Results 1 to 5 of 5

Thread: turbo 3800 lean

  1. #1
    Tuner in Training
    Join Date
    Feb 2019
    Location
    arizona
    Posts
    7

    turbo 3800 lean

    Im having a lot of issues with my tune.. first off, i cant for the life of me dial in the tune telling it the correct injector size which is 80lb/hr seimens deka. i have, instead entered in 54lb/hr. that number is there because its the only one i can get to work. The issue occuring is that i have my ve table basically maxed and am comanding a lot richer than i am getting. if i command for example 7.0 afr using power enrich vs rpm it ends up about 13.5 afr but the car is very slow.. i know this sounds like a bad wideband at this point but this is the third since this issue began. It actually runs out so lean itll completely shut off after a couple seconds under boost but fuel pressure remains perfect.

    My setup: 3800 series 2:kb pistons, hand ported heads, cx racing gt35 turbo, 3" exhaust fender exit, now aem wideband and glowshift narrowband sensors, aem inline fuel pump, seimens deka 80lb/hr injectors, "built" 4l60e

    The troubleshooting ive done: took all hard 90's out of the fuel system, ran all 3/8 hose from the tank to rails, fuel pressure gauge reading 45psi at idle and 60psi under 10psi of boost which to my understanding is perfect, cleaned injectors and checked spray patterns, they look perfect.. tried tuning the right way adding to ve table with no results..the only thing that i can see results from is commanding extremely rich though power enrich afr vs rpm.

    im open to any and all criticism, i want to learn how to tune the right way and i know some/many of my methods are not correct heres the tune file thats been the best so far. og2 first 54.hpt

  2. #2
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    The VE stops are 140kpa, why aren't you using a MAF?

    Never seen anyone run straight speed density on a 3800 computer before with any real luck.
    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
    Tuner in Training
    Join Date
    Feb 2019
    Location
    arizona
    Posts
    7
    I?ve heard that lots before and that?s why most people won?t help me, they say it?s impossible. I was up to 22psi running straight speed density before, I changed exhaust and a couple other things and now it?s giving me this problem. I?m not using maf simply because I know the stock maf won?t support this and I don?t want to have to wire in a card maf and make new tables. I have been playing with this for weeks though so if you believe switching to maf will fix it then I?ll try.. I just wish I knew what the problem was now

  4. #4
    Advanced Tuner ZeroBoostBuick's Avatar
    Join Date
    Aug 2008
    Location
    S.W. Ontario Canada
    Posts
    322
    Northstar maf kit from zzp.

    I think SLP used to sell a 85mm maf for the 3800 as well.
    Last edited by ZeroBoostBuick; 03-07-2020 at 03:16 AM.

  5. #5
    Advanced Tuner
    Join Date
    Feb 2015
    Location
    Perth, Australia
    Posts
    974
    your VE table is maxed because your IFR data is wrong. im assuming your fuel system is a dead head not boost referenced. if thats the case the enter stock IFR data, highlight entire table and repeatedly multiply by 1.02 until the 0KPA vac cell says your injector size.

    if it is boost referenced and has a return line your IFR table needs to be all the same number. 80. your description of fuel pressure suggests this is what it should be.

    once that is right you'll be able to dial in the VE with normal numbers.