Page 1 of 2 12 LastLast
Results 1 to 20 of 21

Thread: Building Initial Tune What?s First

  1. #1

    Building Initial Tune What?s First

    First time tuning, so please bare with me. Where do I start building an initial tune for a new 403 build? All I have to start with is a stock tune. Can someone break down the process of building a new tune for me? Like what area do you focus on first? VE/Idle/Spark.....Car will be SD tuned. Any help would be appreciated. Thanks

  2. #2
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    What's your parts list though?

    So far I can only tell you that you need to change the cylinder volume to match the 403 cubic inches and that you need to set the MAF fail high under the engine diag tab to 0hz and change the 3 MAF dtc's to MIL on first error for speed density. Uncheck the SES box.

    Also if you have no plans to add boost, see if your computer offers a speed density enhanced OS upgrade. If there is a upgrade in the OS tab, I would apply that OS upgrade so you gain back control over the high/low octane timing tables and depending on calibration it will remove the secondary VE table on 1999-2000 truck computers.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    It’s a LS2 based forged 403
    Ls3 cnc’d heads
    Fast 102 Lsxr and 102 throttle body
    Stock ls3 injectors
    Tooley 239/254 .624"/.595" 114+3
    11:1 compression pump gas motor
    It’s in a 98 Camaro. I know the 98 computer is not desired, but it’s what I have to work with at the moment.

  4. #4
    I’m running a Th400 behind it and the speedometer is not hooked up.

  5. #5
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Was it a automatic file to start with a manual file to start with?


    After the MAF fail and cylinder volume change a few more things can be done. Also see if you have a speed density OS upgrade available, be it a 1 bar or 2 bar. Either can work to be honest. I prefer to get rid of the secondary VE table on those older computers when I can.

    Setup your fuel pressure for 58psi. Input the injector data into the calibration. I'll see if I can attach the LS1 to LS3 excel spreadsheet for converting the data.

    Go through your list of DTC's and see what you are or aren't keeping. Like if it's a "racecar" you can set the EVAP stuff off, rear o2 sensors, cat codes etc etc, set them all to no error reported and no SES box.

    A wideband o2 sensor is a must here and you will need to get one into your data logs.

    I'm not sure what to say about adding for base running airflow and overall fueling with the VE because you are adding injector size and cubic inches so it's hard to guess at how much it may need or not need.

    Also in the spark timing tables, try to say the idle timing to around 18-20 degrees and there should be over/underspeed spark corrections tables in there too. You will want to reduce those values by maybe half or more so it can't swing the timing +/- 12-16 degrees.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  6. #6
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Here.
    Attached Files Attached Files
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  7. #7
    Thanks for the help. The stock tune is for a M6. I have the mpvi2. Is there a way to hook up the wide band o2 with the mpvi2? I don’t have the pro version.

  8. #8
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Yes.

    Look up the wideband through the EGR circuit on the web, this forum and youtube video's. It's one of the most common ways to log it other than the pro version or an analog input.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  9. #9
    Ok, I got the car to crank and idle with no surge by doing everything you mentioned above, plus messing with the secondary ve table in the idle areas. From what I read, the car is running on the secondary ve table when in open loop speed density correct? Plus there is not as many columns and rows in the sec ve table. I guess that’s why you was saying do the OS upgrade. I’ll check into that and also get the wideband o2 hooked up and go from there.

  10. #10
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Yeah, if an OS upgrade is available is may be worth while to use it.

    It would remove the sec VE table and give you just one primary table that matches the stock one or if only a 2 bar table was there it just gives you one giant VE table all the way to 210kpa. Being a NA engine, you'd only use half of it but that is fine. Those upgrades do change the MAP sensor settings on you as well for 2 bar's, you can just switch the data back to 1 bar and be on your way.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  11. #11
    It’s a nitrous motor. I have the option for 2 bar.

  12. #12
    Nitrous is direct port, and will be on a stand alone fuel setup

  13. #13
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    The 2 bar OS should still work just fine if you want to use it. If you want the sec VE gone and normal working spark tables in speed density, I'd give it a go.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  14. #14
    Is there a way to turn of the stft? Mine is still trying to correct when I scan.

  15. #15
    98 computer doesn’t have the disable stft option.... but I was able to disable the stft by increasing the ECT vs IAT Closed loop enable tab to 250 F. Now stft and Ltft are both disabled. Time to get a wideband o2.
    Last edited by Jgarretts86; 04-05-2020 at 05:09 PM.

  16. #16
    Ok... I’m getting the VE table dialed in pretty good so far below 4000rpm. Got it within +\~3%. Cranks up and idles good, and returns to idle pretty good when you blurp the throttle. Problem I’m having now is a pretty bad what I would call misfire from when you take off up to about 3500rpm then it seems to clear up. I’m running on a stock 98 spark tune that I added a couple degrees to down low for the idle. Other than that it’s a stock spark tune. High and low octane tables are the same. Once again the car is open loop SD tuned. What do I need to scan/log to see where the misfire is coming from? Or could this still be fuel related? The VE is dialed in in the MAP/Rpm ranges that the miss is happening.

  17. #17
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Does your wideband go really lean or rich when this happens?

    That could let you know if it's a misfire or a lean condition.

    You should be able to log misfires for each cylinder too.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  18. #18
    It doesn’t go lean or rich. I will log for misfires the next time I log it. Would that be “Current Misfire” that I want to log?

  19. #19
    Ok I guess I can’t log misfires running open loop SD. Car has no maf.... that sucks.

  20. #20
    Also have a very noticeable hesitation right off idle.