some of 2. 1.) There is only 1 table for commanded AFR, and it is for while in PE mode. There is also a PID for comanded AFR with this PCM/VCM which will read and log in the scanner. 2.) You should be able to force the fueling to follow that table if you set the TPS Enable % to 1% or even 0% , and are running in closed loop mode with no DTC's or faults present. You will then only enter PE at throttle greater than 1% even if you entered 0 in your table. You should then use a filter to exclude all data gathered outside of that AFR commandable window, (PE Mode).

  4. #4
    Potential Tuner
    Join Date
    Oct 2017
    Posts
    2
    Checking back almost a year later
    Maybe someone else will need these tips in the future if anyone still plays with these old LD9's.

    Idle table is active only when TPS =0
    Part load single and double is active any time TPS does not equal zero and rpm is 3799 or less
    High rpm table is active when tps is not zero and rpm is 3800 or greater


    Hptuners is lacking the following features for this ecu that makes tuning very challenging
    -No injector latency compensation
    -No accell enrichment adjustment
    -No o2 feedback settings
    -No cranking pulse adjustment
    -No warmup adjustments
    -With the car rolling and clutch in the ecu is not referencing the idle table. It is referencing something not defined so it idles pig rich until VSS=0 then it comes back to the idle table and idles properly.

    Even with so many lacking features it is possible to make a daily drivable, strong performing tune on some 750cc injectors.

  5. #5
    Senior Tuner cobaltssoverbooster's Avatar
    Join Date
    Dec 2008
    Location
    Nevada
    Posts
    3,674
    Yeah it's missing stuff buts an early injection computer. It's not going to have a lot. Super bare bones stuff when you run in alpha n

  6. #6
    Tuner in Training
    Join Date
    Jun 2008
    Posts
    19
    Quote Originally Posted by cobaltssoverbooster View Post
    Yeah it's missing stuff buts an early injection computer. It's not going to have a lot. Super bare bones stuff when you run in alpha n
    the gm reflash is a speed density 2 bar tune, not alpha n. just the cars without a reflash are alpha n.